CONTENTS
About

・・・2

Committee

・・・3Sponsors

・・・4

Scientific program

・・・6

Abstracts
Review lectures

・・・11

Progress reports

・・・18

Selected talks

・・・34

Poster A

・・・60

Poster B

・・・135

Author index

・・・213

1

ABOUT
HCI 2022 is the 20th in a series of International Conferenceson the Physics of Highly Charged Ions. The conference
covers the following topics on highly charged ions:
Fundamental

aspects;

StructureandSpectroscopy;

Collisions with Electrons, Ions, Atoms and Molecules;
Interactions with Clusters, Surfaces and Solids; Interactions
with Photons, Plasmas and Strong Field Processes;
Production, Experimental developments and Applications.
IUPAP financially supports HCI2020. The organizers haveassured that the conference is conducted per IUPAP Policies
on Conferences, including Free Circulation of Scientists,
Limited Conference Fees, Participation of women, andHarassment.
This conference is planned to be held in 2020. But, due to thepandemic of COVID-19, it has been postponed for two years
and must have a hybrid style, namely a mixture of onsite andonline participants.

2

COMMITTEEINTERNATIONAL ADVISORY BOARD
F. Aumayr (Austria)

N. Nakamura (Japan)

T. Azuma (Japan)

M. Pajek (Poland)

P. Beiersdorfer (USA)

R. Rivarola (Argentina)

M. Benis (Greece)

M. Safronova (USA)A. Bräuning-Demian (Germany)J. P. Santos (Portugal)

J. Burgdörfer (Austria)

R. Schuch (Sweden)

A. Cassimi (France)

V. Shabaev (Russia)

J. R. Crespo López-Urrutia

E. Sokell (Ireland)(Germany)

T. Stöhlker (Germany)

M. S. Gravielle (Argentina)

J. Tanis (USA)R. Hoekstra (The Netherlands)

K. Tökési (Hungary)J. Hoszowska (Switzerland)

M. Trassinelli (France)

R. Hutton (China)

L. Tribedi (India)

C. Illescas (Spain)

K. Yao (China)

X. Ma (China)

H. Zettergren (Sweden)

LOCAL ORGANIZING COMMITTEE
Hajime Tanuma (Chair, TMU)

Takuya Majima (Kyoto)

Nobuyuki Nakamura (Co-Chair, UEC)

Izumi Murakami (NIFS)

Toshiyuki Azuma (RIKEN)

Yuji Nakano (Rikkyo)

Natsuko Fujita (JAEA)

Takuma Okumura (TMU)

Takato Hirayama (Rikkyo)

Hiroyuki A. Sakaue (NIFS)

Daiji Kato (NIFS)

Tomoko Ohyama-Yamaguchi (TMCIT)

Naoki Kimura (RIKEN)

3

SPONSORSThe Murata Science Foundation

4

5

SCIENTIFIC PROGRAM
Day1: Aug 29th (Mon)
Opening

9:10
9:30

RL-1

10:15

ST-1

10:35

Coffee

11:05

PR-1

11:35

PR-2

12:05

ST-2

Kyoko Matsushita
X-ray observations of cosmic plasmas
Yang YangFirst Laboratory Verification of Magnetic-field-induced Transition
Effect in Fe X
Jyoti Rajput
Addressing Molecular Dissociation using Ion Impact
Alba Jorge
On the importance of dynamical screening in mean-fieldcalculations involvingmany-electron systems
Lokesh C Tribedi
First observation of giant quadrupole plasmon resonance in C60 inhigh perturbation HCI collisions
Lunch

12:25
14:00

PR-3

14:30

ST-3

14:50

ST-4

15:10

ST-5

Zhimin Hu
Relativistic effects on radiative properties and electronic
collisions of highlycharged heavy ions
Naoki Kimura
Lifetime measurement of the microsecond-order electricquadrupole transition: Application of plasma-assisted laser
spectroscopy
Endre Takacs
Analysis of E3 transitions in Ag-like high-Z ions observed with the
NIST EBIT
Sophia Strnat
Elastic x-ray scattering by highly charged ions
Coffee

15:30
16:00

PR-4

16:30

PR-5

Anna Niggas
Charge exchange dynamics of highly charged ions with atomicallythin materials
Lucia Skopinski
Particle emission from 2d materials induced by highly charged ion
impact6

17:00
17:20

ST-6
ST-7

David Scott La Mantia
Radiative Double-Electron Capture by Highly-stripped Ions on
Graphene
Pierre-Michel HillenbrandExperimental Studies of Nonperturbative Dynamics in Heavy-IonAtom Collisions

Day2: Aug 30th (Tue)
9:00

RL-2

9:45

ST-8

10:05

ST-9

10:25

ST-10

Oscar Versolato
Highly charged ions in laser-produced plasma
for state-of-the-art EUV nanolithography
Takeshi Higashiguchi
Charge-separated ion spectra from a laser-produced plasma
Emma Sokell
High resolution imaging of laser plasmas revealing the effects oflaser spot size on plasma emission.
Chunhai Lyu
Inferring the coherence time of EUV pulse trains via spectroscopyof highly charged ions
Coffee

10:45
11:15

PR-6

11:45

PR-7

12:15

ST-11

Baoren Wei
Hydrogen migration in the fragmentation of hydrocarbon dications
Patrick Rousseau
Charge migration in betaine by impact of fast atomic ions
Jatin Yadav
Hydrogen migration in three body fragmentation of acetylene
trication

Lunch

12:35
14:30

RL-3

15:15

ST-12

15:35

ST-13

Klaus Blaum
Precision Measurements of Fundamental Atomic Properties using
Highly Charged Ions in Penning Traps
Jost Herkenhoff
Sympathetic cooling of highly charged ions in a Penning trap using
a self-cooled electron plasma
Kathrin Kromer
Direct high precision measurement of the Q-value of the electron
capture in 163Ho and metastable states in highly charged ions
Break

15:55
17:00
20:00

Poster session
Virtual A

7

Day3: Aug 31st (Wed)
9:00

Poster session
Virtual B

12:00

Lunch

12:00
14:30

RL-4

15:15

ST-14

15:35

ST-15

Piet O. Schmidt
An Optical Atomic Clock Based on a Highly Charged Ion
Christian Warnecke
A superconducting quadrupole resonator for laser-spectroscopyof highly charged ions at highest precision
Elwin A. Dijck
Dynamics of mixed species Coulomb crystals with highly charged
ions in a superconducting Paul trap
Coffee

16:25

PR-8

16:55

ST-16

17:15

ST-17

17:35

ST-18

Michael Lestinsky
First experiments with the CRYRING@ESR
Leonard IsbernerFirst Dielectronic Recombination Measurements at the Cryogenic
Storage Ring
Philip Pfafflein
High-Resolution X-Ray Spectroscopy of He-like Uranium using
Novel Microcalorimeter Detectors
Robert Loetzsch
High resolution measurement of the 2p3/2→2s1/2 intra-shelltransition in He-like uranium

Day4: Sep 1st (Thu)
9:00

RL-5

9:45

PR-9

10:15

PR-10

Marianna S. Safronova
Search for new physics with highly charged ions
Julian C. Berengut
New physics searches with highly charged ion clocks
Anastasia Borschevsky
High accuracy theoretical investigations of highly charged ions
Coffee

10:45
11:10

ST-19

11:30

ST-20

Priti
5p-5s spectrum in highly charged W XII – W XIV Ions
Xiaobin Ding
Collisional-radiative model for the spectra of M1 transition of W53+
ion

8

11:50

ST-21

12:10

ST-22

Hanbing Wang
Laser cooling of relativistic O5+ ions at CSRe: experiment andsimulation
Ken Lukas Ueberholz
First broadband laser cooling and XUV fluorescence detection of
stored relativistic HCI
Excursion+
BanquetDay5: Sep 2nd (Fri)
9:00

PR-11

9:30

PR-12

Wania Wolff
Aromatic molecules revisited under bare helium collision:
experiment and theory
Shuncheng Yan
Fragmentation of the Heteronuclear Cluster by Electron Impact

Coffee

10:00
10:30

Poster session
Onsite

12:30

Lunch

12:30
14:30

RL-6

15:15

PR-13

15:45

PR-14

16:15

ST-23

Jimmy Rangama
Ion interaction with atomic and molecular dimers: a new way oflooking at atoms and molecules
Natalia S. Oreshkina
Theoretical predictions of the structure of heavy muonic atoms
Shinji Okada
Muonic atom X-ray spectroscopy for QED test in strong Coulomb
field
Takuma Okumura
High-resolution spectroscopy of electronic K x rays from muonicatoms
Coffee

16:35
17:05

PR-15

17:35

ST-24

Sonja Bernitt
Resonant photoexcitation of trapped ions for x-ray astrophysics
Adam Hosier
Absolute nuclear radius of iridium from precision measurements
and calculations of EUV and X-ray transitions in highly chargedions9

17:55

ST-25

Phillip Imgram
Laser Spectroscopy of 12C4+: First results towards an all-opticalcharge radius determination

18:15

Summary

Day6: Sep 3rd (Sat)
9:00
Networking
12:30
adjourn

10

REVIEW LECTURES

11

RL-1
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12

RL-2
Highly charged ions in laser-produced plasma
for state-of-the-art EUV nanolithography
Oscar Versolato
Advanced Research Center for Nanolithography (ARCNL),
Science Park 106, 1098XG, Amsterdam, The Netherlands
Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit Amsterdam,
De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
Highly charged tin ions play a key role in the continued miniaturization of semiconductor devices.
Laser-produced plasmas containing such ions produce the extreme ultraviolet (EUV) light that isused in state-of-the-art nanolithography. The short wavelength EUV light, at 13.5nm, enables“printing” the smallest features. The EUV light originates from ¨n=0, n=4–n=4 electronically
excited states in Sn11+–Sn14+ populated through electron impact in the hot and dense plasma [1]. In
the tin system, the exponentially decreasing probability of excitation into multiply excited states isoffset by the near-exponentially increasing density of states, resulting in a particularly prominentcontribution of multiply excited states to the total opacity – and emission of EUV light [2,3]. Thissurprising finding underlines the importance of understanding the spectrum of tin highly charged
ions in detail [4]. In this presentation I will introduce the field of EUV nanolithography and explain
the role of tin plasmas in it, as produced through a series of carefully tailored laser pulses from tin
microdroplets. As I will explain, the research performed at ARCNL on the physics of EUV-emitting
laser-produced plasma ranges from advanced laser development, over studies of fluid dynamic
response of droplets to impact, and radiation-hydrodynamics calculations of, e.g., ion “debris”, to(EUV) spectroscopic studies of tin, in laser-produced plasma and, in collaboration with MPIK in
EBIT plasma. Together, we will seek to answer the question: what really emits that EUV light?

Figure 1: Spectral intensity map of Sn ions trapped in an EBIT [4].
References[1] O.O. Versolato, J. Opt. 24, 054014 (2022)[2] F. Torretti, et al., Nature Comm. 11, 2334 (2020)[3] J. Sheil, et al., J. Phys. B 54, 035002 (2021)[4] J. Scheers, et al., Phys. Rev. A 101, 062511 (2020)

13

RL-3
Precision Measurements of Fundamental Atomic Properties using Highly
Charged Ions in Penning Traps
Klaus Blaum
Max-Planck-Institut für Kernphysik, Heidelberg, Germany

An overview is given on recent mass and g-factor measurements with extreme precision on single
highly charged ions stored in Penning traps. On the one hand, mass measurements provide crucial
information for atomic, nuclear and neutrino physics as well as for testing fundamental interactions
and their symmetries. On the other hand, g-factor measurements of the bound electron in highly
charged hydrogen like ions allow for the determination of fundamental constants and forconstraining Quantum Electrodynamics. The most recent results will be presented and their impact
discussed.

14

RL-4
An Optical Atomic Clock Based on a Highly Charged Ion
Piet O. Schmidt
Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
Institut für Quantenoptik, Leibniz Universität Hannover, Germany.

Optical atomic clocks are the most precise and accurate measurement devices ever constructed,
reaching fractional systematic uncertainties below one part in 1018 [1]. Their exceptional
performance opens up a wide range of applications in fundamental science and technology. The
extreme properties of highly charged ions (HCI) make them highly sensitive probes for tests offundamental physical theories [2, 3]. Furthermore, these properties make them significantly lesssensitive to some of the leading systematic perturbations that affect state-of-the-art optical clocks,
making them exciting candidates for next-generation clocks [4, 2]. The technical challenges thathindered the development of such clocks have now all been overcome, starting with their extraction
from a hot plasma and sympathetic cooling in a linear Paul trap [5], readout of their internal state
via quantum logic spectroscopy [6], and finally the preparation of the HCI in the ground state of
motion of the trap [7], which allows levels of measurement accuracy to be reached that werepreviously limited to singly-charged and neutral atoms. Here, we present the first operation of an
atomic clock based on an HCI (Ar13+ in our case) and a full evaluation of systematic frequency
shifts [8]. The achieved uncertainty is almost eight orders of magnitude lower than any previous
frequency measurements using HCI. Measurements of some key atomic parameters confirm thetheoretical predictions of the favorable properties of HCIs for use in clocks. The comparison to the171
Yb+ E3 optical clock [9] places the frequency of this transition among the most accurately
measured of all time. Furthermore, by comparing the isotope shift between 36Ar13+ and 40Ar13+ toimproved atomic structure calculations, we were able for the first time to resolve the largely
unexplored QED nuclear recoil effects. Finally, prospects for 5th force tests based on isotope shift
spectroscopy of Ca+/Ca14+ isotopes and the high-sensitivity search for a variation of the finestructure constant using HCI will be presented. This demonstrates the suitability of HCI asreferences for high-accuracy optical clocks and to probe for physics beyond the standard model.
References[1] Brewer, S. M. et al., Phys. Rev. Lett. 123, 033201 (2019).
[2] Kozlov, M. G. et al., Rev. Mod. Phys. 90, 045005 (2018).
[3] Safronova, M. S. et al., Rev. Mod. Phys. 90, 025008 (2018).
[4] Schiller, S., Phys. Rev. Lett. 98, 180801 (2007).
[5] Schmöger, L. et al., Science 347, 1233–1236 (2015).
[6] Micke, P. et al., Nature 578, 60–65 (2020).
[7] King, S. A. et al., Phys. Rev. X 11, 041049 (2021).
[8] King, S. A. et al., http://arxiv.org/abs/2205.13053.
[9] Lange, R. et al., Phys. Rev. Lett. 126, 011102 (2021).

15

RL-5

Search for new physics with highly charged ions
Marianna S. Safronova
Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
The development of atomic clocks with systematic uncertainties in the 10-18 range enabled searches
for “new physics” beyond the Standard Model (BSM) of elementary particles and interactions [1].
Highly charged ions (HCIs) in different charge states offer narrow optical transitions that are among
the most sensitive to the BSM effects [2]. Recent experimental advances in trapping, sympathetic
cooling, and quantum logic techniques with HCIs enabled a demonstration of an optical clock basedon a transition in Ar13+ with comprehensively evaluated systematic frequency uncertainty of
2.2×10−17 [3], comparable to that of many optical clocks in operation.
I will give an overview of the application of highly charged ions to search for BSM physics,
including searches for dark matter, variation of fundamental constants, violation of the local
Lorentz invariance, and exotic forces. Proposals with clocks based on Cf15+ and Cf17+ [4,5] will be
described in more detail.
I will also discuss recent theoretical developments in predicting properties of highly charged ions,with application to predicting properties of systems with many valence electrons. The new parallelversion of the configuration interaction code was developed [6] and run on up to 2000 CPUs,
allowing the treatment of more complicated systems. Applications to solving a long-standing puzzle
in astrophysics in Fe16+ [7] and predicting rates of electronic bridge excitation of the nuclear
transition in Th35+ [8] will be reported. Finally, I will discuss a release of the new version of an
online portal for high-precision atomic data and computation [9] and future plans to add data for
more systems and release computer codes.
References[1] M. S. Safronova, D. Budker, D. DeMille, Derek F. Jackson-Kimball, A. Derevianko, andCharles W. Clark, Rev. Mod. Phys. 90, 025008 (2018).
[2] M. G. Kozlov, M. S. Safronova, J. R. Crespo López-Urrutia, P. O. Schmidt, Rev. Mod. Phys. 90,
45005 (2018).
[3] Steven A. King et al., arXiv:2205.13053 (2022).
[4] S. G. Porsev, U. I. Safronova, M. S. Safronova, P. O. Schmidt, A. I. Bondarev, M. G. Kozlov, I.
I. Tupitsyn, Phys. Rev. A 102, 012802 (2020).
[5] Measuring the stability of fundamental constants with a network of clocks, G. Barontini et al.,
EPJ Quantum Technology 9, 12 (2022).
[6] C. Cheung, M. S. Safronova, S. G. Porsev, Symmetry 13 (4), 621 (2021).
[7] Steffen Kühn et al., arXiv:2201.09070, submitted to Phys. Rev. Lett. (2022).
[8] S. G. Porsev, C. Cheung and M. S. Safronova, Quantum Sci. Technol. 6, 034014 (2021).
[9] Parinaz Barakhshan, Adam Marrs, Akshay Bhosale, Bindiya Arora, Rudolf Eigenmann,
Marianna S. Safronova, Portal for High-Precision Atomic Data and Computation (version 2.0).
University of Delaware, Newark, DE, USA. URL: https://www.udel.edu/atom (2022).

16

RL-6
Ion interaction with atomic and molecular dimers: a new way of looking at
atoms and molecules
Jimmy Rangama
CIMAP, CEA/CNRS/ENSICAEN/UNICAEN, BP5133, F-14050 Caen Cedex 04, France

Investigating reactions involving highly charged ions (HCI) and atomic/molecular dimers became achallenging subject in collision physics since the two last decades. However, intramolecular charge
redistribution before dissociation usually limits the access to the primary process detailed
information, as the identification of the active atomic/molecular site [1] in the dimer is lost. Raregas dimers are linked by van der Waals bonds which are much weaker than ionic or covalent bonds
and are associated to larger internuclear/intermolecular distance. What should we expect for such
weakly bound systems, made of two nearly independent atoms/molecules, when excited by impact
of charged particles such as HCI [2]? How the low electron mobility between the two sites of the
dimer target can allow to investigate primary process? To answer these questions, we performedexperiments by using the so-called recoil-ion momentum spectroscopy technique to obtainkinematically complete measurements. Differences observed in the collision dynamics and thesubsequent fragmentation for van der Waals bound targets when compared to covalent boundtargets will be presented and discussed as well as recent results about relaxation processes in thesecollisional systems [3-5].

References[1] W. Iskandar et al, Phys. Rev. Lett. 113, 143241 (2014)[2] W. Iskandar et al, Phys. Rev. Lett. 114, 033201 (2015)[3] A. Méry et al, Phys. Rev. Lett. 118, 233402 (2017)[4] Schulz, Michael. Ion-Atom Collisions: The Few-Body Problem in Dynamic Systems, Berlin,
Boston: De Gruyter (2019). p213-240.
[5] A. Méry et al, Phys. Rev. A 104, 042813 (2021)

17

PROGRESSREPORTS18

PR-1
Addressing Molecular Dissociation using Ion Impact
Jyoti Rajput
Department of Physics and Astrophysics, University of Delhi, Delhi, INDIA
Initiating molecular dissociation by impact of energetic ions presents a case of impulsive excitationof a molecular system. Using such an excitation, a wide range of processes can be studied, postinteraction, by measuring (i) the projectile parameters like charge state and momentum transfer (ii)momentum, energy and/or angular distribution of recoil fragments (iii) momentum, energy and/or
angular distribution of emitted electrons, if any. In its interaction with a molecular target, an energetic ion removes electrons either by electron capture or by ionization or by both. The charge stateand velocity of the energetic ions are tunable parameters and thus allows for exploring the effect ofinteraction strength and interaction time-scales.
In the present talk, few results from our recent experiments on ion-impact induced molecular dissociation will be discussed. In all these experiments a recoil ion momentum spectrometer was used tomeasure the momenta of all fragments (in coincidence) generated during the ion-molecule collision
process. The study on ion impact dissociation of methane (CH4 ) led us to realise that though the
dication of this simple and important molecule have been studied in several ways, yet even the understanding of energetics of this system is far from complete. We reported on observation of threepathways in the kinetic energy release distribution of breakup of [CH4 ]2+ into (H + + CH3+ ) [1].
Two of the pathways have been explained with the help of existing literature but one still remains
unexplained.
Using the analysis method of “native frames” [2], we have proposed a new technique for measuring
the subrotational lifetime of molecular ions [3] which are formed as intermediary species in sequential
breakup of small multiply charged molecules. The proof of principle is given by measuring the
lifetime of SO2+ which is formed as an intermediate in the sequential breakup of SO23+ leading todetection of (O+ , O+ , S + ) as the final set of fragments.
Hydrogen migration and/or bond rearrangement is a phenomenon which has been reported to occur
in the singly and doubly charged species of several small molecules like CH4 , C2 H2 , CH3 OH. The
acetylene (C2 H2 ) molecule is a prototype for studying hydrogen migration on account of being thesmallest molecule having two H atoms which are not attached to the same C atom. Hydrogen migration in this prototype has been studied in a wide range of experiments and the process is reported
to occur on the electronic states of either the monocation or dication of acetylene molecule. From
our experiment and by using the analysis method of “native frames” [2] we have provided the firstexperimental evidence of Hydrogen migration occurring in the tri-cation of this prototype molecule[4].
References[1] J. Rajput, D. Garg, A Cassimi et al. J. Chem. Phys. 156, 154301 (2022)[2] J. Rajput, T. Severt, B. Berry et al. Phys. Rev. Lett. 120, 103001 (2018)[3] J. Rajput, H. Kumar, P. Bhatt and C. P. Safvan, Sci. Rep. 10, 20301 (2020)[4] J. Yadav, C. P. Safvan, P. Bhatt et al. J. Chem. Phys. 156, 141101 (2022)

19

PR-2
On the importance of dynamical screening in mean-field calculations involving
many-electron systems
Alba Jorge
Departamento de Química, Universidad Autónoma de Madrid, Madrid, 28049, Spain
Through the study of ion-atom and ion-molecules collisions, with multielectronic targets and in therange of impact energy of 0.1-100 MeV/u, the treatment under a time-dependent potential thatconsiders the change of the electronic cloud of both the projectile and the target molecule during the
dynamics, is studied. The dynamic screening [1] model allows us to study the importance of thechanges of potentials during the collision in processes such as the electron detachment.
Targets such as Ne, H2O and NH3 and projectile’s charges from 1 to 13 will be considred. A notablechange in the absolute double differential cross sections (DDCS) and single differential crosssections (SDCS) is found when considering a dynamic screening, specially in the the forwardbackward asymmetry, for multielectronic targets, medium charged projectiles and high impact
energies. For low impact energies (250 keV) and a low charged projectile (proton), where theelectron loss of the molecule is much lower, the dynamic screening and non-dynamic screening
versions show little differences.
A detailed insight in the model and a deeper comparison with experiments will be presented at theconference.

Figure 1: •: Measurements [4, 5]. CTMC results for different impact energies and projectiles
colliding on the water molecule are shown as solid black and green dotted lines, with static and with
time-dependent screening, respectively.
References[1] Kirchner, T. et al 2000 Physical Review A 62, 042704[2] Jorge, A. et al 2019 Physical Review A 99 062701[3] Illescas, C. et al 2011 Physical Review A 83 052704[4] Bhattacharjee, S. et al 2018 Eur. Phys. J. D 72, 15 (2018)[5] Bhogale, A. et al (to be published)

20

PR-3
Relativistic effects on radiative properties and electronic collisions of highly
charged heavy ionsZhimin Hu, Xiang Gao*, Ke Yao§, Chensheng Wu*, Naoki Numadate†, Yulong Ma*, Yong Wu*,
Baoren Wei§, Yaming Zou§, and Nobuyuki Nakamura†
Key Laboratory of Radiation Physics and Technology (MOE), Sichuan University, Chengdu 610064,
China*Institute for Applied Physics and Computational Mathematics, Beijing 100088, China§Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Fudan University, Shanghai
200433, China†Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, JapanThe relativistic and quantum electrodynamics (QED) effects in electron–electron interaction can be
described by the Breit interaction, which was first introduced to precisely describe the energy levelsof neutral He by G. Breit around 1930 [1]. In contrast to the minor contribution to atomic structrue,it has been found that the Breit interaction can have a significant contribution to collision processesof highly charged heavy ions with electrons, such as dielectronic recombination [2, 3], electronimpact ionization [4], electron-impact excitation [5], and resonant transfer and excitation [6]. The
unexpectedly large or even dominant contribution in the electronic collisions is attributed to that theBreit term plays an important role in the electron-electron interaction operator [7].
On the other hand, the Breit interaction can hardly be expected to have a significant contribution toradiative transition probabilities. The transition rate is determined by the transition frequency ! andthe transition matrix element hb| ô |ai, where ô represents the operator for the radiative transition.
The Breit interaction has no contribution to the operator ô and only a small contribution to ! andthe wavefunctions of |ai and |bi. Consequently, transition rates are expected to be less affectedby the Breit interaction. In stark contrast to the previous studies, we predicted an unprecedentedly
giant modification by the Breit interaction for electric dipole allowed transitions from the strongly
correlated 1s2s2 2p2 inner shell excited state of B-like heavy ions [8], and it has been experimentallydemonstrated with the electron beam ion traps in Shanghai and Tokyo. We elucidate the underlying
mechanism is due to the drastic change in the wavefunctions of the 1s2s2 2p2 state resulting from therelativistic electron correlation effect appeared as a Breit-interaction-induced avoided crossing [9].
References[1] G. Breit, Phys. Rev. 36, 383 (1930)[2] N. Nakamura, A. P. Kavanagh, H. Watanabe et al., Phys. Rev. Lett. 100, 073203 (2008).
[3] Z. Hu, X. Han, Y. Li, D. Kato, X. Tong, and N. Nakamura, Phys. Rev. Lett. 108, 073002 (2012).
[4] R. E. Marrs, S. R. Elliott, and D. A. Knapp, Phys. Rev. Lett. 72, 4082 (1994)[5] A. Gumberidze, D. B. Thorn, C. J. Fontes et al., Phys. Rev. Lett. 110, 213201 (2013)[6] X. Ma, P. H. Mokler, F. Bosch, A. Gumberidze et al., Phys. Rev. A 68, 042712 (2003)[7] X. Tong, Z. Hu, Y. Li, X. Han et al., J. Phys. B 48, 144002 (2015)[8] C. Wu, L. Xie, Z. Hu, and X. Gao, J. Quant. Spectr. Rad. Transfer 246, 106912 (2020).
[9] Z. Hu, G. Xiong, Z. He, Z. Yang et al., Phys. Rev. A 105, L030801 (2022)

21

PR-4
Charge exchange dynamics of highly charged ionswith atomically thin materials
A. Niggas, M. Werl, F. Aumayr, and R.A. Wilhelm
TU Wien, Institute of Applied Physics, 1040 Vienna, Austria
Upon impact on a material surface, slow highly charged ions deposit up to several tens of keV of theirpotential energy within a material. This leads to an excitation of the material’s electronic system andcan result in material modification (nanostructuring) as well as emission of secondary particles, e.g.
electrons. The emission of electrons due to impact of slow highly charged ions has been studied extensively in the past for several bulk materials [1]. There, however, the resulting electron yield comprises
not only primary electrons emitted by the impinging ion, but also higher-generation electrons fromsub-surface multiplication effects. Using free-standing two-dimensional materials as a target allows
to exclude the latter and thus enables us to study the true ion-induced primary electron emission.
In our experiment, we irradiate monolayers of graphene with highly charged xenon ions and detectcorrelated pairs of emitted electrons (energy, yield) and transmitted ions (charge exchange, scattering
angle, energy loss). Thereby, we are able to distinguish ions transmitted through the atomicallythin layer from ions transmitted through the support structure in order to analyse solely the electron
emission from the 2D material.
Figure 1 shows the electron energy distribution from single-layer graphene (red circles) induced by
impact of 142 keV Xe15+ ions. A bimodal distribution can be observed with peaks at ⇠ 2 eV and⇠ 10 eV. For comparison, we did similar (non-coincident) measurements with highly oriented pyrolitic graphite (HOPG, orange line) which agrees well with the data points achieved from graphene.
To entangle the origin of these distributions we apply de-excitation cascade calculations of highly
charged ions that take into account Auger de-excitation and radiative decay [2].

Figure 1: Electron energy distribution of electrons emitted due to impact of 142 keV Xe15+ ions on
single-layer graphene (red circles) and HOPG (orange line).

References[1] HP. Winter and F. Aumayr, J. Phys. B 32 R39 (1999)[2] K.Tökesi et al., Phys. Rev. A 64 042902 (2001)

22

PR-5
Particle emission from 2d materials induced by highly charged ion impact
L. Skopinski, P. Ernst, L. Breuer, M. Schleberger
Fakultät für Physik and CENIDE, Universität Duisburg-Essen, 47057 Duisburg, Germany
Two-dimensional (2d) materials such as graphene or transition metal dichalcogenides are expected to
be key for novel applications and defect engineering by highly charged ion (HCI) beams could be a
way to modify their unique properties even further.
An ion stores its energy in the form of the kinetic energy Ekin and the so-called potential energy
Epot , the latter corresponding to the energy required to create its respective charge state. Once the ion
impinges on the surface its energy is deposited into the solid and can lead to sputtering. However, thefundamental mechanisms of defect formation due to HCIs are still under investigation.
Here we report on HCI induced damage of supported single layer MoS2 . We used Au substrates
to minimize potential sputtering of the substrate and analyzed the emission of secondary ions andatoms under irradiation. Using laser-assisted time of flight (ToF) mass spectrometry the mass spectra
25

Ekin = 5 keV
98

3

28+
33+
37+
40+

area II

2
1

area I
area II
linear fit of area I
Kozubek et al. Ref [1]20

Mo-SNMSarea I

yield [arb. u.]

signal per HCI [arb. u.]

4

0

15
10
5
0

0

2

4

0

6

5

10

15

20

25

30

35

40

extraction delay [µs]

Epot [keV](a) Extraction delay measurements determined with a ToF
mass spectrometer of emitted particles due to Xeq+ impact.

(b) Yield of particles emitted in area I and area II depending on the potential energy of the projectile.

Figure 1: Analysis of emitted neutral 98 Mo particles sputtered by HCI impact from an 2d MoS2
sample supported on an Au substrate. Evaluation of area I and II from (a) in (b).
are detected with different extraction delays allowing the transformation into a velocity or energy
distribution. [2] In Fig. 1a the signal dependence on the extraction delays is shown. The measured
distributions have at least two contributions around 0.83 µs and 1.75 µs each. While the first one,assigned to kinetic sputtering, increases only slightly the later contribution in area II increases strongly
with the potential energy and is therefore considered to be caused by potential sputtering (Fig. 1b).
The potential sputtering of the substrate supported MoS2 has a similar dependence on the potential
energy as the pore formation found in freestanding MoS2 after irradiation with HCIs.[1]References[1] R. Kozubek et al. J. Phys. Chem. Lett. 10, 904-910 (2019)[2] L. Skopinski et al. Rev. Sci. Instrum. 92, 023909 (2021)

23

PR-6
Hydrogen migration in the fragmentation of hydrocarbon dications
Yu Zhang1,2, Chuanlu Yang3, Long Wei1, Baihui Ren1, Roger Hutton1, Yaming Zou1 and Baoren
Wei1*
2

1
Institute of Modern Physics, Fudan University, Shanghai 200433, China
School of Mathematics &Physics and Information Engineering, Jiaxing University, jiaxing 314001,
China
3
School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China*
brwei@fudan.edu.cn

Proton migration of hydrocarbon molecules plays a vital role in the chemical reactions
concerning, e.g., combustion and interstellar media, which can significantly change themolec lep ope ie and he l in bond ea angemen and/o i ome i a ion p oce e .

Different from the most of previous studies using the light to generate and steer the proton
migration channels, the present study reports the dynamics of corresponding channels intypical hydrocarbon molecules, i.e. CH4, C2H2, C2H4 and C2H6, observed on the 150 kVhighly charged ion collision platform at Fudan University in Shanghai [1-5].
Formation mechanism of H3+ ions from doubly charged hydrocarbons is investigated by
combining charged particle collision experiments and quantum chemistry calculations. The
kinetic energy release (KER) distribution for each H 3+ loss process was measured with thecold target recoil ion momentum spectroscopy. The good agreement between the mean KER
and corresponding theoretical reverse activation energy, related to a transition state and theasymptote of the dissociation products, provides information on the H3+ formation dynamics.
A H2 roaming mechanism is proposed for the formation of H3+.The isomerization channel(C+ +CH2+) in C2H2, (CH+ +CH3+) in C2H4, and (CH2+ +CH4+) in C2H6 is also observed.

References[1] Y. Zhang, T. Jiang, L. Wei, et al, Phys. Rev. A 97, 022703 (2018)[2] Y. Zhang B. Wang, L. Wei, et al, J. Chem. Phys. 150, 204303 (2019)[3] Y. Zhang, L. Wei, C-L. Yang, et al, Phys. Rev. A 100, 052706 (2019)[4] Y. Zhang, B. Ren, C. Yang, et al, Commun. Chem. 3, 160, (2020)[5] L. Wei, C. Lam, Y. Zhang, et al, J. Phys. Chem. Lett. 12, 5789, (2021)

24

PR-7
Charge migration in betaine by impact of fast atomic ionsP. Rousseau1 , J. González-Vázquez2,3 , D. G. Piekarski2 , J. Kopyra4 , A. Domaracka1 , M. Alcamı́3,5 ,L. Adoui1 , B. A. Huber1 , S. Dı́az-Tendero2,3,6 , F. Martı́n2,5,6
1
Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France
Departamento de Quı́mica, Módulo 13, Universidad Autónoma de Madrid, Madrid, Spain
3
Institute for Advanced Research in Chemical Sciences (IadChem),
Universidad Autónoma de Madrid, Madrid, Spain
4
Faculty of Exact and Natural Sciences,
Siedlce University of Natural Sciences and Humanities, Siedlce, Poland
5
Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nano), Madrid, Spain
6
Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
2

Here we exploit the zwitteronic nature of the betaine molecule to induce a double electron capture
from the negatively charged carboxylate group of the molecule in the collision with a low-energy O6+
ion. This results in the formation of a molecular dication with two charges localised to both ends.
Beside the expected charge separation giving two charged fragments associated with both ends, weobserve ion-pairs resulting from the dissociation of doubly charged ends and thus associated with acharge migration following the ionisation.
Nonadiabatic molecular dynamics calculations show that the electronic dynamics associated withcharge migration occurs in the ground state of the betaine dication. It is efficiently populated in ion
collisions by the resonant double electron capture.

Figure 1: Competition between Coulomb explosion and charge migration in the dissociation of betaine dication produced in collision with 48 keV O6+ ions.
References[1] P. Rousseau et al., Sci. Adv. 7, eabg9080 (2021).

25

PR-8

First experiments with the CRYRING@ESR
M.Lestinsky1 for the SPARC collaboration and the CRYRING@ESR
team
1

GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany

The low-energy heavy ion storage ring CRYRING has been transported from
Stockholm to Darmstadt, modernised and reconfigured, and has been integrated
downstream from ESR into the accelerator complex at GSI/FAIR, where it now
operates as CRYRING@ESR. Next to serving as a test platform for novel technologies
of FAIR, it is a user facility for research in many domains.
Ions can be injected injected either in low charge states from a local ion source througha 300 keV/u RFQ linac, or in high charge states up to bare uranium through ESR. This
allows for a very broad access to ions across the entire periodic system.
CRYRING@ESR is able to de- or accelerate the ions and store beams of isotopicallypure species in a desired charge state. With the powerful electron cooling method, thespatial and momentum spread are reduced to provide brilliant beams to thespecification of the experimentalists. This gives an unprecedented access to precision
spectroscopy in highly charged ions, for studying the dynamics of slow collisions instrong fields, for measuring nuclear reactions in the Gamow window, or in materials
science for surface modifications by slow HCI beams, and more1.
All major elements of the facility are now in service and routine operation as a user
facility has been established. The SPARC collaboration of FAIR has prepared several
experimental installations for merged beams electron-ion collisions, for atomic
collisions in a dense gas-jet target, and on collinear laser spectroscopy. The first periodof serving beamtimes to experiment proposals approved by the General Program
Advisory Committee has now been completed. While the data analysis is still largely
ongoing, these first results are already confirming that the high expectations onachievable resolution in spectroscopy experiments have been fulfilled.
We will review our present installations for experiments at the ring, discuss the datafrom first data runs and review the upcoming new installations for the coming years.

References
1. M. Lestinsky, Y. Litvinov, T. Stöhlker (eds.), Eur. Phys. J. Spec. Top 225 (2016)

26

PR-9
New physics searches with highly charged ion clocks
Julian C. Berengut
School of Physics, University of New South Wales, Sydney NSW 2052, Australia
The recent demonstration of spectroscopy in highly charged ions (HCIs) with atomic clock-level accuracy [1] portends a new era of precision atomic experiments. Narrow transitions in HCIs are available
throughout the periodic table, with unique properties that can be exploited to improve searches forphysics beyond the Standard Model such as possible variations in the fine-structure constant [2,3] andviolations of Lorentz invariance [4] (see review [5]).
In some species it is possible to identify HCIs at “orbital crossings”, where different orbitals have approximately the same binding energies. Choosing HCI near orbital crossings allows optical transitions
with high sensitivity to new physics, and many opportunities to control systematics. A demonstrationof narrow optical transitions between the 5p and 4f orbitals was presented in Pr9+ [6].

Figure 1: Grotrian diagram at the 5p 4f orbital crossing in Pr9+ . Blue: experiment; red: CI+MBPT
calculations using AMBiT; orange: Fock-space coupled cluster calculations. Experiment and calculations presented in [6].
References[1] P. Micke et al. Nature 578, 60 (2020); see also arXiv:2205.13053.
[2] S. Schiller, Phys. Rev. Lett. 98, 180801 (2007)[3] J. C. Berengut, V. A. Dzuba, V. V. Flambaum, Phys. Rev. Lett. 105, 120801 (2010); J. C. Berengut,
V. A. Dzuba, V. V. Flambaum, A. Ong, Phys. Rev. Lett. 106, 210802 (2011)[4] R. Shaniv et al., Phys. Rev. Lett. 120, 103202 (2018)[5] M. G. Kozlov, M. S. Safronova, J. R. Crespo López-Urrutia, P. O. Schmidt, Rev. Mod. Phys. 90,
045005 (2018)[6] H. Bekker et al. Nat. Comm. 10, 5651 (2019)27

PR-10High accuracy theoretical investigations of highly charged ions
Anastasia Borschevsky
The Van Swinderen Institute, University of Groningen, The Netherlands

Relativistic coupled cluster is considered one of the most powerful methods for accurate
calculations of properties of heavy and highly charged atoms. Two variants of this method areusually used. The first variant, the single reference coupled cluster approach (SRCCSD(T)) issuitable for calculations of ground state properties in systems which can be well described by asingle determinant. This approach can be used to obtain, for example, ionization potentials andother ground state properties. The second variant is the multireference Fock space coupled cluster
method (FSCC), which is particularly useful for high accuracy calculations of excitation spectra andhyperfine structure parameters.
The talk will provide a brief introduction to the two variants of the relativistic coupled cluster
approach. I will also introduce the recently developed scheme that we use to set uncertainties on thetheoretical results [1]. Such uncertainties are particularly important when using theoreticalpredictions in experimental context. Examples of application of the relativistic coupled cluster tohighly charge ions will be provided.

References[1] P.A.B Haase, E Eliav, M Ilias, and A. Borschevsky,J. Phys. Chem. A 124, 3157 (2020)[2] F. P. Gustafsson, C. M. Ricketts, M. L. Reitsma, R. F. Garcia Ruiz et al., Phys. Rev. A 102,052812 (2020)[3] A. Windberger, J. R. Crespo Lopez-Urrutia, H. Bekker, N. S. Oreshkina, et al., Phys. Rev. Lett.
114, 150801 (2015)[4] A. Windberger, F. Torretti, A. Borschevsky, A. Ryabtsev, S. Dobrodey, H. Bekker, et al., Phys.
Rev. A 94, 012506 (2016)[5] J. Scheers, A. Ryabtsev, A. Borschevsky, J. C. Berengut, K. Haris, et al., Phys. Rev. A 98,
062503 (2018)[6] H. Bekker, A. Borschevsky, Z. Harman, C. H. Keitel, T. Pfeifer, P. O. Schmidt,
J. R. Crespo Lopez-Urrutia, J. C. Berengut, Nature Comm. 10, 5651 (2020)28

PR-11
Aromatic molecules revisited under bare helium collision: experiment and theory
Wania Wolffa, Lucia H. Coutinhoa, Fabio R. de Almeidab, Volker Dangendorfc , Gehard
Hilgersc , Ulrich Giesenc , Alejandra Mendezd, Sebastian Lopezd, Claudia MontanaridaPhysics Institute, Federal University of Rio de Janeiro, IF/UFRJ, Rio de Janeiro, Brazil
Federal Institute of Rio de Janeiro, IFRJ, Nilópolis, Rio de Janeiro, BrazilcPhysikalisch-Technische Bundesanstalt, PTB, Braunschweig, GermanydInstitute of Astronomy and Space Physics, IAFE (CONICET-UBA), Buenos Aires,
Argentinab

Aromatic molecules are of multidisciplinary interest such as in bio-, atmospheric-, andastrochemistry, and are considered resistant to fragmentation to ion-impact in theintermediate energy range. Pyrimidine (C4H4N2), pyridine (C5H5N), and benzonitrile(C6H5CN) were selected respectively as representative molecules in the related fields.
The relevance of measuring the ionization and subsequent fragmentation of suchmolecules has been stressed in many works associated with hadron-therapy1, cloudformation2, and aromatic hydrocarbon formation in the interstellar medium3. Here, wereport the ionization and fragmentation of aromatic molecules under bare helium collision
over a wide range of impact energies, 700 up to 6000 keV, using pulsed beams andextraction fields combined with a high-resolution time-of-flight spectrometer. There arefew fragmentations studies on aromatic molecules following energetic ion interaction.
Previously, fragmentation cross sections were measured for pyrimidine under proton
impact for energies from 300 keV to 16000 keV1. Searching for charge effects on theionization and break-up channels we compared the He2+ data with those measured of 50
to 150 keV protons and 20 to 2000 keV electrons colliding on these aromatic molecules.
To understand the general behaviour of ion-aromatic cross sections we included
theoretical results for the single ionization and electron capture of these species bycombining the atomic cross section of its constituents with a stoichiometric approach4.
These atomic values were obtained within CTMC and CDW-EIS methods and are
examined to probe the importance of the electron capture phenomena at impact energies
ranging from 25 keV to 250 keV. The derived data from this study can help to improvethe estimates of astrophysical, biological and atmospheric models.
1 Rudek, B., Arndt, A., Bennett, D. et al. Ion induced fragmentation cross-sections of
DNA constituents. Eur. Phys. J. D 69, 237 (2015). doi: 10.1140/epjd/e2015-60204-7
2 Bibang, P.C.J., Agnihotri, A.N., Boduch, P. et al. Radiolysis of pyridine in solid
water. Eur. Phys. J. D 75, 57 (2021). doi: 10.1140/epjd/s10053-021-00058-y
3 Brett A. Mcguire, Andrew M. Burkhardt, Sergei Kalenskii, Christopher N.
Shingledecker et al. Detection of the aromatic molecule benzonitrile (c-C6H5CN) in theinterstellar medium, Science 359, 202 (2018) doi: 10.1126/science. aao4890
4 Mendez A. M. P., Montanari C. C., Miraglia J. E. Ionization of biological moleculesby multicharged ions using the stoichiometric model, J. Phys. B: At. Mol. Opt. Phys. 53(2020) 055201. https://doi.org/10.1088/1361-6455/ab6052

29

PR-12
Fragmentation of the Heteronuclear Cluster b Electron Impact
Shuncheng Yan1, 2, D. Li 3, S. B. Zhang3, X. L. Zh 1, 2, S. F. Zhang1, 2, S. X 1, 2, and Xin en Ma1, 2
1

Ins i

e of Modern Ph sics, Chinese Academ of Sciences, Lan ho 730000, China
2
Uni ersi of Chinese Academ of Sciences, Beijing 100049, China
3
School of Ph sics and Informa ion Technolog , Shan i Normal Uni ersi , Xi an 710119, China
Via eak in erac ions s ch as an der Waals bond and h drogen bond, he a oms can condense
in o a cl s er. Then if one a om i hin he cl s er is ioni ed, he follo ing charge or energ ransfer
ill ind ce ne deca mechanisms absen in he isola ed a om. One famo s mechanism is ermedin era omic Co lomb deca (ICD), here he e cess energ ransferred from an e ci ed ion ill
rigger he ioni a ion of a neighboring a om [1]. Recen l , e carried ohe fragmen a ione perimen of he he eron clear cl s er NeAr b elec ron impac a reac ion microscope, e
dis ing ished he ICD follo ing Ne ioni a ion from he ICD follo ing Ar ioni a ion [2]. The
obser ed deca pa h a s ill enhance he ield of lo energ elec rons on he nanoscale, andmanifes s he role of high energ secondar elec rons in a ne proposed radia ion herap scheme
ermed resonan A ger ICD [3].
On he o her hand, he cl s er fragmen a ion is also proposed o con rol chemical reac ions [4, 5],e.g., b embedding a molec le in o a cl s er and ioni ing i s neighboring a om, he follo ing
energ and charge ransfer ill ind ce i s dissocia ion along specific deca pa h a s, and achie ehe goal of selec i e bond clea age. In order o iden if abo e predic ion, e performed hefragmen a ion e perimen of he eron clear cl s er ArCO, here o ions and one elec ron ere
meas red in coincidence. As sho n in fig re.1, he ield ra io of Ar+/C+/O ion pair o Ar+/O+/C ion
pair is abo 6. Compared i h he ield ra io of C+/O ion pair o O+/C ion pair in he isola ed CO,
his al e increases fi e imes. O r obser a ion s gges s ha he polari a ion be een Ar2+ ion and
CO ill lead o he forma ion of ransien (ArCO)2+ ion, hich releases an O a om la er,
conseq en l , he prod ced ArC2+ me as able ion breaks in o Ar+/C+ ion pair. This mechanism
enhances he specific fragmen a ion pa h a CO→C+ + O.

Fig re 1: T o-dimensional TOF correla ion map af er ArCO ioni a ion
References[1] L. S. Cederba m, J. Zobele , and F. Taran elli, Ph sical Re ie Le ers, 79: 4778 (1997).
[2] S. Yan, X. L. Zh , S. F. Zhang, e al., Ph sical Re ie A, 102: 032809(2020).
[3] F. Trin er, M. S. Sch ffler, H. K. Kim, e al., Na re, 505(7485): 664(2014).
[4] L. S. Cederba m, The Jo rnal of Ph sical Chemis r Le ers, 11: 8964(2020)[5] Y. C. Chiang, S. Engin, P. Bao, e al., Ph sical Re ie A, 100: 05270 (2019)1

30

PR-13
Theoretical predictions of the structure of heavy muonic atoms
Natalia S. Oreshkina, Igor A. Valuev, Christoph H. Keitel
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
When coming close to an atom, a muon can be captured by the nucleus and form a hydrogen-likemuonic ion, which is typically also surrounded by atomic electrons. This atomic system is commonlyreferred to as a muonic atom. Due to the muons high mass, it is located much closer to the nucleus;
and, especially for heavy nuclei, this results in big nuclear size effects and a strong dependence ofthe muon bound-state energies on the nuclear charge and current distributions, as well as in large
relativistic effects [1, 2]. A combination of the knowledge about the level structure and experiments
measuring the transition energies in muonic atoms enabled the determination of nuclear parameterslike charge radii, electric quadrupole and magnetic dipole moments [3].
Theoretical predictions of the fine-, hyperfine structure, and dynamical splitting of muonic atoms,
based on rigorous QED calculations will be presented. State-of-the-art techniques from both nuclear
and atomic physics are brought together in order to perform the most comprehensive to date calculations of the quantum-electrodynamics and nuclear contributions. Finally, a long-standing problem offine-structure anomalies in muonic atoms is revisited in the light of the last improvements on nuclearpolarization [4] and self-energy calculations [5].
45
Haga et al.

Present

440ΔSE, in eV

NP 2p1/2 – NP 2p3/2 (eV)

100

-100
-200

43
42
41
40

-300

39
38

-400
4

4.5

5
5.5
NP 1s1/2 (keV)

6

10

6.5

15

20
max jn+1/2

25

30

Figure 1: (left) Theoretical values of the nuclear polarization correction for muonic lead in relation
NP
NP
NP
to the experimentally allowed range for 2p = | E2p
E2p| as a function of | E1s| [4].
1/2
3/2
1/2(right) Self-energy contribution to the 2p1/2 state of muonic tin in units of eV as a function of maximal
intermediate angular momentum jn for different nuclear models and numerical grids [5].
References[1] A. Antognini et al., Phys. Rev. C 101, 054313 (2020)[2] N. Michel, N. S. Oreshkina, and C. H. Keitel, Phys. Rev. A 96, 032510 (2017)[3] N. Michel and N. S. Oreshkina, Phys. Rev. A 99, 042501 (2019)[4] I. A. Valuev, G. Colò, X. Roca-Maza, C. H. Keitel, and N. S. Oreshkina, Phys. Rev. Lett. 128,
203001 (2022)[5] N. S. Oreshkina, https://arxiv.org/abs/2206.01006 (2022)31

PR-14
Muonic atom X-ray spectroscopy for QED test in strong Coulomb field
S. Okada1,2, T. Azuma2,3, D. A. Bennett4, I. Chiu5, W. B. Doriese4, M. S. Durkin4, J. W. Fowler4,
J. D. Gard4, T. Hashimoto6, R. Hayakawa7, G. C. Hilton4, Y. Ichinohe7, P. Indelicato8, T. Isobe2,
S. Kanda9, M. Katsuragawa10, N. Kawamura9, Y. Kino11, K. Mine10, Y. Miyake9, K. M. Morgan4,
K. Ninomiya5, H. Noda5, G. C. O’Neil4, T. Okumura3,2, K. Okutsu11, N. Paul8, C. D. Reinstema4,
D. R. Schmidt4, K. Shimomura9, P. Strasser9, H. Suda3, D. S. Swetz4, T. Takahashi10, S. Takeda10,
S. Takeshita9, M. Tampo9, H. Tatsuno3, Y. Ueno2, J. N. Ullom4, S. Watanabe13, and S. Yamada7
1

Chubu University, Kasugai, Aichi 4878501, Japan,
2
RIKEN, Wako 3510198, Japan,
3
Tokyo Metropolitan University, Tokyo 1920397, Japan,
4
National Institute of Standards and Technology, Boulder, CO 80305, USA,
5
Osaka University, Osaka 5600043, Japan,
6Japan Atomic Energy Agency, Tokai 3191184, Japan,
7
Rikkyo University, Tokyo 1718501, Japan,
8
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University,
Collége de France, Case 74, 4, place Jussieu, 75005 Paris, France,
9
High Energy Accelerator Research Organization (KEK), Tsukuba 3050801, Japan,
10
Kavli IPMU (WPI), The University of Tokyo, Kashiwa, Chiba 2778583, Japan,
11
Tohoku University, Sendai, Miyagi 9808578, Japan,
12
University of Tsukuba, Tsukuba, Ibaraki 3058573, Japan,
13
Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 2525210, JapanA negatively-charged muon can bind to an atomic nucleus via the Coulomb force. This is socalled a “muonic atom” which is essentially hydrogen-like in its electronic structure. Since a muonis 200 times more massive than an electron, a muonic atom has a Bohr radius 200 times smaller
than that of atomic hydrogen. The electric field between the muon and the atomic nucleus is
proportional to the square of the mass ratio of the electron to muon, which is 40,000 times stronger
than that of a normal atom. This allows to test QED in strong field in a very different regime, sinceat such short distances the dominant QED contribution is the vacuum polarization, while it is theself-energy in highly-charged ions [1].
After a negatively-charged muon is captured by the nucleus in a highly excited state, the muon
peels off electrons bound to the nucleus as Auger electrons, and thereby generating highly-charged
muonic atoms in vacuum. While a low-density target is required to avoid rapid refilling of electrons
into the highly charged muonic atom from the surrounding atoms, it has been experimentallydifficult to efficiently stop muons in a low-density target. This is due to their large momentum
distribution via traveling pion decay, resulting in insufficient x-ray yields with the conventional
high-resolution x-ray spectroscopy technology based on diffraction from Bragg crystals, unless one
uses a device like the PSI cyclotron trap.
We conducted high-resolution muonic atom X-ray spectroscopy experiments with low-density
gas target with a combination of the world highest intensity pulsed negative muon beam at J-PARC
MLF MUSE (Tokai, Japan) and an X-ray spectrometer based on a 240-pixel array of superconducting transition-edge-sensor (TES) microcalorimeters which has both excellent energy
resolution and collection efficiency [3,4]. In this presentation we will give an overview of thisproject and the recent progress.
References[1] N. Paul et al., Physical Review Letters 126, 173001 (2021).
[2] S. Okada et al., Journal of Low Temperature Physics 200, 445-451 (2020).
[3] T. Okumura et al., in preparation.

32

PR-15Resonant photoexcitation of trapped ions for x-ray astrophysics
Sonja Bernitt, René Steinbrügge*, Steffen Kühn°, Moto Togawa°, José R. Crespo López-Urrutia°
Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena (Germany)(*) Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany)(°) Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)
Spectroscopic observations in the UV and X-ray bands with the newest generation of highresolution instruments onboard current and future satellite observatories have the potential to reveal
previously inaccessible details of processes in astrophysical plasmas, such as the ones in galaxy
clusters and active galactic nuclei. This is essential for advancing our understanding of extreme
environments and the evolution of the universe.
However, what can be reconstructed from spectra is currently limited by the availability and qualityof atomic data, on which plasma models are built. That is especially the case for highly charged
ions (HCI), ubiquitous in hot astrophysical plasmas [1]. For many years, electron beam ion traps(EBITs) have been valuable tools for laboratory measurements with HCI, providing a wide range ofatomic data, like transtion energies and rates of ionization and recombination processes.
Here, work with the novel compact PolarX-EBIT [2], based on permanent magnets, is presented, inwhich radiation from ultrabrilliant UV and X-ray synchrotron light sources is used to resonantly
excite electronic transitions in trapped HCI. Subsequent fluorescence and changes of ion charge
state are detected, which allows to gather spectroscopic data under well-controlled conditions with
unprecedented resolving powers and signal-to-noise ratios. This yields atomic data valuable not
only for astrophysics but also for benchmarking general atomic structure theory [3].
One such case are the two 2p-3d transitions in Ne-like Fe16+, commonly labelled 3C and 3D, forwhich measurements and calculations of oscillator strengths seemed to disagree significantly [4],until our recent experiments uncovered previously unaccounted-for contributions to the observed
intensities [5].
Furthermore, the unique off-axis electron gun of PolarX-EBIT facilitates new experimental setups,
in which electronic transitions in few-electron HCI are used as accurate and reproducible wavelength references [6].
References[1] G. Betancourt-Martinez et al., arXiv:1903.08213 (2019)[2] P. Micke et al., Rev. Sci. Instrum. 89, 063109 (2018)[3] M. Togawa et al., Phys. Rev. A 102, 052831 (2020)[4] S. Kühn et al., Phys. Rev. Lett. 124, 225001 (2020)[5] S. Kühn et al., arXiv:2201.09070 (2022)[6] M. A. Leutenegger et al., Phys. Rev. Lett. 125, 243001 (2020)

33

SELECTED TALKS

34

ST-1
First Laboratory Verification of Magnetic-field-induced Transition Effectin Fe X
YANG Yang, XU Guoqin, LI Wenxian*, SONG Liudi, SI Ran, CHEN Chongyang, BAI
Xianyong*, TIAN Hui#, XIAO Jun, Roger HUTTON, ZOU Yaming
Shanghai EBIT laboratory, and Key Laboratory of Nuclear Physics and Ion-Beam Application(MOE), Institute of Modern Physics, Fudan University, Shanghai 200433, China*Key Laboratory of Solar Activity, National Astronomical Observatories,
Chinese Academy of Sciences, Beijing 100012, China#
School of Astronomy and Space Science, University of Chinese Academy of Sciences,
Beijing 100049, China

The magnetic field is extremely important for understanding the properties of the solar corona.
However, there are still difficulties in the direct measurement of coronal magnetic fields. The
discovery of the magnetic-field-induced transition (MIT) in Fe X, which was also observed in thecoronal spectra, opened up a new method for measuring the coronal magnetic field. In this work, we
obtained the Fe X extreme ultraviolet (EUV) spectra in the wavelength range of 174–267 Å inShanghai high-temperature superconducting electron beam ion trap, and for the first time, verified
the effect of MIT in Fe X by measuring the line ratios between 257.262 Å and reference line of
226.31 Å (257/226) at different magnetic field strengths. The plasma electron density that may
affect the 257/226 value was also obtained experimentally and then verified by comparing thedensity-sensitive line ratios with the theoretical prediction, and there was good agreement between
them. By comparing the simulated line ratios of 257/226 with the experimental values at given
electron densities and magnetic fields, the critical energy splitting of the fine-structure levels, one of
the most critical parameters to determine the MIT transition rate, was obtained. Possible reasons
which may lead to the difference between the obtained energy splitting and the recommended value
in previous work are discussed. Magnetic field response curves for the 257/226 value were
calculated and compared to the experimental results, which is necessary for future MIT diagnostics.
2.0

LineRatio_257.262 / 226.31

1.9
1.8
1.7

E/cm-1 = 8.6 log Ne/cm-3 = 10.2
E/cm-1 = 8.6 log Ne/cm-3 = 10.4
E/cm-1 = 8.6 log Ne/cm-3 = 10.6
E/cm-1 = 2.29 log Ne/cm-3 = 10.8
E/cm-1 = 2.29 log Ne/cm-3 = 11.0
E/cm-1 = 2.29 log Ne/cm-3 = 11.2

1.6
1.5
1.4
1.3
Experiment data
1255 G
1679 G
2102 G

1.2
1.1
1.0
800

1000

1200

1400 1600 1800
Magnetic field (G)

2000

2200

Theoretical and experimental values of line ratios of 257.262 Å and 226.31 Å versus the magnetic
field

35

ST-2
First observation of giant quadrupole plasmon resonance in C60 in highperturbation HCI collisions
L. C. Tribedi*, S. Kasthurirangan*,†, E. Suraud‡(*) Tata Institute of Fundamental Research, Colaba, Mumbai – 400005, India.
(†) University of Mumbai, Santacruz, Mumbai – 400098, India.
(‡) Laboratoire de Physique Theorique, Universite de Toulouse, F-31062 Toulouse Cedex, France.

2

DDCS d σ/dεdΩ (arb. units)

We give a classic example of using high perturbation caused by HCIs to explore new mechanisms
in ion collisions with a nano-particle namely C60-fullerene. The collective plasmon excitation mode
known as the GPR (giant plasmon resonance), where the entire delocalised valence-electron cloudof C60 oscillates collectively about the ionic shell, has been well-studied using photo-excitation,
electron-impact and ion-impact excitation [1-3]. A direct observation of the dipole mode of the
GPR has been reported earlier [3] by using F9+ ions (q=9, v~12.7 a.u) for which angular distribution
reveals a parabolic shape, characteric of dipole-nature [Fig 1(a)] We have now measured the double
differential cross section (DDCS) at even higher perturbation (q/v) i.e. in collisions with 91 MeV
Si12+ ions (q=12, v~11.4 a.u). The DDCS spectrum at low energy indicates a quadrupole plasmon
resonances (GQPR) in addition to the dipole plasmon (GDPR). The measured DDCS angular
distribution at low energies (around 7-8 eV) reveal a double valley structure [Fig 1(b)] which ischaracteristic of quadrupole resonance. The elegant technique of using high perturbation collision
allows us to identify the characteristic GQPR mechanism. We have unambiguously identified thedipole and quadrupole modes by using state-of-the-art TDDFT calculations[6]. This is the first suchunambiguous experimental demonstration of the quadrupole excitation in atomic system[6].
GPR-DDCS at 10 eV
dipole + quadrupole fit (Q/D = 2.00)

3.0

2.5

2.0

1.5
30

60

90

Angle (deg)

120

150

(a)
(b)
Figure 1: Angular distribution of plasmon-electrons from C60 under fast-ion collisions: (a)Projectile: F9+ (4MeV/u, v=12.7)[3], (b) Si12+ (3.2MeV/u, v=11.4)
References[1] I. V. Hertel et al., Phys. Rev. Lett. 68, 784 (1992).
[2] P. Bolognesi et al., EPJD 66, 254 (2012).
[3] A. H. Kelkar et al., Eur. Phys. J D 74, 157 (2020)[4] D. Misra et al., NIM B 267, 157 (2009).
[5] C-Z. Gao et al., Phys. Rev. A 95, 033427 (2017).
[6] S. Kasthurirangan et al. Phys Rev Letts. (under review)

36

ST-3
Lifetime measurement of the microsecond-order electric-quadrupole transition:
Application of plasma-assisted laser spectroscopy
Naoki Kimura1, Priti2, Susumu Kuma1, Toshiyuki Azuma1, Nobuyuki Nakamura3
1

Atomic, Molecular and Optical Physics Laboratory, RIKEN, Saitama 351-0198, Japan
2
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
3
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan

Lifetime measurements of forbidden transitions in highly charged ions (HCIs) have provided
remarkable examples for evaluating atomic physics theories [1-3]. Previous measurements
employed isolated HCIs in a magnetic ion storage device and observed de-excitation processes frommetastable states prepared in a plasma ion source. This is a useful method for lifetimes on the orderof milliseconds, and has been widely applied for various transitions. However, the conventional
method cannot eliminate re-population effects due to cascade processes from upper energy levels.
This intrinsic problem has prevented the broad extension of the technique to microsecond (µs)-order
lifetime measurements.
Recently, we demonstrated plasma-assisted laser spectroscopy of HCIs trapped in an electron beam
ion trap (EBIT) [4]. In this demonstration, we succeeded in laser excitation between the metastablefine-structure levels of Pd-like HCIs with the aid of plasma excitation processes in the EBIT. Thislaser spectroscopy has the potential to be applied to state-selective lifetime measurements which
avoid the abovementioned problem. In this presentation, we discuss this application and its
prospects by demonstrating the lifetime measurement of the µs-order electric-quadrupole (E2)transition (4d3/2-1 5s1/2)J=2 - 4d10 in Pd-like I7+.

Figure 1: (Left) Concept for the lifetime measurement. (Right) Experimental decay profile.
References[1] J. Doerfert, E. Träbert, A. Wolf, D. Schwalm, O. Uwira, Phys. Rev. Lett. 78, 4355 (1997).
[2] A. Lapierre, et al., Phys. Rev. Lett. 95, 183001 (2005).
[3] E. Träbert, P. Beiersdorfer, G. V. Brown, Phys. Rev. Lett. 98, 263001 (2007).
[4] N. Kimura, et al., submitted.

37

ST-4
Analysis of E3 transitions in Ag-like high-Z ions observed with the NIST EBIT
Dipti*, E. Takacs**, D. La Mantia, Y. Yang**, A. Naing, P. Szypryt***, A.Hosier, J.N. Tan, Yu.
Ralchenko
National Institute of Standards and Technology, Gaithersburg, MD 20899, USA(*) Present address: International Atomic Energy Agency, Vienna A-1400, Austria(**) Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 USA(***) National Institute of Standards and Technology, Boulder, CO 80305, USA

Measurements and analyses of forbidden lines in highly charged ions provide invaluable
information on diverse effects including quantum-electrodynamic and relativistic effects in atomic
structure as well as offer new diagnostic techniques for very hot plasmas. Recently, Sakaue et al [1]reported on observation of electric-octupole (E3) spectral lines in Ag-like W27+ using the compact
electron beam ion trap (EBIT). The well-resolved 4f7/2,5/2-5s transitions were recorded in the extreme
ultraviolet (EUV) spectrum. Using the HULLAC atomic code, the authors of Ref. [1] showed that theE3 lines are strongly enhanced for W and developed an advanced collisional-radiative model which
predicts E3 line intensities for the other members of the isoelectronic sequence.
In this work we report on measurements and identifications of the E3 4f7/2,5/2-5s transitions in
W and other high-Z elements including Re (Z=75), Os (Z=76), and Ir (Z=77). The EUV spectra wererecorded with the NIST EBIT using a grazing-incidence EUV spectrometer. The present higher
resolution results for W and GRASP2K calculations strongly confirm the Ref. [1] findings. Our
collisional-radiative model developed with the NOMAD and FAC codes offers a deep insight into
the population kinetics for Ag-like ions of heavy elements. The simulation allowed the identificationof new spectral lines in the spectra. We will present a detailed discussion of the observed spectra andcomparisons of the measured and simulated line intensities.
References[1] H.A. Sakaue et al, Phys. Rev. 100, 052515 (2019)[2] Yu. Ralchenko, Y. Maron, JQSRT 71, 609 (2001)[3] M.F. Gu, Can. J. Phys. 86, 675 (2008)

38

ST-5

Elastic x-ray scattering by highly charged ionsS. Strnat, J. Sommerfeldt, A.Surzhykov
Physikalisch Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig
Technische Universität Braunschweig, Universitätsplatz 2, 38106 Braunschweig

The elastic scattering of x-rays by atoms and highly charged ions is one of the fundamental
processes in the interaction of radiation with matter. Over the past few years, increasing attention
has been paid to the study of the properties of scattered photons. In particular, the linear polarizationof the outgoing radiation was measured in a recent experiment at the PETRA III synchrotron facility
at DESY in Hamburg [1]. This experiment demonstrated that by analyzing the polarization of thescattered light, one can obtain information not only about the atomic structure of the target atoms,
but also about the polarization of the incident synchrotron radiation. In our poster, we study thepolarization properties of elastically scattered x-rays by highly charged ions and neutral atoms. We
illustrate how the polarization of incident x-rays can be determined only with the polarization of
scattered photons, without any need for the theoretical scattering amplitudes [2]. Moreover, we
explore how the interference between Rayleigh and Delbrück scattering may affect the polarization
properties of the outgoing radiation.

References[1] K. H. Blumenhagen, S. Fritzsche, T Gassner, A. Gumberidze, R. Märtin, N. Schell, D. Seipt, U.
Spillmann, A. Surzhykov, S. Trotsenko, G. Weber, V. A. Yerokhin, and T. Stöhlker, New J. Phys. 18,103034 (2016).
[2] S. Strnat, V. A. Yerokhin, A. V. Volotka, G. Weber, S. Fritzsche, R. A.Müller, A. Surzhykov,
Phys. Rev. A 2021, 103, 012801

39

ST-6
Radiative Double-Electron Capture by Highly-stripped Ions on Graphene
Asghar Kayani*, Khushi Bhatt*, David S. La Mantia†, John A. Tanis*(*) Western Michigan University, Department of Physics, Kalamazoo, Michigan 49008 USA(†) NRC – National Institute of Standards and Technology, Gaithersburg, MD USA
Radiative double-electron capture (RDEC) occurs when the capture of two electrons by an ion isaccompanied by the simultaneous emission of a single photon. This process, fundamental in atomic
collisions, is considered the inverse of double photoionization by a single photon. RDEC has beensuccessfully studied with F9,8+ ions on gas [1] and thin-foil [2] targets. Only recently has it been
investigated for single-layer graphene [3]. This work was done at WMU with the 6-MV tandem vande Graaff accelerator. For the graphene, a target (‫׽‬0.35 nm thick) was mounted on a silicon nitride
grid (200 nm thick) consisting of ‫׽‬6400 holes of 2 µm diameter on a 200 µm thick substrate. A
Si(Li) spectrometer placed at 90° to the beam detected emitted x rays in coincidence withmagnetically separated outgoing charged particles counted with silicon surface-barrier detectors.
In preliminary work for RDEC with graphene [3], results for 2.11 MeV/u F9,8+ ions suggested verylarge cross sections, approaching values found for thin-foil targets when the thickness of thegraphene was about a hundred times smaller. In the present work, the RDEC measurements havebeen repeated with single-layer graphene as well as identical targets that had no graphene on them.
25

F9+ + Graphene

20
15
10
5
0

F9+ + No Graphene
CountsFigure 1 shows new results for RDEC for 2.11 MeV/u F9,8+
incident on graphene where the number of counts is plottedagainst the time difference between the x rays and particles
detected. The upper panel shows the results for F9+ on graphene,
the middle panel for F9+ with no graphene, and the bottom panel
for F8+ incident on the graphene. The top panel for F9+ shows
about 7-8 counts in the peak (near a time difference of 1950 ns)
after background subtraction, the middle panel exhibits no counts
for the target without graphene as expected, and the bottom panel
for F8+ displays counts but none in the peak, a reasonable
expectation for this one-electron ion when compared with earlier
results for F8+ on gas targets [1].

2

1

0

F8+ + Graphene

15

A tentative cross section can be calculated for the F9+ projectile,and the differential value at 90q is 1.3 b, corresponding to a total
cross section (assuming isotropy) of 11 b. These values are morein line with the earlier values found for F9+ incident on gas
targets, but larger by about a factor of 4, and are reasonable inview of the target thickness for the graphene compared to gas.

10
5
0

0

1000

2000

3000

4000

Time (ns)Figure 1: RDEC results for
F9,8+ on single-layer
graphene

Supported in part by NSF Grant No. 1707467.
References[1] D.S. La Mantia et al., Phys. Rev. Lett. 124, 133401 (2020).
[2] D.S. La Mantia, P.N.S. Kumara, C.P. McCoy, J.A. Tanis, Phys. Rev. A 102, 060801(R) (2020)[3] D.S. La Mantia et al., ViCPEAC 2021, Book of Abstracts, p. 108

40

ST-7
Experimental Studies of Nonperturbative Dynamics
in Heavy-Ion-Atom Collisions
P.-M. Hillenbrand1,2 , S. Hagmann2 , D. Banaś3 , E. P. Benis4 , C. Brandau1,2 , O. Forstner2,5,6 ,J. Glorius2 , R. E. Grisenti2 , A. Gumberidze2 , M. O. Herdrich5,6 , M. Lestinsky2 , Yu. A. Litvinov2 ,E. B. Menz2,5,6 , S. Nanos4 , N. Petridis2 , Ph. Pfäfflein2,5,6 , H. Rothard7 M. S. Sanjari2,8 ,U. Spillmann2 , S. Trotsenko2 , M. Vockert5,6 , G. Weber6 , Th. Stöhlker2,5,6
I. Physikalisches Institut, Justus-Liebig-Universität, 35392 Giessen, Germany
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
3Institute of Physics, Jan Kochanowski University, 25-406 Kielce, Poland
4
Department of Physics, University of Ioannina, 45110 Ioannina, Greece
5Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, 07743 Jena, Germany
6
Helmholtz-Institut Jena, 07743 Jena, Germany
7
CIMAP, Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, 14000 Caen, France
8
Aachen University of Applied Sciences, 52066 Aachen, Germany
1

2

Experimental data for atomic collisions of highly-charged ions are essential for benchmarking thetheoretical description of dynamical processes in atomic physics. Of particular challenge is the accurate description of those processes that exceed the applicability of relativistic first-order perturbation
theories. Recently, we have investigated two characteristic cases of such collision systems at the Experimental Storage Ring ESR of the GSI heavy-ion accelerator facility in Darmstadt, Germany:(1) For fast collisions of U89+ projectiles with N2 and Xe targets at 76 MeV/u, we studied the electronloss-to-continuum cusp both experimentally and theoretically. We compared the continuum electron
spectra of the two collision systems, which originate from the ionization of the projectile, and wewere able to identify a clear signature for the nonperturbative character of the collision systems [1].
(2) For slow collisions of Xe54+ and Xe53+ with a Xe target at 30 and 15 MeV/u, we performed
an x-ray spectroscopy experiment focusing on the target K↵ radiation. Experimental data for suchslow symmetric collision systems are important for testing relativistic two-center calculations andprovide an intermediate step towards understanding heavy-ion collisions in super-critical fields. We
used the target K↵ satellite and hypersatellite lines to derive cross-section ratios for double-to-single
target K-shell vacancy production and compared our experimental results to theory applying a fully
relativistic time-dependent two-center approach [2].
At GSI, new prospects of investigating slow Xe54+ -Xe collisions under improved conditions will
now be facilitates by the low-energy heavy-ion storage-ring CRYRING@ESR. Corresponding experiments are currently being devised.
References[1] P.-M. Hillenbrand et al., Phys. Rev. A 104, 012809 (2021).
[2] P.-M. Hillenbrand et al., Phys. Rev. A 105, 022810 (2022).

41

ST-8
Charge-separated ion spectra from a laser-produced plasma
Yuto Nakayama, Takeru Niinuma, Masaki Kume, Hiromu Kawasaki, Hiroki Morita,
Shinichi Namba*, Atsushi Sunahara**, Gerry O’Sullivan***, and Takeshi Higashiguchi
Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585, Japan(*) Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8527, Japan(**) Purdue University, West Lafayette, Indiana 478907, USA(***) University College Dublin, Belfield, Dublin 4, Ireland
Extreme-ultraviolet (EUV) lithography at 13.5 nm is expected to be introduced in high-volume
manufacturing of integrated circuits (ICs) having node sizes less than 10 nm. Lithography at thiswavelength is capable of reaching feature sizes below 5 nm. Beyond that, switching to a shorter
wavelength of around 6.x nm, while maintaining or increasing throughput in the lithography system,
would improve resolution by a further factor of two and extend the technology to feature sizes lesstha 2 nm. Plasmas of the rare-earth elements gadolinium (Gd) and terbium (Tb) produce strong
resonant emission due to the presence of an intense unresolved transition array (UTA) around 6.x
nm in the spectra of their ions. Because the emitting ions in Gd and Tb, plasmas have an electronic
structure largely similar to Sn, they are expected to exhibit a similar spectral behavior, and emit anintense UTA due to 4p - 4d and 4d - 4f transitions at shorter wavelengths [1]. Recently, thesuitability of CO2 laser-produced plasma (LPP) EUV sources based on Gd and Tb has been
demonstrated for efficient, high power operation [2].
We observed the ion debris using an electrostatic analyser (ESA) to separate the charge
states. Figure 1 shows the charge-separated ion energy spectra. The maximum charge state was
Gd17+ (not shown) with a most probable energy higher than 20 keV. We show some dependence ofthe laser intensity and its pulse duration.
109

q+
1
2
3
4

Ion flux (arb. units)

108
107
106

5
6

105

7
8
9
10
11

104
103
102
10

12

0.1

1
10
Kinetic energy (keV)

50

Figure 1: Charge-separated ion spectra from a laser-produced Gd plasma.
References[1] H. Ohashi, T. Higashiguchi, B. Li, Y. Suzuki, M. Kawasaki, T. Kanehara, Y. Aida, S. Torii, T.
Makimura, W. Jiang, P. Dunne, G. O’Sullivan, and N. Nakamura, J. Apppl. Phys. 115, 033302(2014)[2] R. Amano, T.-H. Dinh, A. Sasanuma, G. Arai, H. Hara, Y. Fujii, T. Hatano, T. Ejima, W. Jiang,
A. Sunahara, A. Takahashi, D. Nakamura, T. Okada, K. Sakaue, T. Miura, G. O’Sullivan, and
T. Higashiguchi, Jpn. J. Appl. Phys. (Rapid Commun.) 57, 070311 (2018)

42

ST-9
High resolution imaging of laser plasmas revealing the effects of laser spot sizeon plasma emission
E. Sokell, K. Mongey*, F. O' Reilly, B. Delaney, R. Brady
Atomic, Molecular and Plasma Physics Group, University College Dublin, Ireland*kevin.mongey@ucdconnect.ie
Laser plasmas can produce a high flux of soft x-ray radiation from a small volume, making them ideal
for illumination for applications such as in EUV nano-lithography [1] and in cell imaging via soft xray microscopy [2].

In order to investigate the effects of the focal spot size on the plasma shape and intensity, amolybdenum target was irradiated with a Nd:YaG 1064nm driving laser. Images of the subsequently
formed plasmas ere generated sing a 5 m pinhole hich images soft -ra s thro gh a 1 m Al
filter onto a soft x-ra camera ith a pi el si e of 2.4 m and the imaging a is parallel to the target
and perpendicular to the laser. The filter transmission combined with the camera quantum efficiency
produces images in the 0.5nm to 3nm region. Such images were produced with laser energies ranging
from 20mJ to 271mJ with several laser focus spot sizes.
The plasma images were simulated using a skewed pseudo-Voigt profile combined with regression
techniques to generate noise reduced plasma images. The resulting areas and shapes (the ratio of theplasma widths parallel and perpendicular to the target measured through the centre of a plasma iamge)of the simulated plasma images were measured as demonstrated in Fig 1.

Fig 1: Left: Real plasma image with schematic target drawn. Right: Demonstration of the change inplasma area and plume shape (the ratio of the plume width perpendicular to the target and widthparallel to the target) as a function of lens position fro two labelled energies.
References[1] - Toshihisa Tomie, 2012, Tin laser-produced plasma as the light source for extreme ultraviolet
lihtograph high ol me man fact ring: histor , ideal plasma, present stat s and prospects ,Journal of Micro/Nanolithography MEMS, and MOEMS, Vol. 11, Iss. 2, 1-10
[2] Wach lak P. W. et. al, 2019, A ater indo tomograph based on a laser-plasma doublestream gas-puff target soft X-ra so rce , Applied Physics B, Vol. 125, Iss. 5, 70
This work is supported by Science Foundation Ireland through a Frontiers for the Future Programme Award (19/FFP/6795).

43

ST-10Inferring the coherence time of EUV pulse trains via spectroscopy ofhighly charged ions
Chunhai Lyu, Stefano M. Cavaletto, Christoph H. Keitel, Zoltán Harman
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
Coherent extreme-ultraviolet (EUV) pulse trains are produced via intra-cavity high-harmonic generations of high-intensity infrared pulse trains. They represent well-defined EUV frequency combs thatcan enable high-precision spectroscopy of specific EUV transitions in highly charged ions (HCIs)
with a relative accuracy to the level of !/! = 10 17 . In return, such ionic spectroscopy can also
provide information of the temporal coherence of the EUV frequency combs at timescales ranging
from nanosecond to several seconds.
In this contribution, we present a scheme to interrogate the EUV-comb coherence time via interactions
with highly charged Mg-like ions [1]. The excitation dynamics are simulated [2] for ions interactingwith EUV pulse trains of various temporal coherences. We show that while all EUV pulse trains
induce stepwise excitation of HCIs at the beginning of the interactions, the ionic excitations undergochaotic fluctuations when the coupling time becomes longer than the comb coherence time. These
investigations indicate that one can achieve coherent control of HCIs via current available EUV pulse
trains and enable quantum optics studies in the EUV range.
References[1] C. Lyu, S. M. Cavaletto, C. H. Keitel, Z. Harman, Phys. Rev. Lett. 125, 093201 (2020)[2] C. Lyu, S. M. Cavaletto, C. H. Keitel, Z. Harman, Sci. Rep. 10, 9439 (2020)44

ST-11
Hydrogen migration in three body fragmentation of acetylene trication
Jatin Yadav, C. P. Safvan*, Pragya Bhatt*, Pooja Kumari, Aditya Kumar*, Jyoti Rajput
Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India*Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067, India
We report on the three body fragmentation of [C2H2]3+ into (H+, C+, CH+) fragments in interaction ofneutral acetylene with a slow highly charged ion (Xe9+ having velocity ≈ 0.5 a.u.). The momenta ofall these three fragments were measured in coincidence using the technique of Recoil Ion
Momentum Spectroscopy (RIMS). For this particular fragmentation channel, three different
dissociation pathways are observed, namely concerted breakup in acetylene configuration,
concerted breakup in vinylidene configuration and sequential breakup via [C 2H]2+ intermediate
molecular ion.
To extract information about the different dissociation pathways, we have used Newton diagram [1]and the method of native frames [2] for analysing the momentum correlations. Figure 1(i) shows theγ - KER2 distribution generated by using the method of native frames and by assuming [C2H]2+ as anintermediate ion in sequential mode of breakup. KER2 represents the kinetic energy releaseassociated with the second step of the sequential breakup. The angle between the direction of thefirst two-body breakup and second two-body breakup in their respective centre-of-mass frames isrepresented by angle (γ). The uniform distribution observed parallel to the γ - axis is an evidence ofa long-lived electronic state of the [C2H]2+ molecular ion. The distribution is divided into two
regions A and B based on the value of KER 2 and two separate Newton diagrams are plotted asshown in figure 1(ii) and 1(iii). The semi-circular arc like feature observed in figure 1(ii) is asignature of sequential breakup via [C2H]2+ and the high intensity areas belong to concerted
breakup. In figure 1(iii), the angle between the momentum vectors of H + and C+ take two distinct
values around 25° and 165°. A low value of this angle corresponds to acetylene configuration and ahigh value corresponds to vinylidene configuration.

Figure 1: (i) A distribution of KER2 with γ for all events. (ii) and (iii) shows Newton diagrams forselected values of KER2 as indicated on the figure (see text for more information).
References[1] N. Neumann et. al. Phys. Rev. Lett. 104, 103201 (2010)[2] J. Rajput et. al. Phys. Rev. Lett. 120, 103001 (2018)[3] Jatin Yadav et. al. J. Chem. Phys. (Comm.) 156, 141101 (2022)45

ST-12
Sympathetic cooling of highly charged ions in a Penning trap using aself-cooled electron plasma
Jost Herkenhoff, Menno Door, Sergey Eliseev, Pavel Filianin, Kathrin Kromer, Daniel Lange,
Alexander Rischka, Christoph Schweiger, Sven Sturm, Klaus Blaum
Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
The amazing evolution of precision in recent Penning-trap experiments is driving the need for everimproving cooling techniques. In this talk, the prospect of a new sympathetic cooling technique using
an electron-plasma coupled to a single highly charged ion is presented. Utilizing the synchrotronradiation of electrons in a strong magnetic field enables cooling to very low motional quantum numbers, almost to their ground state. Using a common-resonator, the motion of this self-cooled electron
plasma can be coupled to an ion stored in a spatially separated Penning trap, allowing sympathetic
cooling of all modes of the ion. The extremely low expected temperatures in the milllikelvin range
open up an exciting new frontier of measurements in Penning traps.

46

ST-13
Direct high precision measurement of the 𝑄-value of the electron capture in163
Ho and metastable states in highly charged ionsK. Kromer1, M. Brass2, J. R. Crespo López-Urrutia1, V. Debierre2, M. Door1, H. Dorrer3, Ch. E.
Düllmann3,4,5, S. Eliseev1, C. Enss6, P. Filianin1, L. Gastaldo6, Z. Harman1, M. W. Haverkort2, J.
Herkenhoff1, P. Indelicato7, C. H. Keitel1, D. Lange1, C. Lyu1, Yu. N. Novikov8, D. Renisch4,5, A.
Rischka1, R.X. Schüssler1, Ch. Schweiger1, and K. Blaum1
1
Max-Planck- Institut für Kernphysik, 69117 Heidelberg, Germany
Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
3Institut für Kernchemie, Johannes-Gutenberg-Universität Mainz, 55128 Mainz, Germany
4Helmholtz-Institut Mainz, 55128 Mainz, Germany5
GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
6
Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany
7
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège
de France, 75005 Paris, France
8
NRC K rchato Instit te -Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
2

The high-precision Penning-trap mass spectrometer Pentatrap [1] features a stack of five Penningtraps and determines mass-ratios with a relative uncertainty below 10 ppt. Mass-ratio
determinations of stable and long-lived highly charged ions have numerous applications, among
others, in neutrino physics [2] and the search of possible clock transitions in highly charged ions
(HCI) [3]. The unique features of Pentatrap include access to HCI, a stable 7 T magnet, and acryogenic detection system with single ion phase sensitivity. The latest measurements include the Q
value of the beta-decay of 163Ho with a relative uncertainty of below 7 ppt. In 208Pb a long-lived
metastable electronic state was discovered.

References[1] J. Repp, et al., Appl. Phys. B 107, 983 (2012)[2] J. Gastaldo, et al., Appl. Phys. B 226, 1623 (2017)[3] M.G. Kozlov, et al., Rev. Mod. Phys. 90, 045005 (2018)47

ST-14
A superconducting quadrupole resonator for laser-spectroscopy of highly
charged ions at highest precision
C. Warnecke*, E. Dijck, M. Wehrheim, J. Stark, M. K. Ronser*, A. Graf,
J. Nauta, J.-H. Oelmann*, T. Pfeifer and J. R. Crespo López-Urrutria
Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany(*)Heidelberg Graduate School for Physics, Heidelberg, Germany

Highly charged ions are excellent candidates for novel optical frequency standards [1] and quantum
algorithms [2], since they are very unsusceptible to electromagnetic noise due to the suppression ofe.g. the quadratic Zemann shift scaling with Z-4[1]. However, gaining quantum control over the
motional modes of cold HCI had been a challenge for the last decades since they lack of fast cyclingtransitions for laser cooling. Quantum logic spectroscopy of the M1 transition in Ar13+ which was
sympathetically cooled by a single Be+ logic ion lowered the uncertainty by eight orders ofmagnitude to about 10-15 opening a branch for new frequency standards in near future [3].
Complementing these new types of optical clocks, a cryogenic Paul trap experiment with a quasimonolithic superconducting quadrupole resonator with a high operating quality factor of about
30000 [4] was developed at the Max-Planck-Institute for Nuclear Physics in Heidelberg, Germany
to challenge some of the resulting issues: Due to the high fidelity of the radio-frequency resonanceat about 35 MHz, radial mode heating of the HCI is strongly suppressed. Furthermore, the trappedions are shielded inside the cavity due to the Meissner-Ochsenfeld effect from electromagnetic
noise, reducing decoherence effects and therefore increasing interrogation times of the HCI. We
will present the features of this resonator and provide first characterizations with re-trapped HCI.

Ar14+

Figure 1: Left: Sliced view of the superconducting quadrupole resonator. Right: Single, crystallized
Ar14+ trapped and sympathetically cooled beryllium ions inside it.
References[1] M. G. Kozlov, et al., Rev. Mod. Phys. 90, 045005 (2018)[2] Wineland, David J., et al., Journal of research of NIST 103.3 (1998): 259.
[3] P. Micke, T. Leopold, S. A. King et al., Nature 578, 7793 (2020)[4] J. Stark et al., Rev. Sci. Instr. 92, 083203 (2021)

48

ST-15
Dynamics of mixed species Coulomb crystals with highly charged ions in asuperconducting Paul trap
Elwin A. Dijck, Christian Warnecke, Malte Wehrheim, Michael Karl Rosner, Andrea Graf,
Ruben Henninger, Thomas Pfeifer, José R. Crespo López-Urrutia
Max Planck Institute for Nuclear Physics, Heidelberg, Germany
The CryPTEx-SC project at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany,is designed to perform precise spectroscopy of highly charged ions (HCIs), which are excellent
candidates for the development of next-generation atomic clocks and sensitive probes in the search
for new physics [1]. The spectroscopy trap is formed by merging a linear Paul trap with asuperconducting radio-frequency resonator, providing ultralow-noise radial confining potentials [2].
Control and read-out of HCIs will be implemented using quantum logic spectroscopy with cotrapped Be+ ions.
We present results from the first cold highly charged ions stored in our ion trap. After production of
the HCIs in an electron beam ion trap (EBIT), they are extracted in pulses into an electrostatic
beamline where they are decelerated and bunched. The HCIs are then captured in andsympathetically cooled by a Coulomb crystal of several dozen laser-cooled Be+ ions trapped in thePaul trap beforehand. Subsequent controlled removal of Be+ ions by exciting secular motion is used
to prepare mixed species ion crystals comprising various numbers of Be+ ions and HCIs, down to asingle HCI with a single Be+ ion, the prerequisite for quantum logic spectroscopy.
The flexible retrapping technique will be discussed, which opens up the extensive range of highly
charged ion species to precision studies and additionally allows to explore the dynamics of mixed
species Coulomb crystals consisting of ions with disparate charge-to-mass ratios.

Figure 1: Overview of producing HCIs in an electron beam ion trap, transferring through a beamline
and retrapping in a superconducting resonator Paul trap with example EMCCD image of a mixed
species Coulomb crystal comprising three 9Be+ ions and one 40Ar10+ ion.
References[1] M. G. Kozlov et al., Rev. Mod. Phys. 90, 045005 (2018)[2] J. Stark et al., Rev. Sci. Instrum. 92, 083203 (2021)

49

ST-16First Dielectronic Recombination Measurements
at the Cryogenic Storage Ring
Leonard Isberner1 , Manfred Grieser2 , Robert von Hahn2 , Zoltán Harman2 , Ábel Kálosi3,2 ,Christoph H. Keitel2 , Claude Krantz4 , Daniel Paul3,2 , Suvam Singh2 , Andreas Wolf2 ,Stefan Schippers1 , and Oldřich Novotný2
I. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany
2
Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
3
Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
4
GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
1

The charge balance in plasmas is governed by competing processes for ionization and recombination.
For the understanding and modeling of plasmas in astrophysical environments as well as terrestrial
applications, data on the recombination of atomic ions with free electrons are of high importance [1].
Over the past three decades, such recombination processes have been studied extensively in magnetic
heavy-ion storage rings by applying the electron-ion merged-beams technique [2]. A challenge ofthese experiments is the background produced by electron capture from residual gas. Because of therelatively high vacuum pressure of conventional room temperature magnetic storage rings, measurements were restricted to ions with a high charge-to-mass ratio, which could be stored at sufficiently
high energies where the rate coefficient for residual-gas-related electron capture drops. Data on lowcharged heavy ions are still widely missing.
The electrostatic Cryogenic Storage Ring CSR [3], located at the Max-Planck-Institut für Kernphysik
in Heidelberg, Germany, combines the mass-independent storage of electrostatic storage rings withthe excellent vacuum conditions provided by its fully-cryogenic beam environment. It is equippedwith an electron cooler and a suitable single particle detector. The unique environment of CSR, thus,
is promising for the investigation of electron-ion recombination in low-charged heavy ions.
Here, we report on the first recombination studies with atomic ions at CSR. We have investigateddielectronic recombination of Ne2+ and Xe3+ , where we observed resonant recombination featuresin agreement with quantum-theoretical predictions. Our results clearly demonstrate the feasibility ofatomic recombination studies with heavy low-charged ion species at CSR.
References[1] A. Müller, Adv. At. Mol. Opt. Phys. 55, 293 (2008).
[2] S. Schippers, Nucl. Instrum. Methods Phys. Res., Sect. B 350, 61 (2015).
[3] R. von Hahn et al., Rev. Sci. Instr, 87, 063115 (2016).

50

ST-17High-Resolution X-Ray Spectroscopy of He-like Uranium using Novel
Microcalorimeter Detectors
Ph. Pfäﬄein1,2,3, S. Allgeier4, Z. Andelkovic2, S. Bernitt1,2,3, A. Borovik5, L. Duval6,
A. Fleischmann4, O. Forstner1,2,3, M. Friedrich4, J. Glorius2, A. Gumberidze2, Ch. Hahn1,2,
F. Herfurth2, D. Hengstler4, M. O. Herdrich1,2,3, P.-M. Hillenbrand5, A. Kalinin2, M. Kiﬀer1,3,
F. M. Kröger1,3, M. Kubullek3, P. Kuntz4, M. Lestinsky2, B. Löher2, E. B. Menz1,2,3, T. Over1,3,
N. Petridis2, S. Ringleb1,3, R. S. Sidhu2, U. Spillmann2, S. Trotsenko1,2, A. Warczak7, G. Weber1,2,
B. Zhu1,2,3, C. Enss4, and Th. Stöhlker1,2,3
1

HI Jena, Jena, Germany
GSI, Darmstadt, Germany
3
IOQ, Univ. of Jena, Jena, Germany
4
KIP, Heidelberg Univ., Heidelberg, Germany
5
I.PI, Gießen Univ., Gießen, Germany
6
LKB, Univ. Paris Sorbonne, Paris, France
7
Jagiellonian Univ., Krakow, Poland
2

Helium-like ions are the simplest atomic multibody systems and their study along the isoelectronic
sequence provides a unique testing ground for the interplay of the effects of electron–electron
correlation, relativity and quantum electrodynamics. However, for high-Z ions with nuclear charge
Z > 54, where inner-shell transition energies reach up to 100 keV, there is currently no data
available with high enough resolution and precision to challenge state-of-the-art theory [1]. In thiscontext the recent development of metallic magnetic calorimeter (MMC) detectors is of particularimportance. Their high spectral resolution of a few tens of eV FWHM at 100 keV incident photon
energy in combination with a broad spectral acceptance down to a few keV will enable new types ofprecision x-ray studies [2].
We report on the first application of MMC detectors for high-resolution x-ray spectroscopy at theelectron cooler of the low-energy storage ring CRYRING@ESR at GSI, Darmstadt. Within thepresented experiment, the x-ray emission associated with radiative recombination of storedhydrogen-like uranium ions and cooler electrons was studied. Two MMC detectors developed
within the SPARC collaboration [3] were placed at observation angles of 0° and 180° with respect
to the ion beam axis. Special emphasis will be given to the achieved spectral resolution of better
than 90 eV at x-ray energies close to 100 keV enabling for the first time to resolve the substructureof the Kα1 and Kα2 lines. Furthermore, the various unique aspects resulting from the selected
detection geometry in combination with the broad spectral acceptance of the detectors will bepresented.
References
[1]
[2]
[3]

P. Beiersdorfer and G.V. Brown, Phys. Rev. A 91, 032514 (2015).
S. Kraft-Bermuth et al., Atoms 2018, 59 (2018)
D. Hengstler et al., Phys. Scr. 2015, 014054 (2015)51

ST-18High resolution measurement of the 2p3/2→2s1/2 intra-shell transition in Helike uranium

R Loetzsch1, U Spillmann2, D Banas3, H Beyer2,P Dergham4, L Duval5, J Glorius2, R Grisenti2,
A Gumberidze2, P-M Hillenbrand2, P Indelicato5, Y Litvinov2, P Jagodzinski3, E Lamour4, N Paul5,
G Paulus1,6, N Petridis2, M Scheidel2, R S Sidhu2, S Steydli4, K Szary3, S Trotsenko2, I
Uschmann1,6, G Weber6, T Stoehlker1,2,6 and M Trassinelli5
1Institute of Optics and Quantum Elektronics, Friedrich Schiller University Jena, Jena, Germany
2
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
3Institute of Physics, Jan Kochanowski University, Kielce, Poland
4
Institut des NanoSciences de Paris, CNRS, Sorbonne Universités, Paris, France
5
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research Univ., Collége deFrance, Paris, France
6
Helmholtz-Institut Jena, Jena,Germany
He-like ions, the simplest multi-body atomic systems, offer the possibility to probe QED correlationand electron interaction effects. The theoretical description of these effects in extrem high electricfields, as for high-Z ions, is still challenging and different approaches leaves to different results.
Thus tests by experiments are needed. By measuring the difference in transition energies between
He- and Li-like ions, it is additionally possible to effectively isolate the electron correlations effects.
Precision spectroscopy of He-like heaviest ions is also experimentally very challenging and the
2p3/2 2s1/2 transition in uranium was only measured in an pilot experiment [1] at the ESR withlimited accuracy.
We measured the 2p3/2→2s1/2 transition in He-like uranium at the ESR of GSI, employing a bent
crystal Bragg spectrometer. This allows for an energy resolution of ~2.7 eV and an statisticalaccuracy of ~0.06 eV. By comparing the line to the corresponding transition in Li-like uranium, wereach for an accuracy of ~0.15 eV on the absolute energy of the He-like and ~0.06 eV for the
relative measurement of the two lines. This allows for an unmatched test of electron correlation
effects and two-loop corrections of Quantum Electrodynamics in few electron systems in strong
electric fields with the errors of the measurement comparable to the best theoretical values.
This research has been conducted in the frame-work of the SPARC collaboration, experiment E125
of FAIR Phase-0 supported by GSI. It is further supported by the Extreme Matter Institute EMMI
and by the European Research Council (ERC) under the European Union's Horizon 2020 research
as well as by the innovation pro-gramme (Grant No 682841 "ASTRUm") and the grant agreementn° 6544002, ENSAR2. We acknowledge substantial support by ErUM-FSP APPA (BMBF n°
05P19SJFAA) too.

Figure 1: Detector image of the 2p3/2→2s1/2 transition in He-like uranium. Dispersion is in thehorizontal direction. The slant of the line is due to the Doppler shift.
References[1] M. Trassinelli et al, EPL 87, 63001 (2009)52

ST-195p-5s spectrum in highly charged WXII - WXIV Ions
Priti1⇤ , Momoe Mita2 , Daiji Kato1,3 , Izumi Murakami1,4 ,Hiroyuki A. Sakaue1 , Nobuyuki
Nakamura2
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan
3
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka
816-8580, Japan
4
Department of Fusion Science, Sokendai, Toki, Gifu 509-5292, Japan*priti.priti@nifs.ac.jp
12Spectral lines from highly charged tungsten ions, specially, from WIV-WXVI have been predicted
to be useful in diagnostic of the ITER divertor plasma [1]. Tungsten ions having charge state WXII- WXVI are anticipated to show the transitions lines from the 5p to the 5s subshell in EUV region.
These ions are highly correlated system with an open 4f subshell for which accurate calculations
are challenging. Due to the complexity of observed spectra there was an ambiguity in charge state
identification in previous study [2]. Also, there is no data available for W XII in extreme ultraviolet(EUV) range [3-4]. We present detailed theoretical analysis of 5p-5s transition of W XII–W XIV
ions for the spectroscopic measurements performed at compact electron beam ion trap (CoBIT) [5-6].
The analysis of the observed spectra is based on the detailed collisional-radiative modeling with finestructure sub-levels atomic kinetics. The wavelength and rate of the transitions of W XII–W XIV
ions calculated by the relativistic configuration interaction using flexible atomic code. Theoreticalresults are in reasonable agreement with the experimental observations (⇠18-28nm), which provides
the clear assignment of the ionization stage and corresponding lines.
References[1] J. Clementson et al., J. Phys. B: At. Mol. Opt. Phys. 43, 063104 (2010)[2] W. Li, Z. Shi, Y. Yang, J. Xiao, T. Brage, R. Hutton, and Y. Zou, Phys. Rev. A 91, 062501 (2015).
[3] Kramida A, et al, NIST Atomic Spectra Database, version 5.7.1 (2020).
[4] Priti, M Mita, D Kato, et. al. Phys. Rev. A, 102, 04281 (2020)[5] Nakamura N, et al 2008 Rev. Sci. Instrum. 79 144009[6] Mita M, et al, J. Phys.: Conf. Ser. 675 012019 (2017)53

ST-20Collisional-radiative model for the spectra of M1 transition of W53+ ion
Y. L. Xu1 , X. B. Ding1∗ , Y. Yang2 , K. Yao2 , L. Zhang3 , F. Koike4 , D. Kato5 , I. Murakami5 , H. A.
Sakaue5 , N. Nakamura6 , C. Z. Dong1
Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070,
China
2
Key Laboratory of Applied Ion Beam Ministry of Education, Institute of Modern Physics, Fudan
University, Shanghai 200433, China
3
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230000, China
4
Department of Physics, Sophia University, Tokyo 102-8554, Japan
5
National Institute for Fusion Science, Gifu 509-5292, Japan
6
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan1

The emission spectrum of tungsten ions can be used to diagnose the status of the fusion plasma[1,2].
Based on the experimental study of M1 transition spectrum of W53+ ion by Ralchenko et al. [3], thecollisional-radiative model (CRM) were used to investigate the spectrum.
The configurations included in the present CRM are 3s2 3p6 3d3 , 3s1 3p6 3d4 , and 3s2 3p5 3d4 . In order
to consider the electron correlation effects, the SD excited configurations, such as, 3s1 3p6 3d3 4l(l =0 − 2), 3p6 3d5 , 3p6 3d3 4s2 and 3s2 3p6 3d2 6l(l = 0 − 4) are included as the correlation configurations.
The simulated spectrum is in good agreement with the observed spectrum on the EBIT. Five observed
transitions were identified and assigned to the transitions within the multiplets of the ground configuration. The transition m in Fig1.(c) is predicted to be the M1 transition of W53+ ions which is
not assigned in the previous work. This work provided the knowledge of the highly charged W ionswhich will be helpful for the future investigation on these ions and the fusion plasma.

Figure 1: (a) Radiative transition rate, (b) Intensity from CRM. (c) Experimental spectra from the
EBIT [3]. Each individual transition was assumed to have Gaussian profile with FWHM = 0.02nm.
References[1] Y. Podpaly, J. Clementson, P. Beiersdorfer, et.al, Phys. Rev. A 80, 052504 (2013)[2] X. B. Ding, P. Yang, G. Zhang, et.al, Phys. Lett. A 420, 127758 (2021)[3] Yu. Ralchenko, I. N. Draganic, D. Osin, et.al, Phys. Rev. A 83, 032517 (2011)54

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ST-22First broadband laser cooling and XUV fluorescence detection of stored
relativistic HCIKEN UEBERHOLZ1, LARS BOZYK2, MICHAEL BUSSMANN3,4, NOAH EIZENHÖFER5, VOLKER
HANNEN1, MAX HORST5,6, DANIEL KIEFER5, NILS KIEFER7, SEBASTIAN KLAMMES2, THOMAS
KÜHL2,8, BENEDIKT LANGFELD5, MARKUS LOESER4, XINWEN MA9, WILFRIED NÖRTERSHÄUSER5,6,
RODOLFO SANCHEZ2, ULRICH SCHRAMM4,10, MATHIAS SIEBOLD4, PETER SPILLER2, MARKUSSTECK2, THOMAS STÖHLKER2,8,11, THOMAS WALTHER5,6, HANBING WANG9, CHRISTIANWEINHEIMER1, WEIQIANG WEN9 and DANYAL WINTERS2
1University of Münster, Institute of Nuclear Physics (Germany)
2GSI Darmstadt (Germany), 3CASUS Görlitz (Germany), 4HZDR Dresden (Germany), 5TU

Darmstadt (Germany), 6HFHF Darmstadt (Germany), 7University Kassel (Germany), 8HI Jena
(Germany), 9IMP Lanzhou (China), 10TU Dresden (Germany), 11University Jena (Germany)At the highly relativistic energies and high intensities of the ion beams in the new SIS100
accelerator at FAIR, conventional beam cooling techniques (e.g. electron and stochastic cooling)
have some limitations and laser cooling is a more elaborate and efficient method for cooling.
Despite one specific requirement, i.e. the need for a fast electronic transition in the ions, at the
SIS100 many different ions (element & charge state) can be laser-cooled, owing to the large
magnetic rigidity of the SIS100 (max. 100 Tm). Importantly, the use of new pulsed (rep. rate~MHz) and tunable CW laser systems (UV and VIS wavelengths) will greatly enlarge and enhance
the potential of this cooling method. However, the much higher beam energies at the SIS100 also
require new approaches for in vacuo detection of the fluorescence emitted by the ions, as it isrequired for laser spectroscopy and laser cooling.
In May 2021, an improved XUV fluorescence detection system and a new tunable pulsed UV laser
system were employed for laser cooling of bunched relativistic (47% of c) carbon ions at theExperimental Storage Ring of GSI Helmholtzzentrum Darmstadt, Germany. Successful broadband
laser cooling was demonstrated using this powerful (~200 mW), high repetition rate (~10 MHz) andtunable (wavelength and pulse duration) UV laser system. The experiment and its results will be
discussed.
In addition, we will present our new fluorescence detection and spectroscopy system for the laser
cooling project at the upcoming SIS100 accelerator. The new dispersed flourescence detection
system uses an aberration corrected laminar grating in grazing incidence geometry and an open facemicro-channel plates detector in Chevron stack configuration (sensitive in the soft X-Ray regime)with postion and time sensitive delay-line readout. If no energy resolution is required, the system
can also be used for direct detection of the fluorescence photons with a significantly larger
acceptance.
This work has been supported by the BMBF under contract number 05P19PMFA1 and
05P21RDFA1.

56

ST-23High-resolution spectroscopy of electronic K x rays from muonic atoms
T. Okumura1,2, T. Azuma2,1, D. A. Bennett3, W. B. Doriese3, M. S. Durkin3, J. W. Fowler3,
J. D. Gard3, T. Hashimoto4, R. Hayakawa1,5, G. C. Hilton3, Y. Ichinohe5, P. Indelicato6, T. Isobe2,
S. Kanda7, D. Kato8, M. Katsuragawa9, N. Kawamura7, Y. Kino10, N. Kominato5, Y. Miyake9,
K. M. Morgan3, H. Noda11, G. C. O’Neil3, S. Okada12, K. Okutsu10, H. Oomamiuda5, T. Osawa5,N. Paul6, C. D. Reinstema3, T. Sato5, D. R. Schmidt3, K. Shimomura7, P. Strasser7, H. Suda1,
D. S. Swetz3, T. Takahashi9, S. Takeda9, S. Takeshita7, M. Tampo7, H. Tatsuno1, X. M. Tong13,
Y. Toyama12, Y. Ueno2, J. N. Ullom3, S. Watanabe14, S. Yamada5, and T. Yamashita10
1

Tokyo Metropolitan University, Tokyo 1920397, Japan,
2
RIKEN, Wako 3510198, Japan,
3
National Institute of Standards and Technology, Boulder, CO 80305, USA,
4
Japan Atomic Energy Agency, Tokai 3191184, Japan,
5
Rikkyo University, Tokyo 1718501, Japan,
6
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University,
Collége de France, Case 74, 4, place Jussieu, 75005 Paris, France,
7
High Energy Accelerator Research Organization (KEK), Tsukuba 3050801, Japan,
8
National Institute for Fusion Science (NIFS), Toki, Gifu 5095292, Japan,
9
Kavli IPMU (WPI), The University of Tokyo, Kashiwa, Chiba 2778583, Japan,
10
Tohoku University, Sendai, Miyagi 9808578, Japan,
11
Osaka University, Osaka 5600043, Japan,
12
Chubu University, Kasugai, Aichi 4878501, Japan,
13
University of Tsukuba, Tsukuba, Ibaraki 3058573, Japan,
14
Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 2525210, JapanA muonic atom consists of a negatively-charged muon and a nucleus, sometimes accompanied bybound electrons. When a negative muon encounters an atom, the muon is captured in a highly
excited state of the atom and then deexcites to lower energy levels step-by-step with the emission ofAuger electrons and muonic x rays. Electron holes formed during this cascade process are
immediately filled by the upper-level electrons, e.g., via characteristic x-ray emission.
We carried out high-resolution measurements of electronic K x rays from muonic atoms at JPARC using a state-of-the-art x-ray detector, Transition-Edge Sensor (TES) microcalorimeters.
For muonic Fe ( Fe) in a Fe metal [1], we observed an asymmetric and broad peak of electronic
K x rays, as shown in Figure 1. This feature reflects the dynamics of the cascade process because
the energies of the K x rays are sensitive to the nuclear-charge screening by the muon and electron
holes at the moment of the x-ray emission. In dense targets like metals, electron refilling from thesurrounding follows, which is similar to de-excitation
dynamics of highly-charged ions in metals [2].
On the other hand, for muonic Ar ( Ar) in a gas
phase [3], we found distinctively-resolved several
peaks corresponding to highly-charged muonic atoms
with a few bound electrons, where electron refilling isabsent.
References[1] T. Okumura et al., Phys. Rev. Lett. 127, 053001 (2021).
[2] A. Arnau et al., Surf. Sci. Rep. 27, 113 (1997).
[3] T. Okumura et al., in preparation.

57

Figure 1: electronic K x-ray spectrum.

ST-24Absolute nuclear radius of iridium from precision measurements andcalculations of EUV and X-ray transitions in highly charged ionsA. Hosiera,b , Diptib , R. Silwalc , A. Lapierred , S. A. Blundelle , S. Sandersa , Y. Yanga,b , P. Szyprytf ,G. O’Neilf , J. N. Tanb , A. Naingb , J. D. Gillaspyb,g , J. M. Dreilingb , G. Gwinnerh , A. C. C. Villarid ,Yu. Ralchenkob , E. Takacsa,bDepartment of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978bNational Institute of Standards and Technology, Gaithersburg, MD 20899
c
Department of Physics and Astronomy, Appalachian State University, Boone, NC 28608dFacility for Rare Isotope Beams, 640 S Shaw Ln, East Lansing, MI 48824
eUniversity of Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, FrancefNational Institute of Standards and Technology, Boulder, CO 80305g
National Science Foundation, Alexandria, VA 22314
hUniversity of Manitoba, Winnipeg, MB R3T 2N2, Canadaa

The absolute nuclear radius of 193 Ir [1] has been determined by precisely measuring the relative
difference in charge radii between osmium and iridium isotopes by novel spectroscopic observationsof highly charged ions in the extreme ultraviolet (EUV) and x-ray regime. The electron beam ion trap
(EBIT) at the National Institute of Standards and Technology (NIST) was used at a beam energy ofabout 18 keV to produce highly charged ions of Os and Ir.
The light-emission spectra generated by electron impact excitation were observed using a flat-fieldgrazing-incidence spectrometer [2] over a range of 4 nm to 20 nm and recorded using an EUV CCD
detector with a pixel resolution of about 0.008 nm. Simultaneously, x-ray photons were collectedwith the NIST Transition-Edge Sensor (TES) microcalorimeter [3] over a broadband energy range ofroughly 500 eV to 8000 eV with an energy resolution of around 4 eV.
The dominant spectral lines of both Os and Ir observed in the EUV and x-ray range were Na-like
3s–3p1/2 , 3s 3p3/2 and Mg-like 3s2 –3p1/2 , 3s2 3p3/2 transitions respectively. The difference in the
wavelength between the corresponding Ir and Os transitions was measured over the course of several
days by cycling the injection of Os, Ir into the EBIT. Calibration of the instrument was regularly
performed during the run by injecting Ne and observing lines from trace elements of Xe and Ba.
The observed wavelength differences are directly related to the difference in the mean square radii
through the expansion of the nuclear Seltzer moment. Precision atomic structure calculations were
performed using GRASP2K [4] and RMBPT [5] packages. A comparison with prior nuclear physics
experimental methods will be reported.
References[1] I. Angeli and K. P. Marinova, At. Data Nucl. Data Tables 99, 69 (2013)[2] B. Blagojevic et al., Rev. Sci. Instrum. 76, 083102 (2005)[3] P. Szypryt et al, Review of Scientific Instruments 90, 123107 (2019)[4] P. Jönsson et al. Comput. Phys. Commun. 184, 2197 (2013)[5] S. A. Blundell, Phys. Rev. 47, 1790 (1993)58

ST-25Laser Spectroscopy of 12C4+: First results towards an all-optical charge radiusdetermination
Phillip Imgram, Kristian König, Bernhard Maaß*, Patrick Müller, Wilfried Nörtershäuser
Institute for Nuclear Physics, Technical University of Darmstadt, 64289 Darmstadt, Germany(*) Physics Division, Argonne National Laboratory, Lemont, IL 60439, USA

The size of an object is one of the most obvious observables. This also holds true for very small
objects such as atomic nuclei. Therefore the nuclear size is of scientific interest since the discovery
of its existence by Rutherford. Different measurement techniques have been developed over timesuch as elastic electron scattering or muonic spectroscopy to extract nuclear charge radii whereas
atomic spectroscopy has so far been limited to H and He or to the differential nuclear charge radii ofshort-lived isotopes accessed by collinear laser spectroscopy (CLS). In a new approach we want to
exploit the fast measurement scheme of CLS to optically measure the absolute charge radius offurther He-like ions (Be2+, B3+, C4+, ...) by exciting the ions from the metastable 2 3S1 state, which
has a lifetime of a few 10-100 ms, to the 2 3PJ states. A transition frequency accuracy of approx. 1
MHz is targeted using simultaneous collinear and anticollinear laser spectroscopy. This
experimental value is to be compared with nonrelativistic QED calculations [1] that are currently
being performed. The results will compliment and improve existing measurements of nuclear
charge radii.
The first high-precision collinear laser spectroscopy measurements of 12C4+ have been carried out at
the Collinear Apparatus for Laser Spectroscopy and Applied Physics (COALA) at the Institute of
Nuclear Physics of TU Darmstadt which has recently been upgraded with an electron beam ion
source to produce the highly charged ions. This contribution will summarize the current status of
the project and present first results which will serve to benchmark the QED calculations. This
project is supported by the German Research Foundation (Project-ID 279384907 – SFB1245).

References[1] V. Patkós et al., Phys. Rev. A 103, 042809 (2021)

59

POSTERS A

60

A01
Probing surface magnetism with highly charged ions
P. Dergham1 , F. Aumayr2 , E. Lamour1 S. Macé1 , C. Prigent1 , S. Steydli1 , D. Vernhet1 , M. Werl2 ,R.A. Wilhelm2 , M. Trassinelli1
1Institut des NanoSciences de Paris, UMR 7588 CNRS- Sorbonne Université, Paris, 75005, France
2
Institute of Applied Physics, TU Wien, Vienna, 1040, Austria

The interaction between highly charged ions and surfaces started in the ’90s and it has been deeply
investigated since then. Few studies have been accomplished with surfaces that present some defined magnetic order, as magnetic domains of a ferromagnetic phase. Here, we investigate slow HCI,
during a grazing collision that capture electrons in highly excited states from the very first atomic
layers, which could be in a particular magnetic phase. The working hypothesis is that the subsequent
electron and photon emission bears the fingerprint of the local spin-ordering of the sample allowing
magnetic properties’ characterization of the sample. The ability to detect the presence of a ferromagnetic ordered phase in ion–surface interaction, even with no external magnetic field applied, wasdemonstrated in the past using Auger spectroscopy [1]. In these first attempts, only a qualitative
evidence was obtained and a dispute arose in the scientific community on the general applicabilityof this method. Theoretical studies could not clarify this controversy. The goal of our project is toprovide answers to these questions with a new approach where emitted X-ray photon and ion charge
state (coupled eventually with energy loss) after the collision are simultaneously detected. This experimental method should allow us to characterize the collisional dynamics and provide quantitative
information on the surface magnetization. The coincidence between X-rays and ions with a limited
modification of their charge by the collision will enable us to efficiently identify grazing collisions
for which the interatomic Coulomb decay [2] is not dominant. Indeed, this process does not conserve
the spin orientation and consequently the information about a possible spin orientation of the sample
surface. The energy of the X-rays selected by ion detection coincidence will allow identifying thespin of the populated levels and, accordingly, the magnetic phase of the sample surface. Preliminary
results will be presented.
References[1] M. Unipan, A. Robin, R. Morgenstern and R. Hoekstra, Phys. Rev. Lett. 96, 177601 (2006)[2] R.A. Wilhelm, E. Gruber, J. Schwestka, et al., Phys. Rev. Lett. 119, 103401 (2017)

61

A02
Shape and satellite studies of HCI high-accuracy X-ray spectraby Bayesian methods
M. Trassinelli
Institut des NanoSciences de Paris, UMR 7588 CNRS- Sorbonne Université, Paris, 75005, France
High-accuracy spectroscopy commonly requires dedicated investigations on spectral line modeling to
avoid to add possible systematic errors. For such a kind of problem, analysis of 2 , likelihood values
or other criteria, are normally implemented to choose between the different spectrum modeling. Thesestandard practices are however affected by several problems and, in the first place, their uselessness
if there is no a clear propensity to a specific model. Such issues are fixed by Bayesian statistics in thecontext of which a probability can be assigned to different models/hypotheses from the analysis ofa same set of data. These probabilities are calculated from the integration of the likelihood function
over the model parameter space with the evaluation of the so-called Bayesian evidence. Here I will
apply the Bayesian model selection method in the context of heavy HCI X-ray spectroscopy. In
particular, I will present the result of the analysis of spectral lines corresponding of helium-, lithiumand beryllium-like uranium ions obtained in a recent experiment [1] (fig. left). I will show how
to assign probabilities to different line profiles (Gaussian, Supergaussian, . . . , straight line, curvedline, . . . ) from the evaluation of the Bayesian evidence. Moreover, when the presence of a satellite
line cannot be excluded (fig. right), I will present how to correctly estimate the position of the main
spectral component. These analyses have been obtained by the freely available code nested fit[2] based on the nested sampling algorithm for the evaluation of the Bayesian evidence [3].

Figure 1: Left: 1s2 2p3/2 ! 2s2 2s1/2 lithium-like uranium transition detected by a X-ray CCD
mounted on a high-resolution Bragg spectrometer. Right: Projection on the dispersion axis modeled with two spectral contributions.
References[1] GSI/FAIR phase-0 experiment E125, see R. Lötzsch et al. contribution[2] M. Trassinelli and P. Ciccodicola, Entropy 22, 185 (2020); M. Trassinelli, Proceedings 33, 14(2019); M. Trassinelli, Nucl. Instrum. Methods B 408, 301-312 (2017);
https://github.com/martinit18/nested_fit[3] J. Skilling, Bayesian Anal. 1, 833-859 (2006)

62

A03
Testing QED in heliumlike high-Z ions, a Bayesian approach
M. Trassinelli1 , L. Duval1,2 , P. Indelicato2 , J. Machado2,3 , N. Paul2
Institut des NanoSciences de Paris, UMR 7588 CNRS- Sorbonne Université, Paris, 75005, France
2
Laboratoire Kastler Brossel, Sorbonne Université, ENS-PSL Research University, Collège deFrance, CNRS, 75005 Paris, France
3
Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL),
Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon,
2829-516 Caparica, Portugal

1

Quantum Electrodynamics (QED) is, at present, the most tested foundalental theory, with an accuracyof one part in a trillion for the gyromagnetic factor of free electron. In atomic systems, the situation
is more complex due to the presence of a nucleus structure and even more demanding for heavy
highly charged ions (with Z↵ . 1), due to the non-converging perturbation expansion in Z↵ . 1. In
light of new high-accuracy measurements on He-like ions, in 2012 Chantler and coworkers claimed a
deviation of QED predictions, with a dependency on Z 3 , for the energies of n = 2 ! 1 transitions in
medium/high-Z two-electrons ions [1]. Such a claim has been fought back from more recent studies
via alternative statistical analyses and new measurements [2–5], all confirming QED predictions.
These investigations are however exclusively based on standard (frequentist) statistical methods. Here
we present a new study based on Bayesian probability to test the relevance of a possible deviation of
QED predictions in He-like ion transitions. Differently to frequentist methods, where only criteria
are available to choose among models, Bayesian methods allow to assign probabilities to different
hypotheses (QED is right, a deviation with a dependency on Z, on Z 2 , etc.). The evaluation of eachmodel probability is based on the computation of the Bayesian evidence (marginalized likelihood),
which consist on the integration of the likelihood function over the model parameter values. We
present here the results of new different statistical studies (Bayesian and frequentist), including thevery recent measurements on He-like sulfur and uranium [6], which will be compared with the past
results. In particular, when the same data than Ref. [1], the Bayesian analysis indicates a dependency
on Z 2 as the most probable, and not on Z 3 like Chantler et al [1].
References[1] C.T. Chantler et al., Phys. Rev. Lett. 109, 153001 (2012)[2] S.W. Epp, Phys. Rev. Lett. 110, 159301 (2013).
[3] P. Beiersdorfer and G.V. Brown, Phys. Rev. A 91, 032514 (2015)[4] J. Machado et al., Phys. Rev. A 97, 032517 (2018)[5] P. Indelicato, J. Phys. B 52, 232001 (2019)[6] GSI/FAIR phase-0 experiment E125, see R. Lötzsch et al. contribution

63

A04
Two-loop self-energy corrections to the bound-electron g-factor:
Status of M-term calculations
Bastian Sikora, Vladimir A. Yerokhin*, Christoph H. Keitel and Zoltán Harman
Max Planck Institute for Nuclear Physics, Heidelberg, Germany(*) Center for Advanced Studies, Peter the Great St. Petersburg Polytechnic University, St.
Petersburg, Russia
The theoretical uncertainty of the bound-electron g-factor in heavy hydrogenlike ions is dominatedby uncalculated QED Feynman diagrams with two self-energy loops. Precision calculations of these
diagrams in which the interaction between electron and nucleus is treated exactly are needed to improve the theoretical accuracy of the bound-electron g-factor in the high-Z regime. Results of suchcalculations are highly relevant for ongoing and future experiments with high-Z ions as well as for
an independent determination of fundamental constants such as the electron mass me and the finestructure constant ↵ from the bound-electron g-factor [1]. Furthermore, comparisons of theory andexperiment for heavy ions can serve as a probe for physics beyond the Standard Model after an improvement of the theoretical accuracy through the completion of two-loop calculations [2].
Due to the presence of ultraviolet divergences, two-loop self-energy Feynman diagrams need to be
split into the loop-after-loop (LAL) contribution and the so-called F-, M- and P-terms which requiredifferent analytical and numerical techniques. The F-term corresponds to the ultraviolet divergent
part of the nested and overlapping loop diagrams with free electron propagators inside the self-energy
loops. The M-term corresponds to the ultraviolet finite part of nested and overlapping loop diagrams
in which the Coulomb interaction in intermediate states is taken into account exactly. In our previous work, we have obtained full results for LAL and the F-term [3]. In this work, we present our
results for the M-term contribution. P-term contributions correspond to diagrams which contain bothbound-electron propagators inside the self-energy loops as well as an ultraviolet subdiagram and will
be considered in a future work.

Figure 1: Furry-picture Feynman diagrams of the two-loop self-energy correction to the boundelectron g-factor.
References[1] S. Sturm, I. Arapoglou, A. Egl, et al., Eur. Phys. J.: Spec. Top. 227, 1425 (2019).
[2] V. Debierre, C. H. Keitel and Z. Harman., Phys. Lett. B 807, 135527 (2020).
[3] B. Sikora, V. A. Yerokhin, N. S. Oreshkina, et al., Phys. Rev. Research 2, 012002(R) (2020).

64

A05
Theory of the magnetic moments and hyperfine splitting of 3 He+
Bastian Sikora, Natalia S. Oreshkina, Igor Valuev, Zoltán Harman and Christoph H. Keitel
Max Planck Institute for Nuclear Physics, Heidelberg, Germany
In an external magnetic field, the ground state of the 3 He+ ion is split into into four sublevels due to the
combined hyperfine splitting and Zeeman effect. By measuring transition frequencies between thesesublevels, it is possible to determine the g-factor of the bound electron, the ground-state hyperfine
splitting as well as the shielded magnetic moment of the nucleus [1].
In this work, we present the theoretical calculations of the nuclear shielding constant, the groundstate hyperfine splitting and the bound-electron g-factor [2]. The theoretical uncertainty of the boundelectron g-factor is dominated by the uncertainty of the fine-structure constant ↵. This would allow an
independent determination of ↵ in future, provided that the experimental precision can be improved
accordingly [3]. Combining the experimental value for the shielded nuclear magnetic moment andthe theoretical value for the nuclear shielding constant, we extracted the magnetic moment of the barenucleus with unprecedented precision, enabling new applications in magnetometry. Furthermore, we
extracted the nuclear Zemach radius from the experimental hyperfine splitting value, in tension withthe established literature value [4].
References[1] A. Mooser, A. Rischka, A. Schneider, et al., J. Phys. Conf. Ser. 1138, 012004 (2018).
[2] A. Schneider, B. Sikora, S. Dickopf, et al., Nature, accepted (2022).
[3] J. Zatorski, B. Sikora, S. G. Karshenboim, et al., Phys. Rev. A 96, 012502 (2017).
[4] I. Sick, Phys. Rev. C 90, 064002 (2014).

65

A06
Calculations of Delbrück scattering to all orders in ↵Z
J. Sommerfeldt, V. A. Yerokhin, R. A. Müller, A. Surzhykov
Physikalisch-Technische Bundesanstalt, D-38116 Braunschweig, Germany
Delbrück scattering is the process in which a photon is elastically scattered by the Coulomb field of a
nucleus or ion via the production of virtual electron-positron pairs, see figure 1.

Figure 1: Leading-order Feynman diagram for Delbrück scattering.
It is one of the few non-linear quantum electrodynamical processes that can be observed experimentally [1] and, hence, testing the respective theoretical predictions serves as an important test of the
QED theory in strong electromagnetic fields. However, despite the strong motivation for the theoretical analysis of Delbrück scattering, most of the previous studies have been limited to approximations
regarding the coupling between the virtual electron positron pairs and the nucleus. For example, many
authors have used the first order Born approximation in which all interactions with the Coulomb fieldbeyond the lowest order are neglected [2]. The accuracy of this approximation wanes for higher nuclear charges which are of particular experimental interest. Other methods, like the high-energy largeand small-angle approximation, also have strong limitations on the parameter regimes in which they
are applicable [3].
In this contribution, therefore, we present an efficient approach to calculate amplitudes for Delbrück
scattering [4]. Our formalism is based on the exact analytical Dirac-Coulomb Greens function and,hence, accounts for the interaction with nucleus to all orders including the Coulomb corrections.
References[1] M. Schumacher, Radiat. Phys. Chem. 56 (1999) 101-111[2] P. Papatzacos, K. Mork, Phys. Rev. D 12 (1975) 206-218[3] H. Falkenberg et al., Atomic Data and Nuclear Data Tables 50 (1992) 1-27
[4] J. Sommerfeldt et al., Phys. Rev. A 105 (2022) 022804

66

A07
Direct high precision measurement of the 𝑄-value of the electron capture in163
Ho and metastable states in highly charged ionsK. Kromer1, M. Brass2, J. R. Crespo López-Urrutia1, V. Debierre2, M. Door1, H. Dorrer3, Ch. E.
Düllmann3,4,5, S. Eliseev1, C. Enss6, P. Filianin1, L. Gastaldo6, Z. Harman1, M. W. Haverkort2, J.
Herkenhoff1, P. Indelicato7, C. H. Keitel1, D. Lange1, C. Lyu1, Yu. N. Novikov8, D. Renisch4,5, A.
Rischka1, R.X. Schüssler1, Ch. Schweiger1, and K. Blaum1
1
Max-Planck- Institut für Kernphysik, 69117 Heidelberg, Germany
Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
3Institut für Kernchemie, Johannes-Gutenberg-Universität Mainz, 55128 Mainz, Germany
4Helmholtz-Institut Mainz, 55128 Mainz, Germany5
GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
6
Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany
7
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège
de France, 75005 Paris, France
8
NRC K rchato Instit te -Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
2

The high-precision Penning-trap mass spectrometer Pentatrap [1] features a stack of five Penningtraps and determines mass-ratios with a relative uncertainty below 10 ppt. Mass-ratio
determinations of stable and long-lived highly charged ions have numerous applications, among
others, in neutrino physics [2] and the search of possible clock transitions in highly charged ions
(HCI) [3]. The unique features of Pentatrap include access to HCI, a stable 7 T magnet, and acryogenic detection system with single ion phase sensitivity. The latest measurements include the Q
value of the beta-decay of 163Ho with a relative uncertainty of below 7 ppt. In 208Pb a long-lived
metastable electronic state was discovered.

References[1] J. Repp, et al., Appl. Phys. B 107, 983 (2012)[2] J. Gastaldo, et al., Appl. Phys. B 226, 1623 (2017)[3] M.G. Kozlov, et al., Rev. Mod. Phys. 90, 045005 (2018)

67

A08
High-Resolution X-Ray Spectroscopy of He-like Uranium using Novel
Microcalorimeter Detectors
Ph. Pfäﬄein1,2,3, S. Allgeier4, Z. Andelkovic2, S. Bernitt1,2,3, A. Borovik5, L. Duval6,
A. Fleischmann4, O. Forstner1,2,3, M. Friedrich4, J. Glorius2, A. Gumberidze2, Ch. Hahn1,2,
F. Herfurth2, D. Hengstler4, M. O. Herdrich1,2,3, P.-M. Hillenbrand5, A. Kalinin2, M. Kiﬀer1,3,
F. M. Kröger1,3, M. Kubullek3, P. Kuntz4, M. Lestinsky2, B. Löher2, E. B. Menz1,2,3, T. Over1,3,
N. Petridis2, S. Ringleb1,3, R. S. Sidhu2, U. Spillmann2, S. Trotsenko1,2, A. Warczak7, G. Weber1,2,
B. Zhu1,2,3, C. Enss4, and Th. Stöhlker1,2,3
1

HI Jena, Jena, Germany
GSI, Darmstadt, Germany
3
IOQ, Univ. of Jena, Jena, Germany
4
KIP, Heidelberg Univ., Heidelberg, Germany
5
I.PI, Gießen Univ., Gießen, Germany
6
LKB, Univ. Paris Sorbonne, Paris, France
7
Jagiellonian Univ., Krakow, Poland
2

Helium-like ions are the simplest atomic multibody systems and their study along the isoelectronic
sequence provides a unique testing ground for the interplay of the effects of electron–electron
correlation, relativity and quantum electrodynamics. However, for high-Z ions with nuclear charge
Z > 54, where inner-shell transition energies reach up to 100 keV, there is currently no data
available with high enough resolution and precision to challenge state-of-the-art theory [1]. In thiscontext the recent development of metallic magnetic calorimeter (MMC) detectors is of particularimportance. Their high spectral resolution of a few tens of eV FWHM at 100 keV incident photon
energy in combination with a broad spectral acceptance down to a few keV will enable new types ofprecision x-ray studies [2].
We report on the first application of MMC detectors for high-resolution x-ray spectroscopy at theelectron cooler of the low-energy storage ring CRYRING@ESR at GSI, Darmstadt. Within thepresented experiment, the x-ray emission associated with radiative recombination of storedhydrogen-like uranium ions and cooler electrons was studied. Two MMC detectors developed
within the SPARC collaboration [3] were placed at observation angles of 0° and 180° with respect
to the ion beam axis. Special emphasis will be given to the achieved spectral resolution of better
than 90 eV at x-ray energies close to 100 keV enabling for the first time to resolve the substructureof the Kα1 and Kα2 lines. Furthermore, the various unique aspects resulting from the selected
detection geometry in combination with the broad spectral acceptance of the detectors will bepresented.
References
[1]
[2]
[3]

P. Beiersdorfer and G.V. Brown, Phys. Rev. A 91, 032514 (2015).
S. Kraft-Bermuth et al., Atoms 2018, 59 (2018)
D. Hengstler et al., Phys. Scr. 2015, 014054 (2015)

68

A09
Laser Spectroscopy of 12C4+: First results towards an all-optical charge radiusdetermination
Phillip Imgram, Kristian König, Bernhard Maaß*, Patrick Müller, Wilfried Nörtershäuser
Institute for Nuclear Physics, Technical University of Darmstadt, 64289 Darmstadt, Germany(*) Physics Division, Argonne National Laboratory, Lemont, IL 60439, USA

The size of an object is one of the most obvious observables. This also holds true for very small
objects such as atomic nuclei. Therefore the nuclear size is of scientific interest since the discovery
of its existence by Rutherford. Different measurement techniques have been developed over timesuch as elastic electron scattering or muonic spectroscopy to extract nuclear charge radii whereas
atomic spectroscopy has so far been limited to H and He or to the differential nuclear charge radii ofshort-lived isotopes accessed by collinear laser spectroscopy (CLS). In a new approach we want to
exploit the fast measurement scheme of CLS to optically measure the absolute charge radius offurther He-like ions (Be2+, B3+, C4+, ...) by exciting the ions from the metastable 2 3S1 state, which
has a lifetime of a few 10-100 ms, to the 2 3PJ states. A transition frequency accuracy of approx. 1
MHz is targeted using simultaneous collinear and anticollinear laser spectroscopy. This
experimental value is to be compared with nonrelativistic QED calculations [1] that are currently
being performed. The results will compliment and improve existing measurements of nuclear
charge radii.
The first high-precision collinear laser spectroscopy measurements of 12C4+ have been carried out at
the Collinear Apparatus for Laser Spectroscopy and Applied Physics (COALA) at the Institute of
Nuclear Physics of TU Darmstadt which has recently been upgraded with an electron beam ion
source to produce the highly charged ions. This contribution will summarize the current status of
the project and present first results which will serve to benchmark the QED calculations. This
project is supported by the German Research Foundation (Project-ID 279384907 – SFB1245).

References[1] V. Patkós et al., Phys. Rev. A 103, 042809 (2021)

69

A10
High resolution measurement of the 2p3/2→2s1/2 intra-shell transition in Helike uranium

R Loetzsch1, U Spillmann2, D Banas3, H Beyer2,P Dergham4, L Duval5, J Glorius2, R Grisenti2,
A Gumberidze2, P-M Hillenbrand2, P Indelicato5, Y Litvinov2, P Jagodzinski3, E Lamour4, N Paul5,
G Paulus1,6, N Petridis2, M Scheidel2, R S Sidhu2, S Steydli4, K Szary3, S Trotsenko2, I
Uschmann1,6, G Weber6, T Stoehlker1,2,6 and M Trassinelli5
1Institute of Optics and Quantum Elektronics, Friedrich Schiller University Jena, Jena, Germany
2
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
3Institute of Physics, Jan Kochanowski University, Kielce, Poland
4
Institut des NanoSciences de Paris, CNRS, Sorbonne Universités, Paris, France
5
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research Univ., Collége deFrance, Paris, France
6
Helmholtz-Institut Jena, Jena,Germany
He-like ions, the simplest multi-body atomic systems, offer the possibility to probe QED correlationand electron interaction effects. The theoretical description of these effects in extrem high electricfields, as for high-Z ions, is still challenging and different approaches leaves to different results.
Thus tests by experiments are needed. By measuring the difference in transition energies between
He- and Li-like ions, it is additionally possible to effectively isolate the electron correlations effects.
Precision spectroscopy of He-like heaviest ions is also experimentally very challenging and the
2p3/2 2s1/2 transition in uranium was only measured in an pilot experiment [1] at the ESR withlimited accuracy.
We measured the 2p3/2→2s1/2 transition in He-like uranium at the ESR of GSI, employing a bent
crystal Bragg spectrometer. This allows for an energy resolution of ~2.7 eV and an statisticalaccuracy of ~0.06 eV. By comparing the line to the corresponding transition in Li-like uranium, wereach for an accuracy of ~0.15 eV on the absolute energy of the He-like and ~0.06 eV for the
relative measurement of the two lines. This allows for an unmatched test of electron correlation
effects and two-loop corrections of Quantum Electrodynamics in few electron systems in strong
electric fields with the errors of the measurement comparable to the best theoretical values.
This research has been conducted in the frame-work of the SPARC collaboration, experiment E125
of FAIR Phase-0 supported by GSI. It is further supported by the Extreme Matter Institute EMMI
and by the European Research Council (ERC) under the European Union's Horizon 2020 research
as well as by the innovation pro-gramme (Grant No 682841 "ASTRUm") and the grant agreementn° 6544002, ENSAR2. We acknowledge substantial support by ErUM-FSP APPA (BMBF n°
05P19SJFAA) too.

Figure 1: Detector image of the 2p3/2→2s1/2 transition in He-like uranium. Dispersion is in thehorizontal direction. The slant of the line is due to the Doppler shift.
References[1] M. Trassinelli et al, EPL 87, 63001 (2009)

70

A11
Path integral formalism for Dirac propagators in atomic physics
Sreya Banerjee, Zoltan Harman
Max Planck Institute for Nuclear Physics
Saupfercheckweg 1, 69117 Heidelberg, Germany
Current improvements in the experimental study of highly charged ions allow to determine the various properties of these ions with unprecedented accuracy. The recently constructed PENTATRAP
Penning-trap setup enables a direct access to electron binding energies in a given quantum groundstate, to scrutinize atomic structure theory and quantum electrodynamics with electronvolt precision[1-3]. This suggests a novel formulation of QED, enabling to take into account the strong, nonperturbative effect of the binding nuclear field. The very basic building blocks of perturbative calculations in atomic structure and collision theory are Green’s functions. We extend this study of Green’s
functions, in the nonperturbative regime, using Feynman’s path integral approach.
As a first step towards a full path-integral based formalism, we derive the free propagator describing
the electrons moving in the absence of a potential [4], followed by the propagator in the presence ofa strong attractive Coulomb field or the Dirac Coulomb Green’s function (DCGF). This work is thenfollowed by the calculation of the energy shift due to vacuum polarization using perturbation theory
based on the path integral.
For the free relativistic Dirac particle, the effective Hamiltonian for the iterated Dirac equation is constructed. The corresponding Green’s function is expanded into partial waves in spherical coordinates.
The radial part of this Green’s function is then converted into a path integral, through reparametrisation of the paths by local time rescaling, followed by a one-to-one mapping of the radial variable withthe local time parameter [5]. This yields a closed form of the Green’s function. Following the sameprocedure, the DCGF is diagonalised in Biedenharn’s basis [6] into a radial path integral, the effective
action of which is similar to that of the non-relativistic hydrogen atom. We convert the radial path
integral from Coulomb type to that of an isotropic harmonic oscillator through coordinate transformation along with local time rescaling. As such, an explicit path integral representation of the DCGF isobtained, along with the energy spectrum of the bound states. Once an explicit form of the DCGF isobtained, we use it to study the energy shift produced by the Uehling potential where we constuct themodified action with the insertion of a perturbing potential. The perturbed Green’s function is thenobtained at order n with n insertions of this perturbing potential. The energy perturbation is obtained
from the poles of this Green’s function.
References[1] P. Filianin et al., Phys. Rev. Lett. 127, 072502 (2021)[2] A. Rischka et al., Phys. Rev. Lett. 124, 113001 (2020)[3] R. X. Schüssler et al., Nature 581.7806, 42–46 (2020)[4] S. Banerjee, Z. Harman, (2021) (submitted)[5] I.H. Duru, H. Kleinert, Phys. Lett. B 84, 2, 185–188 (1979)[6] L. C. Biedenharn, Phys. Rev. 126, 845–851 (1962)

71

A12
Multi-configuration Dirac-Hatree-Fock calculations for W67+ and Pb75+
Falta Yadav, Arun Goyal*, Narendra Singh
Department of Physics & Astrophysics, University of Delhi, India-110007*Department of Physics, SLC, University of Delhi, India-110032

Energy levels and radiative data are presented for 15 fine-structure levels belonging to theconfigurations 1s22s22p3, 1s22s12p4 and 1s22p5 of W67+ and Pb75+ ions using general-purpose
relativistic atomic structure package (GRASP2k)[1]. Radiative data have been calculated forelectric dipole (E1) and magnetic quadrupole (M2) among these levels. Our calculated data of W67+
and Pb75+ agree very well with the results presented by C. Naze et al. [2] and J. Li. et al. and H. L.
Zhang and D. H. Sampson [3,4]. We believe that our results may be useful in the areas of
astrophysical investigations and application and fusion plasma research.

References[1] P. Jönsson, G. Gaigalas, J. Bieron, C. F. Fischer, I. P. Grant, Comp. Physics Communic. 9,21972203 (2007)[2] S. Verdebout, C. Naze, P. Jönsson, P. Rynkun, M. Godefroid, G. Gaigalas, Atomic Data andNucl. Data Tab. 5, 1111 (2014)[3] J. Li, X. Zhang, M. Huang, C. Chen, Y. Zou, Journal of Physics B: Atomic, Molec. and Optical
Phys. 3, 035003 (2010)[4] H. L. Zhang, D. H. Sampson, Atomic Data and Nucl. Data Tabl. 2, 153 (1999)

72

A13
Radiative properties of Rb-isoelectronic Technetium (Tc VII), Ruthenium (Ru
VIII) and Rhodium (Rh IX) ions for astrophysical applications
Jyoti, Bindiya Arora
Department of Physics, Guru Nanak Dev University, Amritsar, Punjab 143005, India
In this work, we present high-accuracy spectroscopic properties such as line strengths, transition probabilities and oscillator strengths for allowed transitions among nD3/2,5/2 , n0 S1/2 and n0 P1/2,3/2 (n =4, n0 = 5, 6) states of Rb-isoelectronic Tc (Tc VII), Ru (Ru VIII) and Rh (Rh IX) ions due to their necessity for the analysis of astrophysical phenomena undergoing inside the heavenly bodies containing
Tc, Ru and Rh ions. Due to scarcity of computational data of atomic properties as well as considerable
discrepancies lying within the literature of these ions, the precise determination of these properties isprerequisite. Therefore, for this purpose, we have implemented relativistic many body perturbation
theory (RMBPT) for the evaluation of wave functions of the considered states. For better accuracy,
we have accounted for electron interactions through random phase approximation, Brückner orbitals
and structural radiations of wave functions in our RMBPT method for further evaluation of electric
dipole amplitudes precisely. Combining these values of the observed wavelengths, the above transition properties and radiative lifetimes of a number of excited states of Tc VII, Ru VIII and Rh IX ionshave been calculated. For further validation of our work, we have compared our results with the data
already available in literature.

73

A14
Delhi Penning Trap for measurements of radiative lifetimes of atomic
metastable states
Sugam Kumar1, Deepak Chhimwal2, C.P. Safvan1, W. Quint3, M. Vogel3, L. Nair2
1. Inter-University Accelerator Centre, New Delhi, India
2. Jamia Millia Islamia University, New Delhi, India
3. GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany

The study of forbidden optical transitions of highly ionized atoms is the subject of fundamental
research and plays an essential role in the generation of atomic frequency standards [1], determining
fundamental constants [2], tests of the Standard Model [3], astrophysics [4], and testing quantum
electrodynamics (QED) for simple multi-body systems [2].
A cryogenic Penning trap at Inter-University Accelerator Centre (IUAC), New Delhi, has been
designed and developed to capture highly charged ions of specific m/q from an external Electron
Cyclotron Resonance (ECR) ion source. The highly energetic ions from the ECR ion source aredecelerated before being captured at the center of the Penning trap. The overall schematic of theDelhi Penning Trap (DPT) is shown in figure 1.

Figure 1: (a) Schematic overview of the Delhi Penning Trap, (b) Cross-section view of electrodes
In this paper, recent developments of the DPT at IUAC are described, including the design,
fabrication, testing of the trap, its detection system, and the use of this Penning trap to precisely
measure the radiative lifetimes of metastable states of atomic systems. The first results on themetastable lifetime of the 2 P1/2 o 2 P3/2 transitions in the boron-like ions are expected in the near
future.
References[1] Derevianko et. al. Phys. Rev. Lett. 2012, 109, 180801.
[2] Berengut, et. al. Phys. Rev. Lett. 2010, 105, 120801.
[3] A. Matveev, et. al. Phys. Rev. Lett. 110, 230801 (2013).
[4] Beiersdorfer P., et. al. Science 2003, 300, 1558–1559.

74

A15
InF+ molecule for future nuclear–spin–dependent P–violating experiments
Yuly Chamorro, Anastasia Borschevsky, Lukáš Pǎsteka*
Van Swinderen Institute, University of Groningen(*) Comenius University Bratislava
Precision experiments to measure the nuclear–spin–dependent parity violation (NSD-PV) using diatomic molecular ions are promising. The use of molecules gives the possibility to amplify the observable signals using close-lying opposite parity eigenstates. Specifically, in systems containing
heavy nuclei, the NSD-PV effects are dominated by the P-odd anapole moment contribution. The
measurement of the anapole moment has a relevant impact on nuclear physics as its value is related
to a set of parameters describing low-energy hadronic PV interactions. In this work, we study the
InF+ molecule as a promising candidate for measuring the anapole moment. We use high–accurate
electronic structure methods to calculate the enhancement parameter Wa , which describes the sensitivity of this molecule to the anapole moment, and we estimate the uncertainty in our predictions.
Additionally, we study the suitability of InF+ for laser cooling for the initial experiment steps of the
proposed measurements.

75

A16
Two-photon processes and its relevance to astrophysics and precision atomic
physics
Pedro Amaro, Jorge Machado, Mauro Guerra, José Paulo Santos
Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL),
Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon,
2829-516 Caparica, Portugal
Two-photon processes (TP) have been studied extensively since the birth of quantum mechanics byGöppert-Mayer (1931). The forbidden transition of 2s ! 1s is a prime example of the substantial
experimental and theoretical work dedicated to the first excited state of the simplest atom of hydrogenand this effort was originally triggered from astrophysics. While TP of hydrogen and helium havebeen extensively investigated, both experimentally and theoretically, other elements and ionic statescannot be overlooked for astrophysical models. For example, the first excited state of Be-like ionscannot undergo via a one-photon decay due to the 0 ! 0 selection rule. Therefore, without external
electromagnetic fields and for zero-spin nuclear isotopes, the most dominant decay mode of this stateis a rare TP transition that is very sensitive to relativistic and electronic correlation effects and canhave lifetimes from a few decades to a few minutes, depending on the ion specimen. Only four
theoretical calculations are available with notorious disagreements between each other and without
any experimental measurement (Amaro 2016 [1]).
An overview of the theoretical framework for two-photon related processes that was employed at thegroup LIBPhys-UNL will be provided, together with most recent developments.
References[1] P. Amaro, PRA 4, 93, 032502 (2016)

76

A17
QED calculations of Be-like ions
A. V. Malyshev, Y. S. Kozhedub, I. S. Anisimova, D. A. Glazov,
M. Y. Kaygorodov, I. I. Tupitsyn, V. M. Shabaev
Department of Physics, St. Petersburg State University, St. Petersburg, Russia
Quantum electrodynamic (QED) description of energy levels in highly charged Be-like ions poses
serious challenges for high-precision theoretical physics. The reason is that a number of states of thesame symmetry (including the ground one) are quasi-degenerate and the use of the standard approachbased on a QED perturbation theory for single levels can lead to unsatisfactory results. The situation iscomplicated by a strong interference between the QED and electron–electron correlation effects. We
overcome these and other difficulties by applying the QED perturbation theory for quasi-degeneratelevels. In the developed approach [1,2], the contributions of all the relevant Feynman diagrams up
to the second order are taken into account. The many-electron QED effects are treated in the Furry
picture. The correlation effects of the third and higher orders are accounted for within the Breit
approximation. In addition, the nuclear recoil and nuclear polarization effects are considered.
The developed methods are applied to the QED calculations of the binding and transition energies in
Be-like argon, krypton, molybdenum, xenon, lead, and uranium. The obtained theoretical predictions
are generally in agreement with the available experimental values [3-5]. For the 2s2p 3 P1 –2s2 1 S0transition in xenon, however, some discrepancy with the most precise measurement [6] is found. New
experiments to explore the electronic structure of highly charged Be-like ions are in demand.
References[1] A. V. Malyshev, D. A. Glazov, Y. S. Kozhedub, I. S. Anisimova, M. Y. Kaygorodov, V. M.
Shabaev, and I. I. Tupitsyn, Phys. Rev. Lett. 126, 183001 (2021)[2] A. V. Malyshev, Y. S. Kozhedub, I. S. Anisimova, D. A. Glazov, M. Y. Kaygorodov, I. I. Tupitsyn,
and V. M. Shabaev, Opt. Spectrosc. 129, 652 (2021)[3] B. Denne, G. Magyar, and J. Jacquinot, Phys. Rev. A 40, 3702 (1989)[4] P. Beiersdorfer, H. Chen, D. B. Thorn, and E. Träbert, Phys. Rev. Lett. 95, 233003 (2005)[5] D. Bernhardt et al., J. Phys. B 48, 144008 (2015)[6] E. Träbert, P. Beiersdorfer, J. K. Lepson, and H. Chen, Phys. Rev. A 68, 042501 (2003).

77

A18
Nuclear magnetic shielding in Li- and B-like ionsA. M. Volchkova, V. A. Agababaev*, D. A. Glazov, V. M. Shabaev, A. V. Volotka**
Department of Physics, Saint-Petersburg State University, 199034 Saint-Petersburg, Russia(*) Saint-Petersburg Electrotechnical University ”LETI”, Professor Popov st. 5, 197376
Saint-Petersburg, Russia(**) ITMO University, Kronverkskiy pr. 49, 197101 Saint-Petersburg, Russia
The nuclear magnetic moments are presently in the focus of interest, since the uncertainty of theirdetermination from the widely accepted nuclear magnetic resonance method may be significantly underestimated [1]. An independent method, free from the environment effects which are difficult toestimate, was proposed in [2] and developed further in [3]. It is based on the g-factor measurementin highly charged ions. To implement this method, theoretical calculations are necessary for both theelectron g-factor and the hyperfine-interaction correction, which is also termed as the nuclear magnetic shielding constant.
This constant was previously calculated for H-like [4,5,6], Li-like [7], and B-like ions [8,9]. In Li- andB-like ions the first-order interelectronic-interaction correction was calculated [7,9] with the Coulomb
potential as the zeroth approximation.
Use of the screening potential provides an opportunity to take into account some part of the higherorder contributions. Spread of the results obtained in different potentials allows one to estimate theremaining uncertainty. In this work, we present the corresponding results for the nuclear magnetic
shielding constant in Li- and B-like ions. The calculations are performed within two independent
approaches – the perturbation theory and the finite-field method. In both methods, we use the finite
basis set constructed in the framework of the dual-kinetic-balance (DKB) approach [10,11]. Within
the finite-field method the axially symmetric magnetic field is included in the Dirac Hamiltonian. The
results obtained within both methods are found in good agreement, confirming the correctness of thenumerical procedure.
References[1] L. V. Skripnikov et al., Phys. Rev. Lett. 120, 093001 (2018).
[2] G. Werth et al., in The Hydrogen Atom (Springer, Berlin, 2001), p. 204.
[3] W. Quint et al., Phys. Rev. A 78, 032517 (2008).
[4] D. L. Moskovkin et al., Phys. Rev. A. 70. P. 032105 (2004).
[5] V. A. Yerokhin et al., Phys. Rev. Lett. 107, 043004 (2011).
[6] V. A. Yerokhin et al., Phys. Rev. A. 85, 022512 (2012).
[7] D. L. Moskovkin et al., Opt. Spectrosc. 104, 637 (2008).
[8] A. M. Volchkova et al., Nucl. Instrum. Methods Phys. Res. B. 408, 89 (2017).
[9] A. M. Volchkova et al., Opt. Spectrosk. 129, 1477 (2021).
[10] V. M. Shabaev et al., Phys. Rev. Lett. 93, 130405 (2004).
[11] E. B. Rozenbaum et al., Phys. Rev. A. 89, 012514 (2014).

78

A19
One-Electron Energy Spectra of Heavy Highly Charged Quasimolecules:
Finite-Basis-Set Approach
A. A. Kotov, D. A. Glazov, A. V. Malyshev, V. M. Shabaev, G. Plunien*
Department of Physics, Saint Petersburg State University, Russia(*) Institute für Theoretische Physics, Technische Universität Dresden, Germany
Quasimolecular systems emerging in heavy ion-ion or ion-atom collisions provide a possibility toinvestigate the critical phenomena of the bound-state quantum electrodynamics, e.g., spontaneouselectron-positron pair production. Collisions of highly charged ions with neutral atoms are presently
available for experimental investigations at the GSI Helmholtz Centre for Heavy Ion Research while
the upcoming experiments at the GSI/FAIR [1], NICA [2], and HIAF [3] facilities might even allow
the observation of the heavy ion-ion collision up to U92+ –U92+ . In that case, the total nuclear charge(Z = 184) is larger than the critical one (Zc = 173), the ground one-electron state can “dive” into theDirac negative-energy continuum at small enough internuclear distances [4, 5]. So, this is a strongly
non-perturbative regime of QED and the theoretical calculations for such systems must be performed
to all orders in ↵Z (↵ is the fine-structure constant).
We present the fully relativistic calculations of the ground and a few lowest excited -states of the
few-electron heavy diatomic quasimolecules. Some results for the homonuclear quasimolecules werealready presented in Refs. [6, 7] and compared with the previously published values [8–10]. In thiswork we extend these investigations to the heteronuclear systems, in particular, U–Cf. The dualkinetic-balance approach is employed to solve the Dirac problem [11, 12]. Two different choicesof the coordinate system origin, (1) in the center-of-mass of a quasimolecule and (2) in the centerof a nucleus, are compared for both two-center and monopole-approximation results. This analysis
can be used to quantify the deviation from the yet unknown two-center results, e.g., for the QEDcontributions available only within the monopole approximation so far.
References[1] A. Gumberidze et al., Nucl. Instrum. Meth. Phys. Res. B 267, 248 (2009)[2] G. M. Ter-Akopian et al., Int. J. Mod. Phys. E 24, 1550016 (2015)[3] X. Ma et al., Nucl. Instrum. Meth. Phys. Res. B 408, 169 (2017)[4] Y. B. Zeldovich and V. S. Popov, Sov. Phys. Uspekhi 14, 673 (1972)[5] W. Greiner, B. Müller and J. Rafelski, Quantum Electrodynamics of Strong Fields (SpringerVerlang, Berlin, 1985)[6] A. A. Kotov et al., Atoms 9, 44 (2021)[7] A. A. Kotov et al., X-Ray Spectrom. 49, 110 (2020)[8] G. Soff and W. Greiner, Phys. Rev. A 20, 169 (1979)[9] I. I. Tupitsyn and D. V. Mironova, Opt. Spectrosc. 117, 351 (2014)[10] D. V. Mironova et al., Chem. Phys. 449, 10 (2015)[11] V. M. Shabaev et al., Phys. Rev. Lett. 93, 130405 (2004)[12] E. B. Rozenbaum et al., Phys. Rev. A 89, 012514 (2014)

79

A20
Many-electron effects in the theory of the g factor of lithiumlike ions
D. V. Zinenko1, D. A. Glazov1, V. P. Kosheleva2, A. V. Volotka3 and S. Fritzsche4,5,6
1
Department of Physics, St. Petersburg State University, 199034 St. Petersburg, Russia
Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron
Laser Science, 22761 Hamburg, Germany
3
School of Physics and Engineering, ITMO University, 197101 St. Petersburg, Russia
4
Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
5Helmholtz-Institut Jena, 07743 Jena, Germany
6
GSI Helmholtzzentrum f r Schwerionenforschung GmbH, 64291 Darmstadt, Germany
2

Over the past decades, significant progress has been made in the study of the g factor in highly
charged ions. The measurement accuracy for H-like, Li-like, and B-like ions reached the level of
10 9 10 11 [1-5]. Such high-precision measurements for H-like ions combined with the theoreticalstudies have led to the most accurate up-to-date value of electron mass [6]. Future studies are expected
to provide an independent determination of the fine structure constant [7]. Calculations performed
to date for Li-like ions achieved an accuracy of 10 6 10 9. The theoretical results of Refs. [4,8] agreewith high-precision g-factor measurements for Li-like silicon [2,4] and calcium [3], demonstrating
the most rigorous test of many-electron QED effects in the presence of magnetic field. However, thecorresponding theoretical values obtained in [9,10] disagree with the experiment. To clarify thissituation, we recalculated the most problematic contributions [11], and the results confirmed ourprevious value [4].
At present, the interelectronic-interaction contributions of the first and second order to the g factor of
Li-like ions are calculated within the framework of the bound-state QED. Higher-order contributions
are accounted for within the Breit approximation by nonperturbative methods, for example, the CIDFS method [8]. The computations in this work were performed using a novel approach built on therecursive formulation of perturbation theory with a finite basis set of many-electron wave functions
constructed in the form of Slater determinants [12]. As shown in [4,11], for the third and higher
orders, the perturbation theory provide significantly better accuracy than the CI-DFS method. In ourrecent paper [11], the application of this method to the g factor of Li-like silicon and calcium has
been demonstrated. In this work, these calculations are extended to a wide range of Li-like ions.

References[1] S. Sturm et al., Phys. Rev. A 87, 030501 (R) (2013)[2] A. Wagner et al., Phys. Rev. Lett. 110, 033003 (2013)[3] F. Köhler et al., Nat. Commun. 7, 10246 (2016)[4] D. A. Glazov et al., Phys. Rev. Lett. 123, 173001 (2019)[5] I. Arapaglou et al., Phys. Rev. Lett. 122, 253001 (2019)[6] S. Sturm et al., Nature 506, 467 (2014)[7] V. M. Shabaev et al., J. Phys. Chem. Ref. Data 44, 031205 (2015)[8] A. V. Volotka et al., Phys. Rev. Lett. 112, 253004 (2014)[9] V. A. Yerokhin et al., Phys. Rev. A 102, 022815 (2020)[10] V. A. Yerokhin, C. H. Keitel, Z. Harman, Phys. Rev. A 104, 022814 (2021)[11] V. P. Kosheleva et al., Phys. Rev. Lett. 128, 103001 (2022)[12] D. A. Glazov et al., Nucl. Instr. Methods Phys. Res. B 408, 46 (2017)

80

A21
Recursive perturbation theory for highly charged ionsD. A. Glazov
Department of Physics, Saint Petersburg State University, Russia
Modern high-precision calculations for highly charged ions usually include leading contributions onelectromagnetic interactions within quantum electrodynamics (QED) for bound states. For approximate consideration of higher orders within the relativistic theory of atom, various methods basedon the Dirac-Coulomb-Breit Hamiltonian have been developed. Despite the widespread use of nonperturbative methods, perturbation theory often turns out to be more effective, especially when it isformulated in recursive form to access arbitrary high orders. In [1] the recursive formulation of perturbation theory was combined with a finite basis set in the form of Slater determinants of one-electron
functions constructed by the dual kinetic balance method [2]. The proposed method has been applied
to the calculation of the interelectronic-interaction contribution to the energies of lithium-like andboron-like ions [1,3]. The extension of this method to the case of quasi-degenerate states allowed us
to carry out similar calculations for helium-like ions [4,5]. In addition, in [3,6] the contribution of theinterelectronic interaction to the nuclear recoil effect was calculated for the energies of lithium- andboron-like ions.
The evaluation of quantities such as the g-factor and hyperfine splitting requires that the contributionof the negative-energy solutions of the Dirac equation be properly accounted for. A corresponding
approach was developed in [7] and the interelectronic-interaction corrections of the 3rd and higher
orders to the g-factor and the hyperfine splitting of lithium-like ions were calculated [7–9]. Generalisation of the recursive scheme to the case of several perturbations allows for evaluation of more
subtle effects, such as many-electron QED [7,9] and nuclear recoil contributions [10–12]. The leading contributions of the 1st and 2nd orders have been calculated rigorously within the framework of
the bound-state QED, which together gave the best theoretical accuracy to date for the g-factor oflithium- and boron-like ions.
References[1] D. A. Glazov et al., Nucl. Instr. Meth. Phys. Res. B 408, 46 (2017)[2] V. M. Shabaev et al., Phys. Rev. Lett. 93, 130405 (2004)[3] A. V. Malyshev et al., Phys. Rev. A 96, 022512 (2017)[4] A. V. Malyshev et al., Phys. Rev. A 99, 010501(R) (2019)[5] Y. S. Kozhedub et al., Phys. Rev. A 100, 062506 (2019)[6] A. V. Malyshev et al., Phys. Rev. A 101, 052506 (2020)[7] D. A. Glazov et al., Phys. Rev. Lett. 123, 173001 (2019)[8] V. P. Kosheleva et al., Phys. Rev. Research 2, 013364 (2020)[9] V. P. Kosheleva et al., Phys. Rev. Lett. 128, 103001 (2022)[10] V. M. Shabaev et al., Phys. Rev. Lett. 119, 263001 (2017)[11] V. M. Shabaev et al., Phys. Rev. A 98, 032512 (2018)[12] D. A. Glazov et al., Phys. Rev. A 101, 012515 (2020)

81

A22
g factor of the ground-state of highly charged 229Th ions as a tool to determine
the M1 transition probability between the isomeric and ground nuclear states
V. M. Shabaev, D. A. Glazov, A. M. Ryzhkov, G. Plunien∗ , A. M. Volchkova, and D. V. Zinenko
Department of Physics, St. Petersburg State University, Universitetskaya 7/9, 199034 St. Petersburg,
Russia∗Institut für Theoretische Physik, TU Dresden, Mommsenstrasse 13, Dresden, D-01062, Germany
The exceptionally low-energy (about 8 eV) isomeric state in 229 Th attracts a great interest of atomic
and nuclear physics communities [1-3]. The smaller sensitivity of the nuclear transitions to external
perturbations, compared to electronic transitions in atoms, makes this nucleus an ideal candidate
for the nuclear optical clock which could serve as a new metrological frequency standard [4]. The
practical realization of this application requires the precise knowledge of the excitation energy as wellas other fundamental nuclear properties of the ground and isomeric states. Among these properties,
one should consider the M1 transition probability between the nuclear states.
In this work, we propose to determine the M1 nuclear transition amplitude and hence the lifetimeof the “nuclear clock transition” between the low-lying (∼ 8 eV) isomeric state and the ground stateof 229 Th from a measurement of the ground-state g factor of few-electron 229 Th ions. The approachis based on a nuclear hyperfine mixing (NHM) of the states, which is due to the small excitationenergy of the isomeric state and the strong hyperfine interaction. In 229 Th89+ or 229 Th87+ ions, themixing coefficient enters the g factor of the ion and contains the information about the M1-transition
probability. Hence, the decay property of the isomeric state can be experimentally deduced from an
ion that is in the nuclear ground state. We show that the experimental determination of the groundstate g factor of H-like 229 Th ion to the precision of about 10−7 allows one to get the M1 transition
probability with a few-percent accuracy. Furthermore, a comparison of the measurements of theground-state g factors of H-, Li-like, and B-like 229 Th ions has a potential to improve the result for asingle charge state and to determine the nuclear magnetic moment to a higher accuracy than that of
the currently accepted value. The details of the method and the related calculations can be found in
Ref. [5].
References[1] B. R. Beck, J. A. Becker, P. Beiersdorfer, G. V. Brown, K. J. Moody, J. B. Wilhelmy, F. S. Porter,
C. A. Kilbourne, and R. L. Kelley, Phys. Rev. Lett. 98, 142501 (2007)[2] E. V. Tkalya, Phys. Rev. Lett. 106, 162501 (2011)[3] E. Peik, T. Schumm, M. Safronova, A. Pálffy, J. Weitenberg, and P. G. Thirolf, Quantum Sci.
Technol. 6, 034002 (2021)[4] E. Peik and M. Okhapkin, C. R. Phys. 16, 516 (2015)[5] V. M. Shabaev, D. A. Glazov, A. M. Ryzhkov, C. Brandau, G. Plunien, W. Quint, A. M. Volchkova,
and D. V. Zinenko, Phys. Rev. Lett. 128, 043001 (2022)

82

A23
Evaluation of the 1s22s2p6 - 1s22s22p5 transition energy in fluorine-like nickel
Y.S. Kozhedub, M.Y. Kaygorodov, A.V. Volotka*
Department of Physics, St. Petersburg State University, St. Petersburg, Russia(*) School of Physics and Engineering, ITMO University, St. Petersburg, Russia}
The structure and dynamic properties of highly charged ions up to an extremely high precision are abinitio described by quantum electrodynamics (QED). QED is currently considered to be one of the mostaccurate theories of fundamental interactions. As its extraordinary precision offers unique scientificopportunities, e.g., search for new physics, stringent experimental tests of QED continue to be of highimportance. In comparison with neutral atoms or low-charged ions, many physical phenomena are greatly
enhanced in highly charged ions (HCIs). Moreover HCI are important for diagnostics of hot laboratory
plasma, notably in magnetic nuclear fusion and tokamaks, study of nearly all classes of cosmic x-ray sourcesand etc.
In the present work we focused on study of fluorinelike nickel ions. The QED calculations of thetransition 1s22s2p6 2S1/2 – 1s22s22p5 2P3/2 energy in fluorinelike nickel is based on the QED perturbation theory
in the extended Furry picture. The zero-order Hamiltonian is the Dirac one, where in addition to the nuclear
Coulomb potential a screening potential, which partially accounts for the inter-electronic interaction, isadded. For constructing the perturbative expansion, we use the two-time Green function method [1]. In thepresent calculations, we account entirely for the first-order correction, which are given by the one-photon
exchange and the one-electron self-energy and vacuum polarization diagrams. The second-order diagrams
include the many-electron radiative (so-called screened QED), one-electron two-loop, and two-photon
exchange corrections. Here, we evaluate only the screened QED correction employing the techniques andmethods thoroughly presented in Refs. [2]. For the one-electron two-loop contribution, we use thehydrogenic values from Ref. [3]. The terms which were not accounted for by the rigorous QED theory havebeen evaluated within the Breit approximation employing the configuration-interaction Dirac-Fock-Strum(CI-DFS) method [4]. Thus, the CI-DFS method is used to calculate the second and higher ordersinterelectronic-interaction corrections. Moreover, we have evaluated the recoil correction employing the
many-body relativistic mass shift Hamiltonian [5].
For comparison with the most accurate recent experimental data, which have been obtain using highprecision dieelectronic recombination spectroscopy [6], the energy of autoionization (1s 22s2p6[2S1/2]6s)J=1
state has been evaluated based on the stabilization method (see, e. g. Ref. [7] and references therein). The

obtained results are the most accurate in the literature and in reasonable agreement with recent
experimental data.
References[1] V. M. Shabaev, Phys. Rep. 356, 119 (2002).
[2] Y. S. Kozhedub, A. V. Volotka, A. N. Artemyev, D. A. Glazov, G. Plunien, V. M. Shabaev, I. I.
Tupitsyn, and T. StFhlker, Phys. Rev. A 81, 042513 (2010).
[3] V. A. Yerokhin and V. M. Shabaev, J. Phys. Chem. Ref. Data 44, 033103 (2015).
[4] I. I. Tupitsyn, V. M. Shabaev, J. R. Crespo LHpez-Urrutia, I. DraganiI, R. Soria Orts, and J.
Ullrich, Phys. Rev. A 68, 022511 (2003).
[5] V. M. Shabaev and A. N. Artemyev, J. Phys. B 27, 1307 (1994).
[6] S. X. Wang, Z. K. Huang, W. Q. Wen et al., arXiv:2205.01334.
[7] P. Amaro, J. P. Santos, S. Bhattacharyya, T. K. Mukherjee, and J. K. Saha, Phys. Rev. A 103,
012811 (2021).

83

A24
Radiative rates for E1, E2, M1, and M2 transitions in He-like Cd
D. E. Salhi*1 , S. Manai1,2 , S. Ben Nasr1 , H. Jelassi1
1

Laboratory on Energy and Matter for Nuclear Sciences Development, LR16CNSTN02, National
Center for Nuclear Sciences and Technologies, Sidi Thabet Technopark 2020 Ariana Tunisia.
2
Faculty of Sciences of Bizerte, University of Carthage, Tunisia.
(*) salhidhiaelhak@gmail.com

Atomic data have received a great deal of attention, due to their need for the upcoming ITER project(International Thermonuclear Experimental Reactor). So, extensive spectroscopic studies both experimental and theoretical have been performed in the last years in order to estimate the power loss fromthe impurities in the forthcoming fusion reactors [1]. Accurate values of wavelengths and their errors
are required for interpretation of a wealth of high-resolution data obtained in the last two decades by
the Chandra X-ray Observatory and the European Space Agency’s X-ray Multi-Mirror Mission [2].
As previously published [3,4,5,6,7], we continue to focus on He-like ions. Energy levels, wavelengths,
weighted oscillator strengths, transition probabilities and lifetimes are calculated for all levels of 1s2
and 1snl (n = 2 6) configurations of He-like cadmium ion.
The calculations were carried out using the GRASP2018 code based on the multiconfiguration DiracHartree-Fock (MCDHF) [8]. Transition probabilities are reported for all types of transitions (E1,
E2, M 1 and M 2 transitions). Breit interactions and quantum electrodynamics effects are includedin the RCI calculations. Comparisons were made with other data found in the literature and a good
agreement was found which confirms the reliability of our results. We identified some new datathat are calculated for the first time. This computational approach enables us to present a consistentand improved data set of all important transitions of the Cd XLVII spectrum, which are useful for
identifying transition lines in further investigations.
References[1] A. J. H. Donne et al., Nucl. Fusion 47 S337 (2007)[2] V. A. Yerokhin and A. Surzhykov, J. Phys. Chem. Ref. Data 48 033104 (2019)[3] D. E. Salhi and H. Jelassi, Canadian Journal of Physics 96 3 (2017)[4] D. E. Salhi and H. Jelassi, Orient. J. Phys. Sciences. 2 2 (2017)[5] D. E. Salhi, P. Quinet and H. Jelassi, Atomic Data and Nuclear Data Tables 126 70-157 (2019)[6] D. E. Salhi, S. Ben Nasr and H. Jelassi, Radiation Physics and Chemistry 177 108817 (2020)[7] D. E. Salhi, S. Ben Nasr, S. Manai, H. Jelassi, Results in Physics 23 103960 (2021)[8] C. Froese Fischer, G. Gaigalas, P. Jönsson, J. Bieron, Computer Physics Communications 237
184 (2019)

84

A25
Study of radiative properties of helium isoelectronic sequence
Haikel Jelassi1,2, Dhia Elhak Salhi1,2, Soumaya Manai1,2,3, Sirine Ben Nasr1,2
1Research Laboratory on Energy and Matter for Nuclear Science Development, LR16CNSTN02,
Tunisia2
National Center for Nuclear Science and Technologies, Sidi Thabet Technopark, 2020 Ariana,
Tunisia
3
Faculty of Sciences of Bizerte, University of Carthage, Tunisia

The radiative properties of ions (Z=2-53) belonging to the helium isoelectronic sequence arereported. Energy levels for the ground state and the lowest 1s2l singly excited states are considered.
The effects of correlation effects are studied for the selected ions by increasing the active set (AS).
Relativistic effects such as the Breit interaction and the QED corrections are also computed. The
heavy elements with high Z are of potential interest in controlled thermonuclear fusion andastrophysics. Indeed, they could be used in plasma-facing materials such as the divertors intokamaks or/and could be generated by neutron-induced transmutation of di er or ma erial . So,
extensive spectroscopic studies both experimental and theoretical have been performed in the lastyears in order to estimate the power loss from the impurities in the forthcoming fusion reactors [1].
In this work, two independent theoretical atomic structure computational approaches have been
considered, i.e. the ab initio multiconfiguration Dirac-Hartree-Fock with subsequent relativistic
configuration interaction method (MCDHF-RCI) implemented in the code GRASP2018 [2] and the
Dirac-Fock-Slater (DFS) implemented in the code FAC (Flexible Atomic Code) [3]. The relativistic
configuration interaction method was applied to estimate the electron correlation effects. The
transition probabilities and the oscillator strengths calculated for E1, E2, M1 and M2 transitions
spanning the spectral range from Uv to IR. Our results are compared with available experimental
and other theoretical values. Good agreement was found for the majority of cases. Lifetimes arealso considered in this work, first to check the accuracy of calculated results of transitions rates andsecond, to complete the databases by a complete and accurate values of lifetimes. This can help
future works by experimentalists to compare their results with those results calculated theoretically.
Finally, this study underlines the importance of relativistic corrections especially for the heavy
atomic ions. This computational approach enables us to present a consistent and improved data setof all-important atomic data of the helium isoelectronic sequence, which are useful for identifying
transition lines in further investigations.

References[1] A. J. H. Donne et al., Nucl. Fusion 47 (2007) S337.
[2] C. Froe e Fi cher, G. Gaigala , P. J n on, and J. Biero , Comp . Ph . Comm n., 237 (2019)184.
[3] M.F. Gu, Can. J. Phys. 86 (2008) 675-689.

85

A26
Accurate calculations of atomic data structure for Helium-Like Ions using theConfiguration Interaction approach for singly and doubly excited states
S Manai*1,2 , D E Salhi1 , S Ben Nasr1 and H Jelassi1
1Research laboratory on Energy and Matter for Nuclear Science Development, LR16CNSTN02.
National Center for Nuclear Science and Technologies, Sidi Thabet Technopark 2020 Ariana
Tunisia.
2
Faculty of Sciences of Bizerte, University of Carthage, Tunisia.
(*) manai.soumaya12@gmail.com

Accurate atomic data is considered to be the principal way to effectively solve the future energy problem as a clean and infinite energy resource and it is being developed internationally via the International Thermonuclear Experimental Reactor (IT ER) Project [1]. Then, extensive spectroscopic studies both experimental and theoretical have been performed in the last few years in order to estimate
the power loss from the impurities in the forthcoming fusion reactors. Furthermore, accurate valuesof wavelengths and their errors are required for the interpretation of a wealth of high-resolution dataobtained in the last two decades by the Chandra X-ray Observatory and the European Space Agency’s
X-ray Multi-Mirror Mission. As previously published [2, 3], we continue to focus on Helium-likeions [4]. In this work, energy levels, wavelengths and transitions rates have been calculated for thelowest singly excited 70 levels among 1snl(n  6, l  (n 1)) configurations and the lowest doubly
excited 250 levels arising from the K-vacancy 2ln0 l0 (n0  6, l0  (n0 1)) configurations of heliumlike ions with Z = 5 9. The calculations were performed using the Configuration Interaction (CI)method implemented in the Flexible Atomic Code (F AC) [5]. Some comparisons were made withother available results reported in the literature [6, 7, 8, 9] and some discrepancies have been notedand explained. Finally, the accuracy of the present calculations is enough to facilitate the identification of many observed spectral lines, plasma modelling as well as diagnostics of astrophysical plasmaand controlled thermonuclear fusion.
References[1] A J H, Donne et al, Nucl. Fusion. 47, 337 (2007).
[2] S Manai and H Jelassi, Pramana. 95, 1-9 (2021).
[3] S Ben Nasr, S Manai, D E Salhi, P Quinet and H Jelassi, Atomic Data and Nuclear Data Tables.
135, 101346 (2020).
[4] ”Relativistic theoretical calculations of singly and doubly energy levels, lifetimes, wavelengths,
weighted oscillator strengths and radiative rates for Helium-Like Ions with Z = 5 9”,
S Manai, D E Salhi, S Ben Nasr and H Jelassi, accepted in Results in Physics Journal (April
2022).
[5] M. F. Gu, Canadian Journal of Physics. 86, 675-689 (2008).
[6] G. W. Drake, Canadian Journal of Physics. 66, 586611 (1988).
[7] D A Verner, E M Verner and G J Ferland, Atomic Data and Nuclear Data Tables. 64, 1180 (1996).
[8] K M Aggarwal, T Kato, F P Keenan and I Murakami, Physica Scripta. 83, 015302 (2010).
[9] B Sow, M Sow, Y Gning, A Traore, A S Ndao and A Wague, Radiation Physics and Chemistry.
123, 2530 (2016).

86

A27
Fully-stripped beryllium-ion collisions with atomic hydrogen initially inan excited state
N. W. Antonio,1 C. T. Plowman,1 I. B. Abdurakhmanov, 2 I. Bray,1 and A. S. Kadyrov1
1

Department of Physics, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
2
Pawsey Supercomputing Centre, 1 Bryce Ave, Kensington, WA 6151, Australia

The ITER and JET projects use beryllium-containing materials in plasma facing wallcomponents. Due to the high temperature environments, the erosion of the wall followed byionisation of Be is inevitable. Therefore, collisions between resulting Be ions with atomic
hydrogen can take place when a neutral beam of hydrogen atoms is injected into the plasma
for heating and diagnostic purposes. However, due to the toxicity of Be, there are no
experimental measurements of cross sections for such collisions. This makes theoretical
calculations of beryllium ion collisions with hydrogen [1, 2] the only source of data forplasma modelling. We studied collisions between bare beryllium ions and ground stateatomic hydrogen in our previous work [3]. This was done using the wave-packet convergent
close-coupling (WP-CCC) approach which solves the three-body Schrödinger equation by
employing a two-centre expansion for the total scattering wave function. This work is now
extended to Be4+ ion scattering on hydrogen in its lowest excited states within the projectileenergy domain between 1 keV/u and 500 keV/u. Specifically, this includes collisions withthe hydrogen target initially in the 2s, 2p0 and 2p1 states. Integrated total and state-selective
electron-capture cross sections are calculated. The results suggest that at low energies,
collisions with hydrogen in each considered excited state produce a total electron-capture
cross section approximately an order of magnitude larger than for scattering on the groundstate. However, as projectile energy increases, the cross section for capture from the excitedstates falls well below the H(1s) electron capture cross section. A possible reason for thisobservation could be related with the way the target electron radial densities are distributed
in different initial states. The results obtained in this work are compared to previous
calculations where available. In terms of the n-resolved charge-exchange cross sections,where n is the principal quantum number of the formed Be3+ ion in the final state, significant
disagreement is found between our results and some previous calculations available in theliterature.
References[1] A. Jorge, C. Illescas, and L. M endez, Phys. Rev. A 105, 012811 (2022).
[2] I. Ziaeian and K. Tokesi, The European Physical Journal D 75, 138 (2021).
[3] N. W. Antonio, C. T. Plowman, I. B. Abdurakhmanov, I. Bray, and A. S. Kadyrov, J.
Phys. B: At. Mol. Opt. Phys. 54, 175201 (2021).

87

A28
Coulomb explosion imaging of carbon monoxide dimers
A. Méry, V. Kumar, X. Fléchard*, B. Gervais, S. Guillous, M. Lalande, J. Rangama, W.
Wolff**, A. Cassimi
CIMAP, CEA/CNRS/ENSICAEN/UNICAEN, BP5133, F-14050 Caen Cedex 04, France(*) LPC Caen, Normandie Université, ENSICAEN, UNICAEN, CNRS, 14000 Caen, France(**) Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, Rio deJaneiro 21941-590, Brazil
Experimental results concerning collisions of 135 keV highly charged Ar9+ ions with a carbon
monoxide dimer (CO)2 target will be presented. Cold target recoil ion momentum spectroscopy andCoulomb explosion imaging are used to reconstruct the geometrical structure of the CO dimers. The
three-dimensional structure is deduced from the two-body and three-body dissociation channels
from which both the intermolecular bond length and the relative orientation of the two molecules
axis are determined. For the three-body channels, the experimental data are interpreted with the helpof a Coulomb explosion classical model in which the trajectories of the three emitted fragments are
numerically integrated.
From the (CO+ + CO+) two-body dissociation channel kinetic energy release, we experimentally
determine the equilibrium intermolecular distance to be Re = 4.2 Å. The orientation of both COmolecules with respect to the dimer axis is obtained from the three-body fragmentation of (CO)2q+(q = 3 to 5) and found to be quasi-isotropic which might be due to the residual vibrationaltemperature of the supersonic gas jet [1].

Figure 1: Experimental and simulated Dalitz plots for the (CO+, [C+,O+]), (CO+, [C2+,O+]), (CO+,[C+,O2+]) and (CO+, [C2+,O2+]) fragmentation channels of (CO)23+ induced by 135 keV Ar9+ ion
impact.

References[1] A.Méry et al, Phys. Rev. A 103, 042813 (2021)

88

A29
Investigation of the carbon monoxide dication lifetime using (CO)2 dimer
fragmentation
A. Méry, V. Kumar, X. Fléchard*, B. Gervais, S. Guillous, M. Lalande, J. Rangama, W.
Wolff**, A. Cassimi
CIMAP, CEA/CNRS/ENSICAEN/UNICAEN, BP5133, F-14050 Caen Cedex 04, France(*) LPC Caen, Normandie Université, ENSICAEN, UNICAEN, CNRS, 14000 Caen, France(**) Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, Rio deJaneiro 21941-590, Brazil

Doubly charged diatomic molecular ions have unusual properties leading to a wide range of
lifetimes against dissociation. Their stability depends on both the accessible decay mechanisms andthe position of the populated rovibronic levels with respect to the potential barrier height. The
fragmentation of carbon monoxide dimers induced by collisions with 135 keV Ar9+ ions isinvestigated using the cold target recoil ion momentum spectroscopy technique [1]. The presence ofa neighbor molecule in the dimer serves as a diagnostic tool to probe the lifetimes of the CO2+
molecular dications excited states resulting from the collision. The existence of metastable stateswith lifetimes ranging from 2 ps to 200 ns is clearly evidenced experimentally through a sequential
three-body fragmentation of the dimer, whereas fast dissociation channels are observed in a socalled concerted three-body fragmentation process. The fast fragmentation process leads to a kinetic
energy release distribution also observed in collisions with monomer CO targets. This is found incontradiction with the conclusions of a previous study [2] attributing this fast process to theperturbation induced by the neighbor molecular ion.
Figure 1: Identification of theconcerted and sequential
fragmentation processes in(CO)23+ Æ CO+ + C+ + O+
dissociation channel. (a)Dalitz plot of experimental
data showing the selection
window for concerted andsequential dissociation. (b)Dalitz plot for simulated
concerted fragmentation. (c)CO+ molecular ion kinetic
energy for concerted andsequential fragmentation. (d)Total KER of the three-bodysequential and concerted
fragmentation.

References[1] A.Méry et al, Phys. Rev. A 104, 042813 (2021)[2] X.Ding et al, Phys. Rev. Lett. 118, 153001 (2017)

89

A30
Alpha Particle Transport Modeling in a Realistic Biological Environment
with TILDA-V
C. Champion1, A. Larouze1, M. E. Alcocer-Avila2, M. A. Quinto3, J. M. Monti3
1

Centre Lasers Intenses et Applications, Université de Bordeaux, 33400 Talence, France
2
Institut de Physique des 2 infinis, Université de Lyon, 69100 Villeurbanne, France
3
Instituto de Física, CONICET - Universidad Nacional de Rosario, Rosario, 2000, Argentina
Radiotherapy is nowadays one of the main methods for treating cancers, along with chemotherapy
and surgery. In the current work, we focus on internal vectorized radiotherapy that consists incoupling a radionuclide to a biological molecule (vector) able to target tumor cells. Describing theproperties of such a radio-element thus becomes challenging in medical physics research. ThroughMonte Carlo numerical simulations, it may be possible to describe the radiation-induced energy
deposits in biological samples. However, in order to correctly simulate particle transport in a given
medium, Monte Carlo track structure (MCTS) codes require access to large databases of differential
and total cross sections to describe the various interactions induced by the particles in the biologicalmedium irradiated. In this context, we here detail all the models we developed and implemented
into our TILDA-V code [1] to describe the transport of helium particles in water and DNA
components. For modelling the elastic scattering, we used a quantum-mechanical approach todescribe the interaction potential between the biological samples and the charged particles, that is
implemented into a classical description of the elastic process. For describing the Heq+-induced
ionization, we developed a CDW-EIS prior model with an effective projectile screening. Finally,semi-empirical models were used to model the other inelastic interactions (capture, excitation andelectron loss, see Fig. 1). To check the reliability of the TILDA-V code, we provided comparisonswith literature in terms of range, stopping power and dose profiles for α-particles. Comparisonswith existing data [2,3] exhibited a good agreement.

/

Figure 1: Total cross sections for the different charge states of helium particles in water(He2+: blue; He+: red; He0: green).
References[1] M. A. Quinto et al, Eur. Phys. J. D 71, (2017).
[2] B. Vaziri et al, J. Nucl. Med. 55, 1557 (2014).
[3] D. Lee et al, Radiat. Res. 190, 236 (2018).

90

A31
Performance of a keV/u ion spectrometer for the FISIC platform
M Jolly1 , S Voikopoulos1 , E Lamour1 , A Méry2 , A Bräuning-Demian3 , J-Y Chesnel2 , A
Gumberidze3 , C Hahn4 , A Lévy1 , M Lestinsky3 , S Macé1 , C Prigent1 , JM Ramillon2 , J Rangama2 , P
Rousseau2 , D Schury1 , U Spillmann3 , S Steydli1 , Th Stöhlker3,4,5 , M Trassinelli1 and D Vernhet1
1

Institut des Nanosciences de Paris, Sorbonne Université, CNRS UMR 7588, Paris, 75005, France
2
CIMAP, CEA/CNRS/ENSICAEN/Université de Caen Normandie, Caen, 14050, France
3
GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, 64291, Germany
4
Friedrich-Schiller-Universität Jena, Jena, 07743, Germany
5Helmholtz-Institut Jena, Jena, 07743, Germany

Electronic processes in ion-ion collisions play an important role in astrophysical and fusion plasmas aswell as in ion-matter interaction. In the so-called intermediate velocity regime where the ion stopping
power is maximum, there is a lack of both experimental and theoretical data on the electronic crosssections. The FISIC set-up is a mobile experiment designed to perform collisions between a slow
(keV/u) ion beam coming from the FISIC platform and fast (MeV/u) ion beams, at different facilities.
For the first experiments, the FISIC platform will be connected to the CRYRING storage ring at
GSI [1]. The FISIC platform is equipped upstream the collision zone with an ECR ion source, a lowenergy beam line and an omega-shaped purification system [2], and downstream the collision chamberwith a home-made ion spectrometer (Fig 1a). This set-up is inspired by the ion-ion collisions carriedin the low velocity regime by the Giessen group [3]. The purpose of the ion spectrometer is to separate
the collision products from the main low-energy beam, in view of their detection. It is made of two
90 curved plates to separate the charge states and two Matsuda plates for the focusing of the ion
beams. The detection system currently used consists of a Faraday cup to measure the beam intensity,and a position sensitive detector (two MCPs with a delay-line resistive anode) to image the positionof the other charge states. Test measurements have been performed at the ARIBE facility (GANIL,
Caen). Results compared to numerical simulations carried out by using the SIMION software (Fig 1b)
will be presented. Conclusions and possibilities for improvement of the device will be also discussed.

(a) Ion spectrometer located after the collision chamber(b) Ion trajectory simulations of Arq+ (qfrom 12 to 8) with an energy of 120 keV.

References[1] M. Lestinsky et al, Eur. Phys. J 225, 797-882 (2016)[2] D. Schury et al, Rev. Sci. Instrum. 90 083306 (2019)[3] S. Meuser et al, Rev. Sci. Instrum. 67 2752 (1996)

91

A32
X-ray Emission Study Performed for Hydrogen-like Lead Ions at the Electron
Cooler of CRYRING@ESR
B. Zhu1,2,3,4, A. Gumberidze2, T. Over1,2,3, G. Weber1,2, Z. Andelkovic2, A. Bräuning-Demian2,
R. J. Chen2,5, D. Dmytriiev2, O. Forstner1,2,3, C. Hahn1,2,3, F. Herfurth2, M. O. Herdrich1,2,3,
P.-M. Hillenbrand2,6, A. Kalinin2, F. M. Kröger1,2,3, M. Lestinsky2, Yu. A. Litvinov2,
E. B. Menz1,2,3, W. Middents1,2,3, T. Morgenroth1,2,3, N. Petridis2, Ph. Pfäfflein1,2,3, M. S. Sanjari2,7,R. S. Sidhu2, U. Spillmann2, S. Trotsenko1,2, L. Varga2, G. Vorobyev2, S. Schippers6,8, R. Schuch9,
and Th. Stöhlker1,2,3
2

1Helmholtz Institute Jena, D-07743 Jena, Germany
GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany
3
IOQ, Friedrich-Schiller-Universität Jena, D-07743 Jena, Germany
4
School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
5
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
6
I. Physikalisches Institut, Justus-Liebig-Universität Gießen, D-35392 Giessen, Germany
7
Aachen University of Applied Sciences, D-52005 Aachen, Germany
8
Helmholtz Research Academy Hesse for FAIR, Campus Gießen, D-35392 Giessen, Germany
9
Physics Department, Stockholm University, S-106 91 Stockholm, Sweden

The study of x-ray emission associated with radiative recombination (RR) at ultra-cold coolingconditions, as it prevails at electron cooler devices at ion storage rings, allows for a stringent test of
atomic structure and the investigation of subsequent x-ray emission characteristics. In particular, forhighly charged ions at high Z it enables us to probe in detail the prevalent cascade decay dynamics
and gain more insight into the final state population of the recombination process itself.
We report on an experiment where bare lead ions were decelerated down to 10 MeV/u in the ESR
storage ring at GSI, Darmstadt and injected into CRYRING@ESR [1] and, subsequently, the x-ray
emission of hydrogen-like lead ions were studied at the electron cooler. For this purpose, at theextension part of cooler section dedicated vacuum chambers were used, equipped with beryllium
view ports allowing for x-ray detection under 0° and 180° with respect to the ion beam axis. The xray detection was accomplished by two high-purity, planar germanium x-ray detectors. In order tosuppress the dominant background, stemming from bremsstrahlung caused by cooler electrons andthe natural background, an ion detector was operated downstream to the cooler, enabling all x-ray
events to be registered in coincidence with down-charged Pb81+ ions from electron cooler section.
In this experiment, we observed for the very first time for stored ions the full x-ray emission
pattern. Most remarkably, at 0° no line distortion effects due to delayed emission are present in thewell-defined spectrum, spanning a wide range of x-ray energies (from about 5 to 100 keV), whichenables us to identify fine-structure resolved Lyman, Balmer, and Paschen x-ray lines along with
the RR transitions into the K-, L- and M-shell of the ions. To compare with theory, an elaborate
theoretical model is established taking into account the initial population distribution via RR for all
atomic levels up to Rydberg states with principal quantum number n = 165 in combination withcascade calculations based on time-dependent rate equations. Most notably, this comparison sheds
light on the contribution of prompt and delayed x-ray emission to the observed x-ray spectra,
originating in particular from Yrast transitions into inner shells.
References[1] B. Zhu et al., Phys. Rev. A, in press (2022) and arXiv: 2201.06977.

92

A33
First Dielectronic Recombination Measurements
at the Cryogenic Storage Ring
Leonard Isberner1 , Manfred Grieser2 , Robert von Hahn2 , Zoltán Harman2 , Ábel Kálosi3,2 ,Christoph H. Keitel2 , Claude Krantz4 , Daniel Paul3,2 , Suvam Singh2 , Andreas Wolf2 ,Stefan Schippers1 , and Oldřich Novotný2
I. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany
2
Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
3
Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
4
GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
1

The charge balance in plasmas is governed by competing processes for ionization and recombination.
For the understanding and modeling of plasmas in astrophysical environments as well as terrestrial
applications, data on the recombination of atomic ions with free electrons are of high importance [1].
Over the past three decades, such recombination processes have been studied extensively in magnetic
heavy-ion storage rings by applying the electron-ion merged-beams technique [2]. A challenge ofthese experiments is the background produced by electron capture from residual gas. Because of therelatively high vacuum pressure of conventional room temperature magnetic storage rings, measurements were restricted to ions with a high charge-to-mass ratio, which could be stored at sufficiently
high energies where the rate coefficient for residual-gas-related electron capture drops. Data on lowcharged heavy ions are still widely missing.
The electrostatic Cryogenic Storage Ring CSR [3], located at the Max-Planck-Institut für Kernphysik
in Heidelberg, Germany, combines the mass-independent storage of electrostatic storage rings withthe excellent vacuum conditions provided by its fully-cryogenic beam environment. It is equippedwith an electron cooler and a suitable single particle detector. The unique environment of CSR, thus,
is promising for the investigation of electron-ion recombination in low-charged heavy ions.
Here, we report on the first recombination studies with atomic ions at CSR. We have investigateddielectronic recombination of Ne2+ and Xe3+ , where we observed resonant recombination featuresin agreement with quantum-theoretical predictions. Our results clearly demonstrate the feasibility ofatomic recombination studies with heavy low-charged ion species at CSR.
References[1] A. Müller, Adv. At. Mol. Opt. Phys. 55, 293 (2008).
[2] S. Schippers, Nucl. Instrum. Methods Phys. Res., Sect. B 350, 61 (2015).
[3] R. von Hahn et al., Rev. Sci. Instr, 87, 063115 (2016).

93

A34
Micro-Calorimeters as a Universal Tools for High Resolution Energy
Dispersive Photon Detection
M. O. Herdrich1,2,3, G. Weber1,3, A. Fleischmann4, D. Hengstler4, C. Enss4, S. Trotsenko1,3
and Th. Stöhlker1,2,3
2

1Helmholtz-Institute Jena, Fröbelstieg 3, Jena, Germany
Institute for Optics and Quantum Electronics, Friedrich Schiller University Jena, Germany
3
GSI Helmholtz Center for Heavy Ion Research, Planckstraße 1, Darmstadt, Germany
4
Kirchhoff-Institute for Physics, Ruprecht Karls University, Heidelberg, Germany

Cryogenic micro-calorimeters like the maXs-detectors have proven to be a particularly
promising tool for x-ray spectroscopy experiments as they are proposed within the frame of the
SPARC collaboration [1]. Due to their measurement principle requiring very low operation
temperatures ( 50 𝑚𝐾), they provide an intrinsically high energy resolution (𝐸/Δ𝐸6000) comparable to crystal spectrometers [2]. At the same time, their energy resolution ismostly independent of the measured photon energy, therefore making them operable in a broad
spectral range of energies
0.1 100 𝑘𝑒𝑉 . Thus, they combine the advantages of several
conventional energy dispersive photon detection methods.
However, to achieve this high level of performance, besides a technically challenging operating
setup, the signal readout relies on an almost complete digital signal processing with very few
analog stages. Therefore, calorimeters require a complex signal analysis software based upon adetailed understanding of the detector. During the last years, several experiments wereconducted at the ion storage rings of GSI/FAIR in Darmstadt where calorimeter detectors havebeen deployed for high resolution x-ray spectroscopy. The insights gained during thesecampaigns were used to develop and improve an analysis software API within the frame of thiswork. Results of the analysis will be presented with the particular focus on experiments
performed at the ESR, namely, the study of x-rays produced in collisions of Xe54+ projectiles
with Xe gas atoms at 50 MeV/u as well as for U89+ on N2 collisions at 76 MeV/u (see fig. 1).

Figure 1: X-ray spectrum recorded by a maXs-30 detector resulting from the collision of
U89+ions (76 MeV/u) with a N2 gas-target in the internal target of the ESR of GSI.

References[1] D. Hengstler et al., Phys. Scr. T166 (2015)[2] J. Geist, Dissertation, Heidelberg (2020)

94

A35
Experimental Studies of Nonperturbative Dynamics
in Heavy-Ion-Atom Collisions
P.-M. Hillenbrand1,2 , S. Hagmann2 , D. Banaś3 , E. P. Benis4 , C. Brandau1,2 , O. Forstner2,5,6 ,J. Glorius2 , R. E. Grisenti2 , A. Gumberidze2 , M. O. Herdrich5,6 , M. Lestinsky2 , Yu. A. Litvinov2 ,E. B. Menz2,5,6 , S. Nanos4 , N. Petridis2 , Ph. Pfäfflein2,5,6 , H. Rothard7 M. S. Sanjari2,8 ,U. Spillmann2 , S. Trotsenko2 , M. Vockert5,6 , G. Weber6 , Th. Stöhlker2,5,6
I. Physikalisches Institut, Justus-Liebig-Universität, 35392 Giessen, Germany
GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
3Institute of Physics, Jan Kochanowski University, 25-406 Kielce, Poland
4
Department of Physics, University of Ioannina, 45110 Ioannina, Greece
5Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, 07743 Jena, Germany
6
Helmholtz-Institut Jena, 07743 Jena, Germany
7
CIMAP, Normandie Université, ENSICAEN, UNICAEN, CEA, CNRS, 14000 Caen, France
8
Aachen University of Applied Sciences, 52066 Aachen, Germany
1

2

Experimental data for atomic collisions of highly-charged ions are essential for benchmarking thetheoretical description of dynamical processes in atomic physics. Of particular challenge is the accurate description of those processes that exceed the applicability of relativistic first-order perturbation
theories. Recently, we have investigated two characteristic cases of such collision systems at the Experimental Storage Ring ESR of the GSI heavy-ion accelerator facility in Darmstadt, Germany:(1) For fast collisions of U89+ projectiles with N2 and Xe targets at 76 MeV/u, we studied the electronloss-to-continuum cusp both experimentally and theoretically. We compared the continuum electron
spectra of the two collision systems, which originate from the ionization of the projectile, and wewere able to identify a clear signature for the nonperturbative character of the collision systems [1].
(2) For slow collisions of Xe54+ and Xe53+ with a Xe target at 30 and 15 MeV/u, we performed
an x-ray spectroscopy experiment focusing on the target K↵ radiation. Experimental data for suchslow symmetric collision systems are important for testing relativistic two-center calculations andprovide an intermediate step towards understanding heavy-ion collisions in super-critical fields. We
used the target K↵ satellite and hypersatellite lines to derive cross-section ratios for double-to-single
target K-shell vacancy production and compared our experimental results to theory applying a fully
relativistic time-dependent two-center approach [2].
At GSI, new prospects of investigating slow Xe54+ -Xe collisions under improved conditions will
now be facilitates by the low-energy heavy-ion storage-ring CRYRING@ESR. Corresponding experiments are currently being devised.
References[1] P.-M. Hillenbrand et al., Phys. Rev. A 104, 012809 (2021).
[2] P.-M. Hillenbrand et al., Phys. Rev. A 105, 022810 (2022).

95

A36
High-resolution dielectronic recombination spectroscopy with slow cooled
Pb78+ ions in the CRYRING@ESR storage ring
S. Fuchs1,2,3 , C. Brandau1,3 , E. B. Menz3,4,5 , M. Lestinsky3 , A. Borovik, Jr.1 , Y. N. Zhang6 ,Z. Andelkovic3 , F. Herfurth3 , C. Kozhuharov3 , C. Krantz3 , U. Spillmann3 , M. Steck3 , G. Vorobyev3 ,R. Hess3 , V. Hannen7 , D. Banaś8 , M. Fogle9 , S. Fritzsche4,5 , E. Lindroth10 , X. Ma11 , A. Müller1 ,R. Schuch10 , A. Surzhykov12,13 , M. Trassinelli14 , Th. Stöhlker3,4,5 , Z. Harman15 , and S. Schippers1,2
for the SPARC Collaboration
1
I. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Giessen, Germany
Helmholtz Forschungsakademie Hessen für FAIR, Campus Gießen, 35392 Giessen, Germany
3
GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
4Helmholtz-Institut Jena, 07743 Jena, Germany
5
Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
6
MoE-NSMCM, School of Science, Xi’an Jiaotong University, Xi’an 710049, China
7
Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
8
Institute of Physics, Jan Kochanowski University, 25-406 Kielce, Poland
9
Department of Physics, Auburn University, AL 36849, USA
10
Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
11
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
12
Institut für Mathematische Physik, TU Braunschweig, 38106 Braunschweig, Germany
13
Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
14
Institut des NanoSciences de Paris, CNRS, Sorbonne Université, 75005 Paris, France
15
Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
2

Dielectronic recombination (DR) spectroscopy is a widely used and very successful technique to study
the properties of highly charged ions [1–3]. Its high precision and versatility make it an important
spectroscopic tool in the physics program of the SPARC collaboration, e.g. outlined in Ref. [4]. The
heavy-ion storage ring CRYRING@ESR of the international FAIR facility in Darmstadt is a very
attractive machine for performing DR spectroscopy because of its electron cooler that is equippedwith an ultra-cold electron beam promising highest experimental resolving power. Here, we report on
results from the first DR experiment with highly charged ions at this new facility.
The measured DR spectra of Pb78+ in the electron-ion collision energy range of 0–40 eV cover the
2s2p (3 P1 ) 19` and 2s2p (3 P1 ) 20` resonances resulting from electron capture of the Be-like core.
While the data analysis is still ongoing, the preliminary results show good agreement of relative peak
positions and peak strengths with theoretical calculations using the methodology described in Ref. [5].
For kinematic reasons the resolving power is highest at the lowest collision energies. We will exploit
this in the future using few-electron heavy ions which exhibit DR resonances at energies below 1 eV.
References[1] S. Madzunkov et al., Phys. Rev. A 65, 032505 (2002)[2] S. Schippers, Nucl. Instrum. Methods Phys. Res. B 350, 61 (2015)[3] C. Brandau et al., Phys. Scr. T166, 014022 (2015)[4] M. Lestinsky et al., Eur. Phys. J ST 225, 797 (2016)[5] Z. Harman et al., Phys. Rev. A 99, 012506 (2019)

96

A37
Coherent treatment of transfer excitation processes in swift ion-atom collisions
E. P. Benis1, T. J. M. Zouros2,3, A. Laoutaris2,3, I. Madesis2,3, S. Nanos1,3,
S. Passalidis4 and A. Dubois4
1

Department of Physics, University of Ioannina, GR-45110 Ioannina, Greece2
Department of Physics, University of Crete, GR-70013 Heraklion, Greece
3
Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics,
NCSR “Demokritos”, GR-15310 Ag. Paraskevi, Greece
4
Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement,
F-75005 Paris, France

For more than 40 years since the first ion-atom collision investigations of the two-electron processof electron transfer with excitation (TE) and its resonant (RTE) and non-resonant (NTE) features, asatisfactory quantum mechanical treatment has been lacking. Here, we present the first suchcomprehensive TE treatment using a three-electron close-coupling approach, exemplified by
C4+(1s2) + He collisions at 0.5-18 MeV impact energies.
We focus on the production of the C3+(1s2p2 2D) state, which shows the strongest TE resonanceamongst the KLL states. Single differential cross sections (SDCS) are experimentally determinedusing zero-degree Auger projectile spectroscopy (ZAPS), by detecting the emitted Auger electron at
θ=0ο with respect to the beam direction. Our recently proposed “two-spectra measurement" in situ
technique [1] was applied to separate the C4+(1s2) ground state contributions from the delivered
C4+(1s2, 1s2s 3S) mixed-state beam. Our theoretical treatment considers, for the first time, thedynamics of three active electrons using semiclassical close-coupling calculations within a fullconfiguration interaction approach [2]. This implementation allows for a coupled and coherent
treatment of all processes such as target and projectile excitation, ionization, single electron capture[3], as well as TE and therefore goes well beyond past methods.
The calculated single differential cross sections are found to be in excellent agreement with the
ZAPS measurements at the high impact energies between 6-18 MeV where RTE is prominent. At
the lower energies, 0.5-6 MeV, a second maximum is observed in the theoretical results but could
not be recorded experimentally due to low beam currents provided by our facilities in this regime.
The low energy structure is interpreted through a new nonresonant correlated mechanism, neverconsidered to date. In the conference, detailed information, such as transition probabilities as afunction of impact parameter and energy, will be presented to illustrate the different features of thetwo mechanisms exposed in our results.

References[1] E.P. Benis and T.J.M. Zouros, J. Phys. B 49, 235202 (2016).
[2] J.W. Gao, Y. Wu, J.G. Wang, A. Dubois, and N. Sisourat, Phys. Rev. Lett. 122, 093402 (2019).
[3] I. Madesis, A. Laoutaris, T.J.M. Zouros, E.P. Benis, J.W. Gao, and A. Dubois, Phys. Rev. Lett.
124, 113401 (2020).

97

A38
C

,

,

I.

, K. T k si

Institute for Nuclear Research (Atomki), 4026 Debrecen Bem t r 18/c, Hungar
Doctoral School of Ph sics, Facult of Science and Technolog , Universit of Debrecen, P.O. Bo
400, H-4002, Debrecen, Hungar
Recentl , ionic impurities ith nuclear charges 𝑍 8 are found in the core of thermonuclear fusion
plasmas. These elements are full ioni ed because of the high temperature and densit in the core.
These impurities pla a role in the loss of radiant energ that causes the plasma to cool hen colliding
ith the primar plasma components such as neutral h drogen atoms. Therefore, it is essential to
kno the interaction bet een bare ions and h drogen atoms.
The standard three-bod classical trajector Monte Carlo (CTMC) model is a ell-kno n classicaltreatment for modelling atomic collisions [1]. But due to the lack of quantum features in the standard
model, the CTMC model is not able to describe accuratel the cross sections mostl at lo er impact
energies hen the quantum mechanics characteristic is dominant. Therefore e developed a threebod quasi classical trajector Monte Carlo (QCTMC) model taking into account quantum feature of
the collision s stem, here the Heisenberg correction term is added to the standard classicalHamiltonian of the collision s stem to mimic the Heisenberg uncertaint principle [2-4]. In this ork,e present ioni ation, total and state selective cross sections in the collisions bet een bare ions ith
H(1s). Figure 1 sho s the projectile energ dependent ioni ation and total electron capture crosssections in C6+ + H(1s) collisions. We found that our QCTMC results are in good agreement ith thepreviousl obtained quantum-mechanical results. Our model ith simplicit can time efficientl
provide accurate results here ma be the quantum mechanical ones become complicated [5].
1 -14

( )

( )

2)

1 -16

V(

1 -15

V(

2)

1 -15

1 -17

P
P
J

C MC
QC MC
. P . R , A 49, 645 (1995), P . R . A 50, 5 (1994)

I. J. P. B: A . M . O . P

1 -16. 45, 065203 (2012)

1 -18
10

E

100

(

/

)

1000

P
P
I
H
G

C MC
QC MC
. .
. :A .
.A .D .N .D. .
. :A .
.

.

.
. 45, 065202 (2012)
68, 279 (1998). 12, 3763 (1979)

.

10

100

E

(

/

)

Figure 1: Projectile energ dependent (a) ioni ation (b) total electron capture cross sections in
C6+ + H(1s) collisions.
References[1] K. T k si and G. Hock, Nucl. Instrum Meth. Ph s. Res. B 86, (1994)[2] I. Ziaeian and K. T k si, Atoms 8, (2020)[3] I. Ziaeian and K. T k si, EPJD J. 75, (2021)[4] I. Ziaeian and K. T k si, Sci. Rep. 20164 (2021)[5] I. Ziaeian and K. T k si, At. Data Nucl. Data Tables, https://doi.org/10.1016/j.adt.2022.101509

98

A39
Interaction of C5+ ions with hydrogen atoms
Saed J. Al Atawneh1, 2 and K T k si1
1

2

Institute for Nuclear Research (ATOMKI), 4026 Debrecen Bem tér 18/c, Hungary
Doctoral School of Physics, Faculty of Science and Technology, University of Debrecen, P.O.400,
Debrecen, Hungary

Collisions between multiply charged ions and atomic hydrogen are important in determining theradiation losses and neutral beam heating efficiencies in tokamak plasmas [1]. In this work a 4-bodyclassical trajectory Monte Carlo (CTMC) and a 4-body quasi-classical Monte Carlo (QCTMC)
model of the Kirschbaum and Wilets were used to calculate the cross sections in C5+ and H(1s)collisions. We present target ionization and charge exchange cross sections in the projectile energy
range between 0.833 keV/amu and 5.833 MeV/amu and compared them with previously obtained
results [2]. According to our knowledge, this is the first time to present cross section data using the
QCTMC method for this collision system. Figure 1. shows the target ionization cross sections in acollision between C5+ ions with H atoms as a function of impact energy. We found that the crosssections obtained by the QCTMC model are higher than that of the cross sections calculated by thestandard CTMC model and these cross sections are closer to the previous experimental andtheoretical data. Moreover, we also show that the interaction between the projectile and the target
electrons plays a dominant role in the enhancement of the cross sections at lower energies.
1e-14

(cm2)

1e-15

1e-16

1e-17
1e+3

1e+4

1e+5

1e+6

1e+7

Energy (eV/amu)

Figure 1: Target ionization cross sections in a collision between C5+ ion and H(1s) atom as afunction of impact energy. Blue solid line: The present four-body CTMC results [2]. Green dashedline: The present 4-body QCTMC results [2]. Red circles: The 3-body CTMC calculation by R.K.
Janev et al. Ref [3].
This work has been carried out within the framework of the EUROfusion Consortium, funded by
the European Union via the Euratom Research and Training Programme (Grant Agreement No
101052200 - EUROfusion). Views and opinions expressed are however those of the author(s) onlyand do not necessarily reflect those of the European Union or the European Commission. Neither
the European Union nor the European Commission can be held responsible for them.
References[1] Barnett CF. Atomic physics in the controlled thermonuclear research program. USA (1975). p. 8[2] S. J. A. Ata neh and K. T k si. Nucl. Fusion. 62, 026009 (2021)[3] R.K. Janev and M.R.C. McDowell. Phys. Lett. A. 102, 9 (1984)

99

A40
Ion-impact induced two-body dissociation of methane dicationC P Safvan1 , Jyoti Rajput2 , Diksha Garg2 , A. Cassimi3 , A. Méry3 , X. Fléchard4 , J. Rangama3 ,S. Guillous3 , W. Iskandar5 , A. N. Agnihotri6 , J. Matsumoto7 , R. Ahuja1
Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067, India
2
Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India
3
CIMAP,CEA/CNRS.ENSICAEN/Université Caen Normandie, F-14050 Caen Cedex 04, France
4
Normandie Université, ENSICAEN, UNICAEN, CNRS/IN2P3, LPC Caen, 14000 Caen, France
5
Chemical Science Division, LBNL, Berkeley, California 94720, USA
6
Indian Institute of Technology Delhi, New Delhi - 110016, INDIA
7
Department of Chemistry, Tokyo Metropolitan University, Tokyo 192-0397, Japan1++
The dissociation of CH2+
4 into H and CH3 has been studied using the technique of cold target recoil
ion momentum spectroscopy. The methane dication is formed in the interaction of Ar9+ and N3+ andneutral CH4 molecules, while keeping ion-molecule interaction time as constant. The recoil ions aredetected in coincidence with charge changed projectiles (Ar8+ or Ar7+ and N2+ or N+ ) and results onfour different data sets are presented. We observe three distinct dissociation pathways for each data
set with mean kinetic energy releases of around 4.7 eV, 5.8 eV and 7.9 eV. The electronic states thatare populated correspond to electronic configurations (1t2 ) 2 and (2a1 ) 1 (1t2 ) 1 of CH2+
4 . We havealso been able to estimate the relative branching ratios for the three pathways, and a strong correlation
with the specific nature of the ion-molecule interaction is noted.

+
Figure 1: Typical KER spectra measured for two body breakup of methane dication, CH2+
4 ! H +
CH+
3 . For reference, KER data from a core ionization experiment is also plotted [3]Existing ab-initio calculations [1-3] provide an explanation for the 5.8 eV pathway, and we propose
a possible pathway for the 7.9 eV pathway. However, the pathway leading to 4.7 eV remains to be
explained [4].
References[1] P. E. Siegbahn, Chemical Physics 66, 443 (1982).
[2] R. Flammini et al. New J. Phys. 11, 083006 (2009)[3] J. B. Williams et al. J. Phys B: Atomic, Molecular and Optical Physics 45, 194003, (2012).
[4] J. Rajput et al. J. Chem. Phys. 156, 054301 (2022).

100

A41
Electron emission from methane molecule in fast ion impact ionization
D Chakraborty1, S Maurya1, C Bagdia1, A Bhogale1, L. Gulyas2 and L C Tribedi1, *1

Tata Institute of Fundamental Research, Colaba, Mumbai-400005, India
2
Institute for Nuclear Research, Debrecen 4001, Hungary* lokesh@tifr.res.in

Investigation on ionization of molecules in collisions with fast ions is important in molecularphysics and related sciences. Methane (CH4) is a simpler hydrocarbon molecule which is abundantin ea h a m he e a
ell a in the interstellar medium. Also methane works as a reference
molecule for larger and complicated hydrocarbons, such as, PAH molecules and bio-molecules etc.
We present electron double differential cross section (DDCS) for ionization of methane in 70 MeV
He like Si ion impact. The fast Si ions are obtained from the 14 MV Pelletron accelerator.
Measurement is done for the electron energy region of 1-400 eV and at different scattering angles
between 20°-160°. Energy distributions and angular distributions of the absolute DDCS arecompared with continuum distorted wave-eikonal initial state (CDW-EIS) model using threedifferent target descriptions [Figure 1]. These are the complete neglect of differential orbital(CNDO) approximation and molecular orbital (MO) approximation with bond length, d=0.7 and1.0. It is shown that the calculation with d=1 matches better with experimental data. The C-KLL
Auger peak is observed along with hypersatellite component which appears due to the double K
shell vacancy in carbon atom. Double to single ionization ratio is found to be very large i.e. about
37%. Forward-backward ratio of the e-DDCS shows an oscillatory behaviour which is yet to beunderstood. However, it could possibly arise due to the Young type interference effect from the CH bond in the molecule. Single differential cross section and total cross section are derived byintegrating the DDCS over the energy and scattering angles. Overall we found a very good
agreement with the theoretical model.

Figure 1: Energy distribution of e-DDCS at scattering angle 30° along with CDW-EIS calculations
References[1] E. Herbst, Annual Review of Physical Chemistry 46, 27 (1995)[2] C. Bagdia et al, Physical Review A 104, L060802 (2021)[3] S. T. S. Kovacs et al, Physical Review A 94, 012704 (2016)

101

A42
Hydrogen migration in three body fragmentation of acetylene trication
Jatin Yadav, C. P. Safvan*, Pragya Bhatt*, Pooja Kumari, Aditya Kumar*, Jyoti Rajput
Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India*Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067, India
We report on the three body fragmentation of [C2H2]3+ into (H+, C+, CH+) fragments in interaction ofneutral acetylene with a slow highly charged ion (Xe9+ having velocity ≈ 0.5 a.u.). The momenta ofall these three fragments were measured in coincidence using the technique of Recoil Ion
Momentum Spectroscopy (RIMS). For this particular fragmentation channel, three different
dissociation pathways are observed, namely concerted breakup in acetylene configuration,
concerted breakup in vinylidene configuration and sequential breakup via [C 2H]2+ intermediate
molecular ion.
To extract information about the different dissociation pathways, we have used Newton diagram [1]and the method of native frames [2] for analysing the momentum correlations. Figure 1(i) shows theγ - KER2 distribution generated by using the method of native frames and by assuming [C2H]2+ as anintermediate ion in sequential mode of breakup. KER2 represents the kinetic energy releaseassociated with the second step of the sequential breakup. The angle between the direction of thefirst two-body breakup and second two-body breakup in their respective centre-of-mass frames isrepresented by angle (γ). The uniform distribution observed parallel to the γ - axis is an evidence ofa long-lived electronic state of the [C2H]2+ molecular ion. The distribution is divided into two
regions A and B based on the value of KER 2 and two separate Newton diagrams are plotted asshown in figure 1(ii) and 1(iii). The semi-circular arc like feature observed in figure 1(ii) is asignature of sequential breakup via [C2H]2+ and the high intensity areas belong to concerted
breakup. In figure 1(iii), the angle between the momentum vectors of H + and C+ take two distinct
values around 25° and 165°. A low value of this angle corresponds to acetylene configuration and ahigh value corresponds to vinylidene configuration.

Figure 1: (i) A distribution of KER2 with γ for all events. (ii) and (iii) shows Newton diagrams forselected values of KER2 as indicated on the figure (see text for more information).
References[1] N. Neumann et. al. Phys. Rev. Lett. 104, 103201 (2010)[2] J. Rajput et. al. Phys. Rev. Lett. 120, 103001 (2018)[3] Jatin Yadav et. al. J. Chem. Phys. (Comm.) 156, 141101 (2022)

102

A43
Direct observation of molecular oxygen formation due to ion impact-induced
molecular fragmentation of carbon dioxide
Kamal Kumar*, AKA Siddiki, Jibak Mukherji, Lokesh C. Tribedi, Deepankar Misra
Tata Institute of Fundamental Research, Mumbai-400005, Maharashtra India* kamal.kumar@tifr.res.in

The study of molecular fragmentation upon ion impact is important from the viewpoint ofunderlying fundamental physics, has interests in radiation biology [1], fusion and astrophysicalplasmas [2], to name a few. The mentioned experiment was performed with 0.49 au Xe10+ ionsproduced in ECR (Electron Cyclotron Resonance) ion source, this beam was interacted with
Supersonically cooled jet of neutral CO2 molecules inside COLd Target Recoil Ion Momentum
Spectrometer (COLTRIMS). These Xe10+ ions captured two electrons from the molecule andformed CO22+ ions in the reaction,
Xe10+ + CO2

Xe8+ + CO22+

Xe8+ + C+ + O2+

C+ and O2+ recoil ions were detected in coincidence with charge state changed projectile ion, with
Chevron configured MCP-DLD detector setup.
We also detected other fragmentation channels of CO22+ ions, but this particular channel is of great
importance. After interaction, the newly formed CO22+ ion starts to bend, and after sufficientbending, a new bond formation between two O species takes place, which results in production of
O2+. While the dication was formed, it may have formed in an electronic level which supports thisbending of the molecule.

Figure 1: Dynamics of bending of the CO22+ molecular ion.

References[1] H.J. Lüdde, A. Jorge, M. Horbatsch, T. Kirchner, Atoms 8, 59 (2020).
[2] Patricia Barragán et. al. PHYSICAL REVIEW A 74, 012720 (2006).

103

A44

Development of a COLTRIMS setup to study electrontransfer processes in highly charged ion-atom/molecule
collisions
Md Abul Kalam Azad Siddiki1 , Kamal Kumar1 , Jibak Mukherjee 1 , Nrisimhamurty Madugula2 ,Arnab Khan3 , L.C. Tribedi1 and Deepankar Misra1⇤
1
Tata Institute of Fundamental Research, Mumbai-400005, India
2
Department of Physics, The Ohio State University, Columbus, OH-43210, USA.
3
Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
⇤

dmisra@tifr.res.in

We report on the development of a COLd Target Recoil Ion Momentum Spectrometer (COLTRIMS)[1,2] setup at TIFR, which is built to study various atomic and molecular processes involving the interactionof slow, highly charged ions from an Electron Cyclotron Resonance based Ion Accelerator[3]. We give a
detailed description of the experimental setup along with the development of a beam cleaner and a final
charge state deflector. We have also present some initial results on the single electron-capture process incollisions of Ar8+ ions with He targets. We present the longitudinal momentum transfer and state-selective
Q-value spectrum in case of 2, 4, 6 and 25 keV/u Ar8+ beam in collisions with He. We also report thestate-selective scattering angle distributions for 2, 4, and 6 keV/u collision systems under investigationand explore the effects of dynamical coupling. In the below figure we have shown the two-dimensional
momentum density plot for Ar8+ He collision system.

20
4p 4d+4f
15
p (a.u.)

4s
5s

10

102

5

0
−10

−8

−6
−4
p (a.u.)−20

Figure 1: Two dimensional momentum density plot for 2 keV/amu Ar8+ He SEC process.

References[1] Reinhard Dörneret al, Physics Reports 330.2-3 (2000), pp. 95–192.
[2] Joachim Ullrich et al, Reports on Progress in Physics 66.9 (2003), p. 1463.
[3] A. N. Agnihotri et al, Phys. Scr. T 144, 014038 (2011).

104

A45
Electron capture by highly charged ions in collision with water
Sanjeev Kumar Maurya, Abhijeet Bhogale, Lokesh Tribedi*
Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India*Email: lokesh@tifr.res.in

In case of low energy ion-molecule collisions, such as keV energy range, the electron capture process
dominates over ionization and excitation [1-3]. The strong capture channel has a huge contribution
towards the energy-loss of the projectile inside a medium. This is important particularly in estimating
the Bragg peak (in keV-MeV energy range) of energy-loss for high energy (GeV) ions which are
typically used for hadron therapy. A new experimental setup is developed to study the electron
capture processes using highly charged low energy ion beams. Experiments are carried with highly
charged ions (C ) colliding with water molecule in the energy range 100-1300 keV. The incoming
C beam is collimated by a set of collimators of ID ~1.5 mm and 2.5 mm. Further, the beam is passed
through a gas cell (pressure ~0.08 mtorr) where electron capture process occurs. Thereafter, the beam
is deflected by an electrostatic deflection plate and finally the original beam is collected in a Faraday
cup and beam current is measured by a newly installed femtometer. The beam current is minimized
to ~200 fA. A movable beam stopper is also employed before the micro channel plate (MCP) to stop
the beam. Capture events are detected using a position sensitive detection system comprising of MCPs
and a delay line detector (DLD). In case of C beam, one to four e-capture events are observed,
which is shown in Figure 1. These e-capture events can be a result of pure capture reactions as wellas transfer ionization. Capture cross-section is calculated for one, two, three, and four e-capture
events. Total capture cross-section is also calculated and it is found to decrease sharply with the beamenergy. Capture ratios such as four e-capture to single capture, three to one capture, and two to one
capture are also calculated for different beam energies.

Figure 1: Electron capture spectrum of 100 keV C
one, two, three, and four electron capture.

beam in collision with water, which shows

References[1] H-D Betz, Rev. Mod. Phys., 44 465 (1972).
[2] A N Agnihotri et al., Phys. Rev. A, 85 032711 (2012).
[3] T Liamsuwan and H Nikjoo, Phys. Med. Biol., 58 641 (2013).

105

A46
Production of high charge state of projectile ions inside the target and its role inelectron capture leading to the subshell resolved L shell ionization
Soumya Chatterjee1, Sumana Ghosh1, D. Mitra1, T. Nandi2
1 Department of Physics, University of Kalyani, Kalyani, Nadia 741235, West Bengal, India
2 Inter-University Accelerator Centre, Aruna Asaf Ali Marg, Near Vasant Kunj, New Delhi110067, India

Here in an ultra-thin 76Os target bombarded by 4-6 Mev/u fluorine ions, the inner shell ionisation
mechanism for the L-subshell was investigated. The L X-ray production cross sections of Os were
measured using five distinct beam energies of 19F ions with varied charge states q = 6+, 7+, and 8+
in the energy range of 4–6 MeV/u in this study. We have incorporated multiple ionisation effects byadjusting fluorescence and Coster-Kronig yields while evaluating L-subshell ionisation crosssections deduced from production one. However, this isn't enough to get a satisfactory match
between theory and experiment. We compared our results to theoretical predictions such as I therelativistic semi-classical approximation (RSCA), (ii) the shell wise local plasma approximation(SLPA), and (ii) the ECUSAR theory. Aside from that, the coupled-states model (CSM) and astandard formalism take care of vacancy sharing among subshells and electron capture (EC).
Knowledge of the projectile's charge state “q inside the target is required to determine the capture
cross sections. The Lorentzian charge state distribution was used to calculate projectile charge state
fractions inside the target [1]. The Fermi gas model [2] is used to calculate mean charge state inside
the target, and the Novicov and Teplova approaches are used to calculate the width [3]. Theinterplay between electron capture and loss determines the charge state of the projectile ions inside
the target. We utilised the Lapicki-Losonsky prescription [4], which is based on the OppenheimerBrinkman-Kramers (OBK) approximation [5], to quantify the electron-capture cross sections. Even
when recent fluorescence and Coster-Kronig yields are taken into account, it appears that the theory
ECUSAR-CSM-EC represents the best excitation function curve among all theories, the theoretical
calculations are still roughly a factor of two less than the actual values. Due to a single vacancy,these contradicting observations may raised doubts on the theoretically derived initial atomic
properties. When the L1 fluorescence yield is roughly doubled, parameter optimization indicatesthat experimental findings match theoretical predictions. We support this theory with findings fromother studies of proton-induced L-shell ionisation of uranium atoms [6], as presumably, the proton
beam does not produce SMI in the target. So that the complication of multiple ionisation is ruledout as a source of complexity. It is apparent that reliable measurements and theoreticalcomputations of atomic characteristics need to be re-evaluated immediately.
.
References[1] P. Sharma and T. Nandi, Phys. Plasmas 23, 083102 (2016).
[2] W. Brandt et al., Phys. Rev. Lett. 30, 358 (1973).
[3] Novikov et al. Phys. Lett. A 378, 1286 (2014).
[4] G. Lapicki and W. Losonsky, Phys. Rev. A 15, 896 (1977).
[5] R. May, Phys. Lett. 11, 33 (1964).
[6] Orlic I, SowCand Tang S 1994 At. Data Nucl. Data Tables 56 159–210.

106

A47
Studying Sn ion collisions with H2 molecules to advance EUV nanolithography
K Bijlsma1,2, S Rai1,2, M Salverda1, P Wolff1, L Assink1, A Kleinsmit1, E Lalkens1,
B Neijzen1, I Rabadán3, L Mendéz3, O Versolato2,4, R Hoekstra1,2
1

Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG,
Groningen, The Netherlands
2
Advanced Research Center for Nanolithography, Science Park 106, 1098 XG,
Amsterdam, The Netherlands
3
Departamento de Química, Universidad Autónoma de Madrid, Cantoblanco, 28049,
Madrid, Spain
4
Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit, De Boelelaan 1081,
1081 HV, Amsterdam, The Netherlands
Nanolithography machines of the latest generation work with light in the extreme ultraviolet (EUV)
regime. This light is generated by a laser-produced plasma (LPP) of Sn. Apart from the EUV
photons, the LPP also emits highly-charged Sn ions with up to several tens of keV of energy thatmay damage plasma-facing surfaces. Therefore, industry uses a buffer gas to slow these ions. The
only gas that barely absorbs the EUV light is H2. Further optimization of this technique by
simulations requires accurate atomic data on the energy loss and charge exchange processes incollisions of Sn ions of a specific energy and charge state with H2 molecules. We are working on
obtaining this missing data at the ZERNIKELEIF facility at the University of Groningen where we
can generate a beam of Sn ions of a pre-selected energy (keV range), charge state (up to q = 12),and mass (isotope).
We have obtained the single electron capture cross sections for Sn3+ on H2 and on D2 in the energy
range 1-51 keV [1]. We compare our measurements to semi-classical calculations and find good
agreement at the higher energies. However the experimental values increase more strongly towards
the lower energies. Moreover, we find a substantial isotope effect which is not present in thetheoretical models.
We will also present the first energy-loss distributions obtained from our RFA measurements. These
measurements will be compared to predictions from the simulation software SRIM and also from acode we have developed ourselves, GIonS. With this code we are able to take the ionic nature of the
projectile as well as charge exchange into account.
References[1] S. Rai, K. Bijlsma, I. Rabadán, L. Méndez, P. Wolff, M. Salverda, O. Versolato, R. Hoekstra,
submitted, (2022)

107

A48
Dielectronic recombination in He-like oxygen ionsinvestigated at CRYRING@ESR
W. Biela-Nowaczyk1*, P. Amaro2, C. Brandau3,4, S. Fuchs4,5, F. Grilo2,
M. Lestinsky3, E. B. Menz3,6, S. Schippers4,5, T. St hlker3,6, A. Warczak1
1Institute of Physics, Jagiellonian University, Poland

2Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL),NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
3
GSI Helmholt entr m f r Sch erionenforschung, 64291 Darmstadt, Germany
4
I. Physikalisches Institut, Justus-Liebig-Uni ersit t Gie en, 35392 Gie en, Germany
5Helmholtz Forsch ngsakademie Hessen f r FAIR, Campus Gie en, 35392 Gie en, Germany
6
Helmholtz Institute Jena, 07743 Jena, Germany
Electron-ion
recombinationisa fundamental atomic process occurring inplasmas.
Accurate
experimental
recombination
cross-sections
areparticularly important for astrophysicalmodels. Among the recombination
processes the dielectronic recombination(DR) process especially affects the
dynamics of astrophysical objects [1, 2].
DR is a two-step process. The firststep, called dielectronic capture, isessentially the time reversal of theAuger process. This way, an excitedstate is produced. To complete the DR
process a radiative deexcitation takes
place in a second step. One should note
Figure 1: Preliminary results of measured DRthat autoionization is also a possible
resonances of O6+ ions at CRYRING@ESR electron
deexcitation channel but, in this case, nocooler.
electron-ion recombination can be observed.
In order to provide the experimental data for both high and low temperature plasmas, DR
has been investigated in the Δn=1 and Δn=0 regimes, respectively. The data presented in
Figure 1 was collected for K-Ln (n=L, M, N, ) DR of He-like oxygen ions. Oxygen is oneof the most abundant elements in the Universe and, therefore, is of particular importance[1,2]. The experiment took place at the low-energy storage ring CRYRING@ESR. DR
spectra were measured by applying collision spectroscopy of ions merged in a cold electron
beam [3]. He-like oxygen ions were passing hundreds of thousands times per second a cold
electron beam. This beam was essentially a target, and as a signature for recombination,
O5+ ions were detected. The resonant condition was achieved by changing the relativeelectron-ion energy. This high-precision spectroscopy method has been successfully used
before [3]. It is of special importance within the research program of the SPARC
Collaboration [4].
References[1] A. Burgess, Astron. J. 139, 776 (1964)[2] S. Schippers, J. Phys.: Conf. Ser. 388 012010 (2012)[3] C. Brandau, C. Kozhuharov, M. Lestinsky et al., Phys. Scr. T166, 014022 (2015).
[4] M. Lestinsky et al., Eur. Phys. J. Special Topics 225, 797 (2016)

108

A49
Higher-order recombination processes in Argon ionsobserved via x-ray emission in an EBIT
W. Biela-Nowaczyk1, P. Amaro2, F. Grilo2, D. S. La Mantia3, J.Tanis3, A. Warczak1
1Institute of Physics, Jagiellonian University, Poland
2
Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL),NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
3
Western Michigan University, Kalamazoo, MI 49008, USA
The electron-electron interaction is a crucial aspect of atomic reactions involving electron-ion
recombination. A good understanding of these processes in the laboratory provides diagnostics tools
to determine the physical conditions of plasmas present in astrophysical objects [1]. The most basic
recombination process, which involves the electron-electron interaction, is dielectronic
recombination (DR) [2, 3]. In this resonant process, a free electron is captured while another boundelectron is excited due to the direct interaction between the two electrons. The recombination iscompleted through radiative stabilization of the excited ion. The research presented here wasconducted using an EBIT [4] at Jagiellonian University. The resolution of the x-ray detector
enabled the K-LL DR resonances to be distinguished for He- up to O-like Ar ions. In Figure 1, theprojection of DR spectra on the electron-energy axis is presented. These results encouraged moredetailed studies of trielectronic recombination (TR), specifically KK TR. There, the resonant
capture of a free electron to an ion-bound state transfers two K-shell electrons to a higher atomic
shell. This way, a doubly-excited K-shell state is produced and, in most cases, decays via emissionof two cascade photons. The first electron deexcites to the empty K shell, and thus the hypersatellite
transition (Kαh) occurs by photon emission with energy slightly higher than the second photon. The
following photon refers to the satellite transition (Kαs) when there is only a single vacancy in Kshell. This KK TR process has not been reported yet to the best of our knowledge. This work
presents significant arguments for a successful observation of the KK-LMM TR process in Ar ions.
Figure 2 presents an observed maximum-like behavior of the Kαh/Kαs intensity ratio. Simulationshows the absolute value of background production of the Kαh/Kαs intensity ratio.

Figure 1. DR spectra with electron-beam energy
observed in Ar. K-LL resonances for He- to O-like
Ar ions are shown.

Figure 2. Ratio of Ar hypersatellite to satellite
peaks (Kαh/Kαs) scanned in the expected KKLMM TR electron energy range.

References:[1] T.R. Kallman and P. Palmeri, Rev. Mod. Phys. 79, 79 (2007)[2] T.M.Baumann. Z.Harman, J.Stark et al., Phys. Rev. A 90, 052704 (2014)[3] C.Beilmann, P.H.Mokler, S. Bernitt et al., Phys. Rev. Lett. 107, 143201 (2011)[4] G.Zschornack, M.Schmidt and A.Thorn, CERN Yellow Report 007, 165-201 (2013)

109

a

A50
Dynamical benchmark of the metastable line formation in O VII near thecollisional excitation threshold
Filipe Grilo, José R. Crespo López-Urrutia*, José Marques**, José Paulo Santos, Pedro Amaro
Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL),
Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon,
2829-516 Caparica, Portugal(*) Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany(**)BioISI – Biosystems & Integrative Sciences Institute, Faculdade de Ciências da Universidade deLisboa, Campo Grande, C8, 1749-016, Portugal
X-ray measurements of O VII carried out at the FLASH- Electron Beam Ion Trap (EBIT). The decayof the metastable state 1s2s 3 S1 population was directly observed (mean lifetime of around 956 µs in
the literature [1]) with an electron beam energy scheme defined by a triangular wave. We observed
the He-like dielectronic recombination (DR) KLn structure, as well as resonant excitations (RE)superimposed to collisional excitations (CE) of H-like and He-like ions. A good agreement was foundbetween the experimental results and a preliminary spectrum calculated with Flexible Atomic Code
(FAC). A time dependent Collisional Radiative Model (CRM), based on a previous work [2], wasimplemented to study the physical parameters, in particular to model the spectrum baseline causedby the z-line emissions from the slow decay of the metastable population. This model calculates the
population dynamics of each individual energy level, as well as the resulting emissions, based on thethe ion-electron collisional processes and decay rates between atomic states. The now benchmarked
collisional-excitation cross-sections, which are highly important in astrophysical plasma modeling,
are being compared with calculations obtained from Multiconfiguration Dirac-Fock (MCDF) [3], asall as the main atomic databases relevant in astrophysics.

Figure 1: X-ray emission measurements of O VII compared with the time dependent CRM results fora energy scheme period of 1 ms (left) and 20 ms (right).
References[1] J. R. Crespo López-Urrutia, P. Beiersdorfer, D. W. Savin, Phys. Rev. A, 58, 238 (1998)[2] F. Grilo, C. Shah, S. Kühn, et al., ApJ, 913(2), p.140 (2021)[3] J. Desclaux, Computer Physics Communications, 35, C-288 (1984)

110

A51
Comprehensive laboratory measurements resolving the LMM dieletronic
recombination satellite lines in Ne-like Fe XVII ionsFilipe Grilo1 , Chintan Shah2,3 , Steffen Kühn3,4 , René Steinbrügge5 , Keisuke Fujii6 , José Marques7 ,Ming Feng Gu8 , José Paulo Santos1 , José R. Crespo López-Urrutia3 , Pedro Amaro1
Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL),
Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon,
2829-516 Caparica, Portugal
2
NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA
3
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
4
Heidelberg Graduate School of Fundamental Physics, Ruprecht-Karls-Universität Heidelberg, Im
Neuenheimer Feld 226, 69120 Heidelberg, Germany
5
Deutsches Elektronen-Sychrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
6
Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto
University, Kyoto 615-8540, Japan
7
BioISI – Biosystems & Integrative Sciences Institute, Faculdade de Ciências da Universidade deLisboa, Campo Grande, C8, 1749-016, Portugal
8Space Science Laboratory, University of California, Berkeley, CA 94720, USA1

L-shell transitions of highly charged iron dominate the 15 18Å range of the spectra emitted byastrophysical hot plasmas (MK) [1]. Due to its high ionization potential, Fe XVII is a very stablespecies and its emissions due to dielectronic recombination (DR) can be used as diagnostic tools toevaluate the temperature and electron density of the plasma [2].
We investigate both experimentally and theoretically the DR populating doubly excited configurations
3l3l’ (LMM) in Fe XVII, one of the strongest channel for soft x-ray line formation in this ubiquitous
species [3]. We used two different electron beam ion traps and two complementary measurement
schemes for preparing the Fe XVII samples and evaluating their purity, observing negligible contamination effects [4]. This allowed us to diagnose the electron density in both EBITs. The measurements
in one of the traps enabled the direct observation of spectral dynamics due to population time evolution, from which we achieved a good agreement with a charge-state dynamics simulation, performed
for the experimental conditions. We compare experimental results from both EBITs with an independent storage ring measurement [5], as well as with configuration-interaction, multiconfiguration
Dirac-Fock, and many-body perturbation theories. The latter showed outstanding predictive power incomparison with the combined independent experimental results. From these, we also inferred DR
rate coefficients, which unveiled discrepancies with widely atomic databases.
References[1] G. V. Brown, Canadian Journal of Physics, 86, 199 (2008)[2] L. Gu, C. Shah, J. Mao, et al., Astronomy&Astrophysics, 641, A93 (2020)[3] F. Grilo, C. Shah, S. Kühn, et al., ApJ, 913(2), p.140 (2021)[4] C. Shah, J. R. C. López-Urrutia, M. F. Gu, et al., The Astrophysical Journal, 881, 100 (2019)[5] E. W. Schmidt, D. Bernhardt, J. Hoffmann, et al., Journal of Physics: Conference Series, 163,
12028 (2009)

111

A52
State-selective cross sections for electron capture and excitation in Be4+ + H(2s)collisions at intermediate energies.
Clara Illescas, A Jorge and L. Méndez
Laboratorio Asociado al CIEMAT de Física Atómica y Molecular en Plasmas de Fusión yDepartamento de Química, módulo 13, Universidad Autónoma de Madrid, Cantoblanco, E-28049
Madrid, Spain
Collisions between multiply charged ions and hydrogen atoms are relevant in tokamak plasmas. In
particular, collisions with Be ions are of special interest because Be is a plasma facing material of
tokamaks. On the other hand, excited hydrogen is produced in the plasma and state-selective crosssections between Beq+ ions and H needed in charge-exchange recombination spectroscopy (CXRS)
diagnostics [1,2].
We have employed two computational models to study Be4+ + H(2s) collisions: the classicaltrajectory Monte Carlo (CTMC) method, with two different initial distributions to describe theH(2s) target, and the numerical solution of the time-dependent Schrödinger equation (GTDSE) [3].
We have computed integral n and nl partial cross sections for H excitation and electron capture and,compared the results at two energies: 20 and 100 keV/u. We find a good agreement in the n partial
cross sections in both processes, illustrated in Figure 1. The nl partial electron capture cross sections
exhibit a similar behavior while the agreement is less satisfactory in the nl partial excitation crosssections. We suggest a mechanism of the excitation process in ion collisions with H(2s) that will be
discussed at the Conference.

Figure 1: Integral n partial cross sections for electron capture (left panel) and for excitation (rightpanel) in Be4+ + H(2s) collisions at E= 20 and 100 keV/u. (- Ɣ -) GTDSE; (- Ŷ -) microcanonicalCTMC and (- Ÿ -) hydrogenic-CTMC calculations.
References[1] R. C. Isler, Plasma Phys. Controlled Fusion 36, 171 (1994)[2] R. McDermott et all., Nucl. Fusion 61, 016019 (2021)[3] A. Jorge, C. Illescas, L. Méndez, Phys. Rev. 105, 012811 (2022)

112

A53
First observation of giant quadrupole plasmon resonance in C60 in highperturbation HCI collisions
L. C. Tribedi*, S. Kasthurirangan*,†, E. Suraud‡(*) Tata Institute of Fundamental Research, Colaba, Mumbai – 400005, India.
(†) University of Mumbai, Santacruz, Mumbai – 400098, India.
(‡) Laboratoire de Physique Theorique, Universite de Toulouse, F-31062 Toulouse Cedex, France.

2

DDCS d σ/dεdΩ (arb. units)

We give a classic example of using high perturbation caused by HCIs to explore new mechanisms
in ion collisions with a nano-particle namely C60-fullerene. The collective plasmon excitation mode
known as the GPR (giant plasmon resonance), where the entire delocalised valence-electron cloudof C60 oscillates collectively about the ionic shell, has been well-studied using photo-excitation,
electron-impact and ion-impact excitation [1-3]. A direct observation of the dipole mode of the
GPR has been reported earlier [3] by using F9+ ions (q=9, v~12.7 a.u) for which angular distribution
reveals a parabolic shape, characteric of dipole-nature [Fig 1(a)] We have now measured the double
differential cross section (DDCS) at even higher perturbation (q/v) i.e. in collisions with 91 MeV
Si12+ ions (q=12, v~11.4 a.u). The DDCS spectrum at low energy indicates a quadrupole plasmon
resonances (GQPR) in addition to the dipole plasmon (GDPR). The measured DDCS angular
distribution at low energies (around 7-8 eV) reveal a double valley structure [Fig 1(b)] which ischaracteristic of quadrupole resonance. The elegant technique of using high perturbation collision
allows us to identify the characteristic GQPR mechanism. We have unambiguously identified thedipole and quadrupole modes by using state-of-the-art TDDFT calculations[6]. This is the first suchunambiguous experimental demonstration of the quadrupole excitation in atomic system[6].
GPR-DDCS at 10 eV
dipole + quadrupole fit (Q/D = 2.00)

3.0

2.5

2.0

1.5
30

60

90

Angle (deg)

120

150

(a)
(b)
Figure 1: Angular distribution of plasmon-electrons from C60 under fast-ion collisions: (a)Projectile: F9+ (4MeV/u, v=12.7)[3], (b) Si12+ (3.2MeV/u, v=11.4)
References[1] I. V. Hertel et al., Phys. Rev. Lett. 68, 784 (1992).
[2] P. Bolognesi et al., EPJD 66, 254 (2012).
[3] A. H. Kelkar et al., Eur. Phys. J D 74, 157 (2020)[4] D. Misra et al., NIM B 267, 157 (2009).
[5] C-Z. Gao et al., Phys. Rev. A 95, 033427 (2017).
[6] S. Kasthurirangan et al. Phys Rev Letts. (under review)

113

A54
Transformation of amorphous alloy surface
under impact of slow heavy ions
Marek Moneta
Uniwersytet Łódzki, Katedra Fizyki Ciała Stałego, Pomorska 149, PL 90-236 Łódź, Poland

Amorphous alloys, far from thermodynamic equilibrium, undergo stress relaxation andpartial crystallization if some amount of energy is supplied [1–2]. This transformations under asingle ion impact is related to thresholds, either in the potential energy, 10 keV deposited by slow
highly charged ion (HCI) or in electronic energy loss, 5 keV/nm transferred by swift heavy ion(SHI) [1]. The transfer of energy results in local increase of internal energy followed by structural
and/or magnetic phase transformations.
In this work thin foils of amorphous alloys of Fe73Si16B7Cu1Nb3 were irradiated with 200
keV Ar ions at doses varying from 1010 to 1013Ar/cm2. The process of selective surface
modification during implantation were in-situ monitored with PIXE and it was shown that elements
like Cu, and probably Fe, are preferentially sputtered from the surface, thus enriching it withremaining elements, like Nb, Si or B [2]. This change of surface composition influences on parallelrunning local structural modification of the surface due to delivery of crystallization energy toelectron-ion system. With the use of ex-situ conversion electrons Mossbauer spectroscopy (CEMS)
and transmission electron microscopy (TEM), Fe and Fe(Si) clusters accompanied by Fe3Si andeven Fe23B6 nano-crystals were spotted in the samples irradiated at lower Ar fluence, whereas rather
amorphous structures can be found in samples more heavily implanted with Ar.

References[1] R. Brzozowski, M. Wasiak, P. Uznański, P. Sovak and M. Moneta, J. Alloys & Comp.
(2009) 470.
[2] M. Antoszewska, R. Brzozowski, J. Balcerski, K. Dolecki, E. Frątczak, B.
Pawłowski, M. Moneta, Nucl. Instr. Meth. Phys. Res. B (2013) 310, 27

114

A55
Theoretical model of the nanohillock formation by an impact of slow highly
charged ions on the metal surface
N. N. Nedeljković1 , M.D.Majkić2 , D. Banaś3 , I. Stabrawa3 , M. A. Mirković4
1
Faculty of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade, Serbia
Faculty of Technical Sciences, University of Priština-Kosovska Mitrovica, Knjaza Miloša 7 38220
Kosovska Mitrovica, Serbia
3Institute of Physics, Jan Kochanowski University, Uniwersytecka 7, 25-406 Kielce, Poland
4
University College of Civil Engineering and Geodesy, Hajduk Stankova 2, 11050, Belgrade, Serbia
2

Highly charged ions impinging upon a solid surface modify its structure inducing the formation of
the nanostructures such as hillocks, craters, pits, etc. Theoretical studies of surface nanostructure creation are of fundamental importance for the understanding of the mechanism responsible for surface
modification. For this purpose we propose a theoretical model of the nanohillock formation on themetal nanolayers (gold and titanium) by an impact of the slow highly charged XeZ+ (charge Z ! 1)
ions. We employ the quantum two-state vector model and the micro staircase model for the neutralization energy calculation and the charge dependent ion-atom interaction model for the nuclear
stopping power calculation. The corresponding energies deposit into the surface during the ionicmotion above and below the surface, respectively [1]. The contribution of these two energies in thesurface nanostructure creation is described by the critical ionic velocity [1]: for velocities lower thanthe critical one, the neutralization energy has the main influence and an appearance of the hillocks is
expected, while for the larger velocities the deposited kinetic energy has a dominant effect and surface
structures are craters.
Within the proposed theoretical model we analyze the size of the surface nanohillocks as velocity
dependent quantity. According to the model, the total deposited energy(consisted of the neutralizationenergy and the deposited kinetic energy), induces the decreasing of the initial cohesive energy in theactive volume area of the target in the intermediate stages of the surface modification [2]. That is,during the nanohillock formation the decreasing of the atomic density and the binding energy (peratom) of the target compared to these values of the unmodified metal surface occur. The diametersof the nanohillocks are obtained for a given degree of the target modification. We estimate the target
perturbation in accord with the diameters of the hillocks observed experimentally [3] by the impactof XeZ+ ions upon the titanium and the gold targets.
References[1] M. D. Majkić, N. N. Nedeljković, Vacuum 190, 110301 (2021)[2] E. M. Bringa, K. Nordlund, J. Keinonen, Phys. Rev. B 64, 235426 (2001)[3] I. Stabrawa, D. Banaś, A. Kubala-Kukuś, K. Szary, J. Braziewicz, J. Czub, Ł. Jabłoński, P.
Jagodziński, D. Sobota, M. Pajek, K. Skrzypiec, E. Mendyk, M. Teodorczyk, Nucl. Instrum.
Methods Phys. Res. B 408, 235-240 (2017)

115

A56
Electron binding energy calculations for high-precision determination ofabsolute atomic masses
Chunhai Lyu, Christoph H. Keitel, Zoltán Harman
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
The Heidelberg PENTATRAP experiment can measure the mass of highly charged ions with extraordinary accuracy [1]. This allows us to determine the absolute mass of the corresponding neutral
atoms by adding up the total mass of the ionized electrons as well as their binding energies. While
the mass of the electron has been measured with an accuracy to the level of µeV, the binding energies
are only known with an accuracy of several hundred eV. In this contribution, we combine the multiconfiguration Dirac–Hartree–Fock method and relativistic configuration interactions [2] to calculate
the binding energies with sub-10 eV accuracy. This would 1) improve the relative accuracy of theabsolute mass of various heavy elements around 208 Pb to the level of 10 11 [3], 2) have applications
in direct measurement of neutrino mass [1] as well as constraining the conjectured fifth force [4].
References[1] P. Filianin, C. Lyu, M. Door et al., Phys. Rev. Lett. 127, 072502 (2021)[2] C. F. Fischer, G. Gaigalas, P. Jönsson, J. Bieroń, Comput. Phys. Commun. 237, 184 (2019).
[3] K. Kromer, C. Lyu, M. Door et al., submitted[4] M. Door, C. Lyu, et al., in preparation

116

A57
Inferring the coherence time of EUV pulse trains via spectroscopy ofhighly charged ions
Chunhai Lyu, Stefano M. Cavaletto, Christoph H. Keitel, Zoltán Harman
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
Coherent extreme-ultraviolet (EUV) pulse trains are produced via intra-cavity high-harmonic generations of high-intensity infrared pulse trains. They represent well-defined EUV frequency combs thatcan enable high-precision spectroscopy of specific EUV transitions in highly charged ions (HCIs)
with a relative accuracy to the level of !/! = 10 17 . In return, such ionic spectroscopy can also
provide information of the temporal coherence of the EUV frequency combs at timescales ranging
from nanosecond to several seconds.
In this contribution, we present a scheme to interrogate the EUV-comb coherence time via interactions
with highly charged Mg-like ions [1]. The excitation dynamics are simulated [2] for ions interactingwith EUV pulse trains of various temporal coherences. We show that while all EUV pulse trains
induce stepwise excitation of HCIs at the beginning of the interactions, the ionic excitations undergochaotic fluctuations when the coupling time becomes longer than the comb coherence time. These
investigations indicate that one can achieve coherent control of HCIs via current available EUV pulse
trains and enable quantum optics studies in the EUV range.
References[1] C. Lyu, S. M. Cavaletto, C. H. Keitel, Z. Harman, Phys. Rev. Lett. 125, 093201 (2020)[2] C. Lyu, S. M. Cavaletto, C. H. Keitel, Z. Harman, Sci. Rep. 10, 9439 (2020)

117

A58

Elastic x-ray scattering by highly charged ionsS. Strnat, J. Sommerfeldt, A.Surzhykov
Physikalisch Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig
Technische Universität Braunschweig, Universitätsplatz 2, 38106 Braunschweig

The elastic scattering of x-rays by atoms and highly charged ions is one of the fundamental
processes in the interaction of radiation with matter. Over the past few years, increasing attention
has been paid to the study of the properties of scattered photons. In particular, the linear polarizationof the outgoing radiation was measured in a recent experiment at the PETRA III synchrotron facility
at DESY in Hamburg [1]. This experiment demonstrated that by analyzing the polarization of thescattered light, one can obtain information not only about the atomic structure of the target atoms,
but also about the polarization of the incident synchrotron radiation. In our poster, we study thepolarization properties of elastically scattered x-rays by highly charged ions and neutral atoms. We
illustrate how the polarization of incident x-rays can be determined only with the polarization of
scattered photons, without any need for the theoretical scattering amplitudes [2]. Moreover, we
explore how the interference between Rayleigh and Delbrück scattering may affect the polarization
properties of the outgoing radiation.

References[1] K. H. Blumenhagen, S. Fritzsche, T Gassner, A. Gumberidze, R. Märtin, N. Schell, D. Seipt, U.
Spillmann, A. Surzhykov, S. Trotsenko, G. Weber, V. A. Yerokhin, and T. Stöhlker, New J. Phys. 18,103034 (2016).
[2] S. Strnat, V. A. Yerokhin, A. V. Volotka, G. Weber, S. Fritzsche, R. A.Müller, A. Surzhykov,
Phys. Rev. A 2021, 103, 012801

118

A59
Long-gap laboratory atmospheric discharge
Alexandr Frolov, Jiri Schmidt, Petr Hoffer, Karel Kolacek, Eduardo Oliva*
Department of Pulse Plasma Systems, Institute of Plasma Physics of the Czech Academy of
Sciences, Prague, Czech Republic(*) Universidad Politécnica de Madrid, Madrid, Spain
Despite in the nature a lightning is a relatively frequent and common phenomenon, in its physics
there are still “white places”. At present it seems to be established that the high-energy effects arecaused by runaway electrons. Formerly, all X-ray effects were attributed to thunderclouds withlarge scale electric fields. But Moore et al. in 2001 and Dwyer et al. in 2005 detected emission ofenergetic radiation from rocket-triggered, as well as from natural lightning. Due to thesemeasurements it seems to be proved that vast majority of negative leaders emit hard X-rays andhence produce runaway electrons. For air at standard conditions, relativistic electrons with energies
below several tens of MeV lose energy predominantly via ionization and excitation processes; forhigher energies, the energy losses from bremsstrahlung become important as well.
Our motivation is the study of long-gap laboratory high-voltage discharges in air at atmosphericpressure which it helps to elucidate some processes appearing in lightning and in this way tocontribute to safety of air traffic, sensitive electronics, and to protection of human health. The basic
features of lightning are already known: the runaway electrons are generated and due to that even
X-rays are emitted. It turns out that moment of their birth is reasonably well known, however, thespatial localization as well as the instantaneous local environment are a little bit vague and shouldbe improved. Sufficiently energetic X-rays initiate photonuclear reactions: from atmospheric nuclei
fast neutrons are released, unstable isotopes are created that transform further to stable ones atsimultaneous birth and later annihilation of positrons.
In this work we present results from experiment with long-gap laboratory discharge at atmosphericpressure. After designing and assembling apparatus, the device was electrically tested for a shortcircuit to detect weak regions. Basic measurements of voltage (based on capacitor-resistor divider)and current (by Pearson current monitor) were re-calibrated. After that experiments with longer
discharges (with length from 30 to 50 cm) were performed. All discharges were observed opticallyby photocamera with/without neutral density filter. For most of the experiment, measurements ofboth neutrons (in the first phase using a BDT bubble detector) and X-rays were performed using
two detectors: a BICRON BC408 plastic scintillator (sensitive to X-rays with energy <100 keV)and a Saint-Gobain LaBr3:Ce photomultiplier (X-rays with energy <10 MeV). For spatial
resolution, an X-ray pinhole camera was designed and constructed: consisting of a filter, a pinhole
chamber and a registration plate. Then an attempt was made to stabilize the primary-leader´s head
position by inducing there a disturbance, the source of which will be well separated from the spark.
The development of a long spark discharge at atmospheric pressure in an inhomogeneousenvironment with an injected "plasmoid" (i.e. an aerosol cloud, which is formed during a shortdischarge on the surface of a conductive liquid (e.g. salt water). However, notwithstanding the factthat the inter-electrode distance has been extended to 60 cm, it appears that no hard X-ray emission
is detected in the region of the discharge current maximum, which would be indicative of runaway
electron generation.
Acknowledgement
This work supported by the Grant Agency of the Ministry of Education, Youth and Sports of the
Czech Republic under Contract LTC20061 and by COST through the COST Action TUMIEE(CA17126).

119

A60
Measurement of ion-induced desorption yields for accelerator vacuum
S Steydli1, R Levallois2, M Bender3, S Bilgen4, L Kirsch3, E Lamour1, A Lévy1, C. Prigent1,
G Sattonnay4, C Stodel2, M. Trassinelli1 and V Velthaus3
1

Institut des Nanosciences de Paris, Sorbonne Université, CNRS, Paris, 75005, France
2
GANIL, G a Acc
aIL, Ca , 14076, F a c
3
GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, 64291, Germany
4
IJCLab, Université Paris Sud, CNRS, Orsay, 91405, France

The outgassing due to ion induced desorption is a severe intensity limitation in modern accelerators.
It is produced when an ion beam impacts on a solid target leading to the release of gas molecules
trapped over and inside the material. In accelerators, the targets are mainly the wall of vacuum
vessels, the beam dumps and slits, mostly made in stainless steel, copper or tungsten. The numberof particles removed by incident ion (named the desorption yield, K) can vary from one to several
thousand depending on the beam energy and the nature of the irradiated material. Consequently, thepressure may drastically increase by one or two orders of magnitude with respect to the basepressure affecting strongly the transmission of the ion beam [1, 2, 3].
The surface quality of the material that may be irradiated is a key parameter to reduce significantly
the desorption yield. In the context of the development of accelerators (GSI/FAIR, CERN,GANIL/SPIRAL2), we have studied the impact on the desorption yield of different surface
treatments on samples of stainless steel, copper and tungsten. Samples with various treatments suchas chemical attacks, annealing or beam conditioning have been bombarded with 4.8 MeV/u Ca19+ orCa10+ ions delivered by the UNILAC accelerator at GSI. Absolute values of the desorption yield
have been measured to evaluate the best treatment. Thanks to a calibrated Residual Gas Analyser,
the evolution of the partial pressures of released gas (CO2, CO, H2 or others) under irradiation havebeen obtained. Additionally, the scrubbing effect that corresponds to the cleaning of the surface by
the beam itself (Figure 1) has been investigated.

Figure 1: Scrubbing effect on Cu sample with a 4.8 MeV/uma Ca19+ ion beam.
Description of the experimental setup, the different methods of measurements and the results will
be presented at the conference.
References[1] E Mahner 2009 PRST 11 104801[2] Z Q Dong et al 2017 NIMA 870 73 78[3] E Hedlund et al 2009 NIMA 599 1 8

120

A61
Tank-Circuit Assisted Coupling Method for Sympathetic Laser Cooling ofHighly charged ions in Penning Traps
B. Tu1,2, F. Hahne1, I. Arapoglou1, A. Egl1, F. Heiße1, M. Höcker1, C. König1, J. Morgner1, T.
Sailer1, A. Weigel1, R. Wolf3, K. Blaum1 and S. Sturm1
1

Max Planck Institute for Nuclear Physics, 69117 Heidelberg, Germany
Institute of Modern Physics, Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE),
Fudan University, 200433 Shanghai, China
3
ARC Centre for Engineered Quantum Systems School of Physics, The University of Sydney NSW
2006, Australia

2

Penning traps have been proven as a versatile tool for fundamental physics. A multitude of highprecision measurements have been performed at Penning trap facilities, such as measurements ofatomic masses and magnetic moments or g-factors of elementary particles [1]. Recently, byconfining highly charged ions (HCIs) in Penning traps it provides a unique system to probe atomic
properties and to test Quantum electrodynamics (QED) in strong electric field [2]. In a cryogenic
penning trap, the motional temperature of ions is thermalized with a cryogenic superconducting
tank circuit at 4.2 K. Owing to the particle oscillation amplitude, the accuracy of frequency
determinations is limited by systematic uncertainties caused by anharmonicities arising from field
imperfections and eventually special relativity. In g-factor measurements, a lower particle
temperature furthermore decreases axial frequency fluctuations and thus helps to achieve higher
fidelity of the spin state determination, which is specifically crucial for heavy ions with acomparably small magnetic moment. To reduce the ion temperature into the millikelvin regime,
sympathetic cooling is a common method in rf traps. However, the co-trapping of different ionsleads to drastic modifications of the motion of the ion of interest via the Coulomb interaction inpenning traps. To solve the Coulomb disturbance, a cooling technique proposed by Heinzen andWineland in 1990 is based on the coupling of two species in separate traps that share a common
endcap electrode [3]. This way, the ions can interact via their image charges induced into the shared
endcap electrode. However, with realistic trap parameters the coupling strength is too small toachieve highly efficient sympathetic cooling.
Here, we present a new coupling technique for two ion species in separate traps via a common
superconducting tank circuit which can significantly enhance the coupling strength [4]. At
ALPHATRAP this tank-circuit assisted coupling of two HCIs are investigated by observing theresulting avoided crossing of the coupled frequencies. The determined coupling strength is a factorof 760 larger than the method of common endcap coupling. Furthermore, we propose anintermittent laser cooling method for highly efficient sympathetic cooling. The numericalsimulations show the possibilities of sympathetic cooling of arbitrary types of ions to themillikelvin regime within reasonable cooling times.
References[1] K. Blaum, Yu. N. Novikov and G. Werth, Contemporary Physics 51, 149–175(2010).
[2] K. Blaum, S. Eliseev and S. Sturm, Quantum Sci. Technol. 6, 014002(2021).
[3] D. J. Heinzen, D. J. Wineland, Phys. Rev. A 42, 2977(1990).
[4] B. Tu, et. al., Advanced Quantum Technologies 4, 2100029(2021).

121

A62
A superconducting quadrupole resonator for laser-spectroscopy of highly
charged ions at highest precision
C. Warnecke*, E. Dijck, M. Wehrheim, J. Stark, M. K. Ronser*, A. Graf,
J. Nauta, J.-H. Oelmann*, T. Pfeifer and J. R. Crespo López-Urrutria
Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany(*)Heidelberg Graduate School for Physics, Heidelberg, Germany

Highly charged ions are excellent candidates for novel optical frequency standards [1] and quantum
algorithms [2], since they are very unsusceptible to electromagnetic noise due to the suppression ofe.g. the quadratic Zemann shift scaling with Z-4[1]. However, gaining quantum control over the
motional modes of cold HCI had been a challenge for the last decades since they lack of fast cyclingtransitions for laser cooling. Quantum logic spectroscopy of the M1 transition in Ar13+ which was
sympathetically cooled by a single Be+ logic ion lowered the uncertainty by eight orders ofmagnitude to about 10-15 opening a branch for new frequency standards in near future [3].
Complementing these new types of optical clocks, a cryogenic Paul trap experiment with a quasimonolithic superconducting quadrupole resonator with a high operating quality factor of about
30000 [4] was developed at the Max-Planck-Institute for Nuclear Physics in Heidelberg, Germany
to challenge some of the resulting issues: Due to the high fidelity of the radio-frequency resonanceat about 35 MHz, radial mode heating of the HCI is strongly suppressed. Furthermore, the trappedions are shielded inside the cavity due to the Meissner-Ochsenfeld effect from electromagnetic
noise, reducing decoherence effects and therefore increasing interrogation times of the HCI. We
will present the features of this resonator and provide first characterizations with re-trapped HCI.

Ar14+

Figure 1: Left: Sliced view of the superconducting quadrupole resonator. Right: Single, crystallized
Ar14+ trapped and sympathetically cooled beryllium ions inside it.
References[1] M. G. Kozlov, et al., Rev. Mod. Phys. 90, 045005 (2018)[2] Wineland, David J., et al., Journal of research of NIST 103.3 (1998): 259.
[3] P. Micke, T. Leopold, S. A. King et al., Nature 578, 7793 (2020)[4] J. Stark et al., Rev. Sci. Instr. 92, 083203 (2021)

122

A63
Dynamics of mixed species Coulomb crystals with highly charged ions in asuperconducting Paul trap
Elwin A. Dijck, Christian Warnecke, Malte Wehrheim, Michael Karl Rosner, Andrea Graf,
Ruben Henninger, Thomas Pfeifer, José R. Crespo López-Urrutia
Max Planck Institute for Nuclear Physics, Heidelberg, Germany
The CryPTEx-SC project at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany,is designed to perform precise spectroscopy of highly charged ions (HCIs), which are excellent
candidates for the development of next-generation atomic clocks and sensitive probes in the search
for new physics [1]. The spectroscopy trap is formed by merging a linear Paul trap with asuperconducting radio-frequency resonator, providing ultralow-noise radial confining potentials [2].
Control and read-out of HCIs will be implemented using quantum logic spectroscopy with cotrapped Be+ ions.
We present results from the first cold highly charged ions stored in our ion trap. After production of
the HCIs in an electron beam ion trap (EBIT), they are extracted in pulses into an electrostatic
beamline where they are decelerated and bunched. The HCIs are then captured in andsympathetically cooled by a Coulomb crystal of several dozen laser-cooled Be+ ions trapped in thePaul trap beforehand. Subsequent controlled removal of Be+ ions by exciting secular motion is used
to prepare mixed species ion crystals comprising various numbers of Be+ ions and HCIs, down to asingle HCI with a single Be+ ion, the prerequisite for quantum logic spectroscopy.
The flexible retrapping technique will be discussed, which opens up the extensive range of highly
charged ion species to precision studies and additionally allows to explore the dynamics of mixed
species Coulomb crystals consisting of ions with disparate charge-to-mass ratios.

Figure 1: Overview of producing HCIs in an electron beam ion trap, transferring through a beamline
and retrapping in a superconducting resonator Paul trap with example EMCCD image of a mixed
species Coulomb crystal comprising three 9Be+ ions and one 40Ar10+ ion.
References[1] M. G. Kozlov et al., Rev. Mod. Phys. 90, 045005 (2018)[2] J. Stark et al., Rev. Sci. Instrum. 92, 083203 (2021)

123

A64
Sympathetic cooling of highly charged ions in a Penning trap using aself-cooled electron plasma
Jost Herkenhoff, Menno Door, Sergey Eliseev, Pavel Filianin, Kathrin Kromer, Daniel Lange,
Alexander Rischka, Christoph Schweiger, Sven Sturm, Klaus Blaum
Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
The amazing evolution of precision in recent Penning-trap experiments is driving the need for everimproving cooling techniques. In this talk, the prospect of a new sympathetic cooling technique using
an electron-plasma coupled to a single highly charged ion is presented. Utilizing the synchrotronradiation of electrons in a strong magnetic field enables cooling to very low motional quantum numbers, almost to their ground state. Using a common-resonator, the motion of this self-cooled electron
plasma can be coupled to an ion stored in a spatially separated Penning trap, allowing sympathetic
cooling of all modes of the ion. The extremely low expected temperatures in the milllikelvin range
open up an exciting new frontier of measurements in Penning traps.

124

A65
First broadband laser cooling and XUV fluorescence detection of stored
relativistic HCIKEN UEBERHOLZ1, LARS BOZYK2, MICHAEL BUSSMANN3,4, NOAH EIZENHÖFER5, VOLKER
HANNEN1, MAX HORST5,6, DANIEL KIEFER5, NILS KIEFER7, SEBASTIAN KLAMMES2, THOMAS
KÜHL2,8, BENEDIKT LANGFELD5, MARKUS LOESER4, XINWEN MA9, WILFRIED NÖRTERSHÄUSER5,6,
RODOLFO SANCHEZ2, ULRICH SCHRAMM4,10, MATHIAS SIEBOLD4, PETER SPILLER2, MARKUSSTECK2, THOMAS STÖHLKER2,8,11, THOMAS WALTHER5,6, HANBING WANG9, CHRISTIANWEINHEIMER1, WEIQIANG WEN9 and DANYAL WINTERS2
1University of Münster, Institute of Nuclear Physics (Germany)
2GSI Darmstadt (Germany), 3CASUS Görlitz (Germany), 4HZDR Dresden (Germany), 5TU

Darmstadt (Germany), 6HFHF Darmstadt (Germany), 7University Kassel (Germany), 8HI Jena
(Germany), 9IMP Lanzhou (China), 10TU Dresden (Germany), 11University Jena (Germany)At the highly relativistic energies and high intensities of the ion beams in the new SIS100
accelerator at FAIR, conventional beam cooling techniques (e.g. electron and stochastic cooling)
have some limitations and laser cooling is a more elaborate and efficient method for cooling.
Despite one specific requirement, i.e. the need for a fast electronic transition in the ions, at the
SIS100 many different ions (element & charge state) can be laser-cooled, owing to the large
magnetic rigidity of the SIS100 (max. 100 Tm). Importantly, the use of new pulsed (rep. rate~MHz) and tunable CW laser systems (UV and VIS wavelengths) will greatly enlarge and enhance
the potential of this cooling method. However, the much higher beam energies at the SIS100 also
require new approaches for in vacuo detection of the fluorescence emitted by the ions, as it isrequired for laser spectroscopy and laser cooling.
In May 2021, an improved XUV fluorescence detection system and a new tunable pulsed UV laser
system were employed for laser cooling of bunched relativistic (47% of c) carbon ions at theExperimental Storage Ring of GSI Helmholtzzentrum Darmstadt, Germany. Successful broadband
laser cooling was demonstrated using this powerful (~200 mW), high repetition rate (~10 MHz) andtunable (wavelength and pulse duration) UV laser system. The experiment and its results will be
discussed.
In addition, we will present our new fluorescence detection and spectroscopy system for the laser
cooling project at the upcoming SIS100 accelerator. The new dispersed flourescence detection
system uses an aberration corrected laminar grating in grazing incidence geometry and an open facemicro-channel plates detector in Chevron stack configuration (sensitive in the soft X-Ray regime)with postion and time sensitive delay-line readout. If no energy resolution is required, the system
can also be used for direct detection of the fluorescence photons with a significantly larger
acceptance.
This work has been supported by the BMBF under contract number 05P19PMFA1 and
05P21RDFA1.

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Simultaneous storage of ions and electrons in the HITRAP cooling trap
M. Horst1, S. Rausch1,2, Z. Andelkovic3, S. Fedotova3, W. Geithner3, F. Herfurth3, D. Neidherr3
N. Stallkamp3,4, S. Trotsenko3, G. Vorobjev3, W. Nörtershäuser1,21Institut für Kernphysik, TU Darmstadt, Schloßgartenstr. 9, Darmstadt, Germany
2
Helmholtz Akademie Hessen für FAIR HFHF, TU Darmstadt, Darmstadt, Germany
3
GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt, Germany
4
Institut für Kernphysik, JWGU Frankfurt, Max-von-Laue-Str. 9, Frankfurt a. M., Germany

The HITRAP decelerator facility at the GSI Helmholtzzentrum für Schwerionenforschung inGermany aims to decelerate and cool heavy, highly-charged ions (HCI) like U92+ [1]. After
generating the high charge states at relativistic energies, HITRAP decelerates these ions via a linear
deceleration stage and a cylindrical Penning trap. Within this trap, the ions can be cooled to lowtemperatures before they are ejected and transported to various precision experiments. The usedcooling mechanism in the seven-electrode cooling trap is sympathetic cooling with a cold electron
plasma. Therefore, the ions and electrons are stored simultaneously in a nested trap configuration.
While the electrons constantly lose energy in the high magnetic field through synchrotron radiation,
the hot ions lose energy by Coulomb interaction with the cold plasma. If the ion energy approaches
the eV-regime, the electron plasma has to be ejected to prevent recombination.
We present the current status of the cooling trap and the ongoing progress to demonstrate electron
cooling of extended amounts of heavy HCI for the first time. After optimization of the local pulsed
electron source we manage to produce up to 2x10^9 electrons per pulse. These pulses can betrapped by quickly switching the trap electrodes. Using the retarding field method when ejecting
electrons onto a microchannel plate (MCP), it is possible to measure the energy loss due tosynchrotron radiation and the space charge of the trapped electron cloud.
Besides the local electron source, HITRAP is also equipped with a small EBIT ion source forcommissioning of the cooling trap. This EBIT with permanent magnets can generate different ionswith medium or high charge states (e.g. Ar16+) which can be transported through a low energy
beamline towards the cooling trap [2]. We achieved simultaneous storage of these EBIT ions andelectrons from the local source. In these experiments it has been found that the ions influence theco-trapped electrons, but so far no energy loss of the ions could be observed.
The next step is the enhancement of the ion-electron interaction and demonstration of electron
cooling. This can for example be done by optimizing the injection settings or varying the ion andelectron number. Furthermore, employment of non-destructive detection methods can help tofurther analyze the interaction.
This work is supported by BMBF under contract number 05P19RDFAA.

References[1] H.-J. Kluge, et al.: HITRAP - A facility at GSI for highly charged ions, Advances in Quantum
Chemistry 53 83 (2008)[2] Z. Andelkovic, et al.: Beamline for low-energy transport of highly charged ions at HITRAP,
Nucl. Instrum. Meth. A (2015)

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Commissioning of the HITRAP cooling trap with offline ionsS. Rausch1,2, M. Horst1, Z. Andelkovic3, S. Fedotova3, W. Geithner3, F. Herfurth3, D. Neidherr3,
N. Stallkamp3,4, S. Trotsenko3, G. Vorobyev3, W. Nörtershäuser1,21Institut für Kernphysik, TU Darmstadt, Schloßgartenstr. 9, Darmstadt, Germany
2
Helmholtz Akademie Hessen für FAIR HFHF, TU Darmstadt, Darmstadt, Germany
3
GSI Helmholtzzentrum, Planckstr. 1, Darmstadt, Germany
4
Institut für Kernphysik, JWGU Frankfurt, Max-von-Laue-Str. 9, Frankfurt am Main, Germany
The HITRAP facility at the GSI Helmholtzzentrum für Schwerionenforschung (GSI) in Germany isdesigned to decelerate and cool a bunch of about 105 heavy, highly charged ions (HCI). Produced
by stripping at high energy, the HCI are decelerated eventually in a linear decelerator down to
6 keV/u and captured within a cylindrical Penning trap. In that trap the HCI can be cooled using
various cooling mechanisms such as electron cooling and resistive cooling before being transferredto subsequent experiments [1]. If ions and electrons are stored simultaneously in a so-called nested
trap energy transfer can take place. The electrons cool the transferred energy off by synchrotron
radiation in the strong magnetic field [2].
We present the current status of the HITRAP cooling trap and the next steps of commissioning thissetup with offline ions as well as the preparation for the next online beam time. So far a newly
designed Penning trap has been commissioned and tested. The new, seven-electrode trap design ismore stable and less error prone than the previous version with 21 electrodes.
We were able to investigate the storage of argon ions in various charge states, delivered by a small
EBIT based on permanent magnets with an energy of 4 keV/q. Dependencies of the charge state andkinetic energy on the lifetime of the stored ions were observed. The successful manipulation of the
kinetic energy of the ions, both trapped and ejected, was achieved by applying an offset potential on
all trap electrodes. By ejecting the ion cloud after short storage times of a few µs, we also managed
to determine the magnetron frequency of the stored ion cloud and its dependency on the trap
settings. Moreover, for the first time it was possible to store ions and electrons simultaneously in
the HITRAP cooling trap, although no cooling effect was observed so far.
The next steps will be the improvement of the trap settings for both electrons and ions and the proofof electron cooling. This includes the cooling of argon ions from the local ion source andcommissioning the trap setup for the first time in a GSI beam time with bare 58Ni. One of the main
challenges during this beam time will be the separation of high energy and low energy beam as thelinear decelerator stage of the HITRAP facility will only decelerate parts of the incoming 4 MeV/ubeam down to the desired energy of 6 keV/u [3]. As the separation by time of flight is not possible,
a new detector unit will be installed. This detector will deflect the low energy beam to an off-axis
MCP detector in order to measure and optimize beam transfer towards the trap.
This work is supported by BMBF under contract number 05P19RDFAA.
References[1] H.-J. Kluge, et al.: HITRAP - A facility at GSI for highly charged ions, Advances in Quantum
Chemistry 53 83 (2008)[2] Giancarlo Maero: Cooling of highly charged ions in a Penning trap for HITRAP, Diss. (2008)[3] Herfurth, F., et al.: The HITRAP facility for slow highly charged ions, Physica Scripta
2015.T166 (2015)

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Resonant photoexcitation of trapped ions for x-ray astrophysics
Sonja Bernitt, René Steinbrügge*, Steffen Kühn°, Moto Togawa°, José R. Crespo López-Urrutia°
Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena (Germany)(*) Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany)(°) Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)
Spectroscopic observations in the UV and X-ray bands with the newest generation of highresolution instruments onboard current and future satellite observatories have the potential to reveal
previously inaccessible details of processes in astrophysical plasmas, such as the ones in galaxy
clusters and active galactic nuclei. This is essential for advancing our understanding of extreme
environments and the evolution of the universe.
However, what can be reconstructed from spectra is currently limited by the availability and qualityof atomic data, on which plasma models are built. That is especially the case for highly charged
ions (HCI), ubiquitous in hot astrophysical plasmas [1]. For many years, electron beam ion traps(EBITs) have been valuable tools for laboratory measurements with HCI, providing a wide range ofatomic data, like transtion energies and rates of ionization and recombination processes.
Here, work with the novel compact PolarX-EBIT [2], based on permanent magnets, is presented, inwhich radiation from ultrabrilliant UV and X-ray synchrotron light sources is used to resonantly
excite electronic transitions in trapped HCI. Subsequent fluorescence and changes of ion charge
state are detected, which allows to gather spectroscopic data under well-controlled conditions with
unprecedented resolving powers and signal-to-noise ratios. This yields atomic data valuable not
only for astrophysics but also for benchmarking general atomic structure theory [3].
One such case are the two 2p-3d transitions in Ne-like Fe16+, commonly labelled 3C and 3D, forwhich measurements and calculations of oscillator strengths seemed to disagree significantly [4],until our recent experiments uncovered previously unaccounted-for contributions to the observed
intensities [5].
Furthermore, the unique off-axis electron gun of PolarX-EBIT facilitates new experimental setups,
in which electronic transitions in few-electron HCI are used as accurate and reproducible wavelength references [6].
References[1] G. Betancourt-Martinez et al., arXiv:1903.08213 (2019)[2] P. Micke et al., Rev. Sci. Instrum. 89, 063109 (2018)[3] M. Togawa et al., Phys. Rev. A 102, 052831 (2020)[4] S. Kühn et al., Phys. Rev. Lett. 124, 225001 (2020)[5] S. Kühn et al., arXiv:2201.09070 (2022)[6] M. A. Leutenegger et al., Phys. Rev. Lett. 125, 243001 (2020)

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Recent experimental and computational results on one dimensional colliding
laser-produced plasmas
X. F. Bai, T. McCormack, F. O’Reilly, E. Sokell
School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
Email: emma.sokell@ucd.ie
In the experiment, a time-resolved ICCD camera was deployed to capture the flow behaviour of two
counter-propagating laser-produced plasmas (LPPs) collimated by two face-to-face channels, whichmakes the plasmas close to one dimensional (1-D). Figure 1 shows the early stage of the formation of
the so-called stagnation layer between the two channelled plasmas. At this stage, the plasma gathering
at the collision point between the two plasmas can be clearly observed.
For interpreting and predicting the experimental results, we have built a collection of 1-D fluid modelling code based on [1] and [2] with the ambipolar electric field and collision coupling considered.
Applying the code to colliding LPPs, it predicts an instant shock happens with a huge leap in plasma
temperature and density when the LPPs start colliding, which is the beginning of the stagnation layer
formation that is observed in these experiments. The shock may be utilized to create x-ray sourcesfrom colliding plasmas, possibly with a significant boost in the conversion efficiency from incident
laser power to x-ray radiation and the stagnation layers have the potential to be used as the second
target for dual-laser extreme ultraviolet sources [3].
This research is being funded by the China Scholarship Council (CSC) and University College Dublin(UCD).

Figure 1: Upper: Stagnation layer created between two channelled colliding plasmas. White arrows
show the directions of movement of the two channelled plasmas. Lower: Spatial intensity distribution
along the white dash line.

References[1] P. W. Rambo, J. Denavit, J. Comput. Phys. 92, 185 (1991).
[2] P. W. Rambo, J. Denavit, J. Comput. Phys. 98, 317 (1992).
[3] T. Cummins, C. O’Gorman, P. Dunne, E. Sokell, G. O’Sullivan, P. Hayden, Appl. Phys. Lett. 105,
044101 (2014).

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Laser Produced Plasmas for Atomic Physics and Applications.
E. Sokell1*, R. Brady1, B. Delaney1, K. Mongey1, N. Wong1 and F. O’Reilly1
1School of Physics, University College Dublin, Belfield, Dublin 4, Ireland*email: emma.sokell@ucd.i

The spectra of plasmas produced by focusing the output of high powered lasers, typically Nd:YAG
lasers with pulse lengths of a few nanoseconds, on to higher Z solid elements are quasi continuous[1]. These plasmas can be used for absorption experiments to study low charge state ions present ina second laser produced plasma [2] and have potential as laboratory scale soft x-ray sources [3].
Applications involving high spatial resolution or high spectral resolution measurement typicallyhave a photon throughput limitation where either a small region needs to be illuminated for imaging
or a small slit illuminated for energy selection, and this small area bottleneck leads to very low
system etendue (<10-2 mm2mrad2). Since radiance is at best conserved in an optical system, and it isgiven by the photon flux divided by the etendue, these low etendue systems require a high radiancesource to deliver sufficient photons to the application.
This work focuses on the development of laboratory scale soft x-ray sources (specifically in thewater window between the wavelengths of 2.3 and 4.4 nm). The water window is of especial
significance for applications targeted at the illumination of biological samples. Water is transparent
to these x-rays, but carbon and therefore organic molecules are absorbing. The resulting
transmission of water window soft x-ray photons allows for imaging of unstained, cryofixed,
biological cells.
The objective is to produce sources with a brilliance up to two orders of magnitude higher than thestate of the art, comparable to those achieved at bending magnets of large-scale synchrotron
facilities, which will enable technological developments and scientific studies that are not presently
possible on laboratory scales.
Higher radiance can be achieved by reducing the emitting area and one recent focus has been thedrive to reduce the x-ray emitting area to dimensions of the order of 10μm^2. The work so far has
proven that it is feasible to produce plasmas of this diameter with a relatively high conversion
efficiency into the water window.
This work is supported by Science Foundation Ireland through a Frontiers for the Future
Programme Award (19/FFP/6795).
References[1] P.K. Caroll, E.T. Kennedy and G. O’Sullivan, Optics Letters 2, 72 (1978.
[2] R. Stefanuik, et al, Phys. Rev. A. 101, 033404 (2020).
[3] G. Joseph et al, NIMB, 482, 64 (2020).

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High resolution imaging of laser plasmas revealing the effects of laser spot sizeon plasma emission
E. Sokell, K. Mongey*, F. O' Reilly, B. Delaney, R. Brady
Atomic, Molecular and Plasma Physics Group, University College Dublin, Ireland*kevin.mongey@ucdconnect.ie
Laser plasmas can produce a high flux of soft x-ray radiation from a small volume, making them ideal
for illumination for applications such as in EUV nano-lithography [1] and in cell imaging via soft xray microscopy [2].

In order to investigate the effects of the focal spot size on the plasma shape and intensity, amolybdenum target was irradiated with a Nd:YaG 1064nm driving laser. Images of the subsequently
formed plasmas ere generated sing a 5 m pinhole hich images soft -ra s thro gh a 1 m Al
filter onto a soft x-ra camera ith a pi el si e of 2.4 m and the imaging a is parallel to the target
and perpendicular to the laser. The filter transmission combined with the camera quantum efficiency
produces images in the 0.5nm to 3nm region. Such images were produced with laser energies ranging
from 20mJ to 271mJ with several laser focus spot sizes.
The plasma images were simulated using a skewed pseudo-Voigt profile combined with regression
techniques to generate noise reduced plasma images. The resulting areas and shapes (the ratio of theplasma widths parallel and perpendicular to the target measured through the centre of a plasma iamge)of the simulated plasma images were measured as demonstrated in Fig 1.

Fig 1: Left: Real plasma image with schematic target drawn. Right: Demonstration of the change inplasma area and plume shape (the ratio of the plume width perpendicular to the target and widthparallel to the target) as a function of lens position fro two labelled energies.
References[1] - Toshihisa Tomie, 2012, Tin laser-produced plasma as the light source for extreme ultraviolet
lihtograph high ol me man fact ring: histor , ideal plasma, present stat s and prospects ,Journal of Micro/Nanolithography MEMS, and MOEMS, Vol. 11, Iss. 2, 1-10
[2] Wach lak P. W. et. al, 2019, A ater indo tomograph based on a laser-plasma doublestream gas-puff target soft X-ra so rce , Applied Physics B, Vol. 125, Iss. 5, 70
This work is supported by Science Foundation Ireland through a Frontiers for the Future Programme Award (19/FFP/6795).

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High-Performance X-ray Imaging Spectrometers with Ti/Au Superconducting
Transition-Edge Sensor Microcalorimeter Arrays
K. Nagayoshi1, M. de Wit1, H. Akamatsu1, L. Gottardi1, E. Taralli1, D. Vaccaro1, M.L. Ridder1,
M.P. Bruijn1, J.-R. Gao1,2 and J.W.A. den Herder1,3
1

NWO-I/SRON Netherlands Institute for Space ResearchNiels Bohrweg 4, 2333 CA Leiden, The Netherlands
2
Kavli Institute of Nanoscience, Delft University of Technology
Mekelweg 5, 2628 CD Delft, The Netherlands
3
Astronomical Institute Anton Pannekoek, University of Amsterdam
Science Park 904, 198 XH Amsterdam, The Netherlands
X-ray transition-edge sensor (TES) microcalorimeters are cryogenic non-dispersive spectrometers
inhering a broad dynamic range, high quantum efficiency and most importantly a high spectral
resolving power which is potentially competitive to dispersive instruments. The Athena space X-ray
observatory to be launched in 2034 led by ESA will carry a large array consisting of 2376 TES
microcalorimeters on the focal plane of the X-ray Integral Field Unit (X-IFU) to explore the hot andenergetic universe, taking full advantage of the high energy resolution and the imaging capability.
At SRON we are developing the focal plane assembly for X-IFU, and also TES detector arrays as a
back-up option in the framework of a European technology development program. Our TES
detectors are based on a Ti/Au superconducting thin film of which critical temperature is tuned
around 90 mK. The temperature sensing elements are coupled to overhanging Au/Bi X-ray
absorbers, providing quantum efficiency of 95% up to 7 keV with a pixel filling factor of 96% over
the arrays. We have fabricated and tested various detector chips with 64 and 1024 TES pixels tocultivate a better understanding of how to control the properties of our detectors. We now
constantly measure ~2 eV full-width at half-maximum energy resolution for 5.9 keV X-rays,
encouraging realization of the full-sized TES array for the X-IFU instrument. Furthermore, thefundamental characteristics of our well-performing detectors would be potentially suitable forlaboratory experiments on the physics of highly charged ions in combination with electron beam ion
trap instruments and synchrotron facilities for examples. In this contribution, we will give an
overview of the characteristics and capabilities of these state-of-the-art detectors.

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Review of recent developments in MaMFIS technology
V.P. Ovsyannikov, A.V. Nefiodov*, A.Yu. Ramzdorf, A.A. Levin†
Joint Institute for Nuclear Research, 141980 Dubna, Russia(*) Petersburg Nuclear Physics Institute, 188300 Gatchina, St. Petersburg, Russia(†) Ioffe Institute, 194021 St. Petersburg, Russia
The standard Electron-Beam Ion Source (EBIS) employs smooth electron beam for the successive
ionization of atomic targets (neutral elements and low charged ions) [1]. The highest electron current
density, which is a prerequisite for the production of highly charged ions, can be attained only in thecase of the Brillouin focusing. The ion extraction from the ionization region is carried out by varying
the potentials on different sections of the drift tube.
In the Main Magnetic Focus Ion Source (MaMFIS), highly charged ions are produced and confinedin local ion traps, which appear in crossovers of the rippled electron beam propagating in a drift tube
[2,3]. The electron beam is focused by a thick magnetic lens. In a crossover, the Brillouin limit is
not justified and the electron current density can exceed it by orders of magnitude. The devices arevery compact and reliably operate at room temperature due to the use of permanent magnets andstandard vacuum techniques. The ion extraction from the MaMFIS can be performed by means oftransformation of the shape of electron beam controlled by the bias voltage on the focusing (Wehnelt)
electrode, so that the local ion traps are shifted to the electron collector region. Highly charged ionscan also be extracted from the local ion trap in the radial direction perpendicular to the electron beam
by varying the potential applied to the extractor electrode [2]. One more possibility to extract ionsconfined in the local ion traps can be realized by using the EBIS technology at certain drift tube
diameter-to-length ratio, electron trajectories, and extraction voltage [4].
The electron current density has been assessed indirectly through the measurement of ionization time
and the utmost achievable charge state of the produced highly charged ions. The degree of ionization
is determined from the high-energy part of the characteristic X-ray emission spectrum corresponding
to the radiative recombination of highly charged ions with beam electrons. The most recent studies
were performed in Veksler and Baldin Laboratory of High Energy Physics at the Joint Institute for
Nuclear Research in Dubna. The results obtained for different elements (iridium, cerium, xenon, andbismuth) are consistent with the electron current density of the order of 10 kA/cm2 . The MaMFIS
technology allows one to significantly reduce the confinement time required for an efficient ionizationof bound inner-shell electrons. This is of particular importance both for heavy elements and for very
short-lived radionuclides.
References[1] E.D. Donets, Rev. Sci. Instrum. 69, 614 (1998)[2] V.P. Ovsyannikov, A.V. Nefiodov, Nucl. Instrum. Methods Phys. Res. B 367, 1 (2016)[3] V.P. Ovsyannikov, A.V. Nefiodov, Nucl. Instrum. Methods Phys. Res. B 370, 32 (2016)[4] V.P. Ovsyannikov, A.V. Nefiodov, A.Yu. Boytsov, A.Yu. Ramzdorf, V.I. Stegailov, S.I. Tyutyunnikov, A.A. Levin, Nucl. Instrum. Methods Phys. Res. B 502, 23 (2021)

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Theoretical investigation of dielectronic recombination processes of highly
charged gold ions
W. L. He, S. B. Niu, J. L. Rui, T. X. Ma, L. Y. Xie*, C. Z. Dong
Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070,
Peo le Re blic of China*Email: xiely@nwnu.edu.cn; Email: dongcz@nwnu.edu.cn;
Dielectronic recombination (DR) is a prominent resonant recombination process in collisions ofelectrons with highly charged ions (HCIs) [1]. Gold is one of the particular interest work material in
the indirect laser drive of inertial confinement fusion (ICF). Accurate atomic data of highly ionizedgold ions are essential and important for modelling gold hohlraum-produced plasma [2-3].
In this study, the DR process of Ne-like to Si-like gold ions (Au69+-Au65+) are investigated. The
resonance energies, resonance strengths and cross sections are carefully calculated for L-shell n =1 transitions using the FAC code based on fully relativistic configuration interaction (RCI) method[4]. Using the density matrix formular, the degree of linear polarizations of x-ray dielectronic satellite
lines produced by dominant LMM, LMN DR processes are calculated, and used to obtain the
differential cross section of Au69+-Au65+ ions. Figure 1 illustrated our calculated synthesized LMM
DR spectra of gold ions located at 2.6-5.6 keV energy regions, and compared with the experimental
measurements of electron beam ion trap at Lawrence Livermore National Laboratory by Schneider
et al [3]. Our theoretical results show an excellent agreement with the experimental values.

Diff-Cross Sections (barn/sr)

9000
7500

Au68+

This work
MCDF[3]Expt[3]

FWHM=59eV

Au69+

2p-1
3/2

6000

1800

1200

1200

600

Au67+

4500

1800

0
3.44

3000

600

3.48

3.52

3.56

3.60

3.64

0
4.4

66+

Au

-1
2p-1
1/2 and 2s1/2

4.5

4.7

Au

Au68+

Au65+

1500

4.6

69+

Au67+

0
2.8

3.2

3.6

4.0

4.4

4.8

5.2

5.6

Resonance Energy (keV)

Figure 1: The calculated synthesized LMM DR spectra of Au69+-Au65+ ions in the ground statescompared to the EBIT experimental measurements [3]. The separate contributions from thedifferent ionization stages of 41% Ne-like, 30% Na-like, 18% Mg-like, 4% Al-like and 7% Si-liketarget ions are considered in the calculations.
The work was supported by the National Key Research and Development Program of China underGrant No.2017YFA0402300), the Natural Science Foundation of China (Grant Nos:
12064041,11874051), doctoral research fund of Lanzhou City University (LZCU-BS2019-50).
References[1] L. Y. Xie, J. L. Rui, C. Z. Dong et al. Phys. Rev. A. 105, 012823 (2022)[2] H. R. Griem, Phys. Fluids B 4, 2346 (1992)[3] M. B. Schneider, D. A. Knapp, M. H. Chen et al. Phys. Rev. A. 45, R1291 (1992)[4] M. F. Gu, Can. J. Phys.86, 675 (2008)

135

POSTERS B

136

B01
Analysis of E3 transitions in Ag-like high-Z ions observed with the NIST EBIT
Dipti*, E. Takacs**, D. La Mantia, Y. Yang**, A. Naing, P. Szypryt***, A.Hosier, J.N. Tan, Yu.
Ralchenko
National Institute of Standards and Technology, Gaithersburg, MD 20899, USA(*) Present address: International Atomic Energy Agency, Vienna A-1400, Austria(**) Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 USA(***) National Institute of Standards and Technology, Boulder, CO 80305, USA

Measurements and analyses of forbidden lines in highly charged ions provide invaluable
information on diverse effects including quantum-electrodynamic and relativistic effects in atomic
structure as well as offer new diagnostic techniques for very hot plasmas. Recently, Sakaue et al [1]reported on observation of electric-octupole (E3) spectral lines in Ag-like W27+ using the compact
electron beam ion trap (EBIT). The well-resolved 4f7/2,5/2-5s transitions were recorded in the extreme
ultraviolet (EUV) spectrum. Using the HULLAC atomic code, the authors of Ref. [1] showed that theE3 lines are strongly enhanced for W and developed an advanced collisional-radiative model which
predicts E3 line intensities for the other members of the isoelectronic sequence.
In this work we report on measurements and identifications of the E3 4f7/2,5/2-5s transitions in
W and other high-Z elements including Re (Z=75), Os (Z=76), and Ir (Z=77). The EUV spectra wererecorded with the NIST EBIT using a grazing-incidence EUV spectrometer. The present higher
resolution results for W and GRASP2K calculations strongly confirm the Ref. [1] findings. Our
collisional-radiative model developed with the NOMAD and FAC codes offers a deep insight into
the population kinetics for Ag-like ions of heavy elements. The simulation allowed the identificationof new spectral lines in the spectra. We will present a detailed discussion of the observed spectra andcomparisons of the measured and simulated line intensities.
References[1] H.A. Sakaue et al, Phys. Rev. 100, 052515 (2019)[2] Yu. Ralchenko, Y. Maron, JQSRT 71, 609 (2001)[3] M.F. Gu, Can. J. Phys. 86, 675 (2008)

137

B02
Precision measurements of the 2P1/2-2P3/2 fine-structure splitting in Boron-like
S11+ and Cl12+ at EBIT
X Liu1, 2, X P Zhou1, W Q Wen1,3*, Q F Lu4, C L Yan4, G Q Xu4, J Xiao4†, A V Volotka5, Y S
Kozhedub6, M Y Kaygorodov6, Z K Huang1,3, W L Ma7, S X Wang7, and X Ma1,3
1
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
Institute of Quantum Matter, South China Normal University, Guangzhou, China
3
University of Chinese Academy of Sciences, Beijing, China
4
Shanghai EBIT Laboratory, Institute of Modern Physics, Fudan University, Shanghai, China
5
School of Physics and Engineering, ITMO University, Kronverkskiy prospect, St. Petersburg,
Russia6
Department of Physics, St. Petersburg State University, Universitetskaya, St. Petersburg, Russia
7
Department of Modern Physics, University of Science and Technology of China, Hefei, China
2

Precision measurements of the fine-structure splitting of highly charged ions (HCIs) test
fundamental atomic theory, including strong field quantum electrodynamics (QED) effects, electron
correlation effects, and relativistic and nuclear effects. The fine-structure splitting 1s22s22p 2P1/22
P3/2 transitions in boron-like S11+ and Cl12+ were experimentally measured with a high precision
spectrometer at the Shanghai high-temperature superconducting electron beam ion trap [1]. The M1
transition wavelengths for S11+ and Cl12+ were determined to be 760.9635(29) and 574.1539(26) nm(in air), respectively. Compared to the previously observed results, the accuracies of current
experimental results are improved by more than ten times and 200 times for S11+ and Cl12+,
respectively. Additionally, the M1 transition energies in S11+ and Cl12+ were evaluated within the abinitio QED framework to compare with the experimental data. The present experimental results
agree with the theoretical calculations and provide a possibility to test QED effects and correlation
effects with high accuracy in few-electron highly charged ions. The details can be found in Ref. [2].

Figure 1: (a) Spectra of sulfur obtained at the SH-HtscEBIT with nominal electron beam energies of
480, 530, 570, 620, and 690 eV in the range 737–777 nm. The line is the M1 transition between thefine-structure levels in the 2s22p 2P ground term of boronlike S11+. (b) Spectra of chlorine withnominal electron beam energies of 600, 630, 660, 700, 750, and 800 eV. The line is the M1
transition between the fine-structure levels in the 2s22p 2p ground term of boron-like Cl12+.
References[1] J. Xiao, R. Zhao, X. Jin, et al., IPAC2013 (JACoW, Shanghai, China, 2013), pp. 434–436.
[2] X. Liu, X. P. Zhou, W. Q. Wen, et al., Phys. Rev. A 104, 062804 (2021).

138

B03
Measurement and analysis of EUV emission spectrum fromlaser produced Zn plasma
S. Q. He, M. G. Su, Q. Min, S. Q. Cao, H. Y. Li, H. D. Lu, D. X. Sun and C. Z. Dong
Key laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070,
China
E-mail: sumg@nwnu.edu.cn, dongcz@nwnu.edu.cn
Highly charged ions of znic (Zn) element exist widely in astrophysical plasmas. The atomic data andparameters of plasma can be obtained by studying the spectra of these ions. In this work, the spectrafrom a laser-produced Zn plasma have been investigated using spatio-temporally resolved
spectroscopy.
An emission spectrum of laser-produced Zn plasma in 7-14 nm wavelength region is shown in Figure
1 (a), and it is dominated by three intense banded peaks. In order to explain the structure of the spectra,
the atomic structure parameters of highly charged ions of Zn are calculated using the Cowan suitesof Hartree-Fock configuration interaction codes. It is found that these intense banded peaks attributed
to the 3d-4f transition arrays of Zn6+ up to Zn9+ ions, as shown in Figure 1 (b).
In order to further explain the spectral structure, simulated spectra are obtained by statisticalsummation of atomic data and population information. Population information are calculated by theassumption of a normalized Boltzmann distribution among the excited states and a steady-statecollisional-radiative model. A simulated spectrum with electron temperature 𝑇
20 𝑒𝑉 and electron
density 𝑁
1.46 10 0 𝑐𝑚 are plotted in Figure 2 (a). It can be found the simulated spectrum isin good agreement with the experimental spectrum in the long wavelength region, and the dominantfractional contributions arise from Zn6+ and Zn7+ ions. However, the spectra (Figure 2 (b)) are in good
25 𝑒𝑉 andagreement in the short wavelength region and Zn7+ and Zn8+ ions are predominant as 𝑇
1.69 10 0 𝑐𝑚 . This work can provide reference for similar spectral analysis.
𝑁

Figure 1: The line distrib tions of 3d 4ftransition arrays of Zn6+ to Zn9+.

Figure 2: Comparisons between theexperimental spectrum and simulated spectra.

The work is supported by the National Key Research and Development Program of China (2017YFA0402300), theNatural Science Foundation of China (11874051,11904293, 61965015).

Reference[1] D. Colombant, G. F. Tonon, J. Appl. Phys 44, 3524 (1973)

139

B04
Theoretical investigation of dielectronic recombination processes of highly
charged gold ions
W. L. He, S. B. Niu, J. L. Rui, T. X. Ma, L. Y. Xie*, C. Z. Dong
Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070,
Peo le Re blic of China*Email: xiely@nwnu.edu.cn; Email: dongcz@nwnu.edu.cn;
Dielectronic recombination (DR) is a prominent resonant recombination process in collisions ofelectrons with highly charged ions (HCIs) [1]. Gold is one of the particular interest work material in
the indirect laser drive of inertial confinement fusion (ICF). Accurate atomic data of highly ionizedgold ions are essential and important for modelling gold hohlraum-produced plasma [2-3].
In this study, the DR process of Ne-like to Si-like gold ions (Au69+-Au65+) are investigated. The
resonance energies, resonance strengths and cross sections are carefully calculated for L-shell n =1 transitions using the FAC code based on fully relativistic configuration interaction (RCI) method[4]. Using the density matrix formular, the degree of linear polarizations of x-ray dielectronic satellite
lines produced by dominant LMM, LMN DR processes are calculated, and used to obtain the
differential cross section of Au69+-Au65+ ions. Figure 1 illustrated our calculated synthesized LMM
DR spectra of gold ions located at 2.6-5.6 keV energy regions, and compared with the experimental
measurements of electron beam ion trap at Lawrence Livermore National Laboratory by Schneider
et al [3]. Our theoretical results show an excellent agreement with the experimental values.

Diff-Cross Sections (barn/sr)

9000
7500

Au68+

This work
MCDF[3]Expt[3]

FWHM=59eV

Au69+

2p-1
3/2

6000

1800

1200

1200

600

Au67+

4500

1800

0
3.44

3000

600

3.48

3.52

3.56

3.60

3.64

0
4.4

66+

Au

-1
2p-1
1/2 and 2s1/2

4.5

4.7

Au

Au68+

Au65+

1500

4.6

69+

Au67+

0
2.8

3.2

3.6

4.0

4.4

4.8

5.2

5.6

Resonance Energy (keV)

Figure 1: The calculated synthesized LMM DR spectra of Au69+-Au65+ ions in the ground statescompared to the EBIT experimental measurements [3]. The separate contributions from thedifferent ionization stages of 41% Ne-like, 30% Na-like, 18% Mg-like, 4% Al-like and 7% Si-liketarget ions are considered in the calculations.
The work was supported by the National Key Research and Development Program of China underGrant No.2017YFA0402300), the Natural Science Foundation of China (Grant Nos:
12064041,11874051), doctoral research fund of Lanzhou City University (LZCU-BS2019-50).
References[1] L. Y. Xie, J. L. Rui, C. Z. Dong et al. Phys. Rev. A. 105, 012823 (2022)[2] H. R. Griem, Phys. Fluids B 4, 2346 (1992)[3] M. B. Schneider, D. A. Knapp, M. H. Chen et al. Phys. Rev. A. 45, R1291 (1992)[4] M. F. Gu, Can. J. Phys.86, 675 (2008)

140

B05
Optical Spectroscopy of Ru21+-Ru24+ Ions
Junyu Fan1,2, Yuyuan Qian1, Niu Ben1, Yintao Wang1, Jialin Liu1, Liangyu Huang1,2, Yaming Zou1,2,
Jiguang Li3 and KeYao1,2
1

Shanghai EBIT Laboratory, and Key Laboratory of Nuclear Physics and Ion Beam Application(MOE), Institute of Modern Physics, Fudan University, Shanghai 200433, China
2
Department of Nuclear Science and Technology, Fudan University, Shanghai 200433, China
3
Institute of Applied Physics and Computational Mathematics, Beijing 100088, China

Spectroscopy of highly charged ions is of great interest in the diagnosis of plasma, and also in thestudies of atomic physics, e.g., detection of electron correlation effects. Due to the complex structureof an open 3d-subshell, accurate atomic structure calculation of 3dn configuration is still a challenge.
In this work, optical spectroscopies of highly charged Ru21+-Ru24+ ions are studied in a permanent
magnet electron beam ion trap (EBIT). The charge state distribution of the Ru ions in the EBIT isanalyzed for line identifications, as shown in Fig. 1. With the assistance of the large scale multiconfiguration Dirac-Hartree-Fock calculations [1], more than ten new dipole forbidden lines arerecognized, which could be used as reference data for further atomic structure calculations.

Intensity (Abitrary unit)

1.0 (a)1400 eV
0.5
0.0
1.0
0.5

(b)

1400 eV1180 eV

Ru23+ 1180 eV

1100 eV

1100 eV1000 eV1000 eV

Ru23+

0.0
1.0
0.5
0.0
1.0
0.5
0.0
405

415

425

435 165l (nm)

180

195

210

Wien (V)Figure 1: (a) Electron beam energy dependence of the Ru23+ spectra, (b) the corresponding charge
state distributions.
References[1] P. Jönsson, G. Gaigalas, J. Bieron, C. Froese Fischer, and I.P. Grant, Comput. Phys. Commun.
184, 2197 – 2203 (2013).

141

B06
EUV spectra of laser-produced Cu Plasmas
M. J. Li, M. G. Su, H. Y. Li, S. Q. He, Q. Min, S. Q. Cao, D. X. Sun, and C. Z. Dong
Key Laboratory of Atomic and Molecular Physics & Functional Material of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070,
China
E-mail: sumg@nwnu.edu.cn, dongcz@nwnu.edu.cn
The research on the radiation characteristics and dynamic evolution of laser-produced plasma (LPP)
has always been a very interesting topic in the fields of atomic physics and plasma physics. Cu is
one of the most concerned elements in the field of celestial bodies and fusion research. Studying thespectra of Cu plasma is very helpful for astrophysical plasma diagnosis. In this work, the timeevolving EUV spectra in the range of 8-14 nm are obtained using the spatio-temporal resolved
laser-produced Cu plasma emission spectrum measurement method.
The spectral line distribution characteristics of Cu5+-Cu9+ (3p63dn, n=2-6) ions from 3p and 3dtransition arrays are analyzed based on Hartree-Fock configuration interaction method[1] and thenormalized Boltzmann distribution. Figure 1 shows one of experimental spectrums and thetheoretical spectrum of Cu5+-Cu9+ ions under the electron temperature of 25 eV. It can be found thatthe theoretical peak position of each ion is in good agreement with the experimental peak position,and the spectral profile is also in good agreement.

Figure 1. Comparison between experimental spectrum and theoretical spectra of Cu5+-Cu9+ ionsThis work is supported by the National Natural Science Foundation of China (11874051、12064040,11864036), the Science and technology project of Gansu Province (No. 21JR7RA122).
References[1] R. D. Cowan, The Theory of Atomic Structure and Spectra (University of California Press,
Berkeley, 1981).

142

B07
First Laboratory Verification of Magnetic-field-induced Transition Effectin Fe X
YANG Yang, XU Guoqin, LI Wenxian*, SONG Liudi, SI Ran, CHEN Chongyang, BAI
Xianyong*, TIAN Hui#, XIAO Jun, Roger HUTTON, ZOU Yaming
Shanghai EBIT laboratory, and Key Laboratory of Nuclear Physics and Ion-Beam Application(MOE), Institute of Modern Physics, Fudan University, Shanghai 200433, China*Key Laboratory of Solar Activity, National Astronomical Observatories,
Chinese Academy of Sciences, Beijing 100012, China#
School of Astronomy and Space Science, University of Chinese Academy of Sciences,
Beijing 100049, China

The magnetic field is extremely important for understanding the properties of the solar corona.
However, there are still difficulties in the direct measurement of coronal magnetic fields. The
discovery of the magnetic-field-induced transition (MIT) in Fe X, which was also observed in thecoronal spectra, opened up a new method for measuring the coronal magnetic field. In this work, we
obtained the Fe X extreme ultraviolet (EUV) spectra in the wavelength range of 174–267 Å inShanghai high-temperature superconducting electron beam ion trap, and for the first time, verified
the effect of MIT in Fe X by measuring the line ratios between 257.262 Å and reference line of
226.31 Å (257/226) at different magnetic field strengths. The plasma electron density that may
affect the 257/226 value was also obtained experimentally and then verified by comparing thedensity-sensitive line ratios with the theoretical prediction, and there was good agreement between
them. By comparing the simulated line ratios of 257/226 with the experimental values at given
electron densities and magnetic fields, the critical energy splitting of the fine-structure levels, one of
the most critical parameters to determine the MIT transition rate, was obtained. Possible reasons
which may lead to the difference between the obtained energy splitting and the recommended value
in previous work are discussed. Magnetic field response curves for the 257/226 value were
calculated and compared to the experimental results, which is necessary for future MIT diagnostics.
2.0

LineRatio_257.262 / 226.31

1.9
1.8
1.7

E/cm-1 = 8.6 log Ne/cm-3 = 10.2
E/cm-1 = 8.6 log Ne/cm-3 = 10.4
E/cm-1 = 8.6 log Ne/cm-3 = 10.6
E/cm-1 = 2.29 log Ne/cm-3 = 10.8
E/cm-1 = 2.29 log Ne/cm-3 = 11.0
E/cm-1 = 2.29 log Ne/cm-3 = 11.2

1.6
1.5
1.4
1.3
Experiment data
1255 G
1679 G
2102 G

1.2
1.1
1.0
800

1000

1200

1400 1600 1800
Magnetic field (G)

2000

2200

Theoretical and experimental values of line ratios of 257.262 Å and 226.31 Å versus the magnetic
field

143

B08
Towards Doppler-assisted precision laser spectroscopy of highly charged ionsat the CSRe
D.Y. Chena, H.B. Wanga, W.Q. Wena,*, Z.K. Huanga, D.C. Zhangb, Y.J. Yuana, D. Wintersc,
M. Bussmannd, Th. Walthere, L.J. Maoa, J.C. Yanga, X. Maa,* and Laser Cooling CollaborationaInstitute of Modern Physics, Chinese Academy of Sciences, 730000 Lanzhou, China
School of Physics and Optoelectronic Engineering, Xidian University, 710071, Xi'an, Chinac
GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, GermanydCenter for Advanced Systems Understanding, 02826 Görlitz & HZDR, 01328 Dresden, GermanyeInstitut für Angewandte Physik, Technische Universität Darmstadt, 64289, Darmstadt, Germanyb

The combination of the storage ring CSRe and advanced laser has proven to be an excellent
research platform for atomic physics of highly charged ions (HCIs) [1]. By accelerating stored ions,the ultra-short transition wavelength in HCIs can be Doppler-shifted into a convenient region, wherelaser light is readily available and thus making laser spectroscopy possible. There are two planned
techniques to launch precision laser spectroscopy experiments at the CSRe, as shown in Fig. 1(a):(i) Laser spectroscopy with fluorescence spectrum. An optical detector, as displayed in Fig. 1(b),has been developed for fluorescence photons detection. It is featuring a SiC-made parabolic reflector
with a central slit and an MCP coated with CsI, enables a high-efficiency detection of the UV photons
without affecting the normal operation of the ion beams in the ring, and the collection efficiency isimproved by more than 50 times as compared to the previously installed photon detector [2].
(ii) Laser spectroscopy with Schottky spectrum [3]. Schottky resonator enables a non-destructively
measurement of the revolution frequency of the ion beam with comparable precision. By resonating
excitation of stored ions with a cw laser combined with ion velocity measurement, determined by the
e-cooler voltage, allows a precise measurement of the transition wavelength. The determination of
the 2S1/2-2P1/2 transition of O5+ ions by using the Schottky spectrum in Fig. 1(c) and the related
uncertainties analysis, including e-cooler voltage calibration, space charge effects, angular deviation,etc., are under investigation. Both the development of the optical detector and the investigation of
Schottky spectrum method for the laser spectroscopy experiments at the CSRe are in progress.

Fig. 1: (a) Schematic of the laser spectroscopy experiment of Li-like O5+ ions at the CSRe.
(b) 3D model of the optical detector. (c) Experimental Schottky spectrum of the cw laser interaction
with the coasting ion beam under electron cooling.
References[1] W.Q. Wen, H.B. Wang, Z.K. Huang, et al., Hyperfine Interactions 240, 45 (2019).
[2] D.Y. Chen, H.B. Wang, Z.K. Huang, et al., Nuclear Physics Review, accepted.
[3] D.Y. Chen, H.B. Wang, W.Q. Wen, et al., to be submitted.

144

B09
Re-

e ga

a d

e de

f ca

f

W11+

e

b e a geN Fu, Q Lu, C L Yan, G Q Xu, K Wa g*, C Y Chen, Y Zou, J X a
Shanghai EBIT Laborator , Ke Laborator of Nuclear Ph sics and Ion-Beam Application (MOE),
Institute of Modern Ph sics, Fudan Universit , Shanghai 200433, China(*) Hebei Ke Lab of Optic-electronic Information and Materials, The College of Ph sics Scienceand Technolog , Hebei Universit , Baoding 071002, China
We present a ne investigation of unidentified emission lines in 350 660 nm from W11+ at a compact
electron-beam ion trap in Shanghai [1]. To help the line identification, transition energies of the lo est
48 levels are calculated b the large-scale relativistic configuration interaction and multiconfiguration
Dirac-Hartree-Fock calculation [2 4]. The results from the t o calculations are in good agreement
ith each other and the deviation is 0.66% on average. B using the collisional-radiative model
implemented in the fle ible atomic code, si observed lines for the visible spectrum of W11+ are
identified as magnetic-dipole transitions from 4𝑓 5𝑠 5𝑝 and 4𝑓 5𝑠 5𝑝 configurations.

Figure 1: Spectra obtained at the SH-HtscEBIT

References[1] J. Xiao, R. Zhao, X. Jin, B. Tu, Y. Yang, D. Lu, R. Hutton, Y. Zou, in Proceedings of the 4thInternational Particle Accelerator Conference, IPAC2013 (JACoW, Shanghai, China 2013), pp. 434
436[2] M. F. Gu, Can. J. Phys. 86, 675 (2008)[3] P. Jönsson, G. Gaigalas, J. Biero , C. Froese Fischer, I. P. Grant, Comput. Phys. Commun. 184,2197 (2013)[4] C. Froese Fischer, G. Gaigalas, P. Jönsson, J. Biero , Comput. Phys. Commun. 237, 184 (2019)

145

B10
Dielectronic recombination for Na-like Kr25+ from the CSRm to the CSReZ. K. Huang1, 2, W. Q. Wen1, 2, S. X. Wang3, H. B. Wang1, 2, W. L. Ma3, H. K. Huang1, L. J. Mao1, 2,
J. C. Yang1, 2, Y. J. Yuan1,2, S. F. Zhang1, 2, L. F. Zhu3, X. Ma1,2 , and DR collaboration
1

Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
2
University of Chinese Academy of Sciences, 100049, Beijing, China
3
Hefei National Research Center for Physical Sciences at Microscale and Department of Modern
Physics, University of Science and Technology of China, Anhui 230026, China
Storage rings equipped with electron cooling devices provide a uniquely effective technique todetermine the absolute DR rate coefficients for highly charged ions. The DR experiment for Na-like
Kr25+ in the energy range of 0-70 eV has been performed successfully at the storage ring CSRm [1].
At the beginning of 2020, the electron cooler at the CSRe has been upgraded with an embedded
electron energy fast detuning system, which can support a much broader detuning energy range (±15kV) and allow us to extend the DR spectroscopy from the CSRm to the CSRe. Therefore, moreexperimental candidate ions can be available at the CSRe via the stripping and selection processes inthe second Radioactive Ion Beam Line (RIBLL-2) located between the CSRm and the CSRe. To
evaluate the performance of the newly built experimental platform at the CSRe, we have also carriedout the DR measurement of Na-like Kr25+ ions therein. Fig. 1 (Left) presents the comparison between
the DR spectra for Kr25+ measured at the CSRm and the CSRe. Fig. 1 (Right) presents the details of
the DR rate coefficients for Kr25+ measured at the CSRe within the electron-ion collision energy rangeof 0-150 eV, which encompass all the ǻn=0 (3sĺ3p, 3d) DR resonances. The experimental result
was also compared with the FAC calculation, and a good agreement was achieved by considering thestrong mixing among the low-energy resonances associated with 3ĺ3 and 3ĺ4 core excitations in
the theoretical calculation. The present result demonstrates the reliability and stability for future DR
spectroscopy studies at the CSRe.

Figure 1: (Left) The comparison of the DR spectra for Na-like Kr25+ measured at the storage ring
CSRm (Orange solid curve) and the CSRe (black dotted circles). (Right) The experimental DR rate
spectrum at the CSRe. The red solid line depicts the FAC calculated total DR rate coefficients andthe blue areas are the contribution from the ǻn=1 DR resonances. The vertical marks indicate theresonance positions calculated by FAC calculation (ǻn=1) and Rydberg formula (ǻn=0).
References[1] Z.K. Huang, W.Q. Wen, S.X. Wang, et al., Phys. Rev. A, 2020; 102, 062823.

146

B11
Precision spectroscopy of 2s2p 1P1 →2s2 1S0 in Beryllium-like Cl13+ at EBIT
X. P. Zhou1, X. Liu 1 , W. Q. Wen1,2*, Q. F. Lu3, C. L. Yan3, G.Q. Xu3, J. Xiao3†, Z. K. Huang1,2,
X. Ma1,2
1

Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China ;2
University of Chinese Academy of Sciences, 100049, Beijing, China
3
Shanghai EBIT Laboratory, Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE),
Institute of Modern Physics, Fudan University, Shanghai 200433, China ;Precision measurement experiment of electric-dipole transition between the 2s2p 1P1 and 2s2 1S0 inberyllium-like Cl13+ have been performed in Shanghai High-Temperature Superconducting electron
beam ion trap (SH-HtscEBIT) [1]. Using a portable high resolution soft x-ray and extreme
ultraviolet (EUV) spectrometer [2] for spectral measurement of the extreme ultraviolet region. The
E1 transition wavelength was preliminarily determined to be 237.66(2) Å (in vacuum) with anaccuracy of 85 ppm at electron beam energies of 1000, 1030, 1050 and 1080 eV, respectively (asshow in figure 1). It is possible to test atomic structure theoretical calculations including quantum
electrodynamic (QED) effects and relativistic effects in few-electrons highly charged ions. In
particular, the beryllium-like ions are very suitable for the study of electron-electron correlation
effects because of the two strongly correlated 2s electrons [3]. Subsequent results are being
prepared.

Figure 1: (a) Spectra of chlorine obtained at the SH-HtscEBIT with nominal electron beam energiesof 1000, 1030, 1050 and 1080 eV in the range 220-265 Å. The line is the E1 transition between thefine-structure levels in the 2s2p 1P1 and 2s2 1S0 of beryllium-like Cl13+. (b)Expanded view of theline at 237.6 Å and its Gaussian fit.
References[1] J. Xiao, R. Zhao, X. Jin, et al., IPAC2013 (JACoW, Shanghai, China, 2013), pp. 434–436.
[2] Z. Shi, R. Zhao, W. Li, B. Tu, Y. Yang, J. Xiao, S. Huldt, R. Hutton, Y. Zou, Rev Sci Instrum,85 (2014) 063110.
[3] M.Y. Kaygorodov, Y.S. Kozhedub, I.I. Tupitsyn, A.V. Malyshev, D.A. Glazov, G. Plunien,
V.M. Shabaev, Physical Review A, 99 (2019).

147

B12
Atomic structure and properties of Nd9+ for making an atomic optical clock
Yanmei Yu
Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Novel applications of optical transitions in highly charged ions (HCIs) for frequency metrology andtests for variation of fundamental constants have made them a subject of much interest lately [1].
The rich energy configuration of HCIs offers numerous optical transitions between the ground state
and the long-lived excited states, which can be used for developing high accuracy clocks beyond the
10−18 precision limit [2,3,4]. The compact size of the HCIs makes them insensitive to external fields.
Strong relativistic effects and high ionization energies make the HCI clock transitions highly sensitive
to variation of the fine structure constant αe and dark matter searches. In this work, we propose thehighly charged Sb-like Nd9+ ions as a promising candidate for a high-accuracy optical clock. Theenergy levels, arising from the 5p − 4f orbital crossing in the Nd9+ ions are investigated. To comprehend Nd9+ as a prospective atomic clock, we determine the transition wavelengths, quality factors,
lifetimes, magnetic dipole and electric quadrupole hyperfine structure constants, electric dipole polarizabilities, electric quadrupole moments of the states involved with clock transitions by using a
relativistic multi-reference configuration interaction method. Relativistic sensitivity coefficients tothe variation of the fine-structure constant and violation of local Lorentz invariance are determined,
and various plausible systematics for the development of frequency standards are analyzed [5].
References[1] M. G. Kozlov, M. S. Safronova, J. R. Crespo López-Urrutia, and P. O. Schmidt, Highly charged
ions: Optical clocks and applications in fundamental physics, Rev. Mod. Phys. 90, 045005(2018).
[2] P. Micke, T. Leopold, S. A. King, E. Benkler, L. J. Spiess, L. Schmoger, M. Schwarz, J. R.
Crespo Lopez-Urrutia, P. O. Schmidt, Coherent laser spectroscopy of highly charged ions using
quantum logic, Nature 578, 60 (2020).
[3] H. Bekker, A. Borschevsky, Z. Harman, C. H. Keitel, T. Pfeifer, P.O. Schmidt, J.R. Crespo LópezUrrutia, J.C. Berengut, Detection of the 5p - 4f orbital crossing and its optical clock transitionin Pr9+ , Nat. Comm. 10, 5651 (2019).
[4] Y. M. Yu and B. K. Sahoo, Investigating ground-state fine-structure properties to explore suitability of boronlike S11+ -K14+ and galliumlike Nb10+ -Ru13+ ions as possible atomic clocks, Phys.
Rev. A 97, 041403(R)(2018).
[5] Y. M. Yu, D. Pan, S. L. Chen, B. Arora, H Guan,K. L. Gao, and J. B. Chen, arXiv:2107.10520.

148

B13
Polarization-dependent spectra of KLL dielectronic satellite lines of Ar17+-Ar12+
ions
S. B. Niu, J. H. Deng, Y. L. Ma, L. Y. Xie*, and C. Z. Dong
Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070,
China*E-mail : xiely@nwnu.edu.cn
Collisions of energetic electrons with highly charged ions (HCIs), abundant in hot plasmas, may
lead to emission of anisotropic and polarized characteristic x-rays. Theoretical studies ofpolarization of x-ray lines can provide information on the directionality of the electron currents andthe orientation of the magnetic-field lines in both hot astrophysical and laboratory plasmas [1].
In this work, the polarization properties of dielectronic satellite lines produced by KLL dielectronic
recombination (DR) processes have been studied for highly charged Ar17+-Ar12+ ions. The degree of
linear polarization of dielectronic satellite lines, and polarization-dependent spectra at different
electron beam energy from 2100 eV to 2500 eV are calculated using density matrix formalism [2]and the FAC code [3]. In the calculations, the high-order trielectronic recombination (TR) and
quadruelectronic recombination (QR) processes are also incorporated, and show strong effects onpolarization spectra of Ar13+ and Ar12+ ions.
10-1

Intensity (1011 arb. unit)

40

Ar

20
0
1
0
-1
20

3280

1
0
-1
9
Ar14+
6
Eb=2310eVI^
Eb=2306eV
3
0
3304
3312
3320 3050
3055
3060
3065
3070
3075
1
0
-1
8
6
Ar13+
Eb=2360eV
4
Eb=2220eV
2
0
3120
3130
3020 3025 3030 3035 3040 3045 3050
1
0
-1
3
Ar12+
Eb=2400eV
2
I||

17+

3288

3296

Ar16+

10
0
3090
3100
1
0
-1
30
Ar15+
20
10
0
3072
3076
3080

3110

Eb=2260eV

3084

3088

3080

3055

1
3092

0
2995

3000

3005

3010

3015

3020

Photon Energy (eV)Figure 1: Theoretical polarization-dependent spectrum of Ar17+-Ar14+ ions are calculated at different
energy Eb of the electron beam. I|| and I ⊥ represent intensity associated with parallel andperpendicular polarization state. Dotted vertical line with different colors indicate the positions ofdielectronic satellite lines from the DR (black), TR (red), and QR (blue) processes. The diamonds
show the degree of polarization.
The work was supported by the National Key Research and Development Program of China underGrant No.2017YFA0402300, and the Natural Science Foundation of China (Grant Nos:
12064041,11874051).
References[1] C. Shah, H. Jörg, S. Bernitt, et al. Phys. Rev. A. 92, 042702 (2015)[2] C. Shah, P. Amaro, R. Steinbrügge, et al. APJS. 234, 27 (2018)[3] M. F. Gu, Can. J. Phys. 86, 675 (2008)

149

B14
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150

B15
Cascade effects on the polarization of x-ray emission following electron-impact
excitation of He-like ions with Z = 10-92
M. Y. Jia, S. B. Niu, L. Y. Xie*, J. Jiang, C. Z. Dong
Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070,
People s Rep blic of China*Email: xiely@nwnu.edu.cn
The polarization of x-ray emission from highly charged ions undergoing collisions with electron isimportant for spectroscopic diagnostic of the electron distribution anisotropy in high-temperatureplasmas [1].
In this study, we calculated the degree of linear polarization of the 1s2p 1P1-1s2 1S0 (w) resonance line,
1s2p 3P2-1s2 1S0 (x), 1s2p 3P1-1s2 1S0 (y) intercombination lines, and 1s2s 3S1-1s2 1S0 (z) forbiddenline following electron impact excitation of He-like ions with Z=10-92 using a fully relativistic
distorted-wave method. The cascade contributions from the high-lying levels 1snl (n=2 and 3) to thepolarization properties were investigated, including the electric-dipole (E1) allowed transitions,forbidden (M1, E2, and M2) transitions and two-photon transition (2E1). The results are comparedwith the existing theoretical and experimental values [2-4]. It was found that the radiative cascades
dominate the degree of linear polarization of the z line. Line x shows very small contributions ofradiative cascades.
This work (NC)This work (C)Dipti, et al. (NC) [3]Dipti, et al. (C) [3]
P. Hakel, et al. (NC) [4]
P. Hakel, et al. (C) [4]
D. L. Robbins, et al.(Exp)[2]Dipti, et al. (Exp) [3]
P. Hakel, et al. (Exp) [4]

0.70
0.65

Polarization

0.60
0.55
0.50
0.45

1s2p 1P1-1s2 1S0 (w)

0.40
0.35
5

15

25

35

45

55

65

75

85

95

Atomic number Z

Figure 1: The calculated linear polarizations for the w line of He-like ions at electron-impact
energy near the 1s3l excitation threshold, and compared with the existing theoretical andexperimental values [2-4]. NC represents the values without cascade contributions, and C represents
the ones with cascade contributions included.
The work was supported by the National Kay Research and Development Program of China underGrant No.2017YFA0402300), the NSCF (Grant Nos: 12064041, 11874051).
References[1] M. K. Inal and J. Dubau, J. Phys. Rev. A. 47, 4794 (1993)[2] D. L. Robbins, et al. Phys. Rev. A. 70, 022715 (2004)[3] Dipti, et al. J. Phys. B. 53, 115701 (2020)[4] P. Hakel, et al. Phys. Rev. A. 76, 012716 (2007)

151

B16
Two-electron one-photon and one-electron one-photon transition of inner shellhole state of He-like ions
R. X. Zhao, X. B. Ding, D. H. Zhang, M. W. Zhang*, Y. L. Xue*, D. Y. Yu*, C. Z. Dong
Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070,
China(*) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
The structure and properties of inner shell hollow atoms are one of the hot topics in atomic physics[1].
The Two-electron one-photon (TEOP) transition of the double K hole atoms is essential because it
was caused by the electron correlation effects and will provide a reference for the celestial bodies
and laboratory plasma. He-like ions are the simplest system to investigate such complex transition
process[2].
Based on the fully relativistic multi-configuration Dirac-Hartree-Fock method combined with active
space method[3], the transition energy and probability of N5+ , Ne8+ , Fe24+ , Cu27+ , Xe54+ , and W72+
ions were calculated. For the TEOP transition, the spin forbidden transition is obviously enhancedwith the increase of nuclear charge, which means that the relativistic effect significantly strengthened.
For the OEOP transition, the transition energies of the transitions 1 P1 -1 S0 and 3 P2 -3 S1 are inversedwith the increase of nuclear charge, which might caused by the competition between relativistic effectand electron correlation effects.

Figure 1: Transition spectra of TEOP transition 2s2p-1s2 (left) and OEOP transition 2s2p-1s2s (right)of N5+ , Ne8+ , Fe24+ , Cu27+ , Xe52+ , and W72+ ions.
References[1] J. P. Briand, Phy. Rev. L 37, 59 (1976)[2] X. B. Ding, C. Q. Wu et.al, JQSRT 259, 107426 (2021)[3] P. Jönsson, G. Gaigalas et. al, Comput. Phys. Commun. 184 2197 (2013)

152

B17
Collisional-radiative model for the spectra of M1 transition of W53+ ion
Y. L. Xu1 , X. B. Ding1∗ , Y. Yang2 , K. Yao2 , L. Zhang3 , F. Koike4 , D. Kato5 , I. Murakami5 , H. A.
Sakaue5 , N. Nakamura6 , C. Z. Dong1
Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province,
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070,
China
2
Key Laboratory of Applied Ion Beam Ministry of Education, Institute of Modern Physics, Fudan
University, Shanghai 200433, China
3
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230000, China
4
Department of Physics, Sophia University, Tokyo 102-8554, Japan
5
National Institute for Fusion Science, Gifu 509-5292, Japan
6
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan1

The emission spectrum of tungsten ions can be used to diagnose the status of the fusion plasma[1,2].
Based on the experimental study of M1 transition spectrum of W53+ ion by Ralchenko et al. [3], thecollisional-radiative model (CRM) were used to investigate the spectrum.
The configurations included in the present CRM are 3s2 3p6 3d3 , 3s1 3p6 3d4 , and 3s2 3p5 3d4 . In order
to consider the electron correlation effects, the SD excited configurations, such as, 3s1 3p6 3d3 4l(l =0 − 2), 3p6 3d5 , 3p6 3d3 4s2 and 3s2 3p6 3d2 6l(l = 0 − 4) are included as the correlation configurations.
The simulated spectrum is in good agreement with the observed spectrum on the EBIT. Five observed
transitions were identified and assigned to the transitions within the multiplets of the ground configuration. The transition m in Fig1.(c) is predicted to be the M1 transition of W53+ ions which is
not assigned in the previous work. This work provided the knowledge of the highly charged W ionswhich will be helpful for the future investigation on these ions and the fusion plasma.

Figure 1: (a) Radiative transition rate, (b) Intensity from CRM. (c) Experimental spectra from the
EBIT [3]. Each individual transition was assumed to have Gaussian profile with FWHM = 0.02nm.
References[1] Y. Podpaly, J. Clementson, P. Beiersdorfer, et.al, Phys. Rev. A 80, 052504 (2013)[2] X. B. Ding, P. Yang, G. Zhang, et.al, Phys. Lett. A 420, 127758 (2021)[3] Yu. Ralchenko, I. N. Draganic, D. Osin, et.al, Phys. Rev. A 83, 032517 (2011)

153

B18
Charge-state evolution from W5+ toW7+ at energies below the ionization
potentials
C. L. Yan, Q. Lu, Y.M. Xie, B.L. Li, N. Fu, Y. Zou, C.Y. Cheng, and J. Xiao
Shanghai EBIT Laboratory, Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE),
Institute of Modern Physics, Fudan University, Shanghai 200433, China;
Experiments on an electron-beam ion trap (EBIT) and calculations using flexible atomic code
(FAC) are carried out to study the charge-state evolution from W5+ to W7+. The W7+ line at 574.47
nm is observed with an electron-beam energy of about 48 eV, which is far below the ionization
potentials of W5+ (65 eV) and W6+ (122 eV). Multicharge-state collisional-radiative (CR)
calculations for W5+, W6+, and W7+ are performed with level-to-level processes with configurationinteraction (CI), including direct ionization, collision excitation, radiative recombination, charge
exchange, radiative transition, and autoionization. The CI strongly influences the calculated
ionization cross sections for metastable levels. The CR-simulated spectra agree well with theexperiments, and the calculated effective ionization cross section for W6+ has the same trend as theavailable experimental data[1]. The metastable levels (∼40 eV for W5+; ∼40 and ∼85 eV for W6+)
significantly contribute to the ionization through excitation-autoionization at rather low energies(<50 eV) in the EBIT plasma. These metastable levels could have a considerable influence on the
charge-state evolution of tungsten ions in edge fusion plasma.

Reference:[1] M. Stenke et al., J. Phys. B: At. Mol. Opt. Phys. 28, 2711 (1995).

154

B19
Precise determination of 2s2p5 → 2s2p6 transition energy in fluorine-likenickel utilizing a low-lying dielectronic resonance
S. X. Wang1, Z. K. Huang2, W. Q. Wen2, H. B. Wang2, S. Schippers3, Z. W. Wu4, Y. S. Kozhedub5,
M. Y. Kaygorodov5, A. V. Volotka6, K. Wang7, X. Ma2, L. F. Zhu1 and DR collaboration
1

University of Science and Technology of China, Anhui 230026, China lfzhu@ustc.edu.cn
2
Institute of Modern Physics, CAS, 730000, Lanzhou, China x.ma@impcas.ac.cn
3
Justus-Liebig-Universität Gießen, 35392 Giessen, Germany
4
Northwest Normal University, Lanzhou 730070, China
5
St. Petersburg State University, Universitetskaya 7/9, 199034 St. Petersburg, Russia
6
ITMO University, Kronverkskiy prospekt 49, 197101 St. Petersburg, Russia
7
Hebei University, Baoding 071002, China

Precision spectroscopy of highly-charged ion (HCI) serves as an ideal tool to test the quantum
electrodynamics (QED), relativistic and correlation effects. Dielectronic recombination (DR) occurs
when a free electron is resonantly captured by the ion and the excess energy excites ion core. The
doubly-excited recombined ion can decay via radiations to complete DR or via Auger back to its
original state. The resonant character of DR was recognized as an ideal tool for the precision
spectroscopic studies with HCIs [1-3]. Heavy-ion storage rings with an electron cooler offer aunique opportunity for measuring DR rate coefficients, in particular for the low-lying resonances.
Associated transition energies in HCIs can be determined with a high accuracy when the binding
energy of the captured electron can be calculated accurately. Here we present the precision DR
spectroscopy of fluorine-like nickel [4]. The experimental determination of the collision energy forthe first resonance via (2s2p6[2S1/2]6s)J=1 intermediate state at 86 meV could be performed with anuncertainty of as low as 4 meV. The multi-configuration Dirac-Hartree-Fock and stabilization
methods have been applied for calculating the Rydberg binding energy of the 6s electron. The
2s2p5[2P3/2] → 2s2p6[2S1/2] transition energy in fluorine-like nickel ion is determined to be
149.056(4)exp(10)MCDHF and149.032(4)exp(6)SM, respectively [5]. Moreover, individual theoreticalcontributions to the transition energy have also been evaluated by the ab initio calculation.

Figure 1: Background-subtracted DR rate coefficients and the fitted curves. The green vertical bars
are the fitted resonance positions and strengths. The experimentally derived and theoreticallycalculated 2s2p5[2P3/2] 2s2p6[2S1/2] transition energies in fluorine-like nickel ion are listed.
References[1] E. Lindroth, H. Danared, P. Glans et al., Phys. Rev. Lett. 86, 5027 (2001)[2] S. Kieslich, S. Schippers, W. Shi et al., Phys. Rev. A 70, 042714 (2004)[3] M. Lestinsky, E. Lindroth, D. A. Orlov et al., Phys. Rev. Lett. 100, 033001 (2008)[4] Shu-Xing Wang, Zhong-Kui Huang, Wei-Qiang Wen et al., A&A 627, A171 (2019)[5] S. X. Wang, Z. K. Huang, W. Q. Wen et al., arXiv:2205.01334

155

B20
Identification of magnetic-dipole lines from W25+ ions in the 4f3 ground state
Daiji Kato1,2, Toshiki Umezaki2, Hiroyuki A. Sakaue1, Nobuyuki Nakamura3,1, Tomoko Kawate1,4,
Izumi Murakami1,4
1. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
2. Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka
816-8580, Japan
3. Institute for Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-8585,
Japan
4. Department of Fusion Science, SOKENDAI, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
Optical emission lines of impurity ions in fusion plasmas are useful for high-resolution
measurements and particularly advantageous for fusion plasma diagnostics as mirrors and opticalfibers are available to avoid direct neutron irradiation to detectors. Such magnetic-dipole (M1)transitions in the 2pk configurations of highly charged iron and titanium ions have practically beenused for measurements of ion temperatures, plasma rotations, and radial ion density distributions intokamak plasmas [1,2]. The M1 transitions in the 4fk configurations of highly charged tungsten ionsfall into the optical range, which will be potentially useful for plasma diagnostics of ITER
(International Thermonuclear Experimental Reactor).
Optical emission lines of W25+ have been measured using a compact electron beam ion trap
(CoBIT) [3-5]. In the present work, we assigned the observed lines in 280 – 360 nm and 440 – 600
nm to the emission lines of the M1 transitions in the 4f3 ground state configuration based on spectra
calculated using a collisional-radiative model for W25+ in CoBIT. Our assignments are consistent
with the previous works [4,6]. Two lines at 334.16 nm and 334.58 nm measured with CoBIT wereidentified as the lines observed using Large Helical Device (LHD) [7]. The wavelengths calculatedusing HULLAC [8] agree with those calculated using GRASP2K [9], but they differ by about 3 %from the measurements.

References[1] S. Suckewer and E. Hinnov, Phys. Rev. Lett. 41, 756 (1978)[2] S. Suckewer et al., Phys. Rev. Lett. 43, 207 (1979)[3] A. Komatsu, J. Sakoda, M. Minoshima et al., Plasma Fusion Res. 7, 1201158 (2012)[4] S. Murata, M.S. Safronova, U.I. Safronova, N. Nakamura, X-Ray Spectrometry 49, 200 (2020)[5] S. Era, D. Kato, H.A. Sakaue et al., Atoms 9, 63 (2021)[6] W. Li et al., J. Phys. B: At. Mol. Opt. Phys. 49, 105002 (2016)[7] D. Kato, H.A. Sakaue, I. Murakami et al., Nucl. Fusion 61, 116008 (2021)[8] A. Bar-Shalom, M. Klapisch, J. Oreg, JQSRT 71, 169 (2001)[9] A. Alkauskas, P. Rynkun, G. Gaigalas et al., JQSRT 136, 108 (2014)

156

B21
Lifetime measurement of the microsecond-order electric-quadrupole transition:
Application of plasma-assisted laser spectroscopy
Naoki Kimura1, Priti2, Susumu Kuma1, Toshiyuki Azuma1, Nobuyuki Nakamura3
1

Atomic, Molecular and Optical Physics Laboratory, RIKEN, Saitama 351-0198, Japan
2
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
3
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan

Lifetime measurements of forbidden transitions in highly charged ions (HCIs) have provided
remarkable examples for evaluating atomic physics theories [1-3]. Previous measurements
employed isolated HCIs in a magnetic ion storage device and observed de-excitation processes frommetastable states prepared in a plasma ion source. This is a useful method for lifetimes on the orderof milliseconds, and has been widely applied for various transitions. However, the conventional
method cannot eliminate re-population effects due to cascade processes from upper energy levels.
This intrinsic problem has prevented the broad extension of the technique to microsecond (µs)-order
lifetime measurements.
Recently, we demonstrated plasma-assisted laser spectroscopy of HCIs trapped in an electron beam
ion trap (EBIT) [4]. In this demonstration, we succeeded in laser excitation between the metastablefine-structure levels of Pd-like HCIs with the aid of plasma excitation processes in the EBIT. Thislaser spectroscopy has the potential to be applied to state-selective lifetime measurements which
avoid the abovementioned problem. In this presentation, we discuss this application and its
prospects by demonstrating the lifetime measurement of the µs-order electric-quadrupole (E2)transition (4d3/2-1 5s1/2)J=2 - 4d10 in Pd-like I7+.

Figure 1: (Left) Concept for the lifetime measurement. (Right) Experimental decay profile.
References[1] J. Doerfert, E. Träbert, A. Wolf, D. Schwalm, O. Uwira, Phys. Rev. Lett. 78, 4355 (1997).
[2] A. Lapierre, et al., Phys. Rev. Lett. 95, 183001 (2005).
[3] E. Träbert, P. Beiersdorfer, G. V. Brown, Phys. Rev. Lett. 98, 263001 (2007).
[4] N. Kimura, et al., submitted.

157

B22
Charge exchange spectroscopy of multiply charged erbium ions
Yuki Nishimura1 , Saki Imaizumi1 , Hajime Tanuma1 , Nobuyuki Nakamura2 , Yuichiro Sekiguchi3 ,Shinya Wanajo4 , H.A. Sakaue5 , Daiji Kato5 , Izumi Murakami5 , Masaomi Tanaka6 , andGediminas Gaigalas7
Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397, Japan
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan3
Department of Physics, Toho University, Chiba 274-8510, Japan
4
Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut), 14476 Potsdam, Germany5
National Institute for Fusion Science, Gifu 509-5292, Japan
6
Astronomical Institute, Tohoku University, Sendai 980-8578. Japan
7
Institute of Theoretical Physics and Astronomy, Vilnius University, 10257 Vilnius, Lithuania
1

2The “r-process” during the binary neutron star merger is regarded as the most promising candidate as
the mechanism of the synthesis of heavier elements than iron in the universe [1]. For the first time, thebinary neutron star merger was detected by gravitational-wave detectors Ligo and Virgo on August
17th, 2017, and the corresponding object called a kilonova was observed by optical telescopes [2].
To understand the observed spectrum from the kilonova via a radiative transport simulation, spectroscopic data of heavy elements are necessary. In the previous work, we predicted that triply and lower
charged ions of heavy elements contributed to the photoemission from a kilonova. In particular, lanthanoid elements regard significantly contribute to visible and infrared emissions. However, available
spectroscopic data for heavy element atoms are still limited.
In this work, we have performed spectroscopic experiments for the Er ions, one of the lanthanoid
elements. The multiply charged Er ions were produced by a 14.25 GHz electron cyclotron resonanceion source with the introduction of an Er rod into the oxygen plasma at Tokyo Metropolitan University.
The ion beam was extracted from the plasma by an electric potential difference of 15 kV, and directed
into the collision cell after the charge state separation with a magnetic dipole. The cell was filled witha thin target gas with a pressure that satisfied the single collision conditions. A liquid-nitrogen-cooled
CCD camera installed with a Czerny-Turner type spectrometer detected the photon emission spectrafrom the collision cell.
In this experiment, we used Er4+ and Er5+ for the projectile ions and Ar and N2 for the target gases.
Observed emission spectra show strong target dependence. Since the two targets have the almost samevalue as the ionization potentials, photon emissions from projectiles should be similar according to
the simple understanding of charge exchange reaction between highly charged ions and neural target
gases. Therefore we can easily distinguish the emission lines of Er ions from those of targets. We
also identify not only the emission lines due to the single electron capture but also those due to double
electron capture by comparing the spectra with different projectiles. In this conference, we report
several new lines of multiply charged Er ions, especially those of Er3+ , and we show the candidatesof the transitions by comparison between the experiments and the theoretical calculation [3].
References[1] J.J. Cowan et al., Rev. Mod. Phys. 93, 015002 (2021).
[2] M. Tanaka et al., Publ. Astron. Soc. Japan 69, 102 (2017).
[3] A. Meftah, et al., J. Phys. B 49, 165002 (2016).

158

B23
Detailed analysis of spectra from Ga-like ions of heavy elements observed inhigh temperature plasmas
Chihiro Suzuki, Fumihiro Koike*, Izumi Murakami, Daiji Kato, Naoki Tamura,
Tetsutarou Oishi, Nobuyuki Nakamura**
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan(*) Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan(**) The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu 182-8585, Japan
Extreme ultraviolet (EUV) and soft X-ray emission spectra from highly charged heavy ions are ofgreat interest in a variety of research fields such as nuclear fusion, industrial light source applications
as well as basic atomic physics. Among a wide range of ion stages, spectra of Ga-like ions haverelatively simple structure composed of a few strong isolated lines because of simple ground configuration [Ni]4s2 4p which has only one outermost electron outside the closed 4s subshell. However,experimental and theoretical investigations of spectral lines of Ga-like heavy ions are still incomplete
and their atomic number (Z) dependences have not been fully analyzed yet.
In this study we focus on the experimental and theoretical studies on Z dependence of spectra fromGa-like ions of heavy elements. Experimental spectra were mainly recorded in high temperatureplasmas produced in the Large Helical Device (LHD) at the National Institute for Fusion Science.
In LHD, we have systematically observed EUV and soft X-ray spectra of a variety of elements withatomic numbers from 57 onward under electron temperatures of a few keV [1–3]. As a result, wehave successfully obtained Z dependent wavelengths of several prominent transitions of Ga-like ions,some of which have been experimentally identified for the first time in this study.
The measured wavelengths are compared with theoretical values calculated with a multi-configuration
Dirac Fock code GRASP92. Consequently, we have found that the energy level crossing of [Ni]4s2 4d
and [Ni]4s4p2 configurations takes place between Z=62 and 63 due to configuration interaction [4]. In
addition, we have successfully identified a series of lines due to magnetic dipole transitions between
two sublevels of the ground configuration, [Ni]4s2 4p1/2 and [Ni]4s2 4p3/2 , which is discussed in termsof Z dependent spin-orbit splitting.
References[1] C. Suzuki, F. Koike, I. Murakami, N. Tamura, S. Sudo, Atoms 6, 24 (2018)[2] C. Suzuki, F. Koike, I. Murakami, N. Tamura, S. Sudo, G. O’Sullivan, Atoms 7, 66 (2019)[3] C. Suzuki, F. Koike, I. Murakami, T. Oishi, N. Tamura, Atoms 9, 46 (2021)[4] F. Koike, C. Suzuki, I. Murakami, D. Kato, N. Tamura, N. Nakamura, Phys. Rev. A 105, 032802(2022)159

B24
A collisional-radiative model for water window EUV spectra of bismuth ionsDingbao Song1, Daiji Kato2,1, Hayato Ohashi3, Hiroyuki A. Sakaue2, Nobuyuki Nakamura4,2
1. Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka
816-8580, Japan
2. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
3. Institute of Liberal Arts and Sciences, University of Toyama, Toyama, Toyama 930-8555, Japan
4. Institute for Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-8585,
Japan
Development of water window (2.2 - 4.4 nm) lightsources has been motivated by its application to
imaging of microscopic biological structures, such as
cells and macromolecules, in vivo [1]. Recently,
water window EUV emission spectra of highly
charged bismuth ions were measured [2] using acompact electron beam ion trap (CoBIT) [3,4] atelectron beam energies from 385 to 1140 eV.
Emission lines due to 4f – 5g,6g transitions areobserved in the spectra. We constructed acollisional-radiative (CR) model to simulate thespectra. In the present CR model, collisional
excitation, de-excitation, and ionization by monoenergetic electron beams, and radiative decays via
electric-dipole, quadruple, and octupole andmagnetic-dipole and quadruple transitions are
considered. Energy levels, collisional cross sections,and radiative decay rates of highly charged bismuthions are calculated based on fully relativistic
wavefunctions using HULLAC [5]. The present
calculations agree with the experimental spectra [2].
As shown in Fig. 1, europium-like and samariumlike ions (Bi20+ and Bi21+, respectively) emit a few
strong 4f – 5g,6g lines due to 4f inner-shell Figure 1 : CR model spectra of Bi20+ excitation from the ground states of 4f145s25p and Bi25+ in CoBIT at electron density of 1010
4f145s2, respectively. However, the emission lines of cm-3 and electron beam energies of 560,
promethium-like and neodymium-like ions (Bi22+ 600, 640, 680, 720, and 760 eV,
and Bi23+, respectively) consist of many weaker lines respectively.
because they are due to the 4f inner-shell excitationfrom the long-lived metastable excited states of 4f135s2 [6,7] and 4f135s, respectively.
References[1] J.C. Solem and G.C. Baldwin, Science 218, 229 (1982)[2] H. Ohashi et al., presented in HCI2022[3] N. Nakamura et al., Rev. Sci. Instrum. 79, 063104 (2008)[4] H.A. Sakaue et al., J. Instrum. 5, C08010 (2010)[5] A. Bar-Shalom, M. Klapisch, J.J Oreg, Quant. Spectrosc. Radiat. Transf. 71, 169 (2001)[6] Y. Kobayashi et al., Phys. Rev. A 89, 010501(R) (2014).
[7] D. Kato et al., Nucl. Instrum. Meth. B 408, 16 (2017).

160

B25
Soft x-ray emission spectroscopy of bismuth ions with an electron beam ion trap
Hayato Ohashi1,2, Ryota Iwami2, Dingbao Song3, Daiji Kato3,4, Hiroyuki A. Sakaue4,
Izumi Murakami4,5, Nobuyuki Nakamura5
1

Institute of Liberal Arts and Sciences, University of Toyama, Toyama, Toyama 930-8555, Japan
2
Graduate School of Science and Engineering for Research, University of Toyama, Toyama,
Toyama 930-8555, Japan
3
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka
816-8580, Japan
4
National Institute for Fusion Science, Oroshi-cho, Toki, Gifu 509-5292, Japan
5
Department of Fusion Science, The Graduate University for Advanced Studies (SOKENDAI),
Toki, Gifu 509-5292, Japan
6
Institute for Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-8585,
Japan
Development of plasma light sources for shorter wavelength has reached to soft x-ray region where
the water window (2.3 – 4.4 nm) applied for biological microscopy of cells in vivo. The unresolved
transition arrays (UTAs) of multiply charged bismuth (Bi) ions in laser-produced plasma (LPP)
show its potential as a light source for the laboratory-scale single-shot live cell imaging [1]. Fromthe investigation of characteristics of bismuth ions using an electron beam ion trap (EBIT), n = 4 –n = 4 UTAs contribute to the intense emission of Bi-LPP spectra in the 4 nm region [2].
In this study, we measured soft x-ray emission spectra of multiply charged bismuth ions expecting n= 4 – n = 5 UTAs dominated in the 2–3 nm region with an EBIT.
Bismuth ions were produced in a Compact EBIT [3] with Bi injection using an effusion cell. In the
EBIT, a quasi-monoenergetic electron beam with electron energies of 385–1140 eV interacted withtrapped ions. Emissions from the trapped ions in the soft x-ray region were observed with a flatfield grazing incident spectrometer equipped with a Peltier-cooled charge-coupled device [4].
Experimental spectra are compared with theoretical calculations using the flexible atomic code [5].
Observed dominant water window emissions correspond not only n = 4 – n = 5 transitions but alson = 4 – n = 6 transitions in the 2–3 nm region. Unexpected behaviour of the 4f-5g transition also
observed due to the contribution of long-lived metastable excited states [6, 7]. Theoretical analysis
in detail has discussed in [8] using collisional-radiative model constructed to simulate experimental
spectra.
References[1] T. Wu et al., J. Phys. B: At. Mol. Opt. Phys. 79, 035001 (2016).
[2] H. Ohashi et al., J. Phys.: Conf. Ser. 488, 062017 (2014).
[3] N. Nakamura et al., Rev. Sci. Instrum. 79, 063104 (2008).
[4] H.A. Sakaue et al., J. Instrum. 5, C08010 (2010).
[5] M. F. Gu, AIP Conf. Proc. 730, 127 (2004).
[6] Y. Kobayashi et al., Phys. Rev. A 89, 010501(R) (2014).
[7] D. Kato et al., Nucl. Instrum. Meth. B 408, 16 (2017).
[8] D. Song et al., presented in HCI2022.

161

B26
Atomic Number Dependence of Electric Octupole Decay
in Electron Beam Ion Trap
Hiroyuki. A. Sakaue1, Daiji Kato1,2, Izumi Murakami1,3, Hayato Ohashi4and Nobuyuki Nakamura5
1

National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka
816-8580, Japan3
Department of Fusion Science, The Graduate University for Advanced Studies (SOKENDAI),
Toki, Gifu 509-5292, Japan
4
Institute of Liberal Arts and Sciences, University of Toyama, Toyama, Toyama 930-8555, Japan
5
Institute for Laser Science, The University of Electro-Communications, Chofu, Tokyo 182-8585,
Japan
2

Forbidden transitions of highly charged ions in emission spectra are useful for diagnostics offusion, astrophysical, and laser-produced plasmas since their intensities are sensitive to electron
density and electron energy.
We have performed spectroscopic studies on the emission spectra of highly charged tungsten
ions. Figure 1 shows a typical extreme ultraviolet (EUV) spectrum of highly charged tungsten ionswith an electron beam energy of 870 eV with a compact Electron Beam Ion Trap (CoBIT). The
highest charge state of tungsten ions in CoBIT was 27+ and several emission lines were observed.
Characteristic two lines observed around 90 Å were identified as following transitions:! !"# 4$$% 5& → 4$$% 4(!,$ .
""We reported that these transitions were strongly forbidden electric octupole (E3) transitions in
HCI 2018. Observed emission intensity of E3 transitions is roughly the same as that of 5d-5p (E1)transitions observed around 125 Å even though calculated transition probability (Einstein’s
A-coefficients) of E3 transitions is 1010 times smaller than that of the E1 transition. We concluded
that the observations of the E3 forbidden emission lines were the result of an anomaly in the
branching ratio to 5p from the 5d levels which caused an increase in 5s populations [1]. Thisconclusion suggests that there exist Z-dependent intensities in the E3 transitions along theisoelectronic sequence of highly charged Ag-like ions.
Here, in order to prove the Z-dependence of the E3 transition intensities, we have measured
spectra of highly charged Ag-like ions for Yb, Re, Os, Ir, and Au. For Yb, Re, Os and Ir, sublimatedgases of each carbonyl compound were injected into the trap of CoBIT from the gas injector. For
Au, gold vapor produced in a Knudsen cell was injected into CoBIT.
We have successfully observed E3 forbidden emission lines in Re, Os and Ir as predicted bytheoretical calculations.

Figure 1: Observed EUV spectrum with E3 transitions of W27+ ions.
References[1] H.A.Sakaue, D.Kato, I.Murakami, H.Ohashi, N.Nakamura, Phys. Rev. 100, 052515 (2019)

162

B27
Extreme ultraviolet spectra of Wq+ ions with q=22-24
Izumi Murakami1,2, Tetsutarou Oishi1,2, Daiji Kato1,3, Hiroyuki A. Sakaue1, Motoshi Goto1,2,
Yasuko Kawamoto1, Tomoko Kawate1,2, Akira Sasaki4
1. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
2. Department of Fusion Science, The Graduate University for Advanced Studies, SOKENDAI,
322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
3. Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka
816-8580, Japan
4. Kansai Photon Science Institute, National Institutes for Quantum Science and Technology,
Kizugawa, Kyoto 619-0215, Japan
Tungsten spectra have been studied to examine tungsten impurity behavior and the effect ofradiation power loss in fusion plasmas since tungsten is used as plasma-facing material in fusion
devices and is sputtered by plasma particles. However, some charge states of tungsten ions are notwell studied yet due to the complexity of electron structures of the tungsten ions. Extreme
ultraviolet spectra of tungsten ions have been measured in various fusion devices and electron beam
ion traps (e.g. [1,2]) and examined by comparison of calculated spectra using collisional-radiative(CR) models (e.g., [3,4]). The so-called unresolved transition array (UTA) is observed at 4.5-7nm
wavelength region for plasma with electron temperature ~ 1keV, which is produced by numerous
overlapped 4d-4f and 4p-4d transitions of tungsten ions. The wide two-peak feature of the UTA
profile is not fully understood yet [4], even though recombination processes are included in the CR
model [5] for Wq+ with q=25-39.
Recently we have extended our CR model for Wq+ with q=22-24. Radiative, dielectronic andthree-body recombination processes were included in the model as well as electron-impact
excitation and ionization processes and radiative decays. All atomic data necessary for the CR
model were calculated with HULLAC atomic code [6]. Electron configurations, 4p64d104fm,
4p64d94fm+1, 4p54d104fm+1, 4p64d104fm-1nl (n=5-9, l=0-4), and 4p64d104fm-25lnl’(n=5-9, l,l’=0-4) with
m = 6-4 were considered as relativistic configuration-averaged levels. Fine structure levels of someof these configurations, which are important to calculate spectrum, are used in the CR model. The
calculated spectra of W22+ - W24+ ions with this CR model show wide profiles at 4.5-7nm due tocascade processes from higher levels. We expect that these ions can contribute to the measured
UTA profile. This result is similar to the spectrum of W23+ calculated in [7] without recombination
processes.
We also calculated spectra of n=5-5 transitions at 10-30 nm and found wide profiles. We willcompare with measured spectra of this wavelength region in plasmas of Large Helical Device toexamine the validity of the CR model. Details will be presented at the conference.

References[1] R. Neu et al., Plasma Phys. Control. Fusion 38, A165 (1996)[2] H. A. Sakaue et al., AIP Conf. Proc. 1438, 91 (2012)[3] T. Putterich, R. Neu, R. Dux et al., Plasma Phys. Control. Fusion 50, 085016. (2008)[4] I. Murakami, H. A. Sakaue, C. Suzuki et al., Nucl. Fusion 55, 093016 (2015)[5] I. Murakami, D. Kato, T. Oishi et al., Nucl. Mater. Energy 26, 100923 (2021)[6] A. Bar-Shalom, M. Klapisch, J. Oreg,, J. Quant. Spectrosc. Radiat. Transfer 71, 169 (2001)[7] T. Putterich, V. Jonauskas, R. Neu et al., AIP Conf. Proc. 1545, 132 (2013)

163

B28
Hyperfine splitting of the clock candidate transition in 93Nb10+
Naoki Kimura1, Genichi Kiyama2, Priti3,
Michiharu Wada4, Toshiyuki Azuma1, Nobuyuki Nakamura2
2

1
Atomic, Molecular and Optical Physics Laboratory, RIKEN, Saitama 351-0198, Japan
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan
3
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
4
Wako Nuclear Science Center, Inst. of Particle and Nuclear Studies, High Energy Accelerator
Research Organization (KEK), Saitama 351-0198, Japan

In the last decade, the research on optical transitions of highly charged ions (HCIs) has shown
remarkable progress. Theoretical studies have revealed the advantages of high-precision
spectroscopy of heavy HCIs with many electrons, i.e., HCI clocks, for exploring fundamental
physics beyond the Standard Model. To date, a number of transitions have been proposed as
candidates and experimentally investigated [1]. Micke et al., have demonstrated quantum logic
spectroscopy of HCIs [2], promising realization of HCI clocks. However, there have been no
experimental studies for hyperfine-structures in these candidates, though they are unavoidably
demanded to develop HCI clocks.
In this poster, we present a first experimental observation for hyperfine splitting in HCI clock
candidates. The magnetic-dipole transition 2P1/2 - 2P3/2 in 93Nb10+ [3] was measured by a highresolution visible spectrometer coupled to a compact electron beam ion trap (CoBIT) [4]. The lowmagnetic field condition in CoBIT enables us to perform the hyperfine spectroscopy suppressing
Zeeman and Paschen-Back effects [5]. The observed spectra show a remarkable feature consistent
with the theoretical prediction considering the hyperfine splitting.

References[1] M. G. Kozlov, et al., Rev. Mod. Phys. 90, 045005 (2018).
[2] P. Micke, et al., Nature(London) 578, 60 (2020).
[3] Yan-mei Yu and B. K. Sahoo, Phys. Rev. A 99, 022513 (2019).
[4] N. Nakamura, et al., Rev. Sci. Instrum. 79, 063104 (2008).
[5] N. Kimura, et al., submitted.

164

B29
Detailed analysis of atomic processes relevant to the line intensity ratio of
FeXV(233.9Å/243.8Å) in a compact electron beam ion trap
Norimasa Yamamoto, Hiroyuki A. Sakaue*, Daiji Kato*,**, and Nobuyuki Nakamura***Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan(*) National Institute for Fusion Science, 322-6 Orochi-cho, Toki, Gifu 509-5292, Japan(**) Interdisciplinary Graduate School of Engineering Sciences, Kyushu University,
Fukuoka 816-8580, Japan(***) The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu,
Tokyo 182-8585, Japan

Plasma diagnostics using EUV spectra is performed for solar plasma and fusion plasma etc.
Plasma parameters can be obtained by analyzing the line spectra of ions in the plasmas using acollisional-radiative (CR) model. The CR model is obtained as a quasi-stationary state
approximation to rate equations of transitions between quantum states of the ion. There are two
important points to improve the accuracy of the CR model. One is to use correct probabilities of theatomic process by consulting existing data. The other is the validation of the model by comparing itwith experimental spectra.
An electron-beam-ion-trap (EBIT) plasma consists of trapped ions with a narrow charge state
distribution and a quasi-monoenergetic electron beam, thus the emission spectra from an EBIT
provide ideal benchmarks for the CR model validation. In particular, a compact EBIT (CoBIT)
operating with a low-energy electron beam is useful for measuring the EUV spectra related to thesolar corona.
In this report, we present a theoretical analysis of the experimental line intensity ratios of FeXV
233.9 Å to 243.8 Å using the CR model. In the previous measurements with CoBIT [1-3], it has
been reported that the experimental intensity ratios are significantly larger than theoreticalpredictions at electron densities of 1010 cm-3 or higher.
We constructed a CR model based on atomic data calculated by HULLAC code [4]. Atomic
processes considered in the model are excitation/deexcitation by electron collision, ionization byelectron collision, radiative transition, and autoionization. To have a better understanding of atomic
processes relevant to the line ratio, inflow and outflow of populations of the upper levels of 233.9 Å
and 243.8 Å lines are examined in detail. Then, it is shown that direct inner-shell ionization from Fe
XIV, which has been omitted in the previous studies, can enhance the line intensity ratio. Since
calculations of the line intensity ratio will be affected by differences in atomic data of the model,
the atomic data calculated by HULLAC (e.g. excitation collision strength by electron collision, etc.)
are compared with other available data and investigated impact of the differences in atomic data to
the intensity ratio.

References[1] N. Nakamura et al., Astrophysical Journal 739, 17 (2011)[2] E. Shimizu et al., Journal of Physics: Conference Series 583, 012019 (2015)[3] T. Tsuda et al., Astrophysical Journal 851, 82 (2017)[4] A. Bar-Shalom, M. Klapisch, J. Oreg, Journal of Quantitative Spectroscopy and Radiative
Transfer 71, 169 (2001)

165

B30
5p-5s spectrum in highly charged WXII - WXIV Ions
Priti1⇤ , Momoe Mita2 , Daiji Kato1,3 , Izumi Murakami1,4 ,Hiroyuki A. Sakaue1 , Nobuyuki
Nakamura2
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan
3
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka
816-8580, Japan
4
Department of Fusion Science, Sokendai, Toki, Gifu 509-5292, Japan*priti.priti@nifs.ac.jp
12Spectral lines from highly charged tungsten ions, specially, from WIV-WXVI have been predicted
to be useful in diagnostic of the ITER divertor plasma [1]. Tungsten ions having charge state WXII- WXVI are anticipated to show the transitions lines from the 5p to the 5s subshell in EUV region.
These ions are highly correlated system with an open 4f subshell for which accurate calculations
are challenging. Due to the complexity of observed spectra there was an ambiguity in charge state
identification in previous study [2]. Also, there is no data available for W XII in extreme ultraviolet(EUV) range [3-4]. We present detailed theoretical analysis of 5p-5s transition of W XII–W XIV
ions for the spectroscopic measurements performed at compact electron beam ion trap (CoBIT) [5-6].
The analysis of the observed spectra is based on the detailed collisional-radiative modeling with finestructure sub-levels atomic kinetics. The wavelength and rate of the transitions of W XII–W XIV
ions calculated by the relativistic configuration interaction using flexible atomic code. Theoreticalresults are in reasonable agreement with the experimental observations (⇠18-28nm), which provides
the clear assignment of the ionization stage and corresponding lines.
References[1] J. Clementson et al., J. Phys. B: At. Mol. Opt. Phys. 43, 063104 (2010)[2] W. Li, Z. Shi, Y. Yang, J. Xiao, T. Brage, R. Hutton, and Y. Zou, Phys. Rev. A 91, 062501 (2015).
[3] Kramida A, et al, NIST Atomic Spectra Database, version 5.7.1 (2020).
[4] Priti, M Mita, D Kato, et. al. Phys. Rev. A, 102, 04281 (2020)[5] Nakamura N, et al 2008 Rev. Sci. Instrum. 79 144009[6] Mita M, et al, J. Phys.: Conf. Ser. 675 012019 (2017)

166

B31
High-resolution spectroscopy of electronic K x rays from muonic atoms
T. Okumura1,2, T. Azuma2,1, D. A. Bennett3, W. B. Doriese3, M. S. Durkin3, J. W. Fowler3,
J. D. Gard3, T. Hashimoto4, R. Hayakawa1,5, G. C. Hilton3, Y. Ichinohe5, P. Indelicato6, T. Isobe2,
S. Kanda7, D. Kato8, M. Katsuragawa9, N. Kawamura7, Y. Kino10, N. Kominato5, Y. Miyake9,
K. M. Morgan3, H. Noda11, G. C. O’Neil3, S. Okada12, K. Okutsu10, H. Oomamiuda5, T. Osawa5,N. Paul6, C. D. Reinstema3, T. Sato5, D. R. Schmidt3, K. Shimomura7, P. Strasser7, H. Suda1,
D. S. Swetz3, T. Takahashi9, S. Takeda9, S. Takeshita7, M. Tampo7, H. Tatsuno1, X. M. Tong13,
Y. Toyama12, Y. Ueno2, J. N. Ullom3, S. Watanabe14, S. Yamada5, and T. Yamashita10
1

Tokyo Metropolitan University, Tokyo 1920397, Japan,
2
RIKEN, Wako 3510198, Japan,
3
National Institute of Standards and Technology, Boulder, CO 80305, USA,
4
Japan Atomic Energy Agency, Tokai 3191184, Japan,
5
Rikkyo University, Tokyo 1718501, Japan,
6
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University,
Collége de France, Case 74, 4, place Jussieu, 75005 Paris, France,
7
High Energy Accelerator Research Organization (KEK), Tsukuba 3050801, Japan,
8
National Institute for Fusion Science (NIFS), Toki, Gifu 5095292, Japan,
9
Kavli IPMU (WPI), The University of Tokyo, Kashiwa, Chiba 2778583, Japan,
10
Tohoku University, Sendai, Miyagi 9808578, Japan,
11
Osaka University, Osaka 5600043, Japan,
12
Chubu University, Kasugai, Aichi 4878501, Japan,
13
University of Tsukuba, Tsukuba, Ibaraki 3058573, Japan,
14
Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 2525210, JapanA muonic atom consists of a negatively-charged muon and a nucleus, sometimes accompanied bybound electrons. When a negative muon encounters an atom, the muon is captured in a highly
excited state of the atom and then deexcites to lower energy levels step-by-step with the emission ofAuger electrons and muonic x rays. Electron holes formed during this cascade process are
immediately filled by the upper-level electrons, e.g., via characteristic x-ray emission.
We carried out high-resolution measurements of electronic K x rays from muonic atoms at JPARC using a state-of-the-art x-ray detector, Transition-Edge Sensor (TES) microcalorimeters.
For muonic Fe ( Fe) in a Fe metal [1], we observed an asymmetric and broad peak of electronic
K x rays, as shown in Figure 1. This feature reflects the dynamics of the cascade process because
the energies of the K x rays are sensitive to the nuclear-charge screening by the muon and electron
holes at the moment of the x-ray emission. In dense targets like metals, electron refilling from thesurrounding follows, which is similar to de-excitation
dynamics of highly-charged ions in metals [2].
On the other hand, for muonic Ar ( Ar) in a gas
phase [3], we found distinctively-resolved several
peaks corresponding to highly-charged muonic atoms
with a few bound electrons, where electron refilling isabsent.
References[1] T. Okumura et al., Phys. Rev. Lett. 127, 053001 (2021).
[2] A. Arnau et al., Surf. Sci. Rep. 27, 113 (1997).
[3] T. Okumura et al., in preparation.

167

Figure 1: electronic K x-ray spectrum.

B32
Up to which element the KD1 spectrum shows asymmetry in the experiment?
Y. Ito1, T. Tochio2, M. Yamashita3, S. Fukushima4, A. M. Vlaicu5, J. P. Marques6,
J. M. Sampaio6, M. Guerra7, J. P. Santos7, Ł. Syrocki8, K. Słabkowska8, E. W der8, M. Polasik8,
J. Rzadkiewicz9, P. Indelicato10, Y. Menesguen11, M.-Ch. Lepy11, and F. Parente7
1
RIGAKU Corporation, 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146 Japan
Department of Physics, Faculty of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501, Japan
3
HIT, 3-1-12 Yukihira, Suma-ku, Kobe 654-0037, Japan
4
Kobe Material Testing Laboratory Co., Ltd., 47-13 Nijima,
Harima-cho, Kako-gun, Hyogo 675-0155, JAPAN
5
National Institute of Materials Physics, Bucharest-Magurele,
Atomistilor Strasse 405A, P. O. Box MG-7, 077125 Magurele-IIfov, Romania
6
LIP - Laboratório de Instrumentação e Física Experimental de Partículas,
Av. Prof. Gama Pinto 2, 1649-003 Lisboa, Portugal,
Faculdade de Ciências da Universidade de Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal
7
Laboratorio de Instrumentação, Engenharia Biomédica e Física da Radiação (LIBPhys-UNL),
Departamento de Física, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa,
Monte da Caparica, 2892-516 Caparica, Portugal
8
Faculty of Chemistry, Nicolaus Copernicus University in Toru , Gagarina 7, 87-100 Toru , Poland
9
National Centre for Nuclear Research, 05-400 Otwock, Poland
10
Laboratoire Kastler Brossel, Sorbonne Université,
CNRS, ENS-PSL Research University, Collège de France,
4, place Jussieu, F-75005 Paris, France
2

11

Université Paris-Saclay, CEA, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), F-91120
Palaiseau, France

The KDEx-ray emission spectra of the 3d transition metals exhibit several peculiar asymmetricline profiles not observed in other elements, whose origin has been under investigation and debate.
Several mechanisms such as shake processes, conduction-band collective excitation, exchange, andfinal-state interactions were suggested to account for this effect. However, Deutsch et al.[1], Holzer
et al.[2], Anagnostopoulos et al.[3], Chantler et al.[4], and Ito et al.[5] suggested that the line
shapes in KD1,2 x-ray spectra could be accounted for by the diagram, and 3s, 3p, and 3d spectatorhole transitions. Ito et al. measured systematically the KD1,2 spectra in the elements from Ca to Ge,
using an antiparallel two-crystal x-ray spectrometer, and elucidated the origin of the asymmetry in
the KD1 emission profile, confirming that the broadening of the linewidths of KD2 spectra is due to
L2-L3M4,5 Coster-Kronig transitions. Combined ab initio Dirac-Fock calculations and highresolution x-ray emission measurements of KD1,2 spectra for elements Ca, Ti, and Ge show that theasymmetric line shapes of these emission lines can be fully explained by considering only the
diagram and the 3d spectator transitions [5 and references therein]. Moreover, Se, Y, and Zr KD1,2
spectra were measured using the same type of x-ray spectrometer in order to investigate theelements where the asymmetry of the KD1 spectrum appeared.
Our results show that the asymmetry is observed in the Se KD1,2 spectra, but no asymmetry isobserved in the Y and Zr KD1,2 spectra[6]. We discuss this result in the light of a discussion bymulti-electron transition processes.
Reference[1] Deutsch et al., Phys.Rev.A51,283(1995);[2] Holzer et al., Phys.Rev.A56,4554(1997);[3]Anagnostopoulos et al., Phys.Rev.A60,2018(1999); [4] Chantler et al., Phys.Rev A73,
012508(2006); [5] Y.Ito et al., Phys.Rev.A94,042506(2016); Phys.Rev.A97, 052505(2018); [6] Y.
Ito et al.,Phys.Rev.A102, 052820 (2020).

168

B33
Testing quantum-electrodynamics with accurate measurements of Na-like andMg-like transitions in highly charged Os and Ir
A. Hosiera,b , Diptib , R. Silwalc , A. Lapierred , S. A. Blundelle , S. Sandersa , Y. Yanga,b , P. Szyprytf ,G. O’Neilf , J. N. Tanb , A. Naingb , J. D. Gillaspyb,g , J. M. Dreilingb , G. Gwinnerh , A. C. C. Villarid ,Yu. Ralchenkob , E. Takacsa,bDepartment of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978bNational Institute of Standards and Technology, Gaithersburg, MD 20899
c
Department of Physics and Astronomy, Appalachian State University, Boone, NC 28608dFacility for Rare Isotope Beams, 640 S Shaw Ln, East Lansing, MI 48824
eUniversity of Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, FrancefNational Institute of Standards and Technology, Boulder, CO 80305g
National Science Foundation, Alexandria, VA 22314
hUniversity of Manitoba, Winnipeg, MB R3T 2N2, CanadaaSome of the best tests of many-body quantum electrodynamics (QED) involve highly-charged ionshaving one- and two-valence electrons outside of a closed shell. For these systems, accurate theoretical calculations have been developed and measurements can be performed even in heavy elements
along the isoelectronic sequence [1, 2].
Here we report on measurements and analyses of spectra from Na- and Mg-like ions of Os and Ir
that were created in the electron beam ion trap (EBIT) at the National Institute of Standards andTechnology (NIST). The dominant transitions observed in the extreme ultraviolet (EUV) and x-ray
ranges were Na-like 3s–3p1/2 , 3s 3p3/2 and the Mg-like 3s2 –3p1/2 , 3s2 3p3/2 respectively.
The instruments used to measure the spectra of emitted photons were a flat-field grazing-incidence
EUV spectrometer [2] and the NIST Transition-Edge Sensor (TES) x-ray microcalorimeter [3]. Calculations of wavelengths were performed with multi-configuration Dirac-Hartree-Fock (GRASP2K)[4] and relativistic many-body perturbation theory (RMBPT) [5] packages. Detailed comparisons andsensitivity to QED effects will be presented.
References[1] J. D. Gillaspy et al., Phys. Rev. A, 87, 062503 (2013)[2] J.Sapirstein and K.T. Cheng, Phys. Rev. A, 91, 062508 (2015)[3] B. Blagojevic et al., Rev. Sci. Instrum. 76, 083102 (2005)[4] P. Szypryt et al., Review of Scientific Instruments 90, 123107 (2019)[5] P. Jönsson et al., Comput. Phys. Commun. 184, 2197 (2013)[6] S. A. Blundell, Phys. Rev. 47, 1790 (1993)

169

B34
Absolute nuclear radius of iridium from precision measurements andcalculations of EUV and X-ray transitions in highly charged ionsA. Hosiera,b , Diptib , R. Silwalc , A. Lapierred , S. A. Blundelle , S. Sandersa , Y. Yanga,b , P. Szyprytf ,G. O’Neilf , J. N. Tanb , A. Naingb , J. D. Gillaspyb,g , J. M. Dreilingb , G. Gwinnerh , A. C. C. Villarid ,Yu. Ralchenkob , E. Takacsa,bDepartment of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978bNational Institute of Standards and Technology, Gaithersburg, MD 20899
c
Department of Physics and Astronomy, Appalachian State University, Boone, NC 28608dFacility for Rare Isotope Beams, 640 S Shaw Ln, East Lansing, MI 48824
eUniversity of Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, FrancefNational Institute of Standards and Technology, Boulder, CO 80305g
National Science Foundation, Alexandria, VA 22314
hUniversity of Manitoba, Winnipeg, MB R3T 2N2, Canadaa

The absolute nuclear radius of 193 Ir [1] has been determined by precisely measuring the relative
difference in charge radii between osmium and iridium isotopes by novel spectroscopic observationsof highly charged ions in the extreme ultraviolet (EUV) and x-ray regime. The electron beam ion trap
(EBIT) at the National Institute of Standards and Technology (NIST) was used at a beam energy ofabout 18 keV to produce highly charged ions of Os and Ir.
The light-emission spectra generated by electron impact excitation were observed using a flat-fieldgrazing-incidence spectrometer [2] over a range of 4 nm to 20 nm and recorded using an EUV CCD
detector with a pixel resolution of about 0.008 nm. Simultaneously, x-ray photons were collectedwith the NIST Transition-Edge Sensor (TES) microcalorimeter [3] over a broadband energy range ofroughly 500 eV to 8000 eV with an energy resolution of around 4 eV.
The dominant spectral lines of both Os and Ir observed in the EUV and x-ray range were Na-like
3s–3p1/2 , 3s 3p3/2 and Mg-like 3s2 –3p1/2 , 3s2 3p3/2 transitions respectively. The difference in the
wavelength between the corresponding Ir and Os transitions was measured over the course of several
days by cycling the injection of Os, Ir into the EBIT. Calibration of the instrument was regularly
performed during the run by injecting Ne and observing lines from trace elements of Xe and Ba.
The observed wavelength differences are directly related to the difference in the mean square radii
through the expansion of the nuclear Seltzer moment. Precision atomic structure calculations were
performed using GRASP2K [4] and RMBPT [5] packages. A comparison with prior nuclear physics
experimental methods will be reported.
References[1] I. Angeli and K. P. Marinova, At. Data Nucl. Data Tables 99, 69 (2013)[2] B. Blagojevic et al., Rev. Sci. Instrum. 76, 083102 (2005)[3] P. Szypryt et al, Review of Scientific Instruments 90, 123107 (2019)[4] P. Jönsson et al. Comput. Phys. Commun. 184, 2197 (2013)[5] S. A. Blundell, Phys. Rev. 47, 1790 (1993)

170

B35
Laboratory search for Fe IX solar diagnostic lines at an electron beam ion trap
Elmar Träbert1 , Peter Beiersdorfer2,3 , Gregory V. Brown2 , Natalie Hell2 ,Jaan Lepson3 , Michael Hahn4 , Daniel W. Savin4
2

1
Ruhr-Universität Bochum, AIRUB, 44780 Bochum, Germany
Lawrence Livermore National Laboratory, Physics Department, Livermore, CA 94551, USA
3
University of California, Space Sciences Laboratory, Berkeley, CA 94720, USA
4
Columbia University, Columbia Astrophysics Laboratory, New York, NY 10027, USA

The Fe IX spectrum features two lines in the EUV (at 241.739 Å and 244.909 Å, respectively) thathave the potential to be among the best density diagnostics in the solar spectrum. One line is an
E1 intercombination transition, the other an M 2 transition. However, the diagnostic interpretationof the line ratio of the two lines has been disputed intensely [1]. Density diagnostic line ratios are
sensitive to uncertainties in the atomic data because they depend on many factors, such as collisional
excitation and de-excitation, radiative transitions, and cascades. Observational analyses imply density
uncertainties of factors of 2 to 10 from the atomic data.
It should be interesting to observe the line pair in the laboratory. The low radiative M 2 transition rateof less than 100 s 1 [2] requires the very good vacuum of a cryogenic electron beam ion trap (EBIT)
to reduce the effects of collisional quenching by charge exchange. Figure 1 shows spectra from the
LoWEUS spectrograph at the Livermore SuperEBIT, obtained at two electron beam energies, bothof which are well above the optimum production of the Fe IX spectrum. The lower-energy spectrum
shows partly blended lines at the two Fe IX wavelengths. Higher-resolution measurements with the
HIGGS spectrograph are under way.
This work was supported by NASA H-TIDeS Grant No. 80NSSC20K0916 and was performed in part
under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory
under Contract DE-AC52-07NA27344.
3000
XElectron beam energy
300 eV200 eV

2500

Signal

2000
VIII
(2)

1500
X

IX

1000
IX

500

0
240 242 244 246 248 250 252 254 256 258 260 262 264

Wavelength (Å)

Figure 1: EUV spectra of Fe in the vicinity of the Fe IX lines of interest.
References[1] P.J. Storey, C.J. Zeippen, Mon. Not. R. astron. Soc. 324, L7 (2001).
[2] G. Del Zanna, P.J. Storey, N.R. Badnell, H.E. Mason, Astron. Astrophys. 565, A77 (2014).

171

B36
High-resolution Laboratory Measurements and Identificationof Fe IX Lines near 171Å
Peter Beiersdorfer1,2 , Jaan Lepson1 , Gregory V. Brown2 , Natalie Hell2 , Elmar Träbert3 ,Michael Hahn4 , Daniel W. Savin4
2

1
University of California, Space Sciences Laboratory, Berkeley, CA 94720, USA
Lawrence Livermore National Laboratory, Physics Department, Livermore, CA 94551, USA
3
Ruhr-Universität Bochum, AIRUB, 44780 Bochum, Germany
4
Columbia University, Columbia Astrophysics Laboratory, New York, NY 10027, USA

The Fe IX line at 171 Å dominates the spectra of many astrophysical and laboratory sources. A multitude of weaker Fe IX lines have been predicted in the vicinity of the 171 Å line (cf., the CHIANTI
spectral data base [1]), but they have not been identified in the laboratory. Recently, we have presented measurements performed at the EBIT-I electron beam ion trap facility [2], which we used fortentative identification of more than a dozen new lines of the Fe IX spectrum within a 10 Å interval
centered near the 171 Å line. Some of these lines had formerly been identified as arising from Fe
VII, Fe XIV, or Fe XVI. Here we present new measurements that confirm these recent identifications.
Our measurements carefully stepped through electron energies to clearly determine the charge stateof iron associated with each observed line. Moreover, we have tried to identify additional Fe featuresthat have previously remained unassigned, although they appeared to be either Fe VII or Fe X lines.
This work was supported by NASA H-TIDeS Grant No. 80NSSC20K0916 and was performed in part
under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory
under Contract DE-AC52-07NA27344.
References[1] K. P. Dere, G. Del Zanna, P. R. Young, E. Landi, and R. S. Sutherland, Astrophysical J. Suppl.
241, 2 (2019).
[2] P. Beiersdorfer and E. Träbert, Astrophysical J. 854, 114 (2018).

172

B37
Measurement of the electron-impact ionization cross section of He-like Fe24+
Y. Yang a, Dipti b,*, A. Foster c, A. C. Gall c, G. O'Neil d, P. Szypryt d, A. T. Hosier a, N.
Brickhousec, R. Smith c, J. N. Tan b, A. Naing b, Yu. Ralchenko b, D. Schultz e, E. Takacs a, b
a

Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978bNational Institute of Standards and Technology, Gaithersburg, MD 20899
c
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138
d
National Institute of Standards and Technology, Boulder, CO 80305
eNorthern Arizona University, Flagstaff, AZ*Present address: International Atomic Energy Agency, Vienna A-1400, Austria
Email: yy4@g.clemson.edu

Electron-impact ionization cross sections of He-like Fe24+ were measured at the electron beam
ion trap (EBIT) facility of the National Institute of Standards and Technology (NIST) [1]. X-ray
spectra were recorded at various electron beam energies between 9.2 keV and 18 keV by an array of
192 transition-edge sensor (TES) based x-ray microcalorimeters [2]. The ionization cross sectionsof He-like Fe24+ were determined based on the measured intensity ratio of the(1s 2S1/2 – 2p2
P3/2) to w (1s2 1S0 – 1s2p 1P1) and Lyα2 (1s 2S1/2 – 2p 2P1/2) to w (1s2 1S0 – 1s2p 1P1) lines byconsidering the relevant processes affecting relative emission and ionization balance of the nonMaxwellian plasma. These processes are polarization, cascade contributions, radiative
recombination, and charge exchange which were determined using the atomic kinetics simulations
performed with collisional-radiative code NOMAD [3]. Comparison of the measured cross sections
showed very good agreement with the relativistic convergent closed-coupling calculations [4] at allenergies, while the theoretical predictions based on the non-relativistic and perturbative calculations
widely used in the analysis of astrophysical spectra are higher than the measured values,
particularly at energies close to threshold, illustrating the importance of relativistic effects.
Uncertainty constraints show the limitation of the astrophysical temperature diagnostics capabilityof these transitions. The interpretation of measurements and comparison of the measured crosssections with theoretical calculations will be presented and discussed.
References[1] J. D. Gillaspy, Phys. Scr. T 71, 99 (1997).
[2] P. Szypryt et al. Rev. Sci. Instrum. 90, 123107 (2019).
[3] Yu. Ralchenko et al. J. Quant. Spectr. Rad. Transf. 71, 609 (2001).
[4] D. V. Fursa et al. J. Phys. B: At. Mol. Opt. Phys. 49, 184001 (2016).

173

B38
Electron loss in water molecule impacted by H0 and He0
M A Quinto1 , N Esponda1 , A Larouze2 , C Champion2 , R D Rivarola1 and J M Monti1
Instituto de Fı́sica Rosario (CONICET-UNR), Bv 27 de Febrero 210 bis, 2000 Rosario, Argentina
CELIA, Centre Lasers Intenses et Applications, Université de Bordeaux – CNRS – CEA, F-33400,
Talence, France

1
2

The study of electrons removal in collision of neutral atom with water molecule plays an importantrole in radiobiology. In particular, in radiotherapy during the continuous slowing-down of the ionsbeam, a fraction of them will change of state when its energy approaches the Bragg’s peak region. In a
recent work [1], the ionization of water molecule induced by neutral hydrogen has been investigated.
However, the projectile electron loss process for the same collision system has been scarcely studied.
In the literature, three different sets of experimental data and two semi-empirical analytical models
exist, which have studied this reaction for neutral hydrogen – water molecule collisions. In this work,
we present a theoretical approach to describe the electron loss process in the neutral hydrogen andhelium – water collision. The total cross sections (TCSs), calculated within a quantum mechanical
CDW-EIS, are presented in figure 1. The TCS computed within this approximation, that in case ofneutral projectile fall down to First Born approximation, overestimates the measurements below a
few hundreds of keV. To improve this, a charge corrections have been introduced [2]. As a result,the calculations with charge correction show a better agreement with experimental data and semiempirical predictions.

Figure 1: Electron loss total cross section for H0 and He0 impacted on water vapour.
References[1] M. A. Quinto, J. M. Monti, C. Champion R. D. Rivarola Phys. Rev. A 100, 042704 (2019)[2] N. Esponda, M. A. Quinto, R. D. Rivarola, J. M. Monti, Phys. Rev. A 105, 3 (2022)

174

B39
Electron loss in argon atom impacted by H0 and He0
M A Quinto1 , N Esponda1 , R D Rivarola1 and J M Monti1
1Instituto de Fı́sica Rosario (CONICET-UNR), Bv 27 de Febrero 210 bis, 2000 Rosario, Argentina

The study of electrons removal in collision of neutral projectile with atom is a process of fundamental
importance in many areas of science in particular, radiation damage to biological tissue, in astrophysics and the physics and chemistry of planetary atmospheres. However, neutral projectile, likeneutral hydrogen or helium, induced interactions with atoms and molecule have been rarely experimentally investigated. In this work, we study the electron loss processes by using the continuum
distorted wave-eikonal initial state (CDW-EIS) approximation. The results in term of total cross sections (TCSs) are shown in figure 1. To improve the CDW-EIS approximation in the case of collisions
between neutral atoms, we consider the Barkas’s charge in the initial channel and the dynamic effective charge in the exit one [1]. The Barkas’s charge is a correction used to compute the energy lossof charged particle in the matter. On the other side, the dynamic effective charge was introduced by
McGuire [2] to screen the nuclear projectile charge as a function of the momentum transfer. Whenboth corrections are introduced into the CDW-EIS approximation, the obtained TCSs are in better
agreement with the experimental data.

Figure 1: Electron loss total cross section for H0 and He0 impacted on argon.
References[1] N. Esponda, M. A. Quinto, R. D. Rivarola, J. M. Monti, Phys. Rev. A 105, 3 (2022)[2] J. H. McGuire, N. Stolterfoht, P. R. Simony, Phys. Rev. A 22, 24 (1981)

175

B40
Projectile dynamic screening and binary encounter electron emission
N Esponda*, M A Quinto, R D Rivarola and J M Monti
Instituto de Fı́sica Rosario (CONICET-UNR), Bv 27 de Febrero 210 bis, 2000 Rosario, Argentina.
(*) esponda@ifir-conicet.gov.ar
The so called binary-encounter (BE) electrons are emitted from the target as a result of an energetic
collision where the projectile velocity is higher than the electrons initial orbital velocity. Therefore,
the interaction between the emitted electron with the projectile has a dominant role over the interaction
among the electron and the target. BE collisions are associated to a low impact parameter so highmomentum transfers are involved. In the case of a dressed projectile, the impact parameter lies within
the radius of its K-shell so it could be expectable that the projectile-electron interaction is governedby the projectile’s unscreened nuclear charge ZP . However, the BE peak magnitude in the electron
emission DDCS at 0 does depends on the ionization degree q of the projectile ion. The BE peakmagnitude increases with decreasing q [1,2].
In a previous work [3] we have presented a correction to the continuum distorted wave with eikonal
initial state model, CDW-EIS, based on a dynamic effective charge in the projectile distortion of theexit channel. Depending on the momentum transfer, this correction takes into account situations offull screening or no screening of ZP by the projectile’s bounded electrons. In this work we study ingreater detail the CDW-EIS projectile dynamic charge corrections on the BE emission from an Hetarget. We found a radically different behavior compared to the previous version of the CDW-EIS
model, obtaining now a better agreement with the BE peak q-dependence, up to the measured q’s.

Figure 1: Projectile charge-state q dependence of BE peak DDCS’s relative to bare-ion BE peak DDCS’s.
References[1] P. Richard et al., J. Phys. B 23 L213 (1990)[2] T. J. M. Zouros et al., Phys. Rev. A 53 2272 (1996)[3] N. Esponda, M. A. Quinto, R. D. Rivarola and J. M. Monti Phys. Rev. A 105, 3 (2022)

176

B41
State-selective electron capture in Ne10+ + H(1s) collisions
A. M. Kotian,1 C. T. Plowman,1 I. B. Abdurakhmanov, 2 I. Bray,1 and A. S. Kadyrov1
1

Department of Physics, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
2
Pawsey Supercomputing Centre, 1 Bryce Ave, Kensington, WA 6151, Australia

Collisional data for highly charged ions like Ne10+ are important for astrophysical and fusion
plasma research. We model electron capture and ionisation in fully-stripped neon ion
collisions with ground-state atomic hydrogen using the two-centre wave-packet convergent
close-coupling (WP-CCC) method over the energy range from 1 keV/u to 2 MeV/u. The
calculated total electron-capture cross section agrees very well with the molecular andatomic orbital close-coupling calculations at low and intermediate energies. However, ourresults slightly overestimate the experimental results by Meyer et al. [1], and underestimate
the measurements by Panov et al. [2] available only below 10 keV/u. At higher energies,
where there are no measurements, the results also agree well with the classical trajectoryMonte-Carlo results. Partial !"-resolved electron-capture cross sections, important for fusion
plasma diagnostics, have also been calculated for final states up to ! = 10 [3], where ! and" are the final state principal and angular momentum quantum numbers, respectively. The
results for the dominant channels are generally in good agreement with the atomic-orbital
close-coupling calculations. However, by using a finer energy grid, we detect pronounced
oscillations in the state-selective cross sections for ! ≥ 8 at energies below 10 keV/u. Our
results for the total ionisation cross section differ from previous close-coupling calculations.
However, they are overall in good agreement with the latest classical trajectory Monte-Carlo
results. Previous WP-CCC calculations for collisions of fully-stripped carbon [4] andberyllium [5] ions with atomic hydrogen suggested that the maximum principal quantum
number of bound states !max on the projectile centre required for convergence was roughly
equal to the charge of the incident ion. However, we find this not to be the case for highlycharged ions, such as Ne10+. All the results reported in this work have converged within a
few percent over the entire energy range mentioned above. To maintain such accuracy, inthe most challenging intermediate energy region we had to set !max = 15. In particular, at
100 keV/u the !-resolved cross section peaks at ! = 7 and then drops towards 0 very slowly
with increasing !. Therefore, to achieve convergence in the total electron-capture crosssection within a percent, we had to increase !max to 23. This is more than twice the chargeof the projectile.
References[1] F. W. Meyer, A. M. Howald, C. C. Havener, and R. A. Phaneuf, Phys. Rev. A 32, 3310
(1985).
[2] M. N. Panov, A. A. Basalaev, and K. O. Lozhkin, Phys. Scr. T3, 124 (1983).
[3] A. M. Kotian, C. T. Plowman, I. B. Abdurakhmanov, I. Bray, and A. S. Kadyrov, J.
Phys. B: At. Mol. Opt. Phys. (in press) https://doi.org/10.1088/1361-6455/ac6afb[4] I. B. Abdurakhmanov, K. Massen-Hane, S. U. Alladustov, J. J. Bailey, A. S. Kadyrov,
and I. Bray, Phys. Rev. A 98, 062710 (2018).
[5] N. W. Antonio, C. T. Plowman, I. B. Abdurakhmanov, I. Bray, and A. S. Kadyrov, J.
Phys. B: At. Mol. Opt. Phys. 54, 175201 (2021).

177

B42
State-selective single electron capture in slow N6+-He collisions
Xiaolong Zhu, B. Najjari, Ruitian Zhang, Dalong Guo,Yong Gao, Dongmei Zhao, Shaofeng Zhang
and X. Ma
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
The charge exchange process of highly charged ions colliding with atoms or molecules plays animportant role in different fields, such as X-ray emission from comets, which is attributed to thecharge exchange of the solar wind ions with the neutral components of the comet [1, 2].
In the present work, the state-selective single-electron capture in collisions of N6+ ions with He wassystematically studied at impact energies range from 0.9 to 8.6 keV/u. Our experiments wereconducted at EBIS platform combined with COLTRIMS [3, 4] at the Institute of Modern Physics inLanzhou. The fully differential cross sections have been obtained. From the longitudinal momentum
spectrum of the recoil ions, the single electron captured into n=3 states of the projectile ion isdominant, while the capture n=4 states have a small contribution, and increase gradually with theincrease of the projectile energy. Also, the two-peak structure of the angular differential crosssections was observed. The continuum distorted wave (CDW) approach was used to calculate theangular differential cross sections [5]. The inclusion of the projectile-nucleus target-nucleus (N-N)
interaction, produces better the two-peak structure of the angular differential distribution. The
results show that the nucleus-nucleus interaction plays an important role in slow ion-atom collisions.

Figure 1. (a) The longitudinal momentum spectra and (b) differential cross sections as a function of thescattering angle of the single electron capture in collisions of 6 keV/u N6+ ions on helium. Blue dashed andred solid curves are the CDW calculations without and with N-N interaction, respectively.

This work is supported by the National Key R&D Program of China under Grant Nos.
2017YFA0402400 and 2017YFA0402300.
References[1] Lisse C M et al, Science 274 205 (1996).
[2] Cravens TE et al, Geophys Res Lett. 24 105 (1997).
[3] Zhu X L et al 2019 NIM-B 460 224 (2019).
[4] Ma X et al, Phys Rev A. 83 052707 (2011).
[5] Crothers D and Dubé L, Adv At Mol Opt Phys 30 287 (1992).

178

B43
Simultaneous K-shell double ionization of target and ion in symmetric collision
between Kr26+ and Kr atom at 152 MeV/u
Caojie Shao*, ZhangYong Song*, Hongqiang Zhang #, Pengfei Li#, Zhonglin Liu#, Wei Wang*,
Mingwu Zhang*, Yingli Xue*, Bian Yang*, Junliang Liu* and Deyang Yu**Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China#School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China

In collisions between energetic heavy ions and atoms, the strong Coulomb field of one ofcollision partners can cause double K-shell ionization of the second one [1]. The production of Kshell vacancy in atoms is typical accompanied by the creation of K-shell vacancy in ions. The
production mechanism of K-shell vacancy in collision partners could not be studies for fully
symmetric systems in low collision energy, since target and projectile K radiation could not be
resolved at small Doppler shifts [2]. The development of heavy-ion storage ring provides us an
opportunity to study K-shell vacancy under symmetrical ion-atom collision, in which the desiredenergy and charge state of ion could be conveniently achieved.
Simultaneous K-shell double ionization of target and ion in symmetric collision between Kr26+
ions and Kr atom at 152 MeV/u was studied experimentally at HIRFL-CSR. The K x-rays emitted
from ions and atoms were detected by Silicon Drift Detectors (SDD) mounted at 35°, 60°, and 90°
observation angles with respect to the ion beam direction. Figure 1 shows the typical spectra of Kr
K aec ded b he SDD a he 35 b e aa g e. The K x-rays from projectiles andtargets are effectively separated on account of large Doppler shift at small observation angle. Boththe K h e a e e (K h,s) lines from ions and target appear as shoulder on the high-energy side of
the corresponding Ka e e (K s) peaks, and are visibly distinguished from the satellite
transitions. The K
e of projectile is almost invisible since the ion without electron in M-shellwas employed. The current experimental results are expected to eliminate the influence of M-shelland higher shell electrons on the collision process as well as cascade process by measuring therelative intensity of ions and target lines and their respective structures.

Figure 1: heca ec a f K K a ec ded b he SDD a he 35 b e aa g e.
References[1] D. H. Madison and E. Merzbacher, in Atomic Inner-Shell Processes, Volume I: Ionization andTransition Probabilities, edited by B. Crasemann (Academic Press, Inc., New York,1975).
[2] P. M. Hillenbrand, S. Hagmann, Y. S. Kozhedub, et al, Phys. Rev. A 105, 022810 (2022).

179

B44
Electron-impact ionization of tungsten ions
Bowen Li, Runjia Bao, Lei Chen, Junkui Wei, Ximeng Chen, Gerry O’Sullivan*
School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China*School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
libw@lzu.edu.cn

Tungsten is being considered as a plasma-facing material in magnetically confined fusion devices,such as ITER. Electron collision ionization is a dominant atomic process in fusion plasma which
determines the ionization balance of the non-local thermal equilibrium plasmas. However, the effectof long-lived excited states in low charged ionic stages need to be investigated[1-2]. Moreover,reliable EISI data are not available for many tungsten ions[3].
We used the flexible atomic code (FAC) in the distorted-wave approximation method to calculate
electron-impact single ionization cross sections for tungsten ions. Comparison between the previous
experimental measurement results and present calculation show a prominent contribution ofmetastable states in low charged states such as W7+-W10+ ions[4].
Moreover, we performed calculations of detailed electron- impact single ionization cross sections
for tungsten ions, spanning charge states W38+ - W45+. We demonstrate the importance ofradiative damping on the total electron-impact ionization cross section. The data obtained are
expected to be useful for modelling plasmas for fusion applications, especially for the ITER
community.

Figure 1: (a) Comparison of the present theoretical calculations to the previous experimental andtheoretical data for single ionization from the ground levels of the W7+. (b) Include the contributions
from 29 long-lived metastable states.

References[1] M. Stenke et al., J. Phys. B: At. Mol. Opt. Phys. 28 (1995) 4853.
[2] C. L. Yan, et al., Phys. Rev. A 105 (2022) 032820.
[3] I. Murakami, et al., NIFS DATABASE, https://dbshino.nifs.ac.jp/nifsdb/.
[4] L. Chen, et al., J Quant. Spectrosc. Radiat. Tran. 285 (2022) 108179.

180

B45
Target atomic number dependence of the electron capture into H-like Cs ions
Hongqiang Zhang1,*, Caojie Shao2,3, Bian Yang2,3, Deyang Yu2,3, Zhangyong Song2,3, Pengfei Li1,
Hua Yuan1, Zidong Cheng1, Shuai Ha1, Haowen Zhang1, Yury S. Kozhedub4, Wei Wang2,3,
Mingwu Zhang 2,3, Junliang Liu2,3, Yingli Xue2,3, Chengliang Wan1, Ying Cui1, Ke Yao5,6, Zhihu
Yang2,3, Xiaohong Cai2,3, Reinhold Schuch7, Ximeng Chen1
1

School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu, 730000, P. R.
China
2
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
3
University of Chinese Academy of Sciences, Beijing 100049, China
4
Department of Physics, St. Petersburg State University, St. Petersburg 198504, Russia
5Institute of Modern Physics, Fudan University, Shanghai, 200433, P. R. China
6
Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University,
Shanghai, 200433, P. R. China
7
Physics Department, Stockholm University, S-10691, Stockholm, Sweden

Various x-ray transitions of Csq+и (q is the charge state of the ions) produced by the electron capture
in collisions of 66.4 MeV/u Cs54+ ions with N2, Ar, Kr and Xe atoms have been experimentallystudied at the Heavy Ion Research Facility at Lanzhou–Cooling Storage Ring (HIRFL-CSR). It isfound that the experimental intensity ratio I(K-!)/I(Ly-!) for the possible transitions from theexcited states Cs53*(1s2p-1s2) and Cs54*(2p-1s) for 66.4 MeV/u Cs54+ ions increases as the increaseof the target atomic number. The obtained results are compared with the ratio of the capture crosssections to the excitation cross sections of the projectile electrons, calculated with the relativistic
eikonal approximation and symmetric eikonal approximation, respectively. The obvious deviation
has been found between the experiments and the theoretical calculations. Also, it is found that theexperimental intensity ratio of I(K-β)/I(K-!) for the de-excitaion of Cs53* from the state-selective
nonradiative electron capture of 66.4 MeV/u Cs54+ ions in collisions of N2 to Xe gas target shows an
independence on the target atomic number. This is different from the calculations with therelativistic eikonal approximation, where the obvious increase of the ratio of the theoretical crosssections for the low atomic number of the target is expected. Also, the experimental intensity ratio
is at least 3 times lower than the calculated ratio from the relativistic eikonal approximation. The
possible explanations of the deviations between the experiments and theoretical calculations will
be discussed.

*zhanghq@lzu.edu.cn

181

B46

Dielectronic recombination rate coefficients of C-like Kr30+

W. L. Ma , S. X. Wang1 , Z. K. Huang2 , W. Q. Wen2,3 , H. B. Wang2 , D. Y. Chen2 , X. Liu2 , H. K.
Huang2 , C. Y. Zhang4 , C. Y. Chen4 , L. J. Mao2,3 , X. M. Ma2 , J. Li2 , M. T. Tang2 , K. M. Yan2 , Y. B.
Zhou2 , Y. J. Yuan2,3 , J. C. Yang2,3 , X. Ma2,3 , L. F. Zhu1
1

Hefei National Research Center for Physical Sciences at Microscale and Department of Modern
Physics, University of Science and Technology of China, Anhui 230026, China
2
Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
3
University of Chinese Academy of Sciences, 100049, Beijing, China
4
Shanghai EBIT Laboratory, Institute of Modern Physics, Fudan University, Shanghai 200433, China
1

Dielectronic recombination (DR) rate coefficients for C-like Kr30+ have been measured in the energy
range of 0-60 eV by employing the merged-beam technique at the heavy-ion storage ring CSRe at theInstitute of Modern Physics in Lanzhou, China. The measured spectrum covers the DR resonances associated with the 2s2 2p2 ! 2s2 2p2 , 2s2p3 and 2p4 core excitations. The corresponding DR resonanceenergies and strengths were calculated by the flexible atomic code (FAC) to understand the experimental results. An overall good agreement has been achieved between the experiment and theory, except
for the data below 8 eV. In particular, the contributions from the trielectronic recombination (TR) to
2p4 [1 D2 ]6l states have been identified with the help of the theory. Temperature-dependent plasma recombination rate coefficients were deduced from the measured DR spectrum in the temperature range
103 -107 K and compared with the present FAC calculations as well as previous AUTOSTRUCTURE
data from the literature. The AUTOSTRUCTURE calculation substantially underestimates the rate
coefficients below 104 K, indicating that the low energy resonances were poorly understood before.

Figure 1: (left) Experimental and theoretical DR rate coefficients for the C-like Kr30+ . The colourful
vertical bars represent the corresponding resonance positions calculated by the Rydberg formula. The
shaded areas with the same colours as the text boxes show the corresponding DR contributions. Notethat the prefix text (2s2p3 ) of the core excitations to 2s2p3 is omitted. (right) Experimentally derived
plasma rate coefficients for C-like Kr30+ in the temperature range 103 -107 K along with the present
FAC calculations and the data from Zatsarinny [2].
References[1] W. Q. Wen et al., The Astrophysical Journal. 905, 36 (2020)[2] Zatsarinny et al., Astronomy & Astrophysics. 417, 1173 (2004)

182

B47

Dielectronic recombination of Li-like Ar15+ using a newly self-developed
detuning system at the CSRm
H. K. Huang1,2 , Z. K. Huang1,2 , W. Q. Wen1,2 , H. B. Wang1,2 , S. X. Wang3 , W. L. Ma3 , S. F.
Zhang1,2 , L. F. Zhu3 , X. Ma1,2 and DR collaboration

Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
2
University of Chinese Academy of Sciences, 100049, Beijing, China
3
Hefei National Research Center for Physical Sciences at Microscale and Department of Modern
Physics, University of Science and Technology of China, Anhui 230026, China
1

A self-developed detuning system for the dielectronic recombination (DR) experiment was installedon the electron cooler of heavy-ion storage ring HIRFL-CSRm. To test the stability of this detuning
system, a DR calibration experiment using the Li-like argon ions was performed at the CSRm. As
shown in Figure 1 (a), the experiment was carried out over the energy range of 0 –37 eV, including
all the DR resonance associated with the core excitations of 2s1/2 ! 2p1/2,3/2 . Figure 1 (b) presents
the fitting result of the measured low-energy DR spectrum, i.e., 6 components were used to fit the DR
resonance structure of 2p1/2 10l. The longitudinal and transverse temperatures of the electron beamobtained as the fitting parameters are kTk ⇡ 0.25 meV and kT? ⇡ 30 meV, respectively, which yields
an energy resolution of about 30 meV (FWHM) at the electron-ion collision energy of around 1.2 eV.
Compared with the previous DR experiment of Li-like argon at the CSRm (2015, Huang et al) [2], ahigher energy resolution was achieved in the present measurement. By comparing the measured DR
spectrum with FAC calculation, the angular momentum quantum numbers for the resolved resonancepeaks associated with 2p1/2 10l were well distinguished and the attributed electron configurations
have been indicated in Figure 1 (b) with black vertical bars. The present work provides an important
technical reserve and lays the solid foundation for the DR precision spectroscopy in the future HighIntensity heavy ion Accelerator Facility (HIAF).
4.0

4
(b)

p1/2,1
p3/2,1
p3/2,2
p1/2,0d3/2,2

3

2.5
2.0

2
kT//=0.25(2)meV
kT =30.11(4)meV

1.5
1.0

Strenth(10-18cm2eV)(2p1/210lj)J

3.0

s1/2,0s1/2,1

Rate coefficients(10-9cm3s-1)

3.5

1

0.5
0.0

0
0.4

0.6

0.8

1.0

1.2

1.4

1.6

Energy(eV)Figure 1: (a) The comparison of the experimental and FAC calculated DR rate coefficient of Ar15+
ions. The short line in the figure indicates the distribution of Rydberg energy levels in 1s2 2p1/2 nl and1s2 2p3/2 nl configurations. (b) Fitting of the resonance structure of 1s2 2p1/2 10l (black point). The
black vertical bars are the calculated resonance positions of 1s2 2p1/2 10l. The heights of the shortgreen lines indicate the resonance strengths at the corresponding resonant energies.
References[1] W. Zong, R. Schuch, E. Lindroth, et al., Physical Review A 56 (1997) 386-394.
[2] Z. K. Huang, W. Q. Wen, H. B. Wang, et al., Physica Scripta T166 (2015).

183

B48
State-selective capture in Ar8+ collision with He at 1 keV/u
Ruitian Zhang, Xiaolong Zhu, Dalong Guo, Yong Gao, Shaofeng Zhang, and Xinwen Ma
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
University of Chinese Academy of Sciences, Beijing 100049, China
In slow highly charged ion-atom collisions, principal n and orbital angular momentum l-resolved
state-selective capture cross sections are important due to its applications in hot plasma diagnostics.
Additionally, the nl-resolved state selectivity is important for understanding few-body collision
dynamics, which control the bound quantum-state transition between two-centres.
We report the measurement of state-selective capture between 1 keV/u Ar8+ and He with a cold
target recoil ion momentum spectroscopy at electron beam ion source laboratory in Institute ofModern Physics, Chinese Academy of Sciences. The state-selective capture has been resolved forone 1s electron of He capture into 4s, 4p, 4d + 4f and 5s states of Ar7+ ion, where 4d + 4f capture
dominates over others. The present measurement qualitatively agrees with the previous result [1].

Figure 1: Longitudinal recoil ion momentum P|| in 1 keV/u Ar8+ -He single capture. The open
squares represent the measurement; lines are results from gaussian fitting.
This work is supported by the National Key R&D program of China under Grant Nos.
2017YFA0402400 and 2017YFA0402300, and Strategic Key Research Program of the Chinese
Academy of Sciences (XDB34020000).
References[1] M. A. Abdallah, W. Wolff, H. E. Wolf, Phys. Rev. A 57, 4373 (1998)

184

B49
Theoretical Investigation of Collision strengths for Fe X
Wenxian Li1,*, Connor Ballance2, Tomas Brage3 and Roger Hutton4
1

Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of
Sciences, Beijing 100012, China
2Centre for Theoretical Atomic, Molecular and Optical Physics, Queen’s University Belfast,
University Road, Belfast, BT7 1NN, UK
3
Division of Mathematical Physics, Lund University, Post Office Box 118, SE-221 00 Lund,
Sweden4
Shanghai EBIT laboratory, Institute of Modern physics, Fudan University, Shanghai, China*wxli@nao.cas.cn

We present here a detailed study of electron impact excitation of Fe X, focusing on the need tomodel the extreme ultraviolet (EUV) spectrum of interest for measuring coronal magnetic fieldstrengths using the magnetic-field-induced transition method [1-4]. The energy structures were
calculated using the relativistic GRASP code [5] for 100 jj fine-structure levels from 8
configurations (up to n=5). The energies belonging to the 3s23p5, 3s3p6, and 3s23p43d
configurations were shifted to their predicted National Institute of Standards and Technology values.
The relativistic parallel Dirac atomic R-matrix codes [6] were employed in the scattering
calculations to generate the collision strengths and subsequently the Maxwellian-averaged effective
collision strengths for temperatures in the range of 104 to 107 K. The present effective collision
strengths when compared with previous theoretical studies, are found an overall good agreement for
the EUV transitions of interest in the wavelength range from 170 to 260 Å. In addition, the newcollision data were adopted to model the EUV spectrum of Fe X and obtain the intensity ratios ofthe diagnostic line pairs used to derive the magnetic field strength. Comparisons were madebetween the spectra modelled using the present data with solar observations and other theoreticalstudies.
References[1] W. Li, Y. Yang, B. Tu et al. Astrophys. J., 826, 219 (2016)[2] E. Landi, R. Hutton, T. Brage, and W. Li, Astrophys. J., 904,87 (2020)[3] R. Si, T. Brage, W. Li et al. Astrophys. J. L., 898, L34 (2020)[4] Y. J. Chen, W. Li, H. Tian et. al., Astrophys. J., 920, 116 (2021)[5] F. A. Parpia, C. Froese Fischer, I. P. Grant, Comput. Phys. Commun., 94, 249 (1996)[6] C. P. Ballance, 2019, DARC, http://connorb.freeshell.org

185

B50
Charge-sharing dynamics of dissociating highly charged acetylene ionsafter electron-capture by highly charged ionsJ. Matsumoto, Y. Iwasaki, G. Veshapidze*, and H. Shiromaru
Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan*Faculty of Business, Technology and Education, Ilia State University, Tbilisi 0162, Georgia

After multi-electron capture from covalent molecules, charge-rearrangement occurs until
dissociation. However, it is still unclear where or when the rearrangement is finished and chargesharing is determined. In order to study the charge-sharing dynamics, we observed dissociation ofhighly charged acetylenes (C2H2n+, n = 5, 6). The H+ ions in the acetylene ions dissociate quickly,
which are utilized as probes; that is, the kinetic energy distributions (KED) of two H+ ions reflects
charge distribution of two inner carbon ions. We observed four-body dissociation events of highlycharged acetylene ions by collision with Ar8+ ions at an energy of 120 keV [1].
The experiments were carried out using an apparatus consisting of a position-sensitive time-offlight (PSTOF) device with a large position-sensitive detector (120 mmI) for fragment ions and acharge analyzer for scattered projectile ions. The trigger of the TOF measurements was detection of
scattered Ar5+ ions passing through the collision region, corresponding to five- and six-electron
capture processes with two and three Auger electron emissions from the scattered ions, respectively.
Fig. 1 (a) shows KEDs of H+ ions for the H+C2+C+H+ channel. The KEDs on the C2+ and C+
side are quite similar, indicating equal sharing of the charges in the C23+ ion when both the H+ ionsdissociated from the ion. Fig. 1 (b) shows KEDs of H+ ions for the H+C3+C+H+ channel. The KED
on the C3+ site is higher than its counterpart. However, the difference is much smaller than the pure
Coulombic value for C3+ and C+ sharing at the initial stage of dissociation. In order to estimate a CC distance where charge-sharing was finalized and the corresponding charge distribution of the two
carbon ions, we performed numerical simulations based on the pure Coulomb explosion model. For
the H+C2+C+H+ channel, the charge-sharing is finalized at the distance longer than about 200 pm.
For the H+C3+C+H+ channel, the finalized distance is almost same as that for the H+C2+C+H+
channel, but initial charge distribution is slightly asymmetric.

Fig. 1: (a) KEDs of H+ for the H+C2+C+H+ channel. One from near the C2+ site is shown by a blue dotted line, andthe other from near the C+ site is shown by a red solid line. (b) KEDs for the H+C3+C+H+ channel.

References[1] J. Matsumoto et al., Phys. Rev. A 102, 022819 (2020).

186

B51
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187

B52
Simulation study to aim to elucidate biological effect due tofast highly-charged ion irradiation
Kengo Moribayashi
National Institutes for Quantum and Science and Technology (QST), Japan
In fast highly-charged ion irradiation, a distinguishing feature appears, that is, energy deposition
concentrates near this ion path (IP). Because we think that there is a possibility to produces highrelative biological effectiveness (RBE) owing to this feature, we have developed a new simulation
model [1] to study physical phenomena produced near the IP. This model will allow us to analyze
the motion of the secondary electrons and spatial resolusion for energy deposition of these electrons
on the target in the irradiation of a highly-charged ion closer to reality than conventional models.
Owing to this irradiation, huge number of molecules are ionized along the IP and huge number ofmolecular ions are produced. In our simulation model, we incorporated strong electric field createdby these molecular ions and the effect of this electric field on the motion of secondary electrons.
Note that only our model succeeded to reproduce the trend of the measurement of secondary
electron yield by Kimura et al. [2]. In our previous study, we treated protons and carbon ions as
incident ions where si £ 4 ´ 10-15 cm2, because only these ions are employed in heavy ion beamcancer therapy, where si is the incident ion impact ionization cross section. Because we found someexperiments of more highly-charged ion such as Ar and Fe ions to elucidate the biological effect, si
is extended up to 2 ´ 10-14 cm2 in this study. Figure 1 shows (a) Pse vs. t (= 1/nMsi) and (b) Dr
distribution in the case of si = 1, 1.5, and 2 (´10-14 cm2), where Pse, r, t, nM, and Dr are probabilities
of seconadary electrons escaping this electric field, the distance from the IP, the mean path between
ionization events, the number density of molecules in the target, and the local dose as a function of r,
respectively.

Figure 1: (a) Pse vs. t; £ and ¢ are the results shown in Ref. [1] and simulated here, respectively.
(b) Dr vs. r ; ●,□, and △ corresponds to si = 1, 1.5, and 2 (´10-14 cm2), respectively.
References[1] K. Moribayashi, Jpn. J. Applied Phys., 59, SH0801(2020).
[2] K. Kimura, et.al., Nuclear Instr. Meth. Phys. Res. B 193, 661 (2002).

188

B53
Delayed fragmentation of nucleobases following MeV ion collisions
2

1

T. Nakao,1 R. Takasu,1 H. Tsuchida,1,2 M. Saito,1,2 T. Majima1

Department of Nuclear Engineering, Kyoto University, Kyoto 615-8540, Japan
Quantum Science and Engineering Center, Kyoto University, Uji 611-0011, Japan

Many studies have been performed on dissociation processes of gas-phase biomolecules induced
by energetic ion collisions. One of the characteristic features of dissociation of large polyatomic
molecules, including biomolecules, is delayed fragmentation arising from the increased numberof degrees of freedom [1–3]. Studies of delayed fragmentation processes provide rich information
about the stability of intermediated ions and the dissociation mechanism, which can even involve
neutral fragments [1]. So far, delayed fragmentation of nucleobases has focused on the adenine
molecule with keV ion collisions. This study performs MeV ion irradiation of various gas-phasenucleobase molecules to explore delayed fragmentation pathways in more detail.
The experiments were performed using a 1.7-MV Cockcroft–Walton-type tandem accelerator.
Gas-phase nucleobase targets of adenine, guanine, cytosine, and thymine were irradiated withpulsed beams of 0.5-MeV H+ and 0.6–4.0-MeV Cq+ ( = 1–3). Fragments were analyzed bytime-of-flight (TOF) mass spectrometry. The TOF data were recorded in list mode to analyze
the correlation among the detected fragments.
Figure 1 shows the TOF correlation maps between the first and second TOFs of the two fragments
produced in the same dissociation event of adenine. Delayed processes are observed as long tails.
Some processes were not observed in other experiments with keV ions, probably owing to thelow statistics. We evaluated the lifetime for some dissociation channels. To derive the lifetimeof dissociation from singly charged molecules, we estimated the absolute detection efficiency ofthe micro-channel plate detector for neutral fragments using a novel method. The lifetimes were
determined to be of the order of hundreds of ns to µs.

0.5-MeV H+

2.4-MeV C

2+Figure 1: Time-of-flight correlation maps of the two fragments generated from adenine.
References[1] S. Martin et al., Phys. Rev. A 77, 062513 (2008)[2] F. Alvarado et al., J. Chem. Phys. 127, 034301 (2007)[3] P. Moretto-Capelle et al., J. Chem. Phys. 127, 234311 (2007)

189

B54
Occurrence scattering time for electron-ion collision in nonextensive plasmas
Myoung-Jae Lee, Young-Dae Jung*
Department of Physics, Hanyang University, Seoul, South Korea(*) Department of Applied Physics, Hanyang University, Ansan, South Korea
The occurrence scattering time advance [1] for the electron-ion collision is investigated in a nonextensive plasma including Tsallis q-entropy. The eikonal analysis and the q-distribution function[2] are used to derive the occurrence scattering time as a function of the impact parameter, collisionenergy, scattering angle, and Tsallis entropic index. It is found that the occurrence scattering timeadvance decreases with increasing Tsallis entropic index. It is also shown that the effect of Tsallis
q-entropy on the occurrence scattering time advance increases with an increase of the scattering
angle. In addition, it is found that the effect of Tsallis q-entropy on the occurrence scattering timeadvance decreases in forward scattering domain in nonextensive plasmas.

Figure 1: The scaled occurrence scattering time in nonextensive plasmas.

References[1] T. Suzuki, Euriphys. Lett., 9, 513 (1989)[2] L. A. Gougam and M. Tribeche, Phys. of Plasmas, 18, 062102 (2011)

190

B55
Radiative Double-Electron Capture by Highly-stripped Ions on Graphene
Asghar Kayani*, Khushi Bhatt*, David S. La Mantia†, John A. Tanis*(*) Western Michigan University, Department of Physics, Kalamazoo, Michigan 49008 USA(†) NRC – National Institute of Standards and Technology, Gaithersburg, MD USA
Radiative double-electron capture (RDEC) occurs when the capture of two electrons by an ion isaccompanied by the simultaneous emission of a single photon. This process, fundamental in atomic
collisions, is considered the inverse of double photoionization by a single photon. RDEC has beensuccessfully studied with F9,8+ ions on gas [1] and thin-foil [2] targets. Only recently has it been
investigated for single-layer graphene [3]. This work was done at WMU with the 6-MV tandem vande Graaff accelerator. For the graphene, a target (‫׽‬0.35 nm thick) was mounted on a silicon nitride
grid (200 nm thick) consisting of ‫׽‬6400 holes of 2 µm diameter on a 200 µm thick substrate. A
Si(Li) spectrometer placed at 90° to the beam detected emitted x rays in coincidence withmagnetically separated outgoing charged particles counted with silicon surface-barrier detectors.
In preliminary work for RDEC with graphene [3], results for 2.11 MeV/u F9,8+ ions suggested verylarge cross sections, approaching values found for thin-foil targets when the thickness of thegraphene was about a hundred times smaller. In the present work, the RDEC measurements havebeen repeated with single-layer graphene as well as identical targets that had no graphene on them.
25

F9+ + Graphene

20
15
10
5
0

F9+ + No Graphene
CountsFigure 1 shows new results for RDEC for 2.11 MeV/u F9,8+
incident on graphene where the number of counts is plottedagainst the time difference between the x rays and particles
detected. The upper panel shows the results for F9+ on graphene,
the middle panel for F9+ with no graphene, and the bottom panel
for F8+ incident on the graphene. The top panel for F9+ shows
about 7-8 counts in the peak (near a time difference of 1950 ns)
after background subtraction, the middle panel exhibits no counts
for the target without graphene as expected, and the bottom panel
for F8+ displays counts but none in the peak, a reasonable
expectation for this one-electron ion when compared with earlier
results for F8+ on gas targets [1].

2

1

0

F8+ + Graphene

15

A tentative cross section can be calculated for the F9+ projectile,and the differential value at 90q is 1.3 b, corresponding to a total
cross section (assuming isotropy) of 11 b. These values are morein line with the earlier values found for F9+ incident on gas
targets, but larger by about a factor of 4, and are reasonable inview of the target thickness for the graphene compared to gas.

10
5
0

0

1000

2000

3000

4000

Time (ns)Figure 1: RDEC results for
F9,8+ on single-layer
graphene

Supported in part by NSF Grant No. 1707467.
References[1] D.S. La Mantia et al., Phys. Rev. Lett. 124, 133401 (2020).
[2] D.S. La Mantia, P.N.S. Kumara, C.P. McCoy, J.A. Tanis, Phys. Rev. A 102, 060801(R) (2020)[3] D.S. La Mantia et al., ViCPEAC 2021, Book of Abstracts, p. 108

191

B56
Probing the plasmon resonance in PAHs upon highly charged ion impact
Chandan Bagdia*,#, Laszlo Gulyas†, Lokesh Tribedi*(*)Tata Institute of Fundamental Research, Mumbai, 400005, India(#present address) J. R. Macdonald Laboratory, Kansas State University, Manhattan, 66502, USA(†) Institute for Nuclear Research, Debrecen 4001, Hungary
The polycyclic aromatic hydrocarbons (PAH) are established to be present in the interstellar
medium [1-2] and have attracted a lot of attention in the last few decades. The PAHs are in generalplanar molecules having delocalized π-electron cloud that can oscillate collectively upon external
perturbation. The collective excitation are also known as giant plasmon resonance (GPR), which
results from strong e--e- correlations. We studied the absolute double differential cross section(DDCS) of electron emission using electron spectroscopy as well as the ratio of double-to-single
ionization (DI-to-SI) by using TOF RIMS techniques in collisions with highly charged ions (HCI).
The GPR primarily decays via electron emission. However, observation of the GDPR in the eemission channel is challenging due to the presence of large Coulomb ionization background of
low-energy electrons. A novel idea is demonstrated of using the highly charged ions to create large
perturbation strength in order to excite the plasmons effectively. For the first time, the GPR in a
PAH molecule has been observed as a characteristic peak in the DDCS of electron emission [Fig. 1(a)] and its angular distribution has been studied [3-4].
The DI-to-SI ratios for PAHs upon HCI impact have been found to be substantially large [Fig. 1(b)] as compared to the atoms and smaller gas molecules such as CH4 [5]. The detailed projectile
charge (qp) and velocity (vp) dependence of the ratio has been studied for three different PAH
molecules. The influence of GPR in these PAH molecules resulting from the strong e --ecorrelations has been shown by modeling the qp and vp dependence of the ratio. The detailed resultsof the e-emission, as well as the DI-to-SI ratio will be presented.
250

94 MeV Si13+(a)

DDCS (Mb eV-1 sr-1)

(b)
160

T R

200

70 MeV Si7+ on Coronene
Coronene2+
Coronene+

120

100

Counts150
Fluorene
0.5 x CDW-EIS
3.5 x CH4

50
5

10

50

Coronene3+

80
40

100

Energy (eV)

0

50

100

150

200

250

300

M/Q
o

Figure 1: (a) DDCS of e-emission from fluorene and CH4 at 30 in collisions with 94 MeV Si13+ ion
impact, (b) Typical TOF spectra for coronene molecule in collisions 70 MeV Si7+ ions.
References[1] A G G M Tielens, Annu. Rev. Astron. Astrophys. 46, 289 (2008)[2] A G G M Tielens, Rev. Mod. Phys. 85, 1021 (2013)[3] C. Bagdia et al, Phys. Rev. A (Lett.) 104, L060802 (2021)[4] C. Bagdia et al, J. Phys. B: At. Mol. Opt. Phys. 54, 155202 (2021)[5] C. Bagdia et al, Eur. Phys. J. D 75, 37 (2021)

192

B57
Theoretical and experimental studies on the captured electron
population probability of hydrogen-like O ions in collision with metal
surface
Bing-Zhang Zhang, Xuan Liu, Ming-Wu Zhang, Cao-Jie Shao, Jun-Liang
Liu, Wei Wang, De-Yang Yu, Zhang-Yong Song *Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China

The interaction between highly charged ions and solid surfaces is a complex manybody process, and the population of electron capture into different Rydberg states isimportant information to study this process. Based on the two-state vector model (TVM)[1,2] SURSRVHGE\1HGHOMNRYLüHWDOwe calculated the probability of hydrogen-like O
ions incident on metal targets capturing conduction band electron to different Rydberg
states and gave the most likely ion-surface distance for charge exchange during theneutralization. It is found that a smaller principal quantum number ݊஺ corresponds toa larger Rydberg state probability, and the smaller the neutralization distance, thesmaller the principal quantum number ݊஺ arranged by the ion trapped electrons.
Therefore, the X-rays emitted as the hydrogen-like O ions impinging on the metal
surfaces mainly originate from the de-excitation of the smaller ݊஺ to the ground state.
In addition, in order to verify the calculation results of the model, based on the ECRISof the Institute of modern physics, Chinese Academy of Sciences, the X-ray emission
spectra of hydrogen-like O ions incident on the surface of metal targets (including Al,
Cu, Ni and Fe) were measured, and the transition energies from different high Rydberg
states to ground states were calculated in combination with FAC program. It is foundthat the K-X rays of O ion measured in this experiment mainly come from the 2p-1stransition, which is consistent with the probability calculated by the TVM theory.
1.0

1400

Relative intensity (arb.units)

nA = 2

Probability

0.8
0.6

nA = 3

0.4

nA = 4nA = 5nA = 60.2

nA = 70

6
12
18
Ion-surface distance (a.u.)

n=2

700

350

0

24

Fig. 1. Probability for the electron
captured into the different Rydberg states(݊஺ = 2 െ 7).
References

n=3-7

1050

420

560
700
Energy (eV)840

Fig. 2. X-ray spectra induced by 10
keV/q hydrogen-like O ions impact on
copper surfaces.

[1] 111HGHOMNRYLüDQG0'0DMNLü3K\VLFDO5HYLHZ$76 (4) (2007).
[2] 111HGHOMNRYLü0'0DMNLü'.%RåDQLüDQG5-'RMþLORYLü-RXUQDORI
Physics B: Atomic, Molecular and Optical Physics 49 (12) (2016).

*

Corresponding author: Z.Y.S., email: songzhy@impcas.ac.cn

193

B58
Observation of extreme ultraviolet to visible spectraof tungsten ions with a compact electron ion beam trap
Kota Inadome† , Mayuko Funabashi† , Priti⇤ , Daiji Kato⇤,‡ ,Hiroyuki A. Sakaue⇤ , Izumi Murakami⇤,§ , Nobuyuki Nakamura†,⇤Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan⇤
National Institute for Fusion Science, Gifu 509-5292, Japan‡
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580,
Japan§
Department of Fusion Science, The Graduate University for Advanced Studies, SOKENDAI, Gifu
509-5292, Japan†For the spectroscopic diagnostics of the ITER plasma in the near future, spectroscopic data of tungsten
ions are important. Since the temperature of the ITER plasma spans a wide range from the edge to thecore regions, the charge state of tungsten ions required for the diagnostics also spans a wide range.
An electron beam ion trap (EBIT) is an ideal device for observation and identification of previously
unreported lines of tungsten ions and thus tungsten spectral data have been obtained at several EBIT
facilities [1-4]. However, there is still a lack of data, and further observations and identifications arethus strongly needed.
So far, we have observed spectra of tungsten ions using a compact electron beam ion trap (CoBIT)[5] with a visible spectrometer useful for the 300 to 1000 nm range and an extreme ultraviolet (EUV)
spectrometer useful for the 5 to 30 nm [6]. In order to fill a part of the gap between 30 and 300 nm,
we have recently built a new spectrometer [7], which is useful for the 11 to 124 nm range. Spectra oftungsten ions obtained with these three spectrometers are presented.
References[1] C. Biedermann et al., Phys. Scr. T134, 014026 (2009)[2] J. Clementson and P. Beiersdorfer, Phys. Rev. A 81, 052509 (2010)[3] I. N. Draganic et al., J. Phys. B 44, 025001 (2011)[4] M. L. Qiu et al., J. Phys. B 48, 144029 (2015)[5] N. Nakamura et al., Rev. Sci. Instrum. 79, 063104 (2008)[6] M. Mita et al., Atoms 5, 13 (2017)[7] N. Nakamura et al., J. Phys. Soc. Jpn 90, 114301 (2021)

194

B59
HCI-surface collision experiments with an electron beam ion source
Keigo Soutome, Ryo Okada, Naofumi Nishida⇤ , Makoto Sakurai⇤ , Nobuyuki Nakamura
Institute for Laser Science, The University of Electro-Communications, Tokyo, Japan⇤
Kobe University, Hyogo, Japan
In the collisions of slow highly charged ions (HCIs) with material surfaces, the large potential energyof the ions causes characteristic interactions that are essentially different from those caused by lowcharged ions or fast ions. The characteristic modification of surfaces caused by HCIs is expected to be
applied for nano-scale surface treatment, surface analysis, and so on. Thus the study of HCI-surface
interactions has been one of the most interesting and important subjects in the physics of HCIs formany years.
For performing HCI-surface collision experiments, an electron beam ion source (EBIS) was built in2005 at Kobe university [1]. It has been operated since then for studying characteristic processes
caused by the potential energy of HCIs [2-7]. The Kobe EBIS has recently been moved to the University of Electro-Communications in Tokyo. The current status of the EBIS and the experimental plansin near future are presented.
References[1] M. Sakurai et al., J. Phys: Conf. Ser. 163, 012115 (2009)[2] N. Nishida et al., X-ray Spectrometry 49, 99 (2020)[3] N. Nishida et al., e-J. Surf. Sci. Nanotechnol. 16, 356 (2018)[4] M. Sakurai et al., e-J. Surf. Sci. Nanotechnol. 14, 1 (2016)[5] M. Sakurai et al., Nucl. Instrum. Methods Phys. Res. B 315, 248 (2013)[6] S. Liu et al., Phys. Procedia 32, 173 (2012)[7] S. Liu et al., Phys. Scr. T144 014043 (2011)

195

B60
Observation of vacuum ultraviolet transitions relevant toastrophysical plasmas with a compact electron beam ion trap
Masayoshi Hosoya† , Daiji Kato⇤,‡ , Nobuyuki Nakamura†,⇤Institute for Laser Science, The University of Electro-Communications, Tokyo, Japan⇤
National Institute for Fusion Science, Gifu 509-5292, Japan‡
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580,
Japan†

For the spectroscopic diagnostics of astrophysical hot plasmas, spectroscopic data for transitions inhighly charged ions are important. For example, the solar observation satellite HINODE observes
emissions in the extreme ultraviolet (EUV) range with an EUV imaging spectrometer (EIS) for the
diagnostics of the solar corona. In order to obtain the spectroscopic properties of transitions relevantto the diagnostics with EIS, we observe EUV transitions of HCIs [1-3] with the Tokyo electron beam
ion trap (Tokyo-EBIT) [4] and a compact electron beam ion trap (CoBIT) [5].
As a follow-on of EIS/HINODE, the Solar-C EUVST mission is currently proposed. In this mission,transitions of HCIs are planned to be observed for a wavelength range wider than that in EIS for
investigating not only the solar corona but also the chromosphere to the transition region. The planned
wavelength range spans from 17 to 285 nm, whereas the available wavelength range of the EUV
spectrometer that has been used for the Tokyo-EBIT and CoBIT is 5 to 30 nm. In order to extend
the observation range to a longer wavelength range, we have recently built a new vacuum ultraviolet(VUV) spectrometer useful up to 124 nm [6]. The performance of the new spectrometer and thespectra of ions relevant to the Solar-C EUVST mission, such as 46.5 nm of Ne VII, are presented.
This work was supported by JSPS KAKENHI Grant Number JP19H00665.
References[1] N. Nakamura et al., Astrophys. J. 739, 17 (2011)[2] E. Shimizu et al., Astron. Astrophys. 601, A111 (2017)[3] N. Nakamura et al., Astrophys. J. 921, 115 (2021)[4] N. Nakamura et al., Phys. Scr. T73, 362 (1997)[5] N. Nakamura et al., Rev. Sci. Instrum. 79, 063104 (2008)[6] N. Nakamura et al., J. Phys. Soc. Jpn 90, 114301 (2021)

196

B61
Observation of extreme ultraviolet spectra relevant to the electron density
diagnostics of solar corona active regions
Yasutaka Kono† , Norimasa Yamamoto¶ , Daiji Kato⇤,‡ , Hiroyuki A. Sakaue⇤ , Izumi Murakami⇤,§ ,Hirohisa Hara#,k , Nobuyuki Nakamura†,⇤Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan¶Chubu University, Aichi 487-8501, Japan⇤
National Institute for Fusion Science, Gifu 509-5292, Japan‡
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580,
Japan§
Department of Fusion Science, The Graduate University for Advanced Studies, SOKENDAI, Gifu
509-5292, Japan#National Astronomical Observatory of Japan, Tokyo 181-8588, Japan
kDepartment of Astronomical Science, The Graduate University for Advanced Studies,
SOKENDAI, Tokyo 181-8588, Japan†

Extreme ultraviolet (EUV) emission line intensity ratios of highly charged ions can be used for thedensity diagnostics of the solar corona. For active regions such as flare plasmas, density-sensitive
emission line pairs that can be applied to the high-temperature and high-density ranges are needed.
Ions such as Ar XIII-XIV and Ca XV-XVII are candidates that are useful for the temperature range
Te > 3 MK [1,2].
We present EUV spectra of Ar XIV and Ca XV observed with two electron beam ion traps (EBITs),
the Tokyo-EBIT [3] and CoBIT [4]. The applicability of EUV line ratios in these ions to the density
diagnostics is examined through the comparison of collisional radiative model calculations with thespectra obtained with a well-defined EBIT plasma.
This work was supported by JSPS KAKENHI grant No. JP19H00665.
References[1] K. P. Dere et al., ApJ 40, 341 (1979)[2] N. Nakamura et al., ApJ 921, 115 (2021)[3] N. Nakamura et al., Phys. Scr. T73, 362 (1997)[4] N. Nakamura et al., Rev. Sci. Instrum. 79, 063104 (2008)

197

B62
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198

B63
EUV emission and charge-separated suprathermal ion from a laser-produced
tungsten plasma
Takeru Niinuma, Masaki Kume, Yuto Nakayama, Tsukasa Sugiura, Hiromu Kawasaki,
Hiroki Morita, Shinichi Namba*, Atsushi Sunahara**, Gerry O’Sullivan***, andTakeshi Higashiguchi
Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585, Japan(*) Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8527, Japan(**) Purdue University, West Lafayette, Indiana 478907, USA(***) University College Dublin, Belfield, Dublin 4, Ireland

Photon flux (×1013 photon/nm/sr)

Tungsten (W) is a promising material for plasma-facing components in future magnetic
confinement fusion (MCF) reactors such as ITER. This is because tungsten has desirable properties
as plasma-facing components, for instance low hydrogen retention. However, since tungsten is ahigh-Z heavy element its multiply ionized ions will still have bounded electrons even in the centreof ITER plasmas in an electron temperature range of less than 1 keV [1]. Highly charged tungsten
ions radiate intense emissions in the extreme ultraviolet (EUV) regions, and this results in a large
energy loss of confined plasma. Then it is important to diagnose not only the EUV emission but
also the suprathermal ion generation as contamination.
We observed the EUV spectra and the charge-separated ion spectra from a laser-produced
tungsten plasma. Figure 1 shows the spectral comparison by optical thickness due to the criticaldensity difference of 1 ´ 1021 cm-3 and 4 ´ 1021 cm-3, which are the laser wavelengths of 1064 nm
and 532 nm. We found that the increase emission in 1 nm - 3 nm under optically think condition.
Some peaks in 1.3 nm - 1.5 nm were attributed to W XXXVIII ions. In addition, shorter
wavelength peaks appeared for optically thick condition, as compared to lower optical thickness.
Figure 2 shows the tungsten ion spectra by use of a Faraday cup and an electrostatic analyser (ESA)Time-integrated
spectra of W
at laser wavelength of 1064 nm and the laser intensity of 1 ´ 1014 W/cm2. The maximum kinetic
energy was observed to be 2 MeV due to heavy element of tungsten. We would show somedependences of the spectral behaviors of the EUV emission and the suprathermal ions.
EL = 160 mJ
6

λ (nm)
1064
532

5
4
3
2
1
0
1

2
Wavelength (nm)3

Figure 1: EUV spectra.

Figure 2: Suprathermal ion spectra.

References[1] C. S. Harte, T. Higashiguchi, T. Otsuka, R. D’Arcy, D. Kilbane, and G. O’Sullivan, J. Phys. B
45, 205002 (2012)

199

B64
Status and future perspectives of the U89+ resonant coherent excitation (RCE)experiment at GSI/FAIR
Y. Nakano,1,2 A. Bräuning-Demian,3 A. Ananyeva,3,4 S. Menk,2 K.C. Chartkunchand,2N. Kimura,2S. Harayama,5 H. Bräuning,3 A. Kalinin,3 U. Spillmann,3 C. Kleffner,3 M. Steck,3
S. Litvinov,3 K. Mohr6,7, K. König,6,7 W. Nörtershäuser,6 J. Meisner,8 S. Passon,8 Th. Stöhlker,3,9,10
and T. Azuma2,11
1
Department of Physics, Rikkyo University, Tokyo 171-8501, Japan
Atomic, Molecular and Optical Physics Laboratory, RIKEN, Saitama 351-0198, Japan
3
GSI Helmholtzzentrum für Schwerionenforschung, D-64291 Darmstadt, Germany
4
Johann Wolfgang Goethe Universität, Frankfurt, Germany, 60438 Frankfurt am Main, Germany
5
Department of Physics, Saitama University, Saitama 338-8570, Japan
6
Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
7
Helmholtzakademie Hessen für FAIR, Darmstadt, Germany
8
Physikalisch-Technische Bundesanstalt, Braunschweig, 38116 Germany
9Helmholtz-Institut Jena, D-07743 Jena, Germany
10
Friedrich-Schiller University Jena, 07737 Jena, Germany
11
Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397, Japan2

We have been working on the high-precision spectroscopy of the Li-like U89+ 2s - 2p3/2 transition(4459.37(21) eV) using resonant coherent excitation (RCE) in a thin silicon target. This transition isa well-known target for precise tests of two-loop QED and is often used as a reference line for heavyion x-ray spectroscopy. After the first successful experiment using the 190 MeV/u U89+ provided by
the SIS at GSI [1], we have focused on improving the spectroscopic precision of this method by using
the electron-cooled U beam from the Experimental Storage Ring (ESR) [2]. With the upgradedvoltage divider [3], the transition energy is expected to be measured with a reduced uncertainty ofseveral parts per million on the absolute transition energy. A new attempt to measure the 2s - 2p1/2transition energy (280 eV) is developed using a silicon drift detector with an extremely thin window.
The status of the developments and possible plans for future experiments at the Facility for Antiprotonand Ion Research (FAIR) will be discussed in the poster.
References[1] Nakano, Y., Takano, Y., Ikeda, T., Kanai, Y., Suda, S., Azuma, T., Bräuning, H., BräuningDemian, A., Dauvergne, D., Stöhlker, T., & Yamazaki, Y. (2013). Resonant coherent excitationof the lithiumlike uranium ion: A scheme for heavy-ion spectroscopy. Physical Review A, 87(6), 060501. https://doi.org/10.1103/PhysRevA.87.060501[2] Nakano, Y., Ananyeva, A., Menk, S., Bräuning-Demian, A., Bräuning, H., Kleffner, C.,
Stöhlker, T., & Azuma, T. (2015). Enhancing the energy resolution of resonant coherent
excitation using the cooled U 89+ beam extracted from the ESR. Journal of Physics:
Conference Series, 635(3), 032016. https://doi.org/10.1088/1742-6596/635/3/032016[3] Ullmann, J., Andelkovic, Z., Brandau, C., Dax, A., Geithner, W., Geppert, C., Gorges, C.,
Hammen, M., Hannen, V., Kaufmann, S., König, K., Litvinov, Y. A., Lochmann, M., Maaß, B.,
Meisner, J., Murböck, T., Sánchez, R., Schmidt, M., Schmidt, S., … Nörtershaüser, W. (2017).
High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED.
Nature Communications, 8(May), 1–7. https://doi.org/10.1038/ncomms15484

200

B65
Far-UV emission from the laser-produced plasmaof Al, Cu, Fe, and Inconel alloy targets
H. Ohnishi, S. Tamaki, Y. Shiina, and Y. Nakano
Department of Physics, Rikkyo University, Tokyo 171-8501, Japan
Laser-produced plasma (LPP) has been intensively studied during past decades as a promising lightsource in a wide range of wavelengths. In particular, the EUV and soft X-ray emission from LPP has
attracted considerable attention in the prospect of applications lithography and microscopy. On theother hand, experimental and theoretical studies of LPP in the far-UV region (50-200 nm) are quite
limited compared to those in EUV and soft x-ray region, partly because of the few industrial
applications expected in this region. Nevertheless, photo processes in the far-UV region are crucial
in natural sciences since they trigger the electronic transition of atoms and molecules and promote
chemical reactions. In this contribution, we report on a spectroscopic study of LPP in the far UV
region using a second harmonics of a high-power Nd:YAG laser and various metal targets; Al, Cu,
Fe, and Inconel 600 alloy (Ni/Cr/Fe/Mn). The emission from LPP was analyzed by a vacuum
monochromator with a toroidal grating (1200 G/mm) and a photodiode detector. In Figure 1, the solidline shows an example of the LPP spectra from the Fe target obtained at the laser pulse energy of 520
mJ. We analyzed the laser-power dependence of the spectral shapes and intensities for various target
elements with the help of the LIBS (Laser-Induced Breakdown Spectroscopy) database from NIST
(https://physics.nist.gov/PhysRefData/ASD/LIBS/). The dotted lines show the LIBS simulation for
Fe, Fe+, and Fe2+ calculated for the electron temperature Te = 6.5 eV and the density ne = 6 × 10!"cm-3. The spectrum is composed of many lines, including transitions between excited states of Fe+
and Fe2+. Also, to increase the photon flux at the end of the monochromator, we have developed aparabolic mirror system, which enhanced the spectral intensity by more than an order of magnitude.

Figure 1: The LPP spectrum of Fe observed at the laser pulse energies of 520 mJ. The dotted lines show thesimulation using the LIBS database from NIST.

201

B66
Generation of highly charged Au ion in laser-produced plasma for water
window X-ray radiation sources
J.H. Wang1, M. Kishimoto1, T. Johzaki1, K. Murakami1, C. Kumeda1, T. Higashiguchi2, A.
Sunahara3, H. Ohiro1, K. Yamasaki1and S. Namba1
1

Department of advanced science and engineering, Hiroshima University, 1-4-1 Kagamiyama,
Higashi-hiroshima, Hiroshima 739-8527, Japan2
Department of Electrical and Electronic Engineering, Utsunomiya University, 350 Minemachi
Utsunomiya, Tochigi 321-8505, Japan
3
Center for Material under Extreme Environment, Purdue University, 610 Purdue Mall, West
Lafayette, IN, 47907, U.S
E-mail: d213009@hiroshima-u.ac.jp

Intensity (arb. u.)

Highly ionized plasma generated by a high-power laser pulse radiates bright and short-pulse Xrays. Since X-rays have much shorter wavelength than conventional visible/UV lights, diffraction
limit becomes shorter, making it possible to observe nanoscale objects with higher spatial resolution.
Particularly, X-rays in the water-window (WW) region (2.3-4.4 nm) have shown a considerable
difference in absorption between carbon and oxygen (water), which are the two main constituents ofliving organisms. Therefore, X-ray microscope using WW region has a substantial potential fornanoscale living cells diagnostic.
One of the methods to develop a WW soft X6
Au XXVIII Au XXVII sat.
ray source is to use laser-produced Au plasma.
Au XXVIII sat.
Au XXVII
Au XXIX
Due to the 4d-5f transition in the highly ionized
5 Au XXIX
Au XXVI sat.
sat.
24+
29+
Au XXX
Au XXVI
Au ion attributed to Au ~Au , there is a
Au XXX sat.
Au XXV sat.
4
strong unresolved transition-array (UTA)Au XXVemitted from the plasma, which mainly3
contributes to the emissions at the WW region(Fig. 1). Besides, an enhancement of WW
2emission has also been observed, when a Au
plasma is generated by a commercial Nd:YAG
1
Water window
laser (1064 nm, 7 ns, 1 J) under a low-pressure0
nitrogen gas atmosphere [1]. Based on these
1.8 2.0 2.3 2.5
3.0
3.5
4.0
4.4
facts, the Au laser plasma scheme has become
wavelength (nm)an attractive candidate for the WW X-ray source
Figure 1 Au UTA spectrumwith ns or less pulse duration.
However, considering the cost and the repetition rate for a practical WW X-ray generation, a thintape target is more favorable when compared to the usual planar targets. Not only because thinnertargets can readily be supplied at a repetition rate of >100 Hz, but also they produce less debris
from the vicinity of the plasma, which effectively prevents optics from been damaged [2]. Therefore,
it is necessary to optimize the target thickness as thin as possible, while still holding the conversion
efficiency at a high level. In addition, since the precise gold opacity has not been disclosed, areliable opacity table is craved in the indirect inertial confinement fusion (ICF) science. In addition,
an optimization of the laser focusing spot size under fixed laser energy has also been investigated.
More details will be presented in the poster.
References[1] C. John, et al., Opt. Lett. 44 pp.1439-1442 (2019).
[2] S. Namba, et al., Appl. Phys. Lett. 88 171503 (2006).

202

B67
Charge-separated ion spectra from a laser-produced plasma
Yuto Nakayama, Takeru Niinuma, Masaki Kume, Hiromu Kawasaki, Hiroki Morita,
Shinichi Namba*, Atsushi Sunahara**, Gerry O’Sullivan***, and Takeshi Higashiguchi
Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585, Japan(*) Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8527, Japan(**) Purdue University, West Lafayette, Indiana 478907, USA(***) University College Dublin, Belfield, Dublin 4, Ireland
Extreme-ultraviolet (EUV) lithography at 13.5 nm is expected to be introduced in high-volume
manufacturing of integrated circuits (ICs) having node sizes less than 10 nm. Lithography at thiswavelength is capable of reaching feature sizes below 5 nm. Beyond that, switching to a shorter
wavelength of around 6.x nm, while maintaining or increasing throughput in the lithography system,
would improve resolution by a further factor of two and extend the technology to feature sizes lesstha 2 nm. Plasmas of the rare-earth elements gadolinium (Gd) and terbium (Tb) produce strong
resonant emission due to the presence of an intense unresolved transition array (UTA) around 6.x
nm in the spectra of their ions. Because the emitting ions in Gd and Tb, plasmas have an electronic
structure largely similar to Sn, they are expected to exhibit a similar spectral behavior, and emit anintense UTA due to 4p - 4d and 4d - 4f transitions at shorter wavelengths [1]. Recently, thesuitability of CO2 laser-produced plasma (LPP) EUV sources based on Gd and Tb has been
demonstrated for efficient, high power operation [2].
We observed the ion debris using an electrostatic analyser (ESA) to separate the charge
states. Figure 1 shows the charge-separated ion energy spectra. The maximum charge state was
Gd17+ (not shown) with a most probable energy higher than 20 keV. We show some dependence ofthe laser intensity and its pulse duration.
109

q+
1
2
3
4

Ion flux (arb. units)

108
107
106

5
6

105

7
8
9
10
11

104
103
102
10

12

0.1

1
10
Kinetic energy (keV)

50

Figure 1: Charge-separated ion spectra from a laser-produced Gd plasma.
References[1] H. Ohashi, T. Higashiguchi, B. Li, Y. Suzuki, M. Kawasaki, T. Kanehara, Y. Aida, S. Torii, T.
Makimura, W. Jiang, P. Dunne, G. O’Sullivan, and N. Nakamura, J. Apppl. Phys. 115, 033302(2014)[2] R. Amano, T.-H. Dinh, A. Sasanuma, G. Arai, H. Hara, Y. Fujii, T. Hatano, T. Ejima, W. Jiang,
A. Sunahara, A. Takahashi, D. Nakamura, T. Okada, K. Sakaue, T. Miura, G. O’Sullivan, and
T. Higashiguchi, Jpn. J. Appl. Phys. (Rapid Commun.) 57, 070311 (2018)

203

B68
Spatial Profile Measurement on Line Emissions from Highly Ionized Tungsten
Ions of W41+ to W46+ in the EUV Wavelength Range in the Large Helical Device
Tetsutarou Oishi1,2, Shigeru Morita1,2, Izumi Murakami1,2, Daiji Kato1,3, Hiroyuki A. Sakaue1,
Yasuko Kawamoto1, Tomoko Kawate1,2, Motoshi Goto1,2
1

National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho,
Toki 509-5292, Gifu, Japan2
Department of Fusion Science, The Graduate University for Advanced Studies, SOKENDAI, 3226 Oroshi-cho, Toki 509-5292, Gifu, Japan
3
Interdisciplinary Graduate School of Engineering and Sciences, Kyushu University, Fukuoka 8168580, Japan

Tungsten is a candidate material for plasma-facing components in the divertor region of theinternational thermonuclear experimental reactor (ITER) and future fusion reactors because of its
high melting point, low sputtering yield, and low tritium retention [1]. On the other hand, there is aconcern that tungsten ions with a large atomic number of Z = 74 will cause large energy loss byradiation and ionization when the plasma is contaminated by the tungsten impurity. Therefore, it isvery important to investigate the behavior of tungsten in high temperature plasmas in order tocontrol tungsten transport and establish reliable operation scenarios for fusion reactors.
Spectroscopic studies for emissions released from tungsten ions have been conducted in the Large
Helical Device (LHD), which is a superconducting plasma confinement device with a heliotron
magnetic configuration, for contribution to the tungsten transport study in tungsten divertor fusion
devices and for expansion of the experimental database of tungsten line emissions [2,3]. Tungsten
ions are distributed in the LHD plasma by injecting a pellet consisting of a small piece of tungsten
metal wire enclosed by a carbon tube.
In this study, the spatial profiles of highly-ionized tungsten ions from W41+ to W46+ are measured
via space-resolved extreme ultraviolet (EUV) spectroscopy. By superposing electron cyclotron
resonance heating with continuous neutral beam injection heating after the tungsten pellet injection,
the electron temperature at the plasma center can be maintained above 3 keV, and the emission linesof W41+ to W46+ were observed in the EUV wavelength region as follows; W41+ at 131.2 Å, W42+ at
129.4 Å, W43+ at 126.3 Å, W45+ at 127.0 Å [4], and W46+ at 7.93 Å [5]. The ions with higher
charge states are localized in the central region of the plasma where the electron temperature ishigher. W41+, W42+, and W43+ were distributed in the electron temperature region of about 2 keV,
while W45+ and W46+ were distributed in the electron temperature region of about 3 keV.
This work was partially supported by JSPS KAKENHI grant number 20K03896.

References[1] R. A. Pitts, X. Bonnin, F. Escourbiac et al., Nuclear Materials and Energy 20, 100696 (2019)[2] T. Oishi, S. Morita, D. Kato et al., Atoms 9, 69 (2021)[3] S. Morita, C. F. Dong, D. Kato et al., Proceedings of the International Conference on Atomic,
Molecular, Optical & Nano Physics with Applications, Springer Proceedings in Physics 271, 23(2022)[4] Y. Liu, S. Morita, T. Oishi et al., Plasma and Fusion Research 13, 3402020 (2018)[5] T. Oishi, S. Morita, D. Kato et al., Physica Scripta 96, 025602 (2021)

204

B69
Study on non-Maxwellian electron energy distribution in ECRH plasmas via
Helium-like argon and the satellite lines
T. Kawate, M. Goto, T. Oishi, Y. Kawamoto, I. Yamada, H. Funaba, H. Takahashi
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu JAPANThe motivation of this study is understanding electron energy distribution function (EEDF) in hot
plasmas. EEDF represents a nature of energy transfer and dissipation processes in collisionlessplasmas, e.g. astrophysical objects and thermonuclear fusion plasmas. In fusion plasmas, nonMaxwellian electron energy distribution function (EEDF) is expected during electron cyclotron resonance heating (ECRH), lower hybrid heating, dc heating, and so on. Muto et al. [1] investigated x-ray
bremsstrahlung emission from ECRH plasmas in the Large Helical Device (LHD), and they discovered high-energy electrons up to 200 keV with a bulk plasma of Te ∼4 keV by the x-ray spectra.
Another possible method to diagnose EEDF is population kinetics of ions, i.e., line spectra. X-raylines emitted from helium-like ions and their satellite lines have been used as a temperature diagnostics, and intensities of lines that are formed especially by inner-shell excitation and ionization areaffected by high-energy electrons [2]. Therefore, x-ray line spectroscopy with high spectral resolution
can be a good diagnostics of EEDF.
In the 23rd LHD experimental campaign, we observed helium-like argon lines and the satellite lines
around 3.98 Å in ECRH plasmas. Electron densities of the plasmas were scanned shot by shot in therange of (0.5 - 1.5)×1019 m−3 . Data taken by a Thomson scattering measurement and an electron
cyclotron emission measurement show a sign of suprathermal electron inside the last closed flux
surface under conditions of electron densities of less than 1019 m−3 . The x-ray measurement between
3.973 Å and 4.001 Å was performed by a crystal spectrometer whose spectral resolution is 0.028 mÅ.
We also obtained spatially-resolved extreme ultraviolet spectra emitted from lithium-like argon at
23.5 Å, and confirmed that lithium-like argon ions were populated around the region where a sign ofhigh-energy electron is confirmed.
In the observed x-ray spectra, we find a strange emission line at 3.988 Å, which has not been discussed
observationally in fusion plasmas so far. Its intensity got significant under condition of electron
densities of less than 1019 m−3 , and disappeared when the density got higher. According to calculated
energy levels by Saloman [3], the line seems emitted from a doubly excited state 1s2s3p of lithiumlike argon. We perform calculations of collisional excitation and ionization cross section, radiative
decay and recombination rates, and autoionization rate by the Flexible Atomic Code [4]. We setup
a collisional-radiative model by taking high-energy electrons with isotropic velocity distribution into
account, and compared intensity ratios among the observed emission lines with the measurement
results. We found that the observed intensity of the emission line at 3.988 Å is too high to be explainedby the calculated intensities.
References[1] S. Muto, S. Morita, S. Kubo, et al., , Rev. of Sci. Instr. 74, 1993 (2003)[2] e.g. T. Kato & K. Masai, Research Report NIFS Series, NIFS-197(1992)[3] E. B. Saloman, J. Phys. Chem. Ref. Data 39, 033101 (2010)[4] M. F. Gu, Can. J. Phys. 86, 5 (2008)

205

B70
Commissioning of the UNIST-EBIT: X-ray Resonant Spectroscopy of the Highly
Charged Ions at PAL-XFEL
SungNam Park, Bokkyun Shin, Moses Chung
UNIST (Ulsan National Institute of Science and Technology)

To study highly charged ions (HCIs), UNIST (Ulsan National Institute of Science andTechnology) built an electron beam ion trap (EBIT) to acquire spectral data of individual elementsin their highly charged states. The use of permanent magnets maximizes portability to move in andout of the accelerator beamline. Preliminary experiments on connecting the EBIT with the PALXFEL (Pohang Accelerator Laboratory X-ray Free Electron Laser) hard X-ray beamline have been
carried out over two R&D beam times. During these shifts, X-ray resonant spectroscopy of thehighly charged argon ions with the aid of a monochromatic photon beam from the PAL-XFEL has
been performed. In this work, we present highly charged argon spectroscopic measurements as wellas the preparation of our next experiment with the iron.

References[1] P. Micke et al., Rev. Sci. Instrum. 89, 063109 (2018)

206

B71
Enhancement of gain coefficient of Li-like Al ion 3d-4f soft X-ray laser
oscillation by a single resonator
S. Namba1, J.H. Wang1, Z. Jiawei1 M. Kishimoto1, K. Yamasaki1, N. Hasegawa2, T.H. Dinh2,
M. Ishino2, T. Higashiguchi3 and M. Nishikino2
1

Intensity (x104 CCD count)Department of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama,
Higashihiroshima, Hiroshima, 739-8527, Japan
2
Kansai Photon Science Institute, National Institutes for Quantum Science and Technology (QST),
Kizugawa, Kyoto, 619–0215, Japan3
Department of Electrical and Electronic Engineering, Utsunomiya University, 350 Minemachi
Utsunomiya, Tochigi 321-8505, Japan
E-mail: namba@hiroshima-u.ac.jp
We have tried to develop a compact, high-repetition rate, intense soft X-ray laser (3d-4f transition,
15.47 nm) in Li-like Al ion (Al10+) generaed by laser plasma. In a recombination plasma scheme,
rapid cooling of the plasma due to an adiabatic expansion creates a favorable condition for a
population inversion due to a three-body recombination process. The faster cooling of the electron
temperature leads to a higher recombination rate and thus to a larger population inversion. By
irradiating Al target with 16-pulse train of a joule class Nd:YAG laser (1064 nm, pulse width 400
ps, total energy: ~3 J), we have succeeded in increase of the gain coefficient to g=8.6 /cm. In orderto obtain higher gain coefficient, we optimized the pulse interval of the pump YAG laser, by which
we can control the plasma heating and cooling rates and thus increase the gain. In addition, torealize further enhancement of the gain coefficient, we employed a single resonator, which had a
Mo/Si multilayer flat mirror (reflectitity@15.5nm and 86°: 45%).
In the experiment, Al line shaped plasma was generated by focusing the YAG laser beam byutilizing a prizm lens array. The focus size having a homogeneout spatial intensity distribution was
50 Pm and 11 mm in height and length, respectively. We installed a temporal delay stage to control
the pulse interval of each drive laser. Soft X-ray spectra were collected by a toroidal mirror andfocused onto an entrance slit of a grazing incident spectrometer (flat-field, 1200 grooves/mm).
Spectra were was measured by a CCD camera. By varying the plasma length (laser medium), we
evaluated the gain coefficient for Li-like Al ion 3d-4f transition. On the other hand, the Mo/Si
mirror was installed at 20 mm from the target edge. The laser beam radiated into both target sides
and one of them was reflected by this Mo/Si mirror and subsequently returned in the lasing medium,
resulting in increase of the X-ray intensity
4.5
sigfinicantly due to double path effect.
laser energy: ~3J
4
As a result, the highest gain coefficient was
3.5
obtained at a pulse interval of 250 ps, and the gain
coefficient reached 9.84 /cm. Figure 1 shows the3
typical X-ray laser spectrum. When the plasma
2.5
lengths were over 3 mm, the intensity increased
2linearly in terms of the plasma length, implying that
1.5
the amplification seems to be classified into a gain
1
saturation regime. As for the single resonator
0.5
experiment, the intensity of 15.47 nm X-ray laser0
was increased by only 1.5 times, although the
12
14
16
18
wavelength (nm)geometrical estimation and mirror reflectively
expected the value of 2.57 times. The reason for this FIG. 1 Lasing spectra of 15.47 nm Li-like Al
ion 3d-4f trainstion.
is insufficient alignment of the reflected X-ray beam,by which the reflected laser was not passed through the lasing plasma medium appropriately.

207

B72
Measurements of highly charged Si and Ba ions from the SAO EBIT
Amy Gall a, Adam Foster a, Yang Yang a,b, Endre Takacs b,c, Nancy Brickhouse a ,Eric Silver a , Randall Smith aab

The Center for Astrophysics | Harvard & Smithsonian, Cambridge, MA 02138
Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978
cNational Institute of Standards and Technology, Gaithersburg, MD 20899

The electron beam ion trap (EBIT) facility at the Smithsonian Astrophysical Observatory (SAO) has
been recently brought back online after a silicone coolant leak compromised the vacuum system.
During the recommissioning process the trapping electronics, gas injection, control, and thermal
systems were updated or redesigned to improve performance. Despite the ultra-high vacuum pressure,background gases become highly ionized through electron impact ionization during EBIT operation
and are observable if the ion trap is not periodically dumped, as is the case for all EBITs. As part of ourefforts to characterize the updated EBIT system, the background contaminants were observed using abroadband solid-state X-ray detector while systematically scanning the electron beam energy over abroad energy range. Spectral features resulting from radiative recombination, direct excitation, and theresonant dielectronic recombination processes are reported for various elements including Si from theinitial coolant leak, and Ba from the electron gun cathode. A collisional radiative model was used tohelp identify features and a comparison of the modelled and measured spectra are presented.

208

B73
Selective Field Ionization of Rydberg Atoms for Blackbody Sensing
D. S. La Mantia1 , N. Prajapati2 , M. Simons2 , C. L. Holloway2 , E. B. Norrgard1 , S. P. Eckel1
National Institute of Standards & Technology (NIST), 100 Bureau Dr, Gaithersburg, MD 20899
U.S.A.
National Institute of Standards & Technology, 325 Broadway, Boulder, CO 80305 U.S.A.
Electromagnetic radiation sensing is at the core of modern physics. A ubiquitous source of incoherent radiation isblackbody radiation (BBR): electromagnetic radiation emitted by a body in thermal equilibrium with its environment.
It follows that characterizing BBR is an appropriate technique to accurately assess the temperature of a distant entity.
A thermal radiation detector integrating an invariable quantum system represents the next technological leap in radiation thermometry while being directly traceable to the new
International System of Units (SI).
Rydberg atoms are highly polarizable, and therefore extremely sensitive to electric fields such as BBR. Remarkableadvances in vapor cell technology and laser systems have facilitated the efficient production of Rydberg states in atoms
such as Rb. Efforts are underway at NIST to use Rydberg
atoms as calibration-free, SI-traceable sensors of thermal radiation, thereby characterizing reference blackbodies at the
100 ppm level [1] and greatly reducing the calibration uncertainty for classical thermal radiation sensors. Furthermore,these sensors may serve to reduce the Stark shift uncertainty
in atomic clocks due to BBR, the largest systematic error inthose systems to date.

Figure 1: Procedure for selective
field ionization (SFI) of Rydberg
Rb atoms following blackbody radiation (BBR) interaction.

Selective field ionization (SFI) [2,3] of Rydberg states is the measurement technique to be employed.
Parallel plates will be mounted in a Rb vapor cell. The Rb atoms will be pumped to Rydberg states
via a two-photon process using counter-propagating lasers: a 780 nm laser will induce a 5S ! 5P
transition and a 480 nm laser will bring the Rb to the final nS Rydberg state. The atoms will thenevolve for a variable amount of time in the BBR field absent one laser field, where they will populate neighboring P states or photoionize (much smaller population). An electric field will be applied
between the plates and ramped up to 10 kV/cm to selectively ionize high-lying energy levels in the
Rydberg atoms as the field intensity increases. The ions will then be collected on a cathode, with thetime of arrival determining the state energy and the signal size determining the state population. Measuring the transition rate across many states in the Rydberg atom should give the ability to measure
BBR frequency components from ⇠ 0.1 - 10 THz (⇠ 0 - 100 o C).
References[1] E. B. Norrgard, et al., New Journal of Physics 23, 033037 (2021).
[2] T. F. Gallagher, et al., Phys. Rev. A 16, 1098 (1977).
[3] E. J. Galvez, et al., Phys. Rev. A 51, 4010 (1995).

209

B74
A Compact 0.7 Tesla Electron Beam Ion Trap using Radial NdFeB Arrays†
D. S. La Mantia*, A. S. Naing*, A. Henins*, J. N. Tan*, A. Banducci**, S.M. Brewer***

National Institute of Standards & Technology, Gaithersburg, Maryland, USA**
Colorado State University, Fort Collins, Colorado, USA

We report on the progress at NIST in building a compact electron beam ion trap (EBIT) using drift
tubes embedded with radially magnetized NdFeB arrays to produce a peak field of 0.7 Tesla forintensifying the electron beam at the trap center. This room-temperature EBIT is designed tofacilitate experiments involving highly charged ions with low ionization thresholds, including testsof quantum sensors and development of high-accuracy optical atomic clocks. Although EBIT
devices using superconducting magnets are very versatile, they tend to be costly to operate. It has
been demonstrated that permanent magnets can be suitably configured to replace the B-field
generating solenoid in an EBIT. An early effort at NIST employed a pair of axially magnetized
NdFeB rings yoked by soft-iron drift tubes to produce a peak field of 290 mT at the trap center;observed highly charged ions extracted from this prototype1 included Ne8+, Ar9+, Ar13+, Kr17+, aswell as other species with ionization potential up to 900 eV. To enhance the magnetic field we haveredesigned the architecture along the lines of a similar compact Penning trap2 which utilizes threepairs of radially magnetized rings to yield an axial B-field of approximately 700 mT at the trap
center.
†Supported in part by NIST Grants 70NANB19H162 and 70NANB15H046.

References[1] Manuscript in preparation, A.S. Naing, E.B. Norrgard, B.C. Foo, and J.N. Tan[2] Chapter 5 in Ph.D. Thesis of A.S. Naing, University of Delaware (2021).

210

B75
Observation of extreme ultraviolet spectra relevant to the electron density
diagnostics of solar corona active regions
Yasutaka Kono† , Norimasa Yamamoto¶ , Daiji Kato⇤,‡ , Hiroyuki A. Sakaue⇤ , Izumi Murakami⇤,§ ,Hirohisa Hara#,k , Nobuyuki Nakamura†,⇤Institute for Laser Science, The University of Electro-Communications, Tokyo 182-8585, Japan¶Chubu University, Aichi 487-8501, Japan⇤
National Institute for Fusion Science, Gifu 509-5292, Japan‡
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580,
Japan§
Department of Fusion Science, The Graduate University for Advanced Studies, SOKENDAI, Gifu
509-5292, Japan#National Astronomical Observatory of Japan, Tokyo 181-8588, Japan
kDepartment of Astronomical Science, The Graduate University for Advanced Studies,
SOKENDAI, Tokyo 181-8588, Japan†

Extreme ultraviolet (EUV) emission line intensity ratios of highly charged ions can be used for thedensity diagnostics of the solar corona. For active regions such as flare plasmas, density-sensitive
emission line pairs that can be applied to the high-temperature and high-density ranges are needed.
Ions such as Ar XIII-XIV and Ca XV-XVII are candidates that are useful for the temperature range
Te > 3 MK [1,2].
We present EUV spectra of Ar XIV and Ca XV observed with two electron beam ion traps (EBITs),
the Tokyo-EBIT [3] and CoBIT [4]. The applicability of EUV line ratios in these ions to the density
diagnostics is examined through the comparison of collisional radiative model calculations with thespectra obtained with a well-defined EBIT plasma.
This work was supported by JSPS KAKENHI grant No. JP19H00665.
References[1] K. P. Dere et al., ApJ 40, 341 (1979)[2] N. Nakamura et al., ApJ 921, 115 (2021)[3] N. Nakamura et al., Phys. Scr. T73, 362 (1997)[4] N. Nakamura et al., Rev. Sci. Instrum. 79, 063104 (2008)

211

B76
Observation of vacuum ultraviolet transitions relevant toastrophysical plasmas with a compact electron beam ion trap
Masayoshi Hosoya† , Daiji Kato⇤,‡ , Nobuyuki Nakamura†,⇤Institute for Laser Science, The University of Electro-Communications, Tokyo, Japan⇤
National Institute for Fusion Science, Gifu 509-5292, Japan‡
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580,
Japan†

For the spectroscopic diagnostics of astrophysical hot plasmas, spectroscopic data for transitions inhighly charged ions are important. For example, the solar observation satellite HINODE observes
emissions in the extreme ultraviolet (EUV) range with an EUV imaging spectrometer (EIS) for the
diagnostics of the solar corona. In order to obtain the spectroscopic properties of transitions relevantto the diagnostics with EIS, we observe EUV transitions of HCIs [1-3] with the Tokyo electron beam
ion trap (Tokyo-EBIT) [4] and a compact electron beam ion trap (CoBIT) [5].
As a follow-on of EIS/HINODE, the Solar-C EUVST mission is currently proposed. In this mission,transitions of HCIs are planned to be observed for a wavelength range wider than that in EIS for
investigating not only the solar corona but also the chromosphere to the transition region. The planned
wavelength range spans from 17 to 285 nm, whereas the available wavelength range of the EUV
spectrometer that has been used for the Tokyo-EBIT and CoBIT is 5 to 30 nm. In order to extend
the observation range to a longer wavelength range, we have recently built a new vacuum ultraviolet(VUV) spectrometer useful up to 124 nm [6]. The performance of the new spectrometer and thespectra of ions relevant to the Solar-C EUVST mission, such as 46.5 nm of Ne VII, are presented.
This work was supported by JSPS KAKENHI Grant Number JP19H00665.
References[1] N. Nakamura et al., Astrophys. J. 739, 17 (2011)[2] E. Shimizu et al., Astron. Astrophys. 601, A111 (2017)[3] N. Nakamura et al., Astrophys. J. 921, 115 (2021)[4] N. Nakamura et al., Phys. Scr. T73, 362 (1997)[5] N. Nakamura et al., Rev. Sci. Instrum. 79, 063104 (2008)[6] N. Nakamura et al., J. Phys. Soc. Jpn 90, 114301 (2021)

212

AUTHOR INDEXAgababaev, V.
Agnihotri, A.
Ahuja, R.
Akamatsu, H.
Al Atawneh, S.
Alcocer-Avila, M.
Allgeier, S.
Amaro, P.
Ananyeva, A.
Andelkovic, Z.
Anisimova, I.
Arapoglou, I.
Arora, B.
Assink, L.
Aumayr, F.
Azuma, T.
Bai, X.
Bagdia, C.
Bai, X.
Ballance, C.
Banas, D.
Banducci, A.
Banerjee, S.
Beiersdorfer, P.
Ben Nasr, S.
Bender, M.
Benis, E.
Bennett, D.
Berengut, J.
Bergham, P.
Bernitt, S.
Beyer, H.

A18
A40
A40
A72
A39
A30
A08, ST-17
A16, A48, A49, A50, A51
B64
A08, A36, A66, A67, ST-17
A17
A61
A13
A47
A01
B21, B28, B31, B64, ST-3, ST-23
B07, ST-1
A41, B56
A69
B49
A10, A35, A36, A55, ST-7, ST-18
B74
A11
B35, B36
A24, A25, A26
A60
A35, A37, ST-7
B31, ST-23
PR-9
ST-18
PR-15, A08, A68, ST-17
A10, ST-18

213

Bhatt, K.
Bhatt, P.
Bhogale, A.
Biela-Nowaczyk, W.
Bijlsma, K.
Bilgen, S.
Blaum, K.
Blundell, S.
Borovik, A.
Borovik Jr., A.
Borschevsky, A.
Bozyk, L.
Brady, R.
Brage, T.
Brandau, C.
Brass, M.
Brauning, H.
Brauning-Demian, A.
Brewer, S.
Brickhouse, N.
Brown, G.
Bruijn, M.
Bussmann, M.
Cai, X.
Cao, S.
Cassimi, A.
Cavaletto, S.
Chakraborty, D.
Chamorro Mena, Y.
Champion, C.
Chartkunchand, K.
Chatterjee, S.
Chen, C.
Chen, D.
Chen, X.
Cheng, Z.

B55, ST-6
A42, ST-11
A41, A45
A48, A49
A47
A60
RL-3, A07, A61, A64, ST-12, ST-13
B33, B34, ST-24
A08, ST-17
A36
PR-10, A15
A65, ST-22
A70, A71, ST-9
B49
A35, A36, A48, ST-7
A07, ST-13
B64
A31, B64
B74
B37, B72
B35, B36
A72
A65, B08, B62, ST-21, ST-22
B45
B03, B06
A28, A29, A40
A57, ST-1
A41
A15
A30, B38
B64
A46
B07, B09, B18, B46, ST-1
B08, B46, B62, ST-21
B45
B45

214

Chesnel, J.
Chhimwal, D.
Chung, M.
Crespo LopezUrrutia, J.
Cui, Y.
Ding, X.
Debierre, V.
Delaney, B.
Deng, J.
Dergham, P.
Dijck, E.
Dipti
Dong, C.
Door, M.
Doriese, W.
Dorrer, H.
Dreiling, J.
Dubois, A.
Dullmann, C.
Durkin, M.
Duval, L.
Eckel, S.
Egl, A.
Eizenhofer, N.
Eliseev, S.
Enss, C.
Esponda, N.
Fan, J.
Fedotova, S.
Filianin, P.
Flechard, X.
Fleischmann, A.
Fogle, M.
Forstner, O.
Foster, A.

A31
A14
B70
A07, A50, A51, A62, A63, A68, ST-13, ST-14, ST-15
B45
B16, B17, ST-2
A07, ST-13
A70, A71, ST-9
B13
A01, A10
A62, A63, ST-14, ST-15
B01, B33, B34, B37, ST-4, ST-24
A74, A75, B03, B04, B06, B13, B15, B16, B17, ST-2
A07, A64, ST-12, ST-13
B31, ST-23
A07, ST-13
B33, B34, ST-24
A37
A07, ST-13
B31, ST-23
A03, A08, A10, ST-17, ST-18
B73
A61
A65, ST-22
A07, A64, ST-12, ST-13
A07, A08, A34, ST-13, ST-17
B38, B39, B40
B05
A66, A67
A07, A64, ST-12, ST-13
A28, A29, A40
A08, A34, ST-17
A36
A08, A35, ST-7, ST-17
B37, B72

215

Fowler, J.
Friedrich, M.
Fritzsche, S.
Frolov, A.
Fu, N.
Fuchs, S.
Fujii, K.
Fukushima, S.
Funaba, H.
Funabashi, M.
Gaigalas, G.
Gall, A.
Gao, J.
Gao, Y.
Gard, J.
Garg, D.
Gastaldo, L.
Geithner, W.
Gervais, B.
Ghosh, S.
Gillaspy, J.
Glazov, D.
Glorius, J.
Goto, M.
Gottardi, L.
Goyal, A.
Graf, A.
Grieser, M.
Grilo, F.
Grisenti, R.
Gu, M.
Guerra, M.
Guillous, S.
Gulyas, L.
Gumberidze, A.
Guo, D.

B31, ST-23
A08, ST-17
A20, A36
A59
B09, B18
A36, A48
A51
B32
B69
B58
B22
B37, B72
A72
B42, B48
B31, ST-23
A40
A07, ST-13
A66, A67
A28, A29
A46
B33, B34, ST-24
A20, A17, A18, A19, A21, A22
A08, A10, A35, ST-7, ST-17, ST-18
B27, B68, B69
A72
A12
A63, ST-15
A33, ST-16
A48, A49, A50, A51
A10, A35, ST-7, ST-18
A51
A16, B32
A28, A29, A40
B56
A08, A10, A31, A35, ST-7, ST-17, ST-18
B42, B48

216

Gwinner, G.
Ha, S.
Hagmann, S.
Hahn, C.
Hahn, M.
von Hahn, R.
Hanne, F.
Hannen, V.
Hara, H.
Harayama, S.
Harman, Z.
Hasegawa, N.
Hashimoto, T.
Haverkort, M.
Hayakawa, R.
He, S.
He, W.
Heise, F.
Hell, N.
Hengstler, D.
Henins, A.
Henninger, R.
den Herder, J.
Herdrich, M.
Herfurth, F.
Herkenhoff, J.
Hess, R.
Higashiguchi, T.
Hillenbrand, P.
Hilton, G.
Hocker, M.
Hoekstra, R.
Hoffer, P.
Holloway, C.
Horst, M.
Hosier, A.

B33, B34, ST-24
B45
A35, ST-7
A08, A31, ST-17
B35, B36
A33, ST-16
A61
A36, A65, ST-22
B75
B64
A04, A05, A07, A11, A33, A36, A56, A57, ST-1, ST-13, ST-16
B71
B31, ST-23
A07, ST-13
B31, ST-23
B03, B06
A75, B04
A61
B35, B36
A08, A34, ST-17
B74
A63, ST-15
A72
A08, A34, A35, ST-7, ST-17
A08, A36, A66, A67, ST-17
A07, A64, ST-12, ST-13
A36
B63, B66, B67, B71, ST-8
A08, A10, A35, ST-7, ST-17, ST-18
B31, ST-23
A61
A47
A59
B73
A65, A66, A67, ST-22
B01, B33, B34, B37, ST-4, ST-24

217

Hosoya, M.
Hu, Z.
Huang, H.
Huang, L.
Huang, Z.
Hutton, R.
Ichinohe, Y.
Illescas, C.
Imai, M.
Imaizumi, S.
Imgram, P.
Inadome, K.
Indelicato, P.
Isberner, L.
Ishino, M.
Iskander, W.
Isobe, T.
Ito, Y.
Iwami, R.
Iwasaki, Y.
Jagodzinski, P.
Jelassi, H.
Jia, M.
Jiang, J.
Jiawei, Z.
Jinh, T.
Johzaki, T.
Jolly, M.
Jorge, A.
Jung, Y.
Jyoti
Kadyrov, A.
Kalinin, A.
Kalosi, A.
Kanda, S.
Kasthurirangan, S.

B60, B76
PR-3
B10, B46, B47
B05
B02, B10, B08, B19, B46, B47, B62, ST-21
B07, B49, ST-1
B31, ST-23
A52
B51
B22
A09, ST-25
B58
A03, A07, A10, B31, B32, ST-13, ST-18, ST-23
A33, ST-16
B71
A40
B31, ST-23
B32
B25
B50
A10, ST-18
A24, A25, A26
B15
B15
B71
B71
B66
A31
PR-2, A52
B54
A13
A27, B41
A08, B64, ST-17
A33, ST-16
B31, ST-23
A53, ST-2

218

Kato, D.
Katsuragawa, M.
Kawamoto, Y.
Kawamura, N.
Kawasaki, H.
Kawate, T.
Kawatsura, K.
Kayani, A.
Kaygorodov, M.
Keitel, C.
Khan, A.
Kiefer, D.
Kiffer, M.
Kimura, N.
Kino, Y.
Kishimoto, M.
Kiyama, G.
Klammes, S.
Kleffner, C.
Kleinsmit, A.
Koike, F.
Kolacek, K.
Komaki, K.
Kominato, N.
Konig, C.
Konig, K.
Kono, Y.
Kosheleva, V.
Kotov, A.
Kozhedub, Y.
Kozhuharov, C.
Krantz, C.
Kroger, F.
Kromer, K.
Kubullek, M.

B17, B20, B22, B23, B24, B25, B26, B27, B29, B30, B31, B58, B60,
B68, B75, B76, ST-2, ST-19, ST-23
B31, ST-23
B27, B68, B69
B31, ST-23
B63, B67, ST-8
B20, B27, B68, B69
B51
B55, ST-6
A17, A23, B02, B19
A04, A05, A07, A33, A56, A57, ST-1, ST-13, ST-16
A44
A65, ST-22
A08, ST-17
B21, B28, B64, ST-3
B31, ST-23
B66, B71
B28
A65, ST-22
B64
A47
B17, B23, ST-2
A59
B51
B31, ST-23
A61
A09, B64, ST-25
B75
A20
A19
A17, A23, B02, B19, B45
A36
A33, A36, ST-16
A08, ST-17
A07, A64, ST-12, ST-13
A08, ST-17

219

Kuehl, T.
Kuhn, S.
Kuma, S.
Kumar, A.
Kumar, K.
Kumar, S.
Kumar, V.
Kumari, P.
Kume, M.
Kumeda, C.
Kuntz, P.
La Mantia, D.
Lalande, M.
Lalkens, E.
Lamour, E.
Lange, D.
Langfeld, B.
Laoutaris, A.
Lapierre, A.
Larouze, A.
Lee, M.
Lepson, J.
Lepy, M.
Lestinsky, M.
Levallois, R.
Levin, A.
Levy, A.
Li, B.
Li, H.
Li, J.
Li, M.
Li, P.
Li, W.
Lindroth, E.
Litvinov, Y.
Liu, Ji.

A65, ST-22
A51, A68
B21, ST-3
A42, ST-11
A43, A44
A28, A29
A14
A42, ST-11
B63, B67, ST-8
B66
A08, ST-17
A49, B01, B55, B73, B74, ST-4, ST-6
A28, A29
A47
A01, A10, A31, A60, ST-18
A07, A64, ST-12, ST-13
A65, ST-22
A37
B33, B34, ST-24
A30, B38
B54
B35, B36
B32
PR-8, A08, A31, A35, A36, A48, ST-7, ST-17
A60
A73
A31, A60
B18, B44
B03, B06
B05, B46
B06
B43, B45
B07, B49, ST-1
A36
A10, A35, B64, ST-7, ST-18
B05

220

Liu, Ju.
Liu, X.
Liu, Z.
Loetzsch, R.
Loher, B.
Loser, M.
Lu, H.
Lu, Q.
Lyu, C.
Ma, T.
Ma, W.
Ma, X.
Ma, X.M.
Ma, Y.
Maas, B.
Mace, S.
Machado, J.
Madesis, I.
Majima, T.
Majkic, M.
Malyshev, A.
Manai, S.
Mao, L.
Marques, J.
Matsuda, M.
Matsumoto, J.
Matsushita, K.
Maurya, S.
McCormack, T.
Meisner, J.
Mendez, L.
Menesguen, Y.
Menk, S.
Menz, E.
Mery, A.

B43, B45
B02, B46
B43
A10, ST-18
A08, ST-17
A65, ST-22
B03
B02, B09, B18
A07, A56, A57, ST-1, ST-13
A75, B04
B02, B10, B46, B47
A36, A65, B02, B08, B10, B19, B42, B46, B47, B48, B62, ST-21,
ST-22
B46
A74, B13
A09, ST-25
A01, A31
A03, A16
A37
B53
A55
A17, A19
A24, A25, A26
B08, B10, B46, B62, ST-21
A50, A51, B32
B51
A40, B50
PL-1
A41, A45
A69
B64
A47, A52
B32
B64
A08, A35, A36, A48, ST-7, ST-17
A28, A29, A31, A40

221Mikami, N.
Min, Q.
Mirkovic, M.
Misra, D.
Mita, M.
Mitra, D.
Miyake, Y.
Mohr, K.
Moneta, M.
Mongey, K.
Monti, J.
Morgan, K.
Morgner, J.
Moribayashi, K.
Morita, H.
Morita, S.
Mukherjee, J.
Mukherji, J.
Muller, A.
Muller, P.
Muller, R.
Murakami, I.
Murakami, K.
Murty, M.
Nagayoshi, K.
Naing, A.
Nair, L.
Najjari, B.
Nakamura, N.
Nakano, Y.
Nakao, T.
Nakayama, Y.
Namba, S.
Nandi, T.

B65
B03, B06
A55
A43, A44
B30, ST-19
A46
B31, ST-23
B64
A54
A70, A71, ST-9
A30, B38, B39, B40
B31, ST-23
A61
B52
B63, B67, ST-8
B68
A44
A43
A36
A09, ST-25
A06
B17, B20, B22, B23, B25, B26, B27, B30, B58, B68, B75, ST-2,
ST-19
B66
A44
A72
B01, B33, B34, B37, B74, ST-4, ST-24
A14
B42
B17, B20, B21, B22, B23, B24, B25, B26, B28, B29, B30, B58, B59,
B60, B75, B76, ST-2, ST-3, ST-19
B64, B65
B53
B63, B67, ST-8
B63, B66, B67, B71, ST-8
A46

222

Nanos, S.
Nauta, J.
Nedeljkovic, N.
Nefiodov, A.
Neidherr, D.
Neijzen, B.
Niggas, A.
Niinuma, T.
Nishida, N.
Nishikino, M.
Nishimura, Y.
Nishino, R.
Nishio, K.
Niu, B.
Niu, S.
Noda, H.
Norrgard, E.
Nortershauser, W.
Novikov, Y.
Novotny, O.
O’Neil, G.
O’Reilly, F.
Oelmann, J.
Ohashi, H.
Ohiro, H.
Ohnishi, H.
Oishi, T.
Okada, S.
Okada, R.
Okayasu, S.
Okumura, T.
Okutsu, K.
Oliva, E.
Oomamiuda, H.
Oreshkina, N.
Osawa, T.

A35, A37, ST-7
A62, ST-14
A55
A73
A66, A67
A47
PR-4
B67, ST-8
B59
B71
B22
B65
B51
B05
A75, B04, B13, B15
B31, ST-23
B73
A09, A65, A66, A67, B64, ST-22, ST-25
A07, ST-13
A33, ST-16
B31, B33, B34, ST-23, ST-24
A69, A70, A71, ST-9
A62, ST-14
B24, B25, B26
B66
B65
B23, B27, B68, B69
PR-14, B31, ST-23
B59
B51
B31, ST-23
B31, ST-23
A59
B31, ST-23
PR-13, A05
B31, ST-23

223

Over, T.
Ovsyannikov, V.
O’Neil, G.
O‘Sullivan, G.
Park, S.
Pan, J.
Parente, F.
Passalidis, S.
Passon, S.
Pasteka, L.
Paul, D.
Paul, N.
Paulus, G.
Petridis, N.
Pfafflein, P.
Pfeifer, T.
Plunien, G.
Polasik, M.
Prajapati, N.
Prigent, C.
Priti
Qian, Y.
Quint, W.
Quinto, M.
Rabadan, I.
Rai, S.
Rajput, J.
Ralchenko, Y.
Ramillon, J.
Ramzdorf, A.
Rangama, J.
Rausch, S.
Reintsema, C.
Renitsch, D.
Ridder, M.
Ringleb, S.

A08, ST-17
A73
B37
B63, B67, ST-8
B70
A74
B32
A37
B64
A15
A33, ST-16
A03, A10, B31, ST-18, ST-23
A10, ST-18
A08, A10, A35, ST-7, ST-17, ST-18
A08, A35, ST-7, ST-17
A62, A62, A63, ST-14, ST-15
A19, A22
B32
B73
A01, A31, A60
B21, B28, B30, B58, ST-19, ST-3
B05
A14
A30, B38, B39, B40
A47
A47
PR-1, A40, A42, ST-11
B01, B33, B34, B37, ST-4, ST-24
A31
A73
RL-6, A28, A29, A31, A40
A66, A67
B31, ST-23
A07, ST-13
A72
A08, ST-17

224

Rischka, A.
Rivarola, R.
Rosner, M.
Rothard, H.
Rousseau, P.
Rui, J.
Ryzhkov, A.
Rzadkiewicz, J.
Slabkowska, K.
Safronova, M.
Safvan, C.
Sailer, T.
Saito, M.
Sakaue, H.
Sakurai, M.
Salhi, D.
Salverda, M.
Sampaio, J.
Sanchez, R.
Sanders, S.
Sanjari, S.
Santos, J.
Sasaki, A.
Sataka, M.
Sato, T.
Sattonnay, G.
Savin, D.
Scheidel, M.
Schippers, S.
Schmidt, D.
Schmidt, J.
Schmidt, P.
Schramm, U.
Schuch, R.
Schultz, D.

A07, A64, ST-12, ST-13
B38, B39, B40
A62, A63, ST-14, ST-15
A35, ST-7
PR-7, A31
A74, A75, B04
A22
B32
B32
RL-5
A14, A40, A42, ST-11
A61
B53
B17, B20, B22, B24, B25, B26, B27, B29, B30, B58, B68, B75,
ST-2, ST-19
B59
A24, A25, A26
A47
B32
A65, ST-22
B33, B34, ST-24
A35, ST-7
A50, A16, A51, B32
B27
B51
B31, ST-23
A60
B35, B36
A10, ST-18
A33, A36, A48, B19, ST-16
B31, ST-23
A59
RL-4
A65, ST-22
A36, A74, B45
B37

225

Schury, D.
Schussler, R.
Schweiger, C.
Sekiguchi, Y.
Shabaev, V.
Shah, C.
Shao, C.
Shibata, H.
Shiina, Y.
Shimomura, K.
Shin, B.
Shiromaru, H.
Si, R.
Siddiki, A.
Sidhu, R.
Siebold, M.
Sikora, B.
Silver , E.
Silwal, R.
Simons, M.
Singh, N.
Singh, S.
Skopinski, L.
Smith, R.
Sokell, E.
Sommerfeldt, J.
Song, D.
Song, L.
Song, Z.
Soutome, K.
Spiller, P.
Spillmann, U.
Stabrawa, I.
Stallkamp, N.
Stark, J.
Steck, M.

A31
A07, ST-13
A07, A64, ST-12, ST-13
B22
A17, A18, A19, A22
A51
B43, B45
B51
B65
B31, ST-23
B70
B50
B07, ST-1
A43, A44
A08, A10, A32, ST-17, ST-18
A65, ST-22
A04, A05
B72
B33, B34, ST-24
B73
A12
A33, ST-16
PR-5
B37, B72
A69, A70, A71, ST-9
A06, A58, ST-5
B24, B25
B07, ST-1
B43, B45, B57
B59
A65, ST-22
A08, A10, A31, A35, A36, B64, ST-7, ST-17, ST-18
A55
A66, A67
A62, ST-14
A36, A65, B64, ST-22

226

Steinbrugge, R.
Steydli, S.
Stodel, C.
Stöhlker, T.
Strasser, P.
Strnat, S.
Sturm, S.
Su, M.
Suda, H.
Sugiura, T.
Sun, D.
Sunahara, A.
Suraud, E.
Surzhykov, A.
Suzuki, C.
Swetz, D.
Syrocki, L.
Szary, K.
Szypryt, P.
Tokesi, K.
Takacs, E.
Takahashi, H.
Takahiro, K.
Takasu, R.
Takeda, S.
Takeru, T.
Takeshita, S.
Tamaki, S.
Tampo, M.
Tamura, N.
Tan, J.
Tanaka, M.
Tang, M.
Tanis, J.
Tanuma, H.

A51, A68
A01, A10, A31, A60, ST-18
A60
A08, A10, A31, A34, A35, A36, A48, A65, B64, ST-7, ST-17,
ST-18, ST-22
B31, ST-23
A58, ST-5
A61, A64, ST-12
B03, B06
B31, ST-23
B63
B03, B06
B63, B66, B67, ST-8
A53, ST-2
A06, A36, A58, ST-5
B23
B31, ST-23
B32
A10, ST-18
B01, B33, B34, B37, ST-4, ST-24
A38, A39
B01, B33, B34, B37, B72, ST-4, ST-24
B69
B51
B53
B31, ST-23
B63
B31, ST-23
B65
B31, ST-23
B23
B01, B33, B34, B37, B74, ST-4, ST-24
B22
B46
A49, B55, ST-6
B22

227

Taralli, E.
Tatsuno, H.
Tian, H.
Tochio, T.
Togawa, M.
Tong, X.
Toyama, Y.
Trabert, E.
Trassinelli, M.
Tribedi, L.
Trotsenko, S.
Tsuchida, H.
Tu, B.
Tupitsyn, I.
Ueberholz, K.
Ueno, Y.
Ullom, J.
Umezaki, T.
Uschmann, I.
Vaccaro, D.
Valuev, I.
Velthaus, V.
Vernhet, D.
Versolato, O.
Veshapidze, G.
Villari, A.
Vlaicu, A.
Vockert, M.
Vogel, M.
Voikopoulos, S.
Volchkova, A.
Volotka, A.
Vorobjev, G.
Vorobyev, G.
Wada, M.
Walther, T.

A72
B31, ST-23
B07, ST-1
B32
A68
B31, ST-23
B31, ST-23
B35, B36
A01, A02, A03, A10, A31, A36, A60, ST-18
A41, A43, A44, A45, A53, B56, ST-2
A08, A10, A34, A35, A66, A67, ST-7, ST-17, ST-18
B53
A61
A17
A65, ST-22
B31, ST-23
B31, ST-23
B20
A10, ST-18
A72
A05
A60
A01, A31
RL-2, A47
B50
B33, B34, ST-24
B32
A35, ST-7
A14
A31
A18, A22
A20, A18, A23, B19, B20
A66
A36, A67
B28
A65, B08, B62, ST-21, ST-22

228

Wan, C.
Wanajo, S.
Wang, H.
Wang, J.
Wang, K.
Wang, S.
Wang, W.
Wang, Y.
Warczak, A.
Warnecke, C.
Watanabe, S.
Weber, G.
Weder, E.
Wehrheim, M.
Wei, B.
Weigel, A.
Weinheimer, C.
Wen, W.
Werl, M.
Wilhelm, R.
Winters, D.
de Wit, M.
Wolf, A.
Wolf, R.
Wolff, P.
Wolff, W.
Wong, N.
Wu, Z.
Xiao, J.
Xie, L.
Xie, Y.
Xu, G.
Xu, Y.
Xue, Y.
Yadav, F.
Yadav, J.

B45
B22
A65, B08, B10, B19, B46, B47, B62, ST-21, ST-22
B66, B71
B09, B19
B02, B10, B19, B46, B47
B43, B45
B05
A08, A48, A49, ST-17
A62, A63, ST-14, ST-15
B31, ST-23
A08, A10, A34, A35, ST-7, ST-17, ST-18
B32
A62, A63, ST-14, ST-15
PR-6
A61
A65, ST-22
A65, B02, B08, B10, B19, B46, B47, B62, ST-21, ST-22
A01
A01
A65, B08, B62, ST-21, ST-22
A72
A33, ST-16
A61
A47
PR-11, A28, A29
A70
B19
B02, B07, B09, B18, ST-1
A74, A75, B04, B13, B15
B18
B02, B07, B09, ST-1
B17, ST-2
B16, B43, B45
A12A42, ST-11

229

Yamada, I.
Yamada, S.
Yamamoto, N.
Yamasaki, K.
Yamashita, M.
Yamashita, T.
Yan, C.
Yan, S.
Yang, B.
Yang, J.
Yang, Y.
Yang, Y.
Yang, Z.
Yao, K.
Yerokhin, V.
Yu, D.
Yu, Y.
Yuan, H.
Yuan, Y.
Zhou, P.
Zhang, C.
Zhang, D.C.
Zhang, D.H.
Zhang, H.Q.
Zhang, H.
Zhang, L.
Zhang, M.
Zhang, R.
Zhang, S.
Zhang, Y.
Zhao, D.
Zhao, R.
Zhou, X.
Zhou, Y.
Zhu, B.
Zhu, L.

B69
B31, ST-23
B29, B75
B66, B71
B32
B31, ST-23
B02, B09, B18, B46
PR-12
B43, B45
B08, B10, B46, B62, ST-21
B07, B17, ST-1, ST-2
B01, B33, B34, B37, B72, ST-4, ST-24
B45
B05, B17, B45, ST-2
A04, A06
B16, B43, B45
B12
B45
B08, B10, B46, B62, ST-21
B11
B46
B08, B62, ST-21
B16
B43, B45
B45
B17, ST-2
B16, B43, B45
B42, B48
B10, B42, B47, B48
A36
B42
B16
B02
B46
A08, A32, B47, ST-17
B19, B46, B47

230

Zhu, X.
Ziaeian, I.
Zinenko, D.
Zou, Y.
Zouros, T.

B42, B48
A38
A20, A22
B05, B07, B09, B18, ST-1
A37

231

Post-Post-Deadline Abstracts

A76
Enhanced double and triple ionization of coronene incollisions with low energy protons
Sanjeev Kumar Maurya, Shashank Singh, Chandan Bagdia, Lokesh C Tribedi*
Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India*Email: lokesh@tifr.res.in

The ionization and fragmentation of the polycyclic aromatic hydrocarbons (PAHs) molecules haveattracted special attention due to its importance and abundances of these molecules in the interstellar
medium (ISM) and stellar wind [1–3]. In the present study, the ionization and fragmentation of a PAH
molecule, coronene (C24H12), have been investigated upon impact of proton beam with energies in
the range 30 – 300 keV using a recoil ion momentum spectrometer. This is a two-stage WileyMcLaren type spectrometer with a slight modification by employing a lens in between acceleration
region and the drift tube to obtain higher momentum resolution and larger angular acceptance [4].
Here, two channel electron multipliers (CEMs) are used as the detectors to study the electron-ion
coincidence where electron-CEM provides the start signal and ions are collected in the ion-CEM
gives the stop signal within a chosen range of 20 µs. In the time-of-flight spectrum, single, double,
and triple ionization of coronene with evaporation peaks due to the C2 losses are observed. The double
ionized recoil ion production channel (“doubly ionized”) is found to be the most prominent channel
and the ratio of double to single ionization of coronene is found to decrease with beam energy.
However, in the doubly ionized recoil ion production the TI is also included. The ratios are found tobe significantly large in comparison to previously reported results for the gas target (He and Ne) as
well as PAH molecule such as Fluorene [5]. The ratio of double-to-single ionization is found to be
as large as ~ 3.6 at the lowest energy studied and then reduced to about 1.6 for the highest energy.
Similarly, the 3+/1+ ratio was also found to be more than 1.0. At lowest energy it was ~ 2.0 which
reduced to about 0.7 at higher energy. These ratios are even higher than those observed for a smaller
sized PAH molecule, such as, fluorene. This unexpectedly large doubly or triply ionized recoil-ionsof the PAH molecules could be related to the highly correlated electron cloud and possible plasmonicstates excited during the collisions. The details will be presented.

References[1] A.G.G.M. Tielens, Rev. Mod. Phys. 85, 1021 (2013).
[2] A. Tielens, Annu. Rev. Astron. Astrophys. 46, 289 (2008).
[3] M. L´opez-Puertas, B. Dinelli, A. Adriani, B. Funke, M. Garc´ıa-Comas, M. Moriconi, E.
D’Aversa, C. Boersma, L. Allamandola, Astrophys. J. 770, 132 (2013).
[4] S. Biswas and L. C. Tribedi, Rev. Sci. Instrum., 92, 123304 (2021).
[5] C. Bagdia, S. Biswas, A. Mandal, S. Bhattacharjee, and L. C. Tribedi, EPJ D 75, 37(2021).

A77
Towards Intrinsic Doppler Correction for Precision X-Ray Spectroscopy at
CRYRING@ESR
F. M. Kröger1,2,3 , S. Allgeier4 , Z. Andelkovic3 , S. Bernitt1,2,3 , A. Borovik, Jr.5 , N. Dulaev6 ,L. Duval7 , A. Fleischmann4 , O. Forstner1,2,3 , M. Friedrich4 , J. Glorius3 , A. Gumberidze3 ,Ch. Hahn2,3 , F. Herfurth3 , D. Hengstler4 , M. O. Herdrich1,2,3 , P.-M. Hillenbrand3 , A. Kalinin3 ,M. Kiffer1,2,3 , M. Kubullek1 , P. Kuntz4 , M. Lestinsky3 , B. Löher3 , E. B. Menz1,2,3 , T. Over1,2,3 ,N. Petridis3 , Ph. Pfäfflein1,2,3 , S. Ringleb1,2,3 , R. S. Sidhu3 , V. M. Shabaev6 , U. Spillmann3 ,S. Trotsenko2,3 , I. Tupitsyn6 , A. Warczak8 , G. Weber2,3 , B. Zhu1,2,3 , C. Enss4 , Th. Stöhlker1,2,3
1Friedrich-Schiller-Universität Jena, Jena, Germany
2
Helmholtz Institute Jena, Jena, Germany
3
GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
4
Kirchhoff Institute for Physics, Heidelberg University, Heidelberg, Germany
5
I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen, Germany
6
Department of Physics, St. Petersburg State University, St. Petersburg, Russia
7
Laboratoire Kastler Brossel, Sorbonne Université, Paris, France
8
Jagiellonian University, Kraków, Poland
We will report on the application of novel metallic magnetic calorimeter (MMC) detectors for highresolution x-ray spectroscopy at the electron cooler of the low energy storage ring CRYRING@ESR
at GSI, Darmstadt [1]. Within this experiment, the x-ray emission associated with radiative recombination of cooler electrons and stored hydrogen-like uranium ions was studied with the particularfocus on the K-shell ground-state transitions in helium-like uranium (∼ 98 keV). For this purpose,
two MMC detectors of the type maXs [2], developed within the SPARC collaboration, were placed
under 0◦ and 180◦ with respect to the ion beam axis. Special emphasis will be given to the region of
the M, N→L transitions, which was investigated with a resolution unreached by solid state detectors.
This gave experimental access to the population of specific excited states of U90+ , which for the firsttime could be compared to theoretical predictions, consisting of a detailed simulation of the radiative
recombination and the subsequent decay cascades [3]. Moreover, when assuming that the energy of atleast a few of the recorded transitions is well-known, their observed Doppler shift can be used to determine the ion beam velocity directly from the spectrum. This allows to perform an intrinsic Doppler
correction using only spectral information. A detailed comparison with the conventional method to
conduct the Doppler correction using electron cooler parameters will be discussed.

References[1] Ph. Pfäfflein et al., arXiv:2202.00319 [physics.ins-det] (2022)[2] D. Hengstler et al., Phys. Scr. 2015, 014054 (2015)[3] B. Zhu et al., Phys. Rev. A 105, 052804 (2022)
Note: The results presented are based on work performed in 2021.

B77
4f Photoabsorption in Pt+ to Pt4+.
Eric Doyle, Gerry O’Sullivan, Patrick Hayden, Emma Sokell and Padraig Dunne.
School of Physics, University College Dublin, Belfield, Dublin 4. Ireland.

Detailed knowledge of the inner-shell atomic structure of lowly-ionised species is lacking for mostelements along the 6th row of the Periodic Table, from hafnium to bismuth. This paper presents 4fphotoabsorption spectra of Pt+ to Pt4+ ions, recorded between 9 nm and 18 nm using the dual laser
plasma (DLP) method. Analysis of the spectra was supported by atomic structure calculations using
the Cowan suite of codes, by relativistic time-dependent local density approximation (RTDLDA)
calculations and by comparison along isoelectronic series, particularly with spectra of lowly-ionised
gold plasmas [1]. The spectra show 4f-5d and 4f-6d transitions, broadened by autoionisation
The output of a Q-switched neodymium yttrium aluminium garnet (Nd:YAG) laser (1 Hz, 0.8 J in 6ns) was focused through a plano-convex lens to a 0.5-mm spot on a platinum target to generate aplasma containing the ions of interest. After a variable time delay (30 or 60 ns), a second, similar
laser was focused to maximum intensity (circa 1012 W/cm2) on a tungsten target, to provide an
extreme ultraviolet (XUV) continuum [2]. By increasing the delay between the formation of theplasma containing the platinum ions and the continuum emitted by the second plasma it is possible
to probe successively lower platinum ion stages.
The experimental spectrum recorded at an inter-plasma delay of 30 ns allowed multiple discrete
absorbing features to be optimized in terms of intensity and contrast. Pronounced peaks at 70-75
eV are followed by smaller discrete features at 77 eV and 82 eV and thereafter by a series of strong,well-defined peaks between 90 and 112 eV. Identification of these features, supported by the
Cowan code calculations is summarised as: 4f - 5d transitions are located below 90 eV and 4f - 6dtransitions are found at higher energies, above 90 eV.

References[1] M.G. Su, C.Z. Dong, N. Murphy, G. O’Sullivan, Phys. Rev. A 79, 042507 (2009).
doi:10.1103/PhysRevA.79.042507.
[2] G. O’Sullivan, P. Carroll, P. Dunne, R. Faulkner, C. McGuinness, N. Murphy, J. Phys. BAtomic, Molecular and Optical Physics. 32, 1893-1922 (1999) doi:10.1088/0953-4075/32/8/310