Quantum Beam Application for Sciences
and Industres2023
24-27 April 2023
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Quantum Beam Applicationfor Sciences and Industries ����SANKEN, Osaka University JAPAN&33'.HII)))D.-2J*2D(.-J-!1D-7DK'ILMGE<ENONPCALL FOR PAPERS
Invited Speakers

International Committee

Mei Bai, SLAC/"E3-29(+6"C2$AD"QCEGR"""
Laurent Berthe/"S<==/">@TE"Q:+-27*R
Liming Chen/"E&-2%&-$"F$-("U(2%"C2$AD"Q>&$2-R
Min Chen/"E&-2%&-$"F$-("U(2%"C2$AD"Q>&$2-R
Marie-Emmanuelle Couprie/"EV8;<8"E?27&+(3+(2"Q:+-27*R
Eric Esarey/"8-)+*27*"M*+J*,*?"@-3$(2-,"8-5D"QCEGR
Domenico Furfari/"G$+51."V'*+-3$(2."W45#"QW*+4-2?R
Spencer Gessner/"E8G>/"E3-29(+6"C2$AD"QCEGR"""
Noboru Hasegawa/"XSE</"LEUQF-'-2R
Yusuke Ito/"C2$AD"U(J?("QF-'-2R
Takayasu Kawasaki/"X;X"QF-'-2R
Thomas Kluge/"#*,4&(,3Y!Z*23+14"[+*.6*2!T(..*26(+9"QW*+4-2?R
Masahiko Koizumi/"V.-J-"C2$AD"QF-'-2R
Rodrigo Lopez-Martens/"8VG/";7(,*"S(,?3*7&2$01*"Q:+-27*R
Fesseha Mariam/"8(."G,-4(."@-3$(2-,"8-5D"QCEGR

Kiminori Kondo/"XSE<"LEU"QF-'-2R

Haruo Miyadera/"U(.&$5-";2*+%?"E?.3*4."\"E(,13$(2.">(+'(+-3$(2"QF-'-2R

Omar Hatamleh/"@GEG"F(&2.(2"E'-7*">*23*+"QCEGR

Takeharu Nagai/"V.-J-"C2$AD"QF-'-2R

Laurent Berthe/"S<==/">@TE"Q:+-27*R

Tomas Mocek/"#$8GE;"Q>Y*7&"T*'DR

Ralph Assmann/"[;E^"QW*+4-2?R

Keiichi Nakagawa/"C2$AD"U(J?("QF-'-2R

Sergei Bulanov/";8<!M*-4,$2*."Q>Y*7&"T*'DR

Kei Nakamura/"8-)+*27*"M*+J*,*?"@-3$(2-,"8-5D"QCEGR

Victor Malka/"_*$Y4-22"<2.3$313*"(9"E7$*27*"Q<.+-*,R

Makoto Ochiai/"U(.&$5-";2*+%?"E?.3*4."\"E(,13$(2.">(+'(+-3$(2"QF-'-2R

Jerome Faure/"8VG/";7(,*"S(,?3*7&2$01*"Q:+-27*R

Yoshie Otake/"T<X;@"QF-'-2R"""

Rodrigo Lopez-Martens/"8VG/";7(,*"S(,?3*7&2$01*"Q:+-27*R

Tomokazu Sano/"V.-J-"C2$AD"QF-'-2R

Marie-Emmanuelle Couprie/"EV8;<8"E?27&+(3+(2"Q:+-27*R

Takashi Sekine/"#-4-4-3.1"S&(3(2$7."XDXD"QF-'-2R

Leonida A. Gizzi/"<@V!>@T"I"<@:@"Q<3-,?R

Antoine Snijders/"8-)+*27*"M*+J*,*?"@-3$(2-,"8-5D"QCEGRMin Chen/"E&-2%&-$"F$-(3(2%"C2$AD"Q>&$2-R"

Kentaro Uesugi/"FGET<"QF-'-2R

François Sylla/"E(1+7*8GM!8-.*+"S,-.4-"U*7&2(,(%$*."Q:+-27*R

Takunori Taira/"T<X;@/"ES+$2%!]"I"<=E"QF-'-2R
Tohru Sekino/"V.-J-"C2$AD"QF-'-2R
Takeharu Nagai/"V.-J-"C2$AD"QF-'-2R
Takayoshi Suzuki/"V.-J-"C2$AD"QF-'-2R
Takahiro Kozawa/"V.-J-"C2$AD"QF-'-2R
Kunihiko Nishino/"V.-J-"C2$AD"QF-'-2R
Hidekazu Tanaka/"V.-J-"C2$AD"QF-'-2R
Shinichiro Tanaka/"V.-J-"C2$AD"QF-'-2R
Tomokazu Sano/"V.-J-"C2$AD"QF-'-2R
Kazuto Arakawa/"E&$4-2*"C2$AD"QF-'-2R
Mitsuhiro Yoshida/"X;X"QF-'-2R
Takamitsu Otsuka/"C3.12(4$?-"C2$AD"QF-'-2R
Tomas MoceJ/"#$8GE;"Q>Y*7&"T*'DR"
Domenico Furfari/"G<TMCE"V'*+-3$(2."W45#"QW*+4-2?R

Yasunobu Yamashita/"V.-J-"C2$AD"QF-'-2R

Local Committee
Conference Chairs+,-%&."(*/"<=E"I"EG@X;@/"V.-J-"C2$AD"QF-'-2R"I"S+(%+-4"=-2-%*+/"FEU!=$+-$"S+(%+-4/*0*("*&1*#*$"%/"
EG@X;@/"V.-J-"C2$AD"I"
T<X;@/"ES+$2%!]"QF-'-2R!"#"$%&'"()*/"XSE</"LEU"QF-'-2R

Yoshio Mizuta/"V.-J-"C2$AD"QF-'-2R

Masayo Suzuki/"=$+-$"I"<=E"QF-'-2R

Yoshihide Honda/"V.-J-"C2$AD"QF-'-2R

Atsushi Ueguri/"=$+-$"I"<=E"QF-'-2R

Nanami Fujita/"V.-J-"C2$AD"QF-'-2R

Rie Sumiya/"=$+-$"I"<=E"QF-'-2R

Hisaaki Kato/"V.-J-"C2$AD"I"TG<E"QF-'-2R

Conference Organizers

1

Ofﬁcial Supporters

April 24 (MON)Time

Session / Chair

10:00 - 10:30(each 5 - 10min)

Opening

No.

(Chaired by Y. SANO, T. HOSOKAI and M. KANDO)
10:30 -11:00

Application of high-power lasers

Invited(Chaired by Y. SANO)

24A-01

Speaker
Conference Chair

Affiliation

Tohru SEKINOSANKEN, Osaka U., Japan

Hiroyuki KAMAI

MEXT, Japan

Domenico FURFARI

Airbus, Germany

Application of high-power lasers(Chaired by K. NOMURA)
LUNCH TIME

12:30 - 14:00
14:00 -14:30
Invited14:30 - 15:00
Invited
15:00 -15:30
InvitedGreetings from MEXT (Ministry of Education, Culture, Sports, Science and Technology)
The use of Lights for Structural Performance Enhancement of Metallic Airframes. LEOPARD, a Laser Shock Peening industrial
solution for Maintenance Repair Overhaul Use

Laser-material interaction for science and industry(Chaired by T. MOCEK)

24A-02

Laurent BERTHE

PIMM, CNRS, France

24A-03

Noboru HASEGAWA

KPSI, QST, Japan

New advance on laser shock generation and related applications : Laser shock peening, laser adhesion test and damaging
Development of a laser hammering system for tunnel and bridge concrete inspection using the high-power lasers

12:30 ～ Group Photo
24P-01

Kenichi ISHIKAWA

U. of Tokyo, Japan

Building Artificial Intelligence, Science and Theory for Smart Laser Manufacturing

24P-02

Yusuke ITO

U. of Tokyo, Japan

Ultrafast processing of transparent materials by selective absorption of continuous-wave laser into transiently excited electrons

24P-03

Tomokazu SANO

Osaka U., Japan

Femtosecond Laser-Shock Processing: Fundamentals and Applications

Break

15:30 - 16:00
16:00 -16:30
Invited
16:30 - 17:00
Invited
17:00 -17:30
Invited17:30 -18:00
InvitedWelcome to SANKEN, Osaka University

Break

11:00 -11:30
11:30 -12:00
Invited
12:00 - 12:30
InvitedTitle of talkOpening, welcome to Q-BASIS 2023

Quantum beams for material science and industry(Chaired by T. SANO)
High-power laser development and applications(Chaired by S. TOKITA)

24P-04

Makoto OCHIAI

Toshiba ESS, Japan

24P-05

Kentaro UESUGIJASRI, Japan

Achievements and future expectations of laser applications for energy solutions

24P-06

Tomas MOCEKHiLASE, Czech Rep.

24P-07

Takashi SEKINE

25A-01

Speaker
Haruo MIYADERA

25A-02Fesseha MARIAM

LANL, USAThe LANL Proton radiography Facility and Investigations toward Achromatic Imaging

25A-03

Yoshie OTAKERIKEN, JapanRIKEN Accelerator-driven compact neutron system and its applications and achievements

High speed 2D/3D X-ray imaging at SPring-8
Advanced DPSSL technologies and applications at HiLASE

Hamamatsu Photonics, Japan A 100 J, 10 Hz operation with LD pumped Yb:YAG ceramics laser

April 25 (TUE)Time
9:00 - 9:30
Invited
9:30 - 10:00
Invited
10:00 - 10:30
InvitedSession / Chair

Quantum beam applications for imaging and inspection(Chaired by T. KANAI)

Quantum beams for medical and biological science & engineering(Chaired by M. NOZAKI)

12:30 - 14:00
14:00 -14:30
Invited14:30 - 15:00
Invited
15:00 -15:30
Invited

25A-04Masahiko KOIZUMIOsaka U., Japan

Radiation Sensitization for Radiation Therapy

25A-05

Thomas KLUGE

HZDR, Germany

High Energy Proton Acceleration at DRACO-PW and Radiobiological Applications for Medical Tumor Therapy Research

25A-06

Kiminori KONDOKPSI, QST, Japan

Development of laser driven injector for a compact heavy ion radiotherapy system

LUNCH TIME
（Organization Committee Meeting of US-Japan Forum for Advanced Accelerators）
LBNL, USA
Antoine SNIJDERS
25P-01

Quantum beams for medical and biological science & engineering(Chaired by K. KONDO)

The BELLA PW laser proton beamline: a new platform for ultra-high dose rate radiobiological research

25P-02

Kei NAKAMURA

LBNL, USA

Proton beamlines for radiation biology application at the BELLA PW facility

25P-03

Takayasu KAWASAKIKEK, Japan

Terahertz radiation to amyloid fibrils

Break

15:30 - 16:00
16:00 - 16:30
Invited
16:30 - 17:00
Invited
17:00 -17:20

Title of talkMuon imaging and applications

Break

10:30 - 11:00
11:00 -11:30
Invited
11:30 -12:00
Invited
12:00 - 12:30

Affiliation
Toshiba ESS, Japan

Quantum beams for medical and biological science & engineering

17:20 - 17:40
Invited(Chaired by T. KLUGE)

Banquet19:00 - 21:00

25P-04

Keiichi NAKAGAWA

U. of Tokyo, Japan

Single-shot ultrafast imaging for observation of non-repetitive laser-induced plasma and shockwaves

25P-05

Takeharu NAGAI

Osaka U., JapanUse of quantum beams in improving the properties of glowing pants

25P-06

Tomonao HOSOKAI

Osaka U., Japan

Drug discovery with high-energy electron beams

25P-07

Yasunobu YAMASHITA

Osaka U., Japan

Chemotherapy triggered by electron beams

Senri Hankyu Hotel

April 26 (WED)Time
9:00 - 9:10
9:10 - 9:30
Invited
9:30 - 10:00
Invited
10:00 - 10:30
InvitedSession / Chair

Joint session with U.S. - Japan Forum for Advanced Accelerators

Speaker

Affiliation

Title of talk

26A-01

Mitsuhiro YOSHIDA

KEK, Japan

Introductory talk

26A-02Mei BAI

Stanford, USA

Grand challenges of future colliders

26A-03

Eric ESAREY

LBNL, USA

Laser plasma accelerator research at the BELLA Center

26A-04Robert Joel ENGLAND

Stanford, USA

Particle Acceleration Using Laser-Driven Photonic Structures(Chaired by M. YOSHIDA and M. BAI)
Break

10:30 - 11:00
11:00 -11:30
11:30 -12:00
Invited
12:00 -12:20
Invited12:20 - 15:30
15:30 - 16:00
Invited
16:00 -16:30
Invited
16:30 - 17:00
Invited
17:00 -17:20

Laser electron acceleration and FEL(Chaired by R. LOPEZ-MARTENS)

26A-05

Masaki KANDOKPSI, QST, Japan

Current status of the MIRAI free-electron laser project using laser accelerated electron beams in Japan

26A-06

Marie-Emmanuelle COUPRIE

SOLEIL, France

The COXINEL seeded Free Electron Laser driven by the HZDR Laser Plasma Accelerator

26A-07François Sylla

SourceLAB, France

Laser electron acceleration and FEL(Chaired by M. COUPRIE)
Closing(Chaired by Y. SANO, T. HOSOKAI and M. KANDO)

Poster presentations at SANKEN CReA (Chaired by Y. Gu and A. Rondepierre )Poster No.
Presenter
PO-01
Boyuan Li
PO-02
Alexandre Rondepierre
PO-03
Wenchao Yan
PO-04
Duthika Dilrangi Perera
PO-05
Sadaoki Kojima
PO-06
Masayasu Hata
PO-07
Matthew S Freeman
PO-08
Jinfeng Yang
PO-09
Tsuneto Kanai
PO-10
James Kevin Koga
PO-11
Hitoshi Soyama
PO-12
Daiki Okazaki
PO-13
Shigeki Tokita
PO-14
Kazufumi Nomura
PO-15
Haruya Matsumoto
PO-16
Tatsuhiko Miyatake
PO-17
Kai Huang
PO-18
Yuta Suzuki
PO-19
Yoshio Mizuta
PO-20
Shigeru Yamamoto
PO-21
Yoshihide Honda
PO-22
Thanh-Hung Dinh
PO-23
Alexei Zhidkov
PO-24
Naveen Chandra Pathak
PO-25
Yanjun Gu
PO-26
Zhan Jin
PO-27
Shingo Sato
PO-28
Illia Zymak
PO-29
Masao Gohdo
PO-30
Nobuhiko Nobuhiko
PO-31
Yusa Muroya

26P-01

Rodrigo LOPEZ-MARTENS

LOA, France

Lightwave control of relativistic plasmas

26P-02Liming CHEN

SJTU, China

Ultra-high charge electron acceleration and nuclear applications

26P-03

Min CHENSJTU, China

Recent progresses of laser plasma based electron acceleration and radiation at Shanghai Jiao Tong university
Closing, announcement of Q-BASIS 2024

Conference Chair

Title
Efficient high-order harmonic generation via surface plasma compression with lasers
Challenges to make LPA viable for industrial XFEL sources
Fold-rotational Symmetric Radiation Vortex stem from Nonlinear Thomson Scattering of Intense Laser with Circular Polarization Topology
Development of a compact electron source using self-modulated laser wakefield acceleration driven by a Sub-TW class laser
Induction heating for desorption of surface contamination for high-repetition laser-driven heavy-ion acceleration
Numerical simulation of laser ion injector for quantum scalpel project
LPA-Driven Electron Radiography at OMEGA EP
Ultrafast electron microscopy with relativistic femtosecond electron pulses
Temperature-driven, Sub-100-fs Mode-locked Fiber Oscillators Based on the Symmetry-Broken Nonlinear Polarization Evolution Method
Simulation of self-focusing ultrashort femtosecond lasers in air for the detection of viruses and VOCs
Laser Cavitation Peening Using a Nd:YAG Laser with and without Q-switch
Development of a 6-mJ, 100-Hz, femtosecond Yb:CaF2 regenerative amplifier for driving 4-micron KTA parametric amplifiers
Temperature-driven, Sub-100-fs Mode-locked Fiber Oscillators Based on the Symmetry-Broken Nonlinear Polarization Evolution Method
In-line Detection of Internal Defects in Fillet Welded Sheet of Lap Joint by Laser Ultrasonic and Its Robotic Application Using Microchip Laser
Development of a Start-to-End simulation code for the laser-driven ion injector
Optimization of laser irradiation conditions for high-brightness beam generation in laser-driven ion beams
Temporal measurement of laser wakefield electrons via electro-optic sampling
Development of a high-power terahertz source baced on laser-produced plasma for electron acceleration
Laser peening with microchip laser mounted on a controlled robotic arm
Undulator light source with a compact, slender and lightweight frame based on a magnet technology developed for very-short-period undulators
Current status and prospect of RLQBS in SANKEN
Development of a compact 50 TW laser for energetic quantum beam generation toward practical applications
Plasma Effects on Electron Beam Bunching in External Periodic Fields
Focusing and reduction of correlated energy spread of chirped electron beams in passive plasma lens.
Study of gas jet stability for LWFA in the context of shock injection
An Overview of Laser Wakefield Acceleration Platform in Spring-8
Characterization of Plasma Targets for Electron Beam Generation in Laser Wakefield Acceleration Systems
The electron beam diagnostic system for MeV range high repetition rate LWFA sources
The electronic structure of the solvated electron investigated by pulse radiolysis
Beam pointing control of laser wakefield accelerator by shaping near field profile of laser pulse
Picosecond pump-probe study on radiation-induced primary reaction processes of solutions at extreme conditions

April 27 (THU)

Optional tour

KAIO-BEAMLINE, à modular high repetition rate laser electron accelerator for broad range of applications

Lunch （Q-BASIS 2024 Kickoff Meeting）/ Poster presentations at SANKEN CReA (Chaired by Y. Gu and A. Rondepierre )Bus Tour Schedule
10:30 Departure from Senri Hankyu Hotel
11:50 – 12:45 Lunch(Japanese style)
13:30 Arrival at RIKEN SPring-8 Campus(VisitingSPring-8, SACLA and LAPLACIAN)
16:00 Departure form RIKEN SPring-8 Campus
18:00 Arrival at Senri Hankyu Hotel
18:30 Arrival at Shin-Osaka Station*Arrival time may be delayed due to traffic conditions.

RIKEN SPring-8 Center

2

Invited Talk and Oral Presentation

24A-01

4

5

24A-02
Title: New advance on laser shock generation and related applications : Laser
shock peening, laser adhesion test and damaging.
Laurent Berthe
Labo PIMM - UMR 8006 – Ensam/CNRS/CNAM
151 Boulevard de l’hôpital , 75013 Paris
E-mail: laurent.berthe@cnrs.fr
Keywords: Shocks, laser, Plasma, Material, Material processing
Shocks produced by laser plasma consists in irradiating material with focused beam in the range of
GW/cm2 and ns pulse duration. For applications, target is covered by a transparent medium to confine
plasma and reach higher pressure than in direct regime. In reaction of plasma release, induced stresses inmaterial are in the range of GPA and strain rate of 1e 6s-1. Such sollicitations can be used to reinforce
surfaces (Laser Shot Peening) , adhesion test of interfaces (LASer Adhestion Test), controlled damaging
productions and material study in extreme conditions. This presentation presents recent results on current
issues concerning laser interaction in confined regime (Plasma pressure control, loading for small spot
diameter [1,2]), design process by numerical simulations (In elasto-plastic regime) and development
growing Technology Readiness Level for applications (LSP with High repetition rate [3], Laser beam
quality impact on processes, flexible solid confinement [4]). Some perspectives, new applications andopen issues are also presented for discussions [5].
References[1] Lapostolle, L., Morin, L., Derrien, K., Berthe, L., & Castelnau, O. (2023). Fast numerical estimation of residual
stresses induced by laser shock peening. European Journal of Mechanics-A/Solids, 97, 104844.
[2] Ayad, M., Lapostolle, L., Rondepierre, A., Le Bras, C., Ünaldi, S., Donik, Č., ... & Trdan, U. (2022). New
methodology of dynamical material response of dissimilar FSWed Al alloy joint under high strain rate laser shockloading. Materials & Design, 222, 111080.
[3] Rondepierre, A., Casagrande, O., Rouchausse, Y., Castelnau, O., & Berthe, L. (2022). Development andoptimization of Laser Shock Repeated Dense Peening (LSRDP) using most advanced laser architectures. Optics
Express, 30(7), 10528-10546.
[4] Le Bras, C., Rondepierre, A., Ayad, M., Rouchausse, Y., Gervais, M., Valadon, S., & Berthe, L. (2021). Novelconfinement possibility for laser shock: Use of flexible polymer confinement at 1064 nm wavelength. Metals, 11(9),1467.
[5] Ünaldi, S., Papadopoulos, K., Rondepierre, A., Rouchausse, Y., Karanika, A., Deliane, F., ... & Berthe, L. (2021).
Towards selective laser paint stripping using shock waves produced by laser-plasma interaction for aeronauticalapplications on AA 2024 based substrates. Optics & Laser Technology, 141, 107095.

6

24A-03
Development of a laser hammering system for tunnel and bridge
concrete inspection using the high-power lasers.
Noboru Hasegawa1, Masaharu Nishikino1,2, Hajime Okada1,2,
Shuji Kondo1,2, Katsuya Sakamoto2, Shigeru Kogure2,
Satoshi Tomoto3, Yuki Yamada3 and Hikaru Nakamura4
Presenting
Author’s photo

1

National Institutes for Quantum Science and Technology, Japan2
Photon-Labo. Co., Ltd., Japan
3
CTI Engineering Co., Ltd., Japan
4
Nagoya University
E-mail: hasegawa.noboru@qst.go.jp

Keywords: Inspection of infrastructures, laser hammering, high power laser application
Periodic maintenances are required for safety use of concrete infrastructures such as tunnels and bridges.
Currently, new inspection machines are being considered to solve an insufficiency of inspectors in near
future. For the inspection of tunnel lining concrete, laser hammering system1) has been developed and trial
work was already started with a construction consultant company2) (figure 1). On the other hand, for theinspection of bridge concrete, new technologies are still in the development stage because it requires
long-distance measurement (several tens of meters). In this talk, we introduce the recent development of laser
hammering system for tunnel and bridge.
(a)Scanner

Scann

Impact Laser
1064nm pulse Nd:YAG laser

(c)


Laser Doppler
Vibrometer
532nm C.W. laser& Interferometer

Ablation
White dot：Impact laser
Green line：Laser vibrometer

0

 

0

(b)

0

.

Fig.1 (a) Scheme of Laser hammering system (LHS). (b) Tunnel inspection by LHS. (c) Inspection result of tunnel
joint part.

References[1] N. Hasegawa, H. Okada, S. Kondo, T. Kitamura, M. Nishikino, K. Sakamoto and S. Kogure: Journal of the Societyof Instrument and Control Engineers, Vol.60 No. 11 (2021) pp.765-769.
[2] S. Tomoto, N. Hasegawa, H. Okada, S. Kondo, T. Kitamura, K. Mikami, M. Nishikino, and H. Nakamura: JSCE
Committee of Structural Engineering, Vol.68A (2022) pp.671-684.

7

24P-01
Building artificial intelligence, science and theory
for smart laser manufacturing
Kenichi L. Ishikawa1,2
1

Research Institute for Photon Science and Laser Technology,
The University of Tokyo, Japan
2
Graduate School of Engineering, The University of Tokyo, Japan
E-mail: ishiken@n.t.u-tokyo.ac.jp
Keywords: Ultra-short pulse laser, Laser material processing, Cyber-physical system
Laser processing is a versatile technique with numerous adjustable parameters, such as wavelength, pulse
duration, and pulse energy. Currently, these parameters are optimized through human experience andintuition. However, to address the growing need for mass customization in the emerging super smart
society, we aim to replace these methods with data-driven approaches [1], artificial intelligence (AI), andscientifically grounded theories that highly integrate cyberspace and physical space (CPS). To facilitate
smart production, we develop CPS laser manufacturing that propose optimal processing parameters basedon simulations in cyberspace.
Laser processing is a complex, cutting-edge field that spans multiple scales and disciplines. For example,
how atoms, molecules, and materials behave under intense laser irradiation is at the forefront of atomic,
molecular, optical, and condensed matter physics, involving highly nonlinear, dynamical processes. One of
our focuses is to understand and simulate these strong laser-matter interactions by employing various
techniques, including AI and even starting from the first principles of quantum mechanics. We haveestablished a nationwide STELLA network of approximately 100 researchers, comprising boththeoreticians and experimentalists, with the latter specializing in advanced data collection and operando
measurement techniques.
The deep learning simulators within our network are capable of accurately and efficiently replicating thelaser drilling process in physical space. We are currently developing a range of innovative methods toprecisely calculate the laser-driven electron dynamics and energy transfer from the laser to the materials.
Furthermore, by combining first-principles and molecular dynamics calculations, we can quantitatively
reproduce the ejection of atoms from laser-irradiated surfaces. On a macroscopic scale, our research also
involves the study of multiphysics modeling for complex thermal multiphase flows.
This project is supported by MEXT Quantum Leap Flagship Program (MEXT Q-LEAP) Grant Number
JPMXS0118067246.
References[1] Y. Kobayashi, T. Takahashi, T. Nakazato, H. Sakurai, H. Tamaru, K.L. Ishikawa, K. Sakaue, and S. Tani, “Fully
Automated Data Acquisition for Laser Production Cyber-Physical System,” IEEE Journal of Selected Topics inQuantum Electronics, 27, 8900108 (2021).

8

24P-02Ultrafast processing of transparent materials by selective absorption ofcontinuous-wave laser into transiently excited electrons
Yusuke Ito and Naohiko Sugita
School of Engineering, The University of Tokyo, Japan
E-mail: y.ito@mfg.t.u-tokyo.ac.jp
Keywords: Transient and selective laser processing, Ultrashort pulse laser,
Imaging, Material processing
Femtosecond laser processing of transparent dielectric materials such as glass and sapphire is expected tobe applied in various applications in the fields of photonics, electronics, and bioengineering. These
applications require precision fabrication of holes with a diameter on the order of 10 µm and a depth ofover 100 µm with high speed. However, there are two major problems in femtosecond laser drilling oftransparent dielectric materials: low processing speed and low quality of the generated surface [1]. Because
the depth of the hole drilled by one femtosecond laser pulse is limited to be approximately 1 µm, hundredsof pulses must be focused to create a hole with a depth of over 100 µm. Furthermore, every time laser pulse
is focused, a strong stress wave is generated inside the material, creating cracks which inhibit the precision
processing.
In this talk, we first discuss the mechanisms of emergence of the problems, and then introduce a novel
processing method, transient and selective laser (TSL) processing, which solves both the problems [2]. In
TSL processing, an ultrashort laser pulse is firstly delivered to the material to generate filamentary region(filament) where electrons are excited locally and transiently. Then, a continuous-wave (CW) laser beam,
which has a wavelength transparent to the material, is coaxially delivered to the sample, so that thefilament is selectively heated (Fig. 1(a)). Because the heating process occurs rapidly, the material isimmediately evaporated, and thus ultrafast processing is achieved (Fig. 1(b)). Furthermore, TSL processing
can achieve crackles processing because it requires only one shot of ultrashort laser pulse, resulting in the
reduction of generation of stress waves. The further detail of the technique and physics behind theprocessing will be explained in the talk.

Fig.1 (a) Illustration of transient and selective laser (TSL) processing, (b) comparison of conventional (left) andproposed methods (right).

References[1]

M. Sun, et al., Optics Express 21, 7858 (2013).

[2]

Y. Ito, et al., Applied Physics Letters 113, 061101 (2018).

9

24P-03
Femtosecond Laser-Shock Processing: Fundamentals and Applications
Tomokazu Sano
Graduate School of Engineering, Osaka University, Japan
E-mail: sano@mapse.eng.osaka-u.ac.jp

Keywords: Femtosecond laser, femtosecond laser-driven shock wave, Dry laser peening

Femtosecond laser-shock processing or Dry laser peening (DLP) enables improving fatigue
performance of metallic materials using femtosecond laser pulses without a sacrificial overlay in air. Direct
irradiation of a solid surface with a femtosecond laser pulse drives an intense shock wave that propagates
into the solid. Such a shock wave driven by the femtosecond laser pulse deforms a material plastically.
Heat-affected and melted zones formed by a femtosecond laser pulse are much smaller than those produced
by a nanosecond laser pulse due to its extremely short pulse width. Therefore, peening without a sacrificial
overlay in air is possible using femtosecond laser pulses. The objective of this study is to verify theeffectiveness of the dry laser peening for laser-welded 2024 aluminum alloy containing welding defects byinvestigating the mechanical properties. Changes of hardness, residual stress and fatigue properties oflaser-welded 2024 aluminum alloys between before and after the DLP were investigated in this study. As aresult of plane bending fatigue test of the laser-welded joints, the fatigue life of the DLPed specimen was
improved as much as 15 times in comparison with the as-welded specimen at stress amplitude of 120 MPa.
This DLP is found to be effective to other kinds of aluminum alloys such as 6061 and 7075 aluminumalloys, therefore this process has a potential to be applied to variety of industrial fields such as automotive,
rail, aircraft, and space industries.

References[1] T. Sano, T. Eimura, R. Kashiwabara, T. Matsuda, Y. Isshiki, A. Hirose, S. Tsutsumi, K. Arakawa, T. Hashimoto, K.
Masaki, Y. Sano, "Femtosecond laser peening of 2024 aluminum alloy without a sacrificial overlay under atmosphericconditions," J. Laser Appl. 29, 012005 (2017).
[2] T. Kawashima, T. Sano, A. Hirose, S. Tsutsumi, K. Masaki, K. Arakawa, H. Hori, "Femtosecond Laser Peening ofFriction Stir Welded 7075-T73 Aluminum Alloys," J. Mater. Process. Technol. 262, 111 (2018).
[3] U. Trdan, T. Sano, D. Klobčar, Y. Sano, J. Grum, R. Šturm, "Improvement of corrosion resistance of AA2024-T3
using femtosecond laser peening without protective and confining medium," Corros. Sci. 143, 46 (2018).
[4] M. Yoshida, I. Nishibata, T. Matsuda, Y. Ito, N. Sugita, A. Shiro, T. Shobu, K. Arakawa, A. Hirose, T. Sano,"Influence of pulse duration on mechanical properties and dislocation density of dry laser peened aluminum alloy using
ultrashort pulsed laser-driven shock wave," J. Appl. Phys. 132, 075101 (2022).

10

24P-04
Achievements and future expectations of laser applications
for energy solutions

Presenting
Author’s photo

Makoto Ochiai11

Toshiba Energy Systems and Solutions Corporation, Japan
E-mail: mak.ochiai@toshiba.co.jp

Keywords: Laser peening, Laser-ultrasonics, Microchip lasers, Heavy-ion radiotherapy,
Superconducting rotating gantry
We, Toshiba Energy Systems & Solutions Corporation, provides energy solutions for sustainable society
and life. We offer various solutions in all aspects of energy systems such as “Generation”, “Transmission”,“Storage” and “Smart utilization” with our technologies, products, and services.
In power generation field, we have recently been focusing on renewable energy and CO2 capture andstorage/utilization and so on. However, we originally have delivered more than 2,000 units /over 200GW
of turbine generators to 43 countries around the world and most of them continue to support our daily lives
today. As for nuclear, we have constructed 26 light water reactors in Japan and working on thedecommissioning of Fukushima area, as well as the development of next generation reactors and small
modular reactors.
In particular, operation and maintenance services for power plants are one of the important technologicalfields we have been working on. We have developed and used some laser applications as an inspection,
maintenance and repair technology for major components of power plants such as nuclear reactor internals
and turbine generators for more than 20 years. We have contributed to the stable and safe operation of
power plants by utilizing not only the basic characteristics of lasers, such as high power density and highdirectivity, but also the characteristics that can be applied to remote and narrow areas even in underwater
environments. Our representative technologies include laser peening that prevents the initiation of cracks
on important structures and laser-ultrasonic that detects small cracks to enable efficient repair. We are
currently working on ubiquitous inspection and measurement systems, such as laser-ultrasonics using
microchip lasers, as well as stress corrosion cracking prevention and fatigue strength improvement using
laser peening.
We conduct advanced research not only for future energy, but also for contributing to society withtechnology related to promoting carbon neutrality, improving infrastructure resilience and enhancing
Quality of Life (QoL).
In the QoL field, we are working on “non-surgical cancer treatment,” and have contributed to develop
heavy ion therapy systems including superconducting rotating gantries and beam irradiation functions.
In the future, we will continue to work on technology development related to carbon neutrality, resilience,and QoL by utilizing quantum applied technologies such as superconductivity, accelerators, and lasers.

11

24P-05
High speed 2D/3D X-ray imaging at SPring-8
Kentaro Uesugi, Masato Hoshino, and Akihisa Takeuchi
Japan Synchrotron Radiation Research Institute / SPring-8, Japan
E-mail: ueken@spring8.or.jp
Keywords: Synchrotron Radiation X-ray, High speed imaging, micro-tomography
Synchrotron Radiation X-rays have high brilliance. It is suitable for high-resolution and high-speed X-ray
imaging. Recently effective spatial resolution of 100nm and high-speed imaging of over 20kHz (Figure 1)
have been possible, and phase contrast measurement with concentration resolution of mg/cm3 or higher isalso possible using optical systems for phase measurement.
At SPring-8, these X-ray imaging techniques are available to users by taking advantage of the features ofmultiple beamlines. The measurement targets are various, including biological samples, rocks and minerals,
and metallic materials. Recently, many dynamic observations such as the fracture process of metallic
materials when external force is applied or the structural change of batteries during charging anddischarging have been performed.
These measurement techniques and several measurement examples are shown at the conference.

Fig.1 An example of high-speed X-ray imaging: A fuse blowing due to an overcurrent was captured. BL20B2
Experimental hatch 1 is used. Using a multilayer monochromator at 40 keV X-rays. The pixel size and frame rate are
3.0um/pixel and 20kHz, respectively.

Fig.2 The time lapse CT images of tensile loading of rubber. The number at the left bottom shows the time in sec fromthe begging of CT scan.

12

24P-06
Advanced DPSSL technologies and applications at HiLASE
Tomas Mocek
HiLASE Centre of Excellence, Institute of Physics of the Czech Academy of Sciences,
Czechia
tomas.mocek@hilase.cz

Keywords: diode pumped solid state laser, high average power laser, material processing
Recent advances in high average power laser technologies and applications at the HiLASE CoE will bepresented. We have demonstrated efficient and stable operation of diode pumped solid state laser system
BIVOJ delivering 145 J, 10 ns, 1030 nm pulses at 10 Hz thus confirming the power scalability ofmulti-slab cryogenic gas-cooled Yb:YAG amplifier technology. Recently, we have achieved kilowatt-classhigh energy frequency conversion at 515 nm and half-kilowatt-class at 343 nm, respectively. We havedeveloped advanced thin-disk laser platform PERLA generating 1-ps pulses with an average power of afew hundred watts, exceptional beam quality and power stability. Both laser systems are used for diverse
hi-tech industrial and scientific applications.
References[1] M. Divoky, J. Pilar, M. Hanus, P. Navratil, O. Denk, P. Severova, P. Mason, T. Butcher, S. Banerjee, M. De Vido,
C. Edwards, J. Collier, M. Smrz, and T. Mocek, “150 J DPSSL operating at 1.5 kW level,” Opt. Lett. 46, 5771-5773(2021).
[2] O. Slezák, M. Sawicka‑Chyla, M. Divoký, J. Pilař, M. Smrž & T. Mocek, “Thermal‑stress‑induced birefringence
management of complex laser systems by means of polarimetry,” Sci. Rep. 12, 18334 (2022).
[3] P. Hauschwitz, J. Martan, R. Bičišťová, C. Beltrami, D. Moskal, A. Brodsky, N. Kaplan, J. Mužík, D.
Štepánková, J. Brajer, D. Rostohar, J. Kopeček, L. Prokešová, M. Honner, V. Lang, M. Smrž & T. Mocek,“LIPSS‑based functional surfaces produced by multi‑beam nanostructuring with 2601 beams and real‑time thermal
processes measurement,” Sci. Rep. 11, 22944 (2021).
[4] V. Istokskaia, M. Tosca, L. Giuffrida, J. Psikal, F. Grepl, V. Kantarelou, S. Stancek, S. Di Siena, A. Hadjikyriacou,
A. McIlvenny, Y. Levy, J. Huynh, M. Cimrman, P. Pleskunov, D. Nikitin, A. Choukourov, F. Belloni, A. Picciotto, S.
Kar, M. Borghesi, A. Lucianetti, T. Mocek & D. Margarone, “A multi-MeV alpha particle source via proton-boron
fusion driven by a 10-GW tabletop laser,” Commun. Phys. 6, 27 (2023).

13

24P-07
Repetitive 100 J class LD pumped cryogenic Yb:YAG ceramics Laser
Takashi Sekine, Takaaki Morita, Yuki Muramatsu, Yuma Hatano
Yuki Ikeya, Yoshinori Tamaoki, Yoshinori Kato,and Toshiyuki Kawashima
Central research laboratory, Hamamatsu Photonics K.K., Japan
E-mail: t-sekine@crl.hpk.co.jp

Keywords: Laser diode, Solid-state laser, Yb:YAG ceramics, Helium gas coolingHigh energy with repetitive pulsed diode-pumped solid-state lasers(DPSSLs) with over 1 kW average
power are developed for industrial and academic applications fields such as laser processing, laser
acceleration, laser fusion and so on[1-7]. As a feasibility study of 10 kW average power with 1 kJ at 10 Hz
pulsed laser, we are developing 250 J at 10 Hz laser with laser diode(LD) pumped cryogenically cooled
Yb:YAG ceramics laser(Fig. 1). As a results, we have demonstrated a 253 J laser energy output with 0.2
Hz repetition rate(Fig. 2)[6]. And now, we are focused on the development for 10 Hz operation with 250 J
energy. This research aim to clarify the possibility and technical issues to realize 1 kJ at 10 Hz output withcryogenic helium gas cooled Yb:YAG ceramics.

Fig.1 LD pumped 250 J Yb:YAG ceramics laser.

Fig.2 characteristics of 250 J DPSSL.

References[1]

P. Mason, M. Divoký, K. Ertel, et al., Optica 4 (2017) 438.

[2]E. Sistrunk, T. Spinka, A. Bayramian, et al., in Conference on Lasers and Electro-Optics, OSA Technical Digest(Optica Publishing Group, 2017) Sth1L2.
[3]

D. Albach, M. Loeser, M. Siebold, and U. Schramm, High Power Laser Sci. Eng. 7 (2019) e1.

[4]

T. Sekine, T. Kurita, M. Kurata, et al. High Energy Density Phys. 36 (2020) 100800.

[5]

M. Divoký, J. Pilař, M. Hanuš, et al., Opt. Lett. 46 (2021) 5771.

[6]

T. Sekine, T. Kurita, Y. Hatano, et al., Opt. Express. 30 (2022) 44385[7]

J. Ogino, S. Tokita, S. Kitajima, et al., Opt. Cont. 1 (2022) 1270.

14

25A-01［化技開］-2023005 HN-2023-1520

Muon Imaging and Applications
Haruo Miyadera
Toshiba Energy Systems & Solutions Corporation, Japan
E-mail: haruo.miyadera@toshiba.co.jp
Keywords: Cosmic-ray muon, muon imaging, muon tracker
Cosmic-ray muons are created when highly energetic particles collide with the Earth’s upper atmosphere.
Initially, pions and kaons are produced which decay into muons, and at ground level, the muon flux is 104/m2/min. Cosmic-ray muon transmission imaging was invented in the 1950s [1] and applied to an Egyptianpyramid [2], and other large-scale objects. A more sensitive technique, muon scattering imaging, wasinvented at Los Alamos National Laboratory, which measures the scattering angles of muons [3]. The
muon scattering imaging is selective to high-Z dense materials and is used to detect shielded packages ofnuclear materials in a background of normal cargo [4]. Though the muon scattering tomography is arelatively new imaging method, many applications have been explored [5], and some muon trackers are
already commercialized. Other nuclear applications include measurement of a reactor [6] and a dry cask:
the world’s first muon reactor imaging was carried out in collaboration with Toshiba Coperation and
LANL at Toshiba Nuclear Critical Assembly in 2013, where a reactor core and other reactor components
were clearly imaged with a four-week measurement using LANL’s Mini Muon Tracker of 1.2×1.2 m2
detection area as shown in Fig. 1 [7].

Fig.1 Geometry of reactor imaging at Toshiba NCA (left). Slices through the tomography in 10-cm steps along a line
connecting the detector centers (right)

References[1] E.P. George, Commonwealth Engineer, 455 (July 1, 1955).
[2] L.W. Alvarez et al., Science 167, 832, (1970); K. Morishima et al., Nature 552, pages386–390(2017).
[3] K. Borozdin et al., Nature 422, 277 (2003).
[4] H. Miyadera and C.L. Morris, Appl. Optics 61, C154 (2022).
[5] C.L. Morris et al., Science & Global Security 16, 37 (2008).
[6] H. Miyadera et al., AIP Advances 3, 052133 (2013).
[7] C.L. Morris et al., Appl. Phys. Lett. 104, 024110 (2014); T. Sugita et al., J. Nucl. Sci. and Tech. 51, 1024 (2014).

15

25A-02
The LANL Proton radiography Facility and Investigations toward Achromatic Imaging
Fesseha Mariam, Los Alamos National Laboratory, Los Alamos, NM
Proton radiography (pRad) at LANL is an imaging modality best suited for imaging densematerials up to 50 g/cm-2 at time scales of 100 ns. The temporal structure of the LANSCE 800 MeV
proton beam allows the flexibility for multi-frame imaging over the duration of dynamic processes lasting
up to 20 microsec or more. The LANL pRad facility has so far provided invaluable data on dynamic
processes such as explosives and explosives-driven shock in materials. However, it is limited bychromatic effects that degrade the resolution of off-energy protons. Work currently underway aims toeliminate or mitigate these chromatic effects using a second-order achromatic magneto-optic imager. Our
team aims to design, fabricate and test such an imager using low-energy electron beams (~25MeV) at the
Idaho Accelerator Center. If successful, this will serve as a prototype that can be scaled up for use with
800-MeV protons. We will discuss the benefits and complexities of achromatic imaging over existing
capabilities.

16

25A-03
RIKEN Accelerator-driven compact neutron system andits applications and achievements
Author: Yoshie Otake1
Affiliation:
1
RAP, Neutron Beam Technology Team, RIKEN, Japan,
2
T-RANS, Japan,
E-mail: yotake@riken.jp
Author’s photo
Keywords: Compact neutron system, non-destructive test, infrastructure, Quantum beams, Salt
meter
We have been developing and upgrading Compact Neutron Systems and their applications at RIKEN since
2013[1]. There are two major goals of RANS project. One of the objectives is to construct a floor-standing
type of compact neutron systems that enables non-destructive evaluation and analysis of materials andcomponents using low-energy neutrons, which has not been possible until now on-site, and to demonstrate
its achievements, thereby contributing to industrial applications and human resource development. Anothermajor objective is to develop and demonstrate outdoors new, transportable, compact neutron systems forpreventive maintenance of bridges and other large infrastructure structures, thereby contributing toextending the service life of social capital.

Neutron scattering experiments such as imaging, neutron

diffraction, and small-angle scattering have been performed on RANS and RANS-II, including for externaluser applications. As an urgent issue to prevent bridge accidents, we have developed an ultra-compact
neutron salt meter, RANS-μ, for salt damage, which is one of the three most common causes of bridge
accidents and have already conducted measurements on actual bridges[2]. In addition, we have succeededin visualizing sedimentation by scattered neutron imaging, which visualizes the internal degradation ofbridge decks from the road surface [3]. Efforts toward the practical application of RANS project will also
be presented.

Fig.1 RANS challenge, RANS, RANS-II, III, μFig.2 RANS-μ

at a bridge

References[1] Y.Otake, Applications of Laser-Driven Particle Acceleration eds. Paul Bolton, Katia Parodi, Jörg Schreiber(chapter 19) , June 5 (2018) pp.291-314 CRC Pres.
[2] Wakabayashi, et.al., J. Neutron Res. 24, no. 3-4, pp. 411-419, (2022).
[3] K.Fujita, et.al., Proceedings of The 22th Symposium on Decks of Highway bridges, (2020)pp.47-52

17

25A-04

Radiation Sensitization for Radiation Therapy
Masahiko Koizumi, Kazumasa Minami
Sensitization of radiotherapy is necessary to improve the clinical outcome of radiotherapy, i.e.,tumor control and reduced damage to normal tissue.
In other words, it is necessary to increase the sensitivity of radiotherapy that means theeffectiveness of radiotherapy in controlling tumors at equivalent doses.
For this purpose, three types of sensitizations can be considered: physical sensitization,
chemical sensitization, and biological sensitization.
Physical sensitization is the enhancement of physical effects by focusing on the physicalproperties of the radiation itself.
Physical sensitization includes spatial and temporal sensitization.
Spatial intensification is to increase the concentration of the dose to the tumor site. Recent
developments in radiotherapy equipment have focused on increasing the concentration of thedose and spatial physical sensitization. These include stereotactic irradiation (SRI) andintensity-modulated irradiation (IMRT) in external irradiation, and image-guided
radiotherapy (IGRT) to accommodate occasional positional changes.
Temporal sensitization is also aimed at enhancing the effect of radiation irradiation bycontrolling it over time. The effect is enhanced by irradiating the same dose for a shorter
period of time. In other words, the effect is enhanced by increasing the dose rate. In terms ofdose rate, methods to increase the conventional dose rate of about 2 Gy/minute have beenfavored, and this has become known as ultra-high dose rate irradiation (Ultra HDR), which is
now attracting attention as FLASH Therapy. The conventional fractionated irradiation
method has been used for a long time, in which fractionated irradiation is performed acrossdays to wait for recovery of normal cells and tissues and to extend the interval between
irradiations.
Temporal and spatial physical sensitization is in any case aimed at enhancing the therapeutic
effect = tumor control - normal exposure.
Chemical sensitization is a chemical method of sensitization by means of drugs. It is achemical method to enhance the effect of the treatment by administering a chemical substance(drug) at or above the equivalent dose. The drug is namely “radiosensitizer”. Tumor control
in radiotherapy is mainly focused on the indirect effects of DNA double-strand breaks causedby reactive oxygen species (ROS) damage. The tumor environment is hypoxic, and in a
hypoxic environment, subsequent tumor control is reduced due to inferior ROS damage. The
radiosensitizers that supplement this, i.e., cover the hypoxic environment by introducing
oxidizing substances that substitute for ROS, have proven to be useful. These are called18

hypoxia sensitizers. Although chemical sensitizers, i.e. radiosensitizer have been tried for along time, not many attempts have been made for clinical use in humans because of theincreased risk of adverse events such as neurotoxicity. Recently, our laboratory has been
investigating the use of a photosensitizing agent called Lavurchin, which is a photosensitizing
substance produced by a deep-sea red alga. Other chemotherapeutic agents provide additive
sensitization, which is used in combination therapy to enhance the therapeutic effect.
The last type of bio sensitization is one in which biological effects are used to enhance theradiotherapy efficacy ratio. Recently, immune effects have been attracting attention, andimmune checkpoint inhibitors (ICIs) with CTLA-4 and PD-L1 antibodies by Dr. Allison and
Dr. Honjo, who received the Nobel Prize in 2018, have significantly improved tumor control.
The ICIs work well with RT to restore the original anti-tumor immunity of the body byinitiating an immune response through antigen presentation by the tumor-inflammatory
effect of RT and removing the immunosuppressive effects that cause the anti-tumor effect in
the process. It is known that RT + ICI can enhance the abscopal effect, which has been
increasingly investigated in recent years.
As described above, radio sensitization, i.e., enhancement of the simple irradiation effect ofradiation by increasing the ratio of physical, chemical, and biological effects, has been gaining
momentum. This is leading to the clinical application of radio sensitization, which increases
the efficacy ratio of radiotherapy, i.e., tumor control is enhanced and normal tissues are better
protected.

19

25A-05
Title: High Energy Proton Acceleration at DRACO-PW andRadiobiological Applications for Medical Tumor Therapy Research
S. Assenbaum1,2, C. Bernert1,2, E. Beyreuther1, S. Bock1, E. Bodenstein5,
F.-E. Brack1,2, K. Brüchner1,2,5 , T. E. Cowan1,2, N. Dover3,4, M. Garten1,2,
L. Gaus1,2, R. Gebhardt1, I. Goethel1,2, U. Helbig1, L. Karsch1,5, H. Kiriyama3,
T. Kluge1, A. Kon3, S. Kraft1, M. Krause1,5,6,7,8,9, F. Kroll1, E. Lessmann1,
U. Masood1, S. Meister1, J. Metzkes-Ng1, M. Nishuichi3, A. Nossula1,
J. Pawelke1,5, J. Pietzsch1,2, T. Püschel1, M. Reimold1,2, M. Rehwald1,2,
C. Richter1,5,6,7,8 , H.-P. Schlenvoigt1, U. Schramm1,2, M. E. P. Umlandt1,2,
T. Ziegler1,2, K. Zeil1,

1) Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany2) Technische Universität Dresden, Dresden Germany
3) Kansai Photon Science Institute, National Institutes for Quantum and Radiological
Science & Technology, Kyoto, Japan
4) John Adams Institute for Accelerator Science, Imperial College London, London, United
Kingdom5) OncoRay—National Center for Radiation Research in Oncology, Faculty of Medicine
and University Hospital Carl Gustav Carus, TU Dresden, Helmholtz-Zentrum
Dresden-Rossendorf, Dresden, Germany6) German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, Germany7) National Center for Tumor Diseases (NCT), Partner Site Dresden: German Cancer
Research Center (DKFZ), Faculty of Medicine and University Hospital Carl Gustav
Carus, Technische Universität Dresden, Germany, Helmholtz
Association/Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany8) Department of Radiotherapy and Radiation Oncology, Faculty of Medicine andUniversity Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden,
Germany9) Department for Radiotherapy and Radiooncology, University Hospital Carl Gustav Carus,
Technische Universität Dresden, Dresden, Germany
E-mail: q.basis2023.office@gmail.com
Keywords: Ultra-short pulse laser, Proton acceleration, Tumor therapy
In this talk I will report on the latest progress in the laser proton acceleration program at HZDR that isdedicated to apply next generation laser plasma based ion acceleration to tumor therapy. We performed theworld’s first model-conform dose-controlled animal irradiation with laser accelerated protons. I will outline
the enhancements of the laser system and process understanding that lead to this milestone and touch on
the next steps towards laser-plasma accelerators that are applicable for medical and biological tumor
irradiation studies.

20

25A-06
Development of laser driven injector for a compact heavy ion
radiotherapy system
Kiminori Kondo1
1

Kansai Photon Science Institute,
Institutes for Quantum Science and Technology, Japan
E-mail: kondo.kiminori@qst.go.jp

Keywords: Heavy ion radiotherapy, Laser driven ion acceleration, Injector, Quantum Scalpel
One of the most important advantage of laser driven acceleration, the size of the energetic accelerator could
be much smaller than the conventional accelerator. Then the researcher of laser driven ion acceleration
mentions that the possibility of the compact and the low cost particle cancer therapy machine, which will
enable to bring the innovation in the radiotherapy. However, a few decades have passed from the start of
the real experimental laser driven ion acceleration study. Not only ion acceleration, but also electron
acceleration is not used as the real accelerator for some application. In Japan, JST-MIRAI large scale
project has started from Nov. 2017, which is total ten years project. This project includes the developmentof not only electron accelerator for the compact XFEL but heavy ion injector for the heavy ion cancer
therapy machine. The laser driven heavy ion injector could be installed for the next generation heavy ion
cancer therapy machine called “Quantum Scalpel”[1]. In this system, the main accelerator is asynchrotron based on the super conducting magnet technology. Then the most important requirement to thelaser driven heavy ion injector is the production of enough number of several MeV/u-class carbon beams
continuously
In this study, the development of Quantum Scalpel will be introduced, and a present condition of thedevelopment of the laser driven carbon beam injector will be also shown.

Fig.1 Schematic drawing of Quantum Scalpel. The injector for the main synchrotron accelerator could be based on thelaser driven ion acceleration phenomena.

References[1]

https://www.qst.go.jp/site/qst-kakushin/39695.html

21

25P-01
The BELLA PW laser proton beamline: a new platform for ultra-high dose
rate radiobiological research
A. M. Snijders*, J. L. Inman, L. Obst-Huebl, K. Nakamura, J. H. Bin, S. Hakimi, L.
Geulig, H. Chang, Q. Ji, J. De Chant, A. J. Gonsalves, S. S. Bulanov, J. van Tilborg,
S. E. Celniker, Z. Kober, C. B. Schroeder, C. G. R. Geddes, B. Simmons, T.
Schenkel, S. Steinke, C. Ralston, E. Esarey, J.-H. Mao
Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA*Corresponding author: amsnijders@lbl.gov

Keywords: Laser driven ion acceleration, proton therapy, radiation therapy

Radiotherapy is the current standard of care for more than 50% of all cancer patients. Recently,
the beneficial differential effects on tumor versus normal tissues using the delivery of single, highradiation doses of >10 Gy at ultra-high dose rates (UHDR), has received increasing attention andis called the FLASH radiotherapy (FLASH RT) effect. However, extensive radiobiologicalresearch with UHDR electrons, X-rays, protons or carbon ions has not yet completely identified
the underlying mechanisms of action for FLASH RT. Accelerator capabilities at the BELLA
LasernetUS node at LBNL were extended by adding a magnetic proton transport system to the
newly commissioned iP2 beamline. This allowed us to deliver petawatt laser-driven (LD) proton
pulses of 10 MeV energy to irradiate radiobiological samples in vivo at ultra-high instantaneous
dose rate (UHIDR). We investigated the differential sparing of LD protons on healthy tissues invivo by measuring acute skin damage and late radiation-induced fibrosis in murine ears after highdose radiation exposure. In a first experiment at iP2, we demonstrated the irradiation of 7 mmdiameter patches of mice ear in vivo with proton doses up to 39 Gy at an IDR of 108 Gy/s. Results
were compared to conventional dose rate exposures, and the analysis of the biological data ispending. To further investigate the mechanism of the FLASH effect, we tested X-ray effects on
peptide oxidation with the CONVDR X-rays (300 kVp) and at the Advanced Light Source
synchrotron at LBNL, using UHDR 8-20 keV photons. These experiments will be repeated at the
BELLA iP2 beamline. Current work is focused on determining the mechanism of the FLASH
effect using UHDR LD protons and expanding our studies to investigate the efficacy of UHDRLD protons in eradicating tumor cells using mouse xenograft models. We will summarize ourresults to date.
Funding Acknowledgements
Work supported by U.S. Department of Energy Office of Science, Offices of Fusion Energy Sciences andHigh Energy Physics, Contract No. DE-AC02-05CH11231 and LaserNetUS (https://www.lasernetus.org/)and LBNL Laboratory Directed Research and Development Grant, PI A. M. Snijders

2225P-02
Proton beamlines and applications at the BELLA PW facility
Kei Nakamura, Lieselotte Obst-Huebl, Sahel Hakimi, Jared De Chant,
Jian-Hui Bin, Laura Geulig, Qing Ji, Thomas Schenkel, Jian-Hua Mao,
Jamie Inman, Antoine Snijders, Axel Huebl, Stepan Bulanov, Jean-Luc Vay,
Anthony J. Gonsalves, Jeroen van Tilborg, Carl B. Schroeder, Eric Esarey,
and Cameron G. R. Geddes
Lawrence Berkeley National Laboratory, USA
E-mail: KNakamura@LBL.GOV
s photoKeywords: Laser-driven ion acceleration, Proton therapy, Defect engineering.
The BELLA Center has been pursuing laser-plasma acceleration (LPA) of electrons since its inception [1].
Laser-driven ion acceleration has also been explored at the BELLA PW facility with a relatively large fnumber (~65) focus, providing protons up to 8 MeV with 35 J laser energy on target [2]. In 2022, a second
interaction point (iP2) with a small f-number (~2.5) focus has been developed [3], enabling an on-target laser
intensity beyond 1021 W/cm2 and therefore higher energy ion beam generation. The iP2 has beencommissioned with up to 17 J laser energy on target, providing a proton energy cut-off of 40 MeV. This
presentation introduces our laser-driven proton beamlines at both large and small f-number interaction points
as well as applications of laser-driven ion beams, such as ultra-high dose rate radiobiology and defectengineering [4,5].

Figure 1: Schematics of the BELLA PW facility [1] including the new iP2 area on the bottom left.

References[1] K. Nakamura, et al., Journal of the Particle Accelerator Society of Japan 19, 205 (2023).
[2] S. Steinke, et al., PRAB 23, 021302 (2020).
[3] S. Hakimi, et al., Phys. Plasmas 29, 083102 (2022).
[4] J. H. Bin, L. Obst-Huebl, et al., Scientific Reports 12, 1585 (2022).
[5] W. Redjem, et al., Communications Materials 4, 22 (2023).
Funding note: Work supported by U.S. Department of Energy Office of Science, Offices of Fusion Energy Sciencesand High Energy Physics, under Contract No. DE-AC02-05CH11231, LaserNetUS (www.lasernetus.org).

23

25P-03
Terahertz radiation to amyloid fibrils
Takayasu Kawasaki1, Yuusuke Yamaguchi2, Hideaki Kitahara2,
Akinori Irizawa3,4, and Masahiko Tani2
Accelerator Laboratory, KEK, Japan
Research Center for Development of Far-Infrared Region,
University of Fukui, Japan
3
SANKEN, Osaka University, Japan4
SR Center, Ritsumeikan University, Japan
E-mail: takayasu.kawasaki@kek.jp
1

2

Keywords: Terahertz, Free electron laser, amyloid fibrils, Gyrotron, Sub-millimeter wave
Physical engineering techniques using terahertz beams have been attracted in chemical, biological, andmaterial research fields. Also, the high-power radiation from the infrared light source can give theremarkable effects to biological materials distinct from a simple thermal treatment. Amyloid fibrils work as
multi-functional players in medical and biomaterials fields. A common feature in the structure of amyloid
fibrils is a fibrous conformation that is rigid and insoluble in water, and it is often difficult to regulate thestacking formation unless using high temperature and denaturants. We discovered that amyloid fibrils canbe conformationally controlled by using high-power terahertz beams from a free-electron laser andgyrotron (Fig. 1). In this talk, we would like to show our studies on the effects of terahertz radiation on theamyloid fibrils and discuss about the potential use of the far-infrared radiation to regulate the biomolecular
self-assembly [1-3].

Fig.1 Dissociation and re-association of amyloid fibrils by terahertz beams

References[1] Takayasu Kawasaki, Koichi Tsukiyama and Akinori Irizawa, Sci. Rep., 9, 10636 (2019).
[2] Takayasu Kawasaki, Yuusuke Yamaguchi, Tomomi Ueda, Yuya Ishikawa, Toyonari Yaji, Toshiaki Ohta, Koichi
Tsukiyama, Toshitaka Idehara, Masatoshi Saiki, and Masahiko Tani, Biomed. Opt. Express, 11(9), 5341-5351(2020).
[3] Takayasu Kawasaki, Yuusuke Yamaguchi, Hideaki Kitahara, Akinori Irizawa, and Masahiko Tani,
Biomolecules, 12(9), 1326 (2022).

24

25P-04
Single-shot ultrafast imaging for observation of non-repetitive
laser-induced plasma and shockwaves
Keiichi Nakagawa
Graduate School of Engineering, The University of Tokyo, Japan
E-mail: kei@bmpe.t.u-tokyo.ac.jp
Keywords: Ultra-short pulse laser, Ultrafast imaging, Bioimaging, Material processing
Laser-induced plasmas and shockwaves have unique properties and the potential to produce newtechnology or improve the performance of existing techniques in not only basic studies but also the
medical field1 and industry2. To capture these ultrafast phenomena, time-resolved pump-probe imaging isutilized. In this method, the images of target phenomena are obtained one by one by changing the delay
time (time difference between the pump pulse and probe pulse). Although this method achieves a high time
resolution in the imaging, the technique cannot be applied to non-repetitive events. Recently, we developed
an ultrafast single-shot imaging method called Sequentially timed all-optical mapping photography(STAMP) that allows us to capture poorly reproducible ultrafast phenomena3,4. STAMP is an all-opticalimaging method based on optical ‘mapping’: the projection of the target’s spatial profile from the time
domain to the spatial domain. The STAMP system consists of an ultrafast laser source, temporal mapping
device (TMD; to produce a chirped-pulse or pulse train depending on the imaging timescales), spatial
mapping device (SMD; to perform spectral imaging), image sensor, and computer. With the recent
improvements in TMD and SMD, we achieved visualization of the detailed behaviors of plasma dynamics
and acoustic dynamics induced by ultrashort laser pulses.
In this talk, I will introduce the biomedical applications we developed based on laser-induced phenomena
first, then present the recent development of our single-shot imaging technology to visualize and analyze
the non-repetitive laser-induced plasma and shockwaves.
References[1] A. Ishijima, U. Yagyu, K. Kitamura, A. Tsukamoto, I. Sakuma and K. Nakagawa*, “Nonlinear photoacoustic
waves for light guiding to deep tissue sites” Optics Letters 44, 3006-3009 (2019).
[2] T. Nozawa and K. Nakagawa, “Understanding diffusion layer agitation by cavitation in electroplating based onhigh-speed monitoring.” Ultrasonics Sonochemistry 81, 105856 (2021).
[3] K. Nakagawa, A. Iwasaki, Y. Oishi, R. Horisaki, A. Tsukamoto, A. Nakamura, K. Hirosawa, H. Liao, T. Ushida,
K. Goda, F. Kannari and I. Sakuma, “Sequentially timed all-optical mapping photography (STAMP)” Nature
Photonics 8, 695–700 (2014).
[4] T. Saiki, T. Hosobata, Y. Kono, M. Takeda, A. Ishijima, Miu Tamamitsu, Y. Kitagawa, K. Goda, S. Morita, S.
Ozaki, K. Motohara, Y. Yamagata, K. Nakagawa* and I. Sakuma, “ Sequentially timed all-optical mapping
photography boosted by a branched 4ƒ system with a slicing mirror.” Optics Express 28, 31914-31922 (2020).

25

25P-05
Use of quantum beams in improving the properties of glowing pants
Kenji Osabe, Sachiko Tojo, Yusa Muroya, Yoshio Mizuta, Yoshihide
Honda, Tomonao Hosokai, Takeharu Nagai
SANKEN, Osaka University, Japan
E-mail: ng1@sanken.osaka-u.ac.jp

Keywords: Gamma-radiation, electron beam, mutagenesis, bioluminescence, FRET
There are many bioluminescent organisms in nature, such as fireflies, bacteria and mushrooms, and theluminescent proteins from these organisms have been used for countless biological studies.
Bioluminescence is produced upon catalysis of the oxidation reaction of the substrate (luciferin) by theluminescent enzyme (luciferase). The genes that produce luciferin and luciferase has been elucidated fromthe glowing mushroom species [1], and we cloned and introduced these genes into the plant genome tocreate autoluminescent plants that can be used for various applications including bioimaging. However, thecurrent luminescence intensity is insufficient for observing intercellular or intracellular phenomena. As an
approach to increase the luminescence intensity, we will irradiate the seeds of the autoluminescent plantwith gamma- or electron beam to induce random mutations in the genome to create a population of various
mutants. We aim to find a mutant with enhanced mutation that can be used to further analyze and identify
the mutated gene/s that lead to luminescence enhancement. In combination with a technique to enhanceluminescence intensity by the fusion of a fluorescent protein (Nano-lantern technology), we aim to produce
a bright and multicoloured autoluminescent plant that can be used not only for various biological studies,but also as an electricity-free light source to help build a sustainable society.

Tobacco (Nicotiana benthamiana)

Arabidopsis thaliana
Fig.1 Autoluminescent plants generated using the luminescent genes from mushroom.

References[1] Mitiouchkina T, Mishin AS, Somermeyer LG, Markina NM, Chepurnyh TV, Guglya EB, et al.. Plants withgenetically encoded autoluminescence. Nat Biotechnol. 2020 Aug;38(8):944-946. doi: 10.1038/s41587-020-0500-9.

26

25P-06
Drug discovery with high-energy electron beams
Tomonao Hosokai1,2, Yasunobu Yamashita1,2, Yusa Muroya1,2,
Yoshio Mizuta1,2, Kazumasa Minami1,3, Yudai Hirai1, Jin Zhan1,2,
Alexei Zhidkov1,2, Yoshihide Honda1, Masahiko Koizumi1,3, Takayoshi Suzuki1
1
SANKEN, Osaka University, Japan
2
SPring-8 Center, RIKEN, Japan
3
Graduate School of Medicine, Osaka University, Japan
E-mail: hosokai@sanken.osaka-u.ac.jp
Keywords: Laser wakefield acceleration (LWFA), Electron beams, Prodrugs, Chemotherapy
Laser wakefield acceleration (LWFA) is expected to be a next-generation accelerator capable ofaccelerating electron beams with energies above the GeV class on the scale of a small table-top device.
Under the JST-MIRAI project, our research team has been conducting research and development of the
LWFA with the aim of amplification in XUV wavelength range of the free-electron laser (FEL). Since thequality of the LWFA electron beam has been dramatically improved by the progress of this FEL research,
we decided to explore applications of LWFA that can be implemented in society at an early stage inparallel with the FEL research, and started research on drug discovery using high-energy electron beams
and prodrugs with our teams in beam physics, organic chemistry, radiation chemistry and radiation
oncology.
A prodrug is a drug whose chemical structure is converted to an inactive form so that the drug does
not work after it enters the body and before it reaches the site of disease in chemotherapy. Afteradministration, an external or internal stimulus (trigger) at the disease site (affected area) converts thechemical structure back to the active form and causes the drug to function, so that the drug is potent only at
the target site and is expected to reduce systemic side effects. When the human body is irradiated, free
radicals and reactive oxygen species are generated in body tissues through the ionization or excitation ofwater molecules. The use of chemical reactions based on the indirect action of these reactive molecularspecies for prodrug activation has been investigated, and recently there have been reports of prodrug
activation using x-ray irradiation as an external trigger [1]. However, when targeting localized lesions deepin the trunk, an external trigger of beams with high enough energy to penetrate and reach deep into thetrunk, and with sharp directivity that does not spread in the body, is required.
In order to investigate the potential of high energy electron beams of tens to hundreds of MeV asexternal triggers, we first started to study prodrug activation using ~30 MeV electron beams of the L-band
LINAC at SANKEN. The target is irradiated with the electron beams at clinically acceptable doses of 5 Gyor less; in vitro experiments prodrug activation and growth inhibition of human cervical tumor HeLa cells
and in vivo experiments inhibition of tumor growth in xenograft mouse models are investigated.
In this presentation, beam drug discovery research will be presented as a realistic application ofcompact high energy electron accelerators, including laser accelerators.
References[1] Geng, J.; Zhang, Y. Gao, Q.; Neumann, K.; Dong, H.; Porter, H.; Potter, M.; Ren, H.; Argyle, D.;
Bradley, M. Nat. Chem., 2021, 13, 805–810.

27

25P-07
Chemotherapy triggered by electron beams
Yasunobu Yamashita1,2, Yusa Muroya1,2, Yoshio Mizuta1,2, Yudai Hirai1,
Kazumasa Minami1,3, Alexei Zhidkov1,2, Yoshihide Honda1, Yukihiro Itoh1,
Yuri Takada1, Takahiro Kozawa1, Masahiko Koizumi1,3, Tomonao Hosokai1,2
and Takayoshi Suzuki1
SANKEN, Osaka University, Japan
2
RIKEN SPring-8 Center, Japan
3
Graduate School of Medicine, Osaka University, Japan
E-mail: yyamashita@sanken.osaka-u.ac.jp
1

Keywords: prodrugs, quantum beams, pulse radiolysis, chemotherapy
Chemotherapy is one of the pillars of cancer treatment, along with surgery and radiation therapy. It
suppresses the growth of cancer cells using anticancer agents. However, even approved drugs have
limitations such as their high toxicity and serious side effects on normal cells or tissues, due to their low
selectivity for tumor cells. To eliminate these undesirable properties and improve efficacy, the prodrug
strategy is often used. Prodrugs are intrinsically inactive forms that are converted to active forms byexogenous or endogenous stimulation, and they are expected to control drug activity in tumor cells or
tissues. In general, prodrugs are designed by masking the functional group of a bioactive compound
essential to its drug activity (Fig. 1). In recent years, some reports have been shown that prodrugs can bephysically activated by X-rays, with spatio-temporally control [1]. However, their tissue permeability is
insufficient for clinical applications targeting deep lesions. Therefore, we thought that radiation that canreach at deeper tissues is available as a complementary method to X-rays. In this context, we focused onhigh-energy electron beams, which have superior properties in terms of tissue penetration. So far, we haveachieved the activation of prodrugs by electron beams in vitro, and we have tested the electron
beam-prodrug activation in cell-based assays and mouse experiments. In this presentation, our detailed
studies on the activation of prodrug by electron beams, including its pharmacological effects and thereaction process will be introduced.

Fig.1 Prodrug activation by electron beams
References[1] Bradley, M. et al., Nat. Chem., 2021, 13, 805–810.

28

26A-01

Introductory talkMitsuhiro Yoshisda

29

26A-02
Grand challenges of future colliders
M. BaiSLAC National Accelerator Laboratory, USA
E-mail: mbai@slac.stanford.edu
Keywords: Higgs factory, energy frontierDuring the recent US high energy physics strategy process, aka Snowmass, the enthusiasm
towards beyond-the-LHC energy frontier has been evident. Several new proposals for next highenergy colliders including Higgs factories such as Cool Copper Collider were presented andevaluated together with well-known proposed ILC, CLIC, FCC-ee, CEPC by the Implementation
Task Force. This talk will provide a brief overview of the evaluation. Design study on
demonstrating the Cool Copper Collider technology as well as grand challenges for reachingultimate colliders will also be presented.

30

26A-03
Laser-Plasma Accelerator Research at the BELLA Center
Eric Esarey, Kei Nakamura, Anthony Gonsalves, Jeroen van Tilborg, Carl
Schroeder, and Cameron Geddes
Lawrence Berkeley National Laboratory, USA
E-mail: EHEsarey@lbl,gov
Keywords: Laser-plasma accelerators, electron acceleration.
This talk will summarize the current activities of the BELLA Center on laser-plasma
accelerator (LPA) research and applications. This will include a description of the newly commissioned
extensions to the BELLA PW laser, namely the second beamline (2BL) and the interaction point two (IP2)beamline and target chamber [1]. 2BL provides a second beamline to the interaction point one chamber,
along with the first beamline, where experiments are done on LPAs. The primary objectives areexperiments on laser-generated plasma channels to yield electron energies near 10 GeV, and the highefficiency staging of LPA modules at the multi-GeV level. IP2 provides a new short focal length capability
to provide ultrahigh laser intensity for experiments on ion acceleration and high energy density science.
The BELLA Center also houses two independent 100 TW lasers that are used for a wide variety of studies,including x-ray generation by Thomson scattering and LPA-driven free electron laser research. Also
discussed will be the development of fiber lasers that use coherent combining in both space and time toenable high average power at kHz repetition rates and beyond.

Figure 1: Schematics of the BELLA PW facility [1] showing new 2BL and iP2 beamlines.

References[1] K. Nakamura et al., Journal of the Particle Accelerator Society of Japan 19, 205 (2023).
Funding note: Work supported by U.S. Department of Energy Office of Science, Offices of High Energy Physics andFusion Energy Sciences, under Contract No. DE-AC02-05CH11231, and LaserNetUS (www.lasernetus.org).

31

26A-04
Title: Particle Acceleration Using Laser-Driven Photonic Structures
R. Joel England1, Robert L. Byer2, Peter Hommelhoff 3
1

SLAC National Accelerator Laboratory, Menlo Park CA, USA
2
Stanford University, Stanford CA, USA
3Friedrich-Alexander-University, Erlangen, Germany
E-mail: england@slac.stanford.edu

Keywords: Laser, acceleration, on-chip, photonic, nanofabrication
Acceleration of particles in photonic nanostructures fabricated using semiconductor manufacturing
techniques and driven by ultrafast solid-state lasers is a new and promising approach to developing future
generations of compact particle accelerators. Substantial progress has been made in this area in recent
years, fueled by a growing international collaboration of universities, national laboratories, and companies.
Performance of these micro-accelerator devices is ultimately limited by laser-induced material breakdown
limits, which can be substantially higher for optically driven dielectrics than for radio-frequency metallic
cavities traditionally used in modern particle accelerators, allowing for 1 to 2 orders of magnitude increasein achievable accelerating fields. The lasers required for this approach are commercially available withmoderate (micro-Joule class) pulse energies and repetition rates in the MHz regime. We summarize
progress to date and outline potential near-term applications and offshoot technologies.

Fig.1 Experimental setup (a) and measured energy spectrum (b) for recent experimental results to accelerate a captured
electron bunch from a tip emission source by 16.5 keV over 480µm interaction length in a dielectric laser accelerator.

References[1] R. Shiloh, et al., "Electron phase-space control in photonic chip-based particle acceleration," Nature 597, 498 (2021).
[2] N. Sapra, et al., "On-Chip Integrated Laser-Driven Particle Accelerator," Science 367, 79-83 (2020).
[3] R. J. England, et al., "Dielectric Laser Accelerators," Rev. Mod. Phys. 86, 1337 (2014).
[4] U. Niedermayer, et al., "Design of a scalable integrated nanophotonic electron accelerator on a chip," Phys. Rev.
Applied 16, 024022 (2021).

32

26P-05
Current status of the MIRAI free-electron laser projectusing laser-accelerated electron beams in Japan
Masaki Kando1,2,3, Zhan Jin2,3, Kai Huang1,3, Nobuhiko Nakanii2,3,Zhenzhe Lei2,3, Yoshio Mizuta2,3, Alexandre F. Rondpierre2,3, Toshiya Muto4,
Driss Oumbarek-Espinos2,3, Naveen Pathak2, Yanjun Gu2, Shingo Sato2,3,Alexei G. Zhidkov2,Shigeru Yamamoto5,3, Tomonao Hosokai2,31

Kansai Photon Science Institute,
National Institutes for Quantum Science and Technology, Japan
2
SANKEN, Osaka University, Japan
3
Laser Accelerator R&D Team, RIKEN SPring-8 Center, Japan
4
Research Center for Electron Photon Science, Tohoku University, Japan
5
High Energy Accelerator Research Organization, Japan
E-mail: kando.masaki@qst.go.jp
Keywords: laser acceleration, free-electron laser, laser wakefield acceleration
We aim to realize a compact, X-ray free-electron laser (FEL) based on laser wakefield acceleration(LWFA) through the JST MIRAI program (Creating new values that meet social and industrial needs byscience and technology) [1]. As a milestone goal, we pursue to demonstrate lasing in self-amplified
spontaneous emission (SASE) regime in the extreme ultraviolet wavelength. Here, we show our recent
electron beam parameters achieved in our laser electron platform LAPLACIAN in RIKEN SPring-8 Center[2]. The platform equips with a dedicated Ti: sapphire laser system with three beamlines. Currently, we use
a single beam to generate electron beams using a conical gas-jet target with a razor blade that employs
localized density-ramp injection. Manipulating laser profile [3] produces high-quality electron beams witha charge of >10 pC, an energy of 200-400 MeV, and a relative energy spread smaller than 1%(root-mean-square). We show our achieved beam parameters allow lasing at the XUV (extreme ultraviolet)
regime with a 2-m-length undulator of the undulator strength K=1.4 and the period of 10 mm.
In the talk, we discuss the LWFA electron beam parameters and the calculation of SASE FEL, thecurrent beamline preparation status, and the plan for the FEL experiment.

Fig.1 An experimental setup at the LAPLACIAN facility in SPring-8 Center.

References[1] https://www.jst.go.jp/mirai/en/program/large-scale-type/theme01.html[2] M. Kando et al., JINST 17 T06001 (2022).
[3] N. Nakanii et al., Appl. Phys. Express 16, 026001 (2023).

33

26A-06
The COXINEL seeded Free Electron Laser driven by the HZDR L aser
Plasma Accelerator

Marie-Emmanuelle Couprie1, on behalf of the COXINEL team1

Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190
Saint-Aubin, France
E-mail: couprie@synchrotron-soleil.fr

Keywords: Q-BASIS, Ultra-short pulse laser, Free Electron Laser
Laser Plasma Accelerators (LPAs), reaching gigavolt-per-centimeter accelerating fields, can generate highpeak current, low emittance and GeV class electron beams that can be qualified by a Free Electron Laser(FEL) application. Electron beam transport [1] along the COXINEL line has been mastered and undulator
radiation has been controlled [2] with the line installed at Laboratoire d’Optique Appliquée. We firstdescribe the commissioning of the COXINEL beamline driven by the HZDR plasma accelerator, including
electron beam transport, undulator spontaneous emission and tuning for FEL. We report on experimental
demonstration of FEL lasing at 270 nm in a seeded configuration [3]. Control over the radiation
wavelength is achieved with an improved bandwidth stability. Furthermore, the appearance of interference
fringes, resulting from the interaction between the phase-locked emitted radiation and the seed, confirms
longitudinal coherence, representing an essential feature of seeded FELs. These results are in good
agreement with by ELEGANT (beam transport) and GENESIS (FEL) simulations.

References[1] T. André et al., “Control of laser plasma accelerated electrons for light sources”, Nature Comm. 1334 (2018)[2] A. Ghaith et al., “Tunable High Spatio-Spectral Purity Undulator Radiation from a Transported Laser Plasma
Accelerated Electron Beam”, Scientific Reports 9: 19020 (2019).
[3] M. Labat, J.P. Couperus Cabadağ, A. Ghaith, A. Irman, et al “Seeded free-electron laser drive by acompact laser plasma accelerator” Nat. Photon. (2022). https://doi.org/10.1038/s41566-022-01104-w

34

26A-07

KAIO-BEAMLINE, à modular high repetition rate laser electron
accelerator for broad range of applications
François SYLLA

35

Lightwave control of relativistic laser-matter interactions
Rodrigo Lopez-Martens, Jaismeen Kaur, Zhao Cheng, Stefan Haessler, Julius Huijts,
Lucas Rovige, Aline Vernier, Igor Andriyash, Jérôme Faure.
Laboratoire d’Optique Appliquée, Institut Polytechnique de Paris, ENSTA Paris, Ecole
Polytechnique, CNRS
E-mail: rodrigo.lopez-martens@ensta-paris.fr
Keywords: Ultra-short pulse laser, relativistic interactions, high harmonic generation, electron
acceleration, carrier-envelope phase, coherent control.
Lightwave control of collective electron dynamics during relativistic laser-plasma interactions ischallenging as it requires few-cycle driver laser pulses with relativistic intensity (> 1018 W/cm2)
and controlled carrier-envelope phase (CEP), combined together with a target system (gas, liquid
or solid) featuring extremely well-controlled interaction conditions from shot to shot. The Salle
Noire 2.0 laser system developed at the Laboratoire d’Optique Appliquée delivers CEP-stable, TW
peak power, 1.5 cycle NIR transients (3.5 fs at 780 nm) with high-temporal contrast (> 1010) at 1
kHz repetition rate with a 300 mrad shot-to-shot CEP stability [1]. This unique laser system has
opened the door to studying relativistic laser-plasma interactions with unprecedented precision: weshow how we can control the spatio-spectral properties of both high-harmonic and electron beams
simultaneously emitted by plasma mirrors formed on solid density targets [2] and relativistic
electron beams produced by laser-wakefield acceleration in sub-critical gas jets [3].

Top: Schematic representation of the relativistic plasma mirror set-up (a), measured electron distribution (b) and highharmonic spectra (c) for two CEP values offset by π. Bottom: Schematic representation of the laser-wakefield electron
accelerator in a gas jet (a) and measured CEP-dependent electron beam pointing (b) and energy spectrum (c).

References[1] M. Ouillé et al. Light Sci. Appl., 9(1): 2047–7538, 2020.
[2] F. Boehle et al. J. Phys. Photonics, 2(3): 034010, 2020.
[3] J. Huijts et al. Phys. Rev. X, 12: 011036, 2022.

36

26P-02Ultra-high charge electron acceleration for nuclear applications
Liming Chen1*, Jie Feng1, Yaojun Li1, WenZhao Wang1, Jie Zhang1,2
School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai
200240, China
2
Lab of Optics Physics and Institute of Physics, Chinese Academy of Sciences,
Beijing 100180, China*E-mail: lmchen@sjtu.edu.cn
1

Keywords: Laser wakefield acceleration, electron beam charge, Isomeric state, unclear excitation
Laser plasma acceleration is not only suitable for advance accelerator, but also possess great potential for
plasma exciter or collider. At present, main research topics in this field focus on the quality improvementof accelerated electron beam. On the other hand, the laser plasma accelerator also has extremely highelectron density which will produce high brightness gamma ray source and intense neutron source,
resulting in powerful tool for nuclear physics research.
Recently, our team has carried out systematic studies on electron acceleration with large charge. For
example, we used a solid target to realize relativistic electron acceleration of 100 nC [1] with very small
divergence angle; And achieved stable acceleration of ~ 20 nC and electron energy of tens MeV inhigh-density gas targets, through a novel efficient injection that the atom inner shell electrons are ionized
and continuously injected into multiple plasma bubbles [2].
Based on new experimental results of electron acceleration obtained, we have carried out the research of"laser-plasma exciter". Firstly, a high brightness neutron source [3] is obtained by driving a solid target
with an electron beam. Then, using the nonlinear resonance of Kr clusters excited by intense laser, the83Kr isomeric state is achieved experimentally with peak efficiency 2x10^15 p/s [4]. And also, with
optimized high charge electron beam driven (γ,n) reaction, the peak flux of neutron source reaches to10^21 n/cm^2/s, which is comparable to Supernova [5].
In order to carry out the experimental verification of laser "plasma exciter" and extremely strong field QED,
we are constructing the "laboratory astrophysics research platform" (LAP) in TsungDao Lee Institute, forthe nuclear astrophysics research in relativistic.

References[1] Y. Ma et al., PNAS 115, 6980(2018)[2] J. Feng et al., arXiv: 2203. 06454[3] J. Feng et al., HEDP 36, 100753(2020)[4] J. Feng et al., PRL 128, 052501(2022)[5] Y. J. Li et al., 10, e33(2022)

37

26P-03
Recent progresses of laser plasma based electron acceleration andradiation at Shanghai Jiao Tong university
Min Chen, Xinzhe Zhu, Boyuan Li, Feng Liu, Jianlong Li, Zewu Bi, Xulei Ge,
Wenchao Yan, Liming Chen, Zhengming Sheng, and Jie Zhang,

Key Laboratory for Laser Plasmas (Ministry of Education),
Shanghai Jiao Tong University, China
E-mail: minchen@sjtu.edu.cn
Keywords: laser plasma, wakefield acceleration, plasma channel, high harmonics generation
Laser plasma based electron acceleration and radiation have many applications. Aiming to the high energy
electron acceleration and intense harmonics generation, we have performed both theoretical andexperimental studies. A curved plasma channel has been proposed to guide intense lasers for multistage
laser wakefield acceleration [1,2]. In our recent experiment we found that when the channel curvatureradius is gradually increased and the laser incidence offset is optimized, the stable laser guiding is possible
and wakefields can be excited in the curved channel. Electrons with maximum energy of 0.7GeV havebeen observed. Our results show that such a channel exhibits good potential for seamless multi-stage laser
wakefield acceleration. For high harmonics generation in laser solid interaction, we also experimentallydemonstrate that efficient harmonics can be achieved directly by compressing large-scale surface plasma
via the radiation pressure of a circularly polarized normally incident prepulse. The harmonic generation
efficiency obtained by this method is comparable to that obtained with optimized plasma scale length byhigh-contrast lasers. Our scheme does not rely on high-contrast lasers and is robust and easy to implement.
Thus, it may pave a way for the development of intense extreme ultraviolet sources and future applications
with high repetition rates [3,4]. A 200+300TW two-laser system platform will be installed in SJTU. The
research plans, such as staged wakefield acceleration, Thomson scattering and plasma optics studies on thisplatform, will be introduced.
References[1] J. Luo, M. Chen, W.Y. Wu, S.M. Weng, Z.M. Sheng, C.B. Schroeder, D.A. Jaroszynski, E. Esarey, W.P. Leemans,
W.B. Mori, and J. Zhang, “Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channels”,
Phys. Rev. Lett., 120,154801 (2018)[2] Zhu Xin-Zhe, Li Bo-Yuan, Liu Feng, Li Jian-Long, Bi Ze-Wu, Lu Lin, Yuan Xiao-Hui, Yan Wen-Chao, Chen Min,
Chen Li-Ming, Sheng Zheng-Ming, Zhang Jie, “Experimental study on capillary discharge for laser plasma wakeacceleration”, Acta Phys. Sin., 71(9), 095202 (2022)[3] B.Y. Li, F. Liu, M. Chen, F.Y. Wu, J.W. Wang, L. Lu, J.L. Li, X.L. Ge, X.H. Yuan, W.C. Yan, L.M. Chen, Z.M.
Sheng, and J. Zhang, “Experimental Demonstration of Efficient Harmonic Generation via Surface Plasma
Compression with Lasers”, Phys. Rev. Lett., 128, 244801 (2022)[4] B.Y. Li, F. Liu, M. Chen, Z.Y. Chen, X.H. Yuan, S.M. Weng, T. Jin, S.G. Rykovanov, J.W. Wang, Z.M. Sheng,
and J. Zhang, “High-quality high-order harmonic generation through pre-plasma truncation”, Phys. Rev. E, 100,053207 (2019)38

Poster presentation(April, 26, 12:20 – 15:30, SANKEN, CReA)

PO-01

Efficient high-order harmonic generation via surface plasmacompression with lasers
Boyuan Li1, Feng Liu1, Min Chen1, Fuyuan Wu1, Wenchao Yan1,
Liming Chen1, Zhengming Sheng1,2 and Jie Zhang1,2
Key Laboratory for Laser Plasmas (MOE), School of Physics
and Astronomy, Shanghai Jiao Tong University, Shanghai, China
2
Tsung-Dao Lee Institute, Shanghai Jiao Tong University,
Shanghai, China
E-mail: liby1990@sjtu.edu.cn
1

Keywords: High-order harmonic generation, Laser contrast, Normally incident prepulse, Surface
plasma compression
The efficiency of high-order harmonic generation from a relativistic laser interacting with solid targets
depends greatly on surface plasma distribution. The usual method of enhancing efficiency involves tuning
the plasma scale length carefully by improving the laser contrast [1]. Here, we experimentally demonstratethat efficient harmonics can be achieved directly by compressing large-scale surface plasma via theradiation pressure of a circularly polarized normally incident prepulse. The harmonic generation efficiency
obtained by this method is comparable to that obtained with optimized plasma scale length by high-contrast
lasers, and the harmonic spectrum plateaus at high orders. Our scheme does not rely on high-contrast lasers
and is robust and easy to implement. Thus, it may pave a way for the development of intense extreme
ultraviolet sources and future applications with high repetition rates. Moreover, our studies also reveal thatthe preplasma can be actively tailored into a curved surface using the radiation pressure of a normally
incident prepulse. This may also be an efficient way to focus relativistic harmonics [2] or to produce
high-order vortex harmonics [3].

Fig.1 Experimental setup

References[1] S. Kahaly et al. Phys. Rev. Lett. 110, 175001 (2013); F. Dollar et al. Phys. Rev. Lett. 110, 175002 (2013).
[2] H. Vincenti Phys. Rev. Lett. 123, 105001 (2019).
[3] J. W. Wang et al. Nat. Commun. 10, 5554 (2019).

40

PO-02

Challenges to make LPA viable for industrial XFEL sources
Alexandre RONDEPIERRE1,2,* , Driss OUMBAREK ESPINOS1,2,*
and Tomonao HOSOKAI1,2.
SANKEN, Osaka University, Japan
Laser Accelerator R&D Team, RIKEN SPring-8 Center, Japan
E-mail: alexandre.rondepierre@sanken.osaka-u.ac.jp*: authors contributed equally to this work
1

2

Keywords: LWFA, Laser wavefront, Halo, Electron control
Since its inception by Tajima and Dawson [1] Laser plasma acceleration (LPA) has gained traction
as an alternative to classic RF accelerators.
LPA offers high acceleration gradients (up to 10s of GeV/m) making possible the generation of GeV
electrons in tens of cm [2]. Multiple uses for LPA systems are already being seriously considered including
their use as electron beam sources for Free Electron Laser. The generation of LPA based FEL has been
recently demonstrated [3,4]. However, achieving proper electron beam parameters for such use in aconsistent manner and a reliable coupling with the undulator is non-trivial and still under research.
Being able to provide a reliable and clean laser source for LPA is a key part to go towards industrial
applications. One important issue lies with instabilities induced by imperfect beam tainted with aberrations.
It has already been shown that real laser beams, with poor focus quality, can be detrimental for electron
generations [5,6].
The presented work introduces the LAPLACIAN (Laser Acceleration Platform as a Coordinated
Innovation Anchor, Fig.1) experimental facility inside the MIRAI project framework. The LAPLACIAN
facility, situated in the SPRING-8 site, aims for the generation of X-ray FEL with relativistic electrons(GeV) from an LPA source in a beamline of under 10 m (from electron source to radiation diagnostics). In
LAPLACIAN, multiple gas targets and LPA schemes are being studied and also the combined use ofmagneto-optics and plasma-based optics for coupling the source with the undulator.
This work will present an overview of the facility, its capabilities, and the raised challenges. Current
investigations to improve LPA, both from the laser part and electron generation and transportation, will beshown. First results regarding electron generation as function of a controlled aberrated laser are presented.

Fig.1 Laser system at LAPLACIAN facility.

41

References[1] Tajima, T., & Dawson, J. M. (1979). Laser electron accelerator. Physical Review Letters, 43(4), 267.
[2] Gonsalves, A. J., Nakamura, K., Daniels, J., Benedetti, C., Pieronek, C., De Raadt, T. C. H., ... & Leemans, W. P.
(2019). Petawatt laser guiding and electron beam acceleration to 8 GeV in a laser-heated capillary discharge waveguide.
Physical review letters, 122(8), 084801.
[3] Wang, W., Feng, K., Ke, L., Yu, C., Xu, Y., Qi, R., ... & Xu, Z. (2021). Free-electron lasing at 27 nanometres
based on a laser wakefield accelerator. Nature, 595(7868), 516-520.
[4] Labat, M., Cabadağ, J. C., Ghaith, A., Irman, A., Berlioux, A., Berteaud, P., Oumbarek-Espinos, D., ... & Couprie,
M. E. (2022). Seeded free-electron laser driven by a compact laser plasma accelerator. Nature Photonics, 1-7.
[5] Nakanii, N., Hosokai, T., Iwasa, K., Pathak, N.C., ... & Kodama, R. (2016). Effect of halo on the stability ofelectron bunches in laser wakefield acceleration. EPL, 113(34002).
[6] Ferri, J., Davoine, X., Fourmaux, S., Kieffer, J.C., Corde,S. and Lifschitz, A. (2016). Effect of experimental laser
imperfections on laser wakefield acceleration and betatron source. Nature Scientific Report, 6:27846.

42

PO-03Fold-rotational Symmetric Radiation Vortex stem from Nonlinear
Thomson Scattering of Intense Laser with Circular Polarization Topology
Wenchao Yan* Weijun Zhou Liming Chen
Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy,
Shanghai Jiao Tong University, Shanghai 200240, China
Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai
200240, China* Email: wenchaoyan@sjtu.edu.cn
The radiation carries the angular momentum has been extensively applied in particle manipulation,
nuclear excitation, and state diagnostics. New conceptions of the high energy radiation vortex would
extremely extend the field of application. Herein, we discovered the interesting structured radiationvortex in the nonlinear Thomson scattering between the relativistic electron slice and ultra-intense
circularly polarized Laguerre-Gaussian laser. In the nonlinear scattering process, the radiation nearfield could be redistributed into structured patterns that imprinted by the so-called `fold-rotational
symmetry' of the laser field, which is characterized by the quantum numbers of the spin (𝜎) and orbit(𝑙) angular momentum. These processes were illustrated by both theoretical analysis and numericalcalculations. With the specific (𝜎, 𝑙) combination, the radiation pattern will turn into the dynamic
radiation focusing, and form an extremely small gamma-ray focus with an unprecedented intensity
𝐼𝑝 = 3 × 1019 𝑊/𝑐𝑚2 , which is highly beneficial for the researches on the nuclear physics andquantum electrodynamics.

Figure. The radiation field strength and corresponding radiation intensity distributions on the detective plane.

43PO-04Development of a compact electron source using self-modulated laser
wakefield acceleration driven by a Sub-TW class laser
Duthika D. Perera, Takamitsu P. Otsuka, Daiki Nishida, Takahiro Gunji,
Kouichi Iida, Kouske Kataya, Noboru Yugami
Presenting
Author’s photo

Graduate School of Regional development and Creativity,
Utsunomiya University, Japan
E-mail: d.perera2022@lwfa.oe.utsunomiya-u.ac.jp

Keywords: Plasma, Laser wakefield acceleration, Particle-in-cell simulation, Electron beam
Since, Tajima and Dawson reported the concept of laser wakefield acceleration (LWFA), many
experimental and theoretical work have been reported [1]. LWFA has a large acceleration gradient due tothe use of high-density plasma. Moreover, the acceleration distance exceeds the Rayleigh length, resulting
in a large energy gain. A. J. Gonsalves et al. reported the feasibility of petawatt laser guidance and electron
beam acceleration up to 8 GeV in capillary discharge waveguide [2]. LWFA experiment using a Sub-TW
class laser that can be operated in a small-scale laboratory has been also performed, and generation of a MeV
class electron beam by a self-modulated laser wakefield acceleration method has been reported [3].
We simulate a laser pulse interacting with a plasma density of 1020 cm-3 by using a two-dimensional particlein-cell code. The laser energy is 120 mJ with 120 fs of pulse duration (full width at half maximum). The laser
intensity is 2.0 × 1018 W/cm2 (normalized vector potential a0 = 1). As shown in Figure 1 the laser pulse
produces wakefiled in which the envelope of the laser electric field is modulated, achieving a large electricfield. We also preparing the experiment to confirm the simulation result. Figure 2 shows the diagram of theexperimental setup. We plan to conduct LWFA experiment using a 1 TW Ti:Sapphire laser system which
produce 120 mJ of energy with 120 fs of pulse duration (FWHM). In our poster presentation, we plan to
10

750
500

y [+m]

5

250

0

0
-250

-5
-10

-500
50

60

70

x [+m]

80

90

-750

Fig. 1 Electric field in x direction of laser axis propagation from two-Electric field Ex [GV/m]

discuss using simulation results etc.

Fig. 2 Experimental setup.

dimensional particle-in-cell code simulation result.

References[1] T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979).
[2] A. J. Gonsalves et al., Phys. Rev. Lett. 122, 084801 (2019).
[3] A. J. Goers et al., Phys. Rev. Lett. 115, 194802 (2015). F. Salehi et al., Opt. Lett. 42, 215 (2017).

44

PO-05

Induction heating for desorption of surface contamination for
high-repetition laser-driven heavy-ion acceleration
Sadaoki Kojima1, Tatsuhiko Miyatake1,2, Hironao Sakaki1,2, Hiroyoshi
Kuroki3, Yusuke Shimizu3, Hisanori Harada3, Norihiro Inoue3, Thanh
Hung Dinh1, Masayasu Hata1, Noboru Hasegawa1, Michiaki Mori1,
Masahiko Ishino1, Mamiko Nishiuchi1, Kotaro Kondo1, Masaharu
Nishikino1, Masaki Kando1, Toshiyuki Shirai4, and Kiminori Kondo1

1Kansai Photon Science Institute, National Institutes for Quantum Science and Technology, Japan
2Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Japan.
3Hitachi Zosen Corporation, Japan
4Department of Accelerator and Medical Physics, National Institutes for Quantum Science andTechnology, Japan

E-mail: kojima.sadaoki@qst.go.jp
Keywords: Laser-driven particle acceleration, Radiation cancer therapy, heavy-ion
We report on a first demonstration of surface contamination cleaning from high repetitive supplying thintape target for laser-driven heavy-ion acceleration. Contaminants (mainly water vapor and hydrocarbons),
including protons, are adsorbed on the surface of materials exposed to low vacuum (>10–3 Pa),
suppressing heavy-ion acceleration. The newly developed contamination cleaner heats a 5

m thick nickel

tape to over 400°C in 100 ms by induction heating, and it can scale to laser-driven heavy-ion acceleration
at rates over 10 Hz in the future. Furthermore, the Langmuir adsorption model adequately explained thetemperature dependence of desorption and readsorption of adsorbed molecules on a heated target surface,
and the temperature required for proton-free heavy-ion acceleration can be estimated. This type ofcontamination cleaner is the basis for laser-driven compact heavy-ion accelerators, which will reduce thefacility size and construction cost of heavy-ion cancer therapy devices and enable their widespread use.

Figure. 1. The finite element analysis code (Femtet ver. 2021) was used to analyze the heating process.
(a) Schematic view of setup. (b) Magnetic flux flow inside the nickel foil. (c) Eddy current flow inside the nickel foil.
(d) Temperature distribution of the heated nickel tape.

45

PO-06

Numerical simulation of laser ion injector for quantum scalpel project

Masayasu Hata1, Sadaoki Kojima1, and Kiminori Kondo1
1

KPSI, QST, Japan
E-mail: hata.masayasu@qst.go.jp

Keywords: Laser ion injector, Carbon ion acceleration, Particle-In-Cell simulation
The National Institutes for Quantum Science and Technology (QST) is currently conducting the quantum
scalpel project, which aims to improve the performance and miniaturization of heavy ion cancer therapy
devices, which are highly effective in treatment [1,2]. The “Quantum scalpel” means cancer therapy using
a quantum beam without a real scalpel in a body. It’s a treatment method with minimal side effects, making
it possible for patients to go to the hospital (day surgery) and be treated for cancer while working. The fifth
generation of heavy ion cancer therapy devices, namely the Quantum Scalpel consists of the laser ion
injector, super-conducting synchrotron, and super-conducting rotating gantry. It is required to miniaturize
the ion injector and synchrotron to develop compact heavy ion cancer therapy devices. In the quantum
scalpel project, the synchrotron and injector will be miniaturized by introducing super-conducting
technology and replacing the conventional linear accelerator with the laser ion injector, respectively. Laser
ion acceleration has a large acceleration gradient and its technique is expected to develop a compact ion
injector [3].
The requirement for the injector of the quantum scalpel is the 10 Hz generation of more than 108 of 4
MeV/u C6+ ions with 1% energy bandwidth. However, at the point of the laser acceleration, the 10%
energy bandwidth of these ions is allowable. The 10% energy bandwidth of these carbon ions iscompressed to 1% using the phase rotation technique after the laser acceleration and then they aretransported to the synchrotron.
We have conducted quasi-1D and 2D PIC simulations to verify the condition of C6+ generation. Thesesimulation results agree with the simple model that roughly predicts the maximum sheath strength andachievable ionization degree. We have also discussed simulation results in the cases of Carbon coated Nitargets.
References[1] K. Noda, “Progress of radiotherapy technology with HIMAC,” J. Phys.: Conf. Ser. 1154, 012019 (2019).
[2] H. Ishikawa et al., “Carbon-ion radiotherapy for urological cancers,” Int. J. Uro. 29, 1109–1119 (2022).
[3] M. Nishiuchi et al., “Dynamics of laser-driven heavy-ion acceleration clarified by ion charge states”, Phys. Rev.
Res. 2, 033081 (2020).

46

PO-07

LPA-Driven Electron Radiography at OMEGA EP
Matthew Freeman1, Gerrit Bruhaug2, Levi Neukirch1, Frank Merrill1, Carl Wilde1, Jessica Shaw2
1

Los Alamos National Laboratory, Los Alamos, NM, USA
2
Laboratory for Laser Energetics, Rochester, NY, USA
E-mail: msf@lanl.gov

Keywords: Ultra-short pulse laser, Imaging, Electron radiography, LPA-drive

Recently, a sub-picosecond, laser-plasma accelerator (LPA)-driven flash electron
radiography source has been demonstrated at the OMEGA extended performance (EP)laser system at the Laboratory for Laser Energetics (LLE) in Rochester, NY.1 This enables
the visualization of ultra-fast, ultra-thin dynamic processes and associated electromagnetic
fields, with potential application as an inertial confinement fusion diagnostic. Using thisultra-fast, high-flux LPA-driven electron source, high quality radiography has been
demonstrated with an areal density sensitivity from 7 mg cm-2 of aluminum up to 3 g cm-2
of tungsten, and a spatial resolution of 75 µm.2 Work is underway to implement a magnetic
lens system at OMEGA EP that could increase spatial resolution to 10 µm or better, andallow for better quantification of magnetic field imaging,3 as shown in Fig. 1.

Fig.1: Conceptual visualization of magnetic-lensing implemented with LPA-driven eRad at OMEGA EP (at left), and aclose up of the sidelighter beam in green, generating an electron source to enter a magnetic lens system (at right).

References[1] Shaw, J. L., et al. "Microcoulomb (0.7±0.4 0.2 μC) laser plasma accelerator on
OMEGA EP." Scientific Reports 11.1 (2021): 7498.
[2] Bruhaug, G., et al. "Single-shot electron radiography using a laser–plasma accelerator."
Scientific Reports 13.1 (2023): 2227.
[3] Merrill, Frank, et al. "Electron radiography." Nuclear Instruments and Methods inPhysics Research Section B: Beam Interactions with Materials and Atoms 261.1-2 (2007):
382-386.

47

PO-08Ultrafast electron microscopy with relativistic femtosecond electron
pulsesJinfeng Yang1, Masao Gohdo1, and Yoichi Yoshida1
1

SANKEN, Osaka University, Japan

E-mail: yang@sanken.osaka-u.ac.jp
Keywords: Ultrafast electron microscopy, Femtosecond-pulsed electron beam, Imaging,
Structural dynamics
Femtosecond atomic-scale imaging is a most challenging subject in materials science and has long
been a cherished dream tool for scientists wishing to study ultrafast structural dynamics in various
materials. In this research, we aim to develop an innovative relativistic femtosecond-pulsed electron
microscope by combining a radio-frequency electron acceleration technology into high-voltage
electron microscope. In this paper, we reported the concept and construction of the relativistic
femtosecond-pulsed electron microscope. Some demonstrations of electron diffraction and imaging
with 3-MeV-energy femtosecond electron pulses were presented. The single-shot imaging of
micro-crystals with femtosecond electron pulse was reported. Recently, we have succeeded to observe
the TEM images of 40-nm-diamter gold nanoparticles with femtosecond electron pulses in our UEM.
The potential of ultrafast relativistic electron microscope was discussed.
This work was supported by a Basic Research (A) (No. 21H04654, No. 22246127, No. 26246026, andNo. 17H01060) of Grant-in-Aid for Scientific Research from MEXT, Japan.

Fig 1. Ultrafast electron microscopy using RF electron gun and TEM image of gold nanoparticles using relativistic
femtosecond electron pulses.

References[1] J. Yang, K. Gen, N. Naruse, S. Sakakihara, Y. Yoshida, Quantum Beam Science 4, 4 (2020).
[2] J. Yang and Y. Yoshida, Advances in Condensed Matter Physics, 2019, 9739241(2019).
[3] J. Yang, Y. Yoshida, H. Yasuda, Microscopy, 67, 291-295(2018).

48

PO-09Supercontinuum-seeded 4-micron KTA optical parametric amplifier
for seeding TW-class Fe:ZnSe multipass amplifiers
Tsuneto Kanai1,*, Edgar Kaksis2, Audrius Pugžlys2, Andrius Baltuška2,
Daiki Okazaki1, Ryo Yasuhara3, and Shigeki Tokita1
Institute for Chemical Research, Kyoto University, Japan
Photonics Institute, Vienna University of Technology, Austria
3
National Institute for Fusion Science, Japan
E-mail: goldwell74@gmail.com
1
2

Keywords: Ultra-short pulse laser, Mid-IR, Optical parametric amplifier
Driven by the λ2 energy scaling law of strong field phenomena [1], high-power optical parametricamplifiers (OPAs) in the 3–10 µm [2-4] bands attract much attention as the next generation sources forattosecond science and its related areas.

While such mid-IR OPAs have almost all of the required features

for attosecond physic such as stabilized carrier-envelope phase, wavelength tunability, power-scaling, etc.,
excellent pulse energy scaling of 4-micron Fe:ZnSe(S)-based laser [5] can surpass that of the mid-IR OPAs.
By carefully combining the Fe:ZnSe(S) as a booster of KTA OPA, we are constructing a novel all-in-one
hybrid laser system for attosecond physics, plasma physics, and related area [Fig. 1(a)].

In this work, wereport our recent development of a three-stage 4-micron KTA OPA driven by a homemade Yb:CaF2 CPA[Fig. 1(b,c)], which will play crucial roles as a seed laser of the hybrid system.

Fig.1 (a) The OPA/CPA hybrid system and setup for attosecond physics. (b,c) Observed spectra of
the signal waves (b) and the idler waves (c) from the developed KTA OPA.

T.K. acknowledges financial support by SPIRITS 2022 of Kyoto University, THE AMADAOUNDATION, MATSUO FOUNDATION, and Japan Society for the Promotion of Science (JSPS,
23H01877, 21H04474). S.T. is financially supported by JSPS (21H01845) and the New Energy andIndustrial Technology Development Organization (NEDO, JPNP20004).
References[1]

T. Popmintchev et al., Science 336, 1287 (2012).

[2]

G. Andriukaitis, T. Balčiūnas, S. Ališauskas, A. Pugžlys, A. Baltuška, T. Popmintchev, M.-C. Chen, M. M.
Murnane, and H. C. Kapteyn, Opt. Lett. 36, 2755 (2011);[3]

T. Kanai, Y. Lee, M. Seo, and D. E. Kim, J. Opt. Soc. Am. B 36, 2407 (2019).

[4]

T. Kanai, P. Malevich, S. S. Kangaparambil, K. Ishida, M. Mizui, K. Yamanouchi, H. Hoogland, R. Holzwarth,A. Pugžlys, and A. Baltuška, Opt. Lett. 42, 683 (2017).

[5]

H. Uehara, T. Tsunai, B. Han, K. Goya, R. Yasuhara, F. Potemkin, J. Kawanaka, and S. Tokita, Opt. Lett. 45,
2788 (2020).

49

PO-10

Simulation of self-focusing ultrashort femtosecond lasers in air for thedetection of viruses and VOCsJames K. Koga1
1

Kansai Photon Science Institute, The National Institutes for Quantum
Science and Technology (QST), Japan
E-mail: koga.james@qst.go.jp

Keywords: Ultra-short pulse laser, Simulation, Self-focusing, Laser Induced Breakdown
The COVID-19 pandemic brought to the forefront the need to be able to quickly detect whether viruses arepresent or not in the air. We have proposed using laser-induced breakdown spectroscopy (LIBS) using
ultrashort femtosecond lasers to detect them directly or indirectly via the presence of volatile organic
compounds (VOCs). Ultrashort laser pulse propagation simulations, which solve the nonlinear Schrödinger
equation [1], are being performed for air. Since the laser pulse has sufficiently high power to self-focus, it
generates a plasma filament [2]. We will show the temperature and density of the plasma which are generated.
The strength of the initial focusing of the laser pulse influences the plasma density and propagation
characteristics [3]. So, we will also briefly discuss this in relation to the possibility of detection.

Fig.1 Simulation of laser pulse (red) and plasma density (green): initial (top) and after propagating 1.4 cm in air(bottom).

References[1] J. K. Koga, K. Moribayashi, Y. Fukuda et al., J. Phys. D: Appl. Phys. 43, 025204 (2010).
[2] A. Couarion and A. Mysyrowicz, Phys. Rep. 441, 47 (2007).
[3] J. K. Koga, J. Opt. Soc. Am. B 26, 930 (2009).

Acknowledgements
This research was supported by the crowdfunding project, ’Can lasers detect viruses in air?’, using the academic
crowdfunding platform ‘academist’. The computations were performed with the supercomputer HPE SGI8600 at JAEA
Tokai.

50

PO-11

Laser Cavitation Peening Using a Nd:YAG Laserwith and without Q-switch
Hitoshi Soyama1
Department of Finemechanics, Tohoku University, Japan
E-mail: soyama@mm.mech.tohoku.ac.jp

1

Keywords: Cavitation, Laser peening, Normal oscillation, Pulse width, 3D-metal, Fatigue strength
Additive manufactured three dimensional metals (3D-metal) attractive materials for medical implants.
However, fatigue strength of 3D-metal is nearly half of bulk metals, and then the improvement of fatigue
strength of 3D-metal is big issue.
At submerged laser peening, a bubble which behave cavitation bubble, i.e., “laser cavitation”, is generated
after laser ablation, and the impact induced by laser cavitation was bigger than that of laser ablation [1-2].
The peening using laser cavitation is named as “laser cavitation peening”. At conventional laser cavitation
peening, a Nd:YAG laser with Q-switch was used. If a Nd:YAG laser without Q-switch, i.e., normal
oscilation, can be used for laser cavitation peening, the reputation frequency can be improved to about 1000
times that of conventional systems, as the other laser such as a fiber laser can be used.
Figure 1 shows the aspect of laser cavitation produced by a Nd:YAG laser at normal oscillation. Figure 2
reveals the typical case of pressure detected by a hydrophone. As shown in Fig. 1, laser cavitation was
generated by the laser pulse with 200 µs. At the laser cavitation collapse, the pressure was detected as shownin Fig. 2. Namely, a Nd:YAG laser at normal oscillation can be utilized for laser cavitation peening.
This research was partly supported by JSPS KAKENHI grant numbers 23H01292 and 22KK0050.

Pressure detected byhydrophone pH kPa

Fig. 1 Aspect of laser cavitation produced by Nd:YAG laser without Q-switch
6.00
3.00
0.00
-3.00
-6.00

-0.2

0.0

0.2
0.4
0.6
Time after irradiated pulse laser t

0.8
ms

1.0

Fig. 2 Pressures of laser ablation and laser cavitation collapse produced by Nd:YAG laser without Q-switch

References[1] H.Soyama and A.M.Korsunsky, Journal of Materials Processing Technology, Vol. 305, (2022), 117586.
[2] H.Soyama, Metals, Vol. 11, No. 4, (2021), 531.

51

PO-12Development of a 6-mJ, 100-Hz, femtosecond Yb:CaF2 regenerative
amplifier for driving 4-micron KTA parametric amplifiers
Edgar Kaksis1, Tsuneto Kanai2 , Audrius Pugžlys1, Andrius Baltuška1,
Daiki Okazaki2,*, Ryo Yasuhara3, and Shigeki Tokita2
Photonics Institute, Vienna University of Technology, Austria
Institute for Chemical Research, Kyoto University, Japan
3
National Institute for Fusion Science, Japan
E-mail: okazaki@laser.kuicr.kyoto-u.ac.jp
1
2

Presenting
Author’s
Keywords:
Ultra-short pulse laser, Mid-IR, Optical parametric amplifier
photo
The laser diode (LD) pumped Yb-doped lasers attract much attention from their robustness, compact size,and low cost, and frequently adopted as ideal drivers for mid-IR optical parametric amplifiers (OPAs) [1,2].
Among the Yb-doped host materials, Yb:CaF2 has advantages in high energy and ultrashort pulse operation[3] because of its broad gain bandwidth over 20 nm and long fluorescence lifetime of 2.4 ms.

In thiswork, by adopting Yb:CaF2 as the laser medium and a Yb-fiber oscillator mode-locked via nonlinear
polarization evolution scheme [4], we develop a compact and robust 6-mJ, 100-Hz, femtosecond
regenerative amplifier for driving 4-micron KTA OPA, which will be used for studies ofattosecond/zeptosecond physics.

The schematic diagram of our laser system is depicted in Fig. 1(a) andthe achieved maximum power and highest pulse energy are 600 mW and 6 mJ, respectively [Fig. 1(b,c)].

Fig.1. (a) The experimental setup. (b) Typical spectra for the 6-mJ, 100-Hz setting (red curve) and the
2-mJ, 300-Hz setting (blue curve). (c) Typical output power as a function of the LD current.

T.K. acknowledges financial support by SPIRITS 2022 of Kyoto University, THE AMADAOUNDATION, MATSUO FOUNDATION, and Japan Society for the Promotion of Science (JSPS,
23H01877, 21H04474). S.T. is financially supported by JSPS (21H01845) and the New Energy andIndustrial Technology Development Organization (NEDO, JPNP20004).
References[1]

T. Kanai, Y. Lee, M. Seo, and D. E. Kim, J. Opt. Soc. Am. B 36, 2407 (2019).

[2]

G. Fan, T. Balčiūnas, T. Kanai, T. Flöry, G. Andriukaitis, B. E. Schmidt, F. Légaré, and A. Baltuška, Optica 3,1308 (2016).

[3]

X. Guo, S. Tokita, and J. Kawanaka, Appl. Phys. B 125, 143 (2019); G. Machinet et al., Opt. Lett. 38, 4008
(2013); T. Balčiūnas et al., Opt. Lett. 37, 2547 (2012); A. Kessler et al., Opt. Lett. 39, 1333 (2014).

[4]

T. Kanai, G. Okada, and S. Tokita, Conference on Lasers and Electro-Optics (Optical Society of America, 2023),
SM1F.2 (2023).

52

PO-13Temperature-driven, Sub-100-fs Mode-locked Fiber Oscillators
Based on the Symmetry-Broken Nonlinear Polarization Evolution Method
Tsuneto Kanai1,*, George Okada2, and Shigeki Tokita1
Institute for Chemical Research, Kyoto University,
Gokasyo, Uji, Kyoto 611-0011, Japan
2
Spectronix Corp., 3-28-15 Tarumicho, Suita, Osaka 564-0062, Japan
E-mail: goldwell74@gmail.com

1

Keywords: Ultra-short pulse laser, fiber laser, nonlinear polarization evolution
All fiber polarization maintaining (PM) mode-locked oscillators attract much attention from its simplicity,robustness, and low manufacturing cost.

Passive mode locking in all-PM ytterbium (Yb) fiber oscillators

has been demonstrated by means of material saturable absorbers (SAs) [1,2] and virtual SAs based on
nonlinear polarization rotation (NPE) [3,4] and nonlinear amplifying loop mirror (NALM) [5].

Recently,

J. Szczepanek et al., demonstrated a novel NPE-based virtual SA with zero group velocity mismatching(GVM) between the two orthogonally polarized SA-inducing paths [3].

The proposed NPE-SA iscomposed of symmetrically-spliced three PM fiber segments and the length inaccuracy of the segments
must be within a small fraction of the beat length of the PM fibers.

Furthermore, the use of the bothpolarization components in the NPE SA part makes the mode-locking sensitive to the mechanical stress.
In this work, we propose a mildly symmetry-broken NPE SA as a mode-locker and demonstrate anenvironmentally-stable, sub-100-fs mode-locked fiber oscillators.

The proposed NPE SA enables ones tocontrol the GVM into small desirable regions for self-starting region of the mode-locking via controlling
the temperature of the NPE SA part.

A Peltier device is adopted for the precise temperature controllingand by robustly gluing the NPE SA part onto the device with thermally conductive resin, the influence of
mechanical stress-induced birefringence is also disentangled.

The achieved power and pulse duration

after compression were 33.7 mW (18.31 MHz, 1030 nm) and 96 fs, respectively, and the stablemode-locking started automatically in a few seconds after starting the temperature control.

Fig.1 (a) The experimental setup. BPF: bandpass filter, YDF, ytterbium-doped fiber, WDM:
wavelength division multiplexer, and OC: output coupler. (b) Detailed illustration of thesymmetry-broken NPE SA. (c) Measured output spectrum. (d) Intensity autocorrelation trace,
which supports the pulse duration 96 fs of the compressed output pulses.

T.K. acknowledges financial support by SPIRITS 2022 of Kyoto University, THE AMADAOUNDATION, MATSUO FOUNDATION, and Japan Society for the Promotion of Science (JSPS,
23H01877, 21H04474). S.T. is financially supported by JSPS (21H01845) and the New Energy andIndustrial Technology Development Organization (NEDO, JPNP20004).
References[1]

J.-B. Lecourt et al., Opt. Express 20, 11918 (2012).

[2]

R. I. Woodward et al., IEEE Photonics Technol. Lett. 26, 1672 (2014).

53

[3]

J. Szczepanek, T. M. Karda´s, C. Radzewicz, and Y. Stepanenko, Opt. Lett. 42, 575 (2017).

[4]

T. Kanai, G. Okada, and S. Tokita, Conference on Lasers and Electro-Optics (Optical Society of America, 2023),
SM1F.2 (2023).

[5]

M. Erkintalo, C. Aguergaray, A. Runge, and N. G. R. Broderick, Opt. Express 20, 22669 (2012).

54

PO-14In-line Detection of Internal Defects in Fillet Welded Sheet of Lap Joint
by Laser Ultrasonic and Its Robotic Application Using Microchip Laser
Kazufumi Nomura1, Taketo Matsuida1, Keiji Kadota2, Seiya Nitta2, Tetsuo
Era2, and Satoru Asai2
Graduate School of Engineering, Osaka University, JapanDAIHEN Welding and Joining Research Alliance Laboratories, Joining
and Welding Research Institute, Osaka University, Japan
1

Presenting
Author’s photo2

E-mail: nomura@mapse.eng.osaka-u.ac.jp
Keywords: Laser ultrasonics, Galvanized steel sheet, Blowholes, Non-contact, Small size laser
A blowhole is a problem in lap joint welding of galvanized steel sheets, often used in automobile
manufacturing. This study developed a defect detection method using laser ultrasonic for blowholes. The
laser ultrasonic measurement is a non-contact method for generating and detecting the ultrasonic waves,
has high spatial resolution due to the point-to-point operation, and can be applied to non-planar surfaces. In
a lap joint welding with a thickness of 2.3 mm and 1.6 mm, the attenuation of the reflected signal from theback surface of the lower plate of the ultrasonics excited on the weld bead was effectively captured in thetargeted cross-section. Resultantly, the presence or absence of blow holes was determined. The automatic
defect judgment algorithm was derived and applied to moving measurements at high speed. Furthermore,
in-line measurement was realized by a robot system equipped with a microchip laser.
Lasers for US generation and
US detection
3-8 -5
Blowhole

Small & Movable(defect)O
2.3 or 1.6(Unit : mm)

4

2

3

1

0

0
-5

-3

-1 1
x [mm]

Without defect3

Microchip laser↓
Galvano mirror↓
Focal system

Detection
unit

2

1

Target(Connected by
1inch lens tubes)

-5

-3

-1 1
x [mm]

3

Generation
unit-5.0E4

3

Fixed

2.0E4

5

4
Time [ms]Time [ms]z
5

LU devicex

Lap joint specimen

Lap joint specimen

With defectFig. 1 Blowhole detection

Fig. 2 Robotic system using microchip laser

References[1] C. B. Scruby, L. E. Drain: Laser Ultrasonic, Techniques and Applications, Bristol, Adam Hilger (1990)[2] K. Nomura et al.: Study on Blowhole Detection in Fillet Welded Sheet of Lap Joint by Laser Ultrasonic Technique,
Quarterly Journal of the Japan Welding Society, 41, 1 (2023) 141-149

55

PO-15

Title: Development of a Start-to-End simulation code for thelaser-driven ion injector
Haruya Matsumoto1, Hironao Sakaki1,2, Keisuke Nagashima2,
Masayasu Hata2, Tomoyuki Endo2, Yukinobu Watanabe1
Interdisciplinary Graduate School of Engineering Sciences,
Kyushu University, Kasuga, Fukuoka, Japan
2
Kansai Photon Science Institutes for Quantum and Radiological
Science and Technology, Kyoto, Japan
E-mail: matsumoto.haruya.876@s.kyushu-u.ac.jp
1

Keywords: Q-BASIS, TNSA acceleration, Plasma simulation, Particle-in-Cell（PIC） simulation

We plan to develop a laser-driven ion injector as an application of laser-driven ion
acceleration [1]. For this development, it is necessary to design a beam transport method
for the efficient use of the laser-driven ion accelerator beam through appropriate
simulation. This simulation code needs to manage the entire process, from the laser partto the end of the injector (start-to-end). In other words, a "versatile simulation code" must
be developed that can freely calculate the time evolution of the electromagnetic field overa wide range of time scales, from the femtosecond regime for lasers (on the order of afew micrometers) to the nanosecond regime for ion beams (on the order of several
meters).
Therefore, we develop a new code for this purpose, based on the basic PIC codedeveloped at QST Kansai. In this presentation the progress and plans of the development
will be shown.

Fig.1 Image of Start-to-End Simulation
References[1] S. P. Hatchett et.al. Phys. Plasmas 7 2076 (2000).

56

PO-16

Title: Optimization of laser irradiation conditions for high-brightness
beam generation in laser-driven ion beams
Tatsuhiko Miyatake1,2, Sadaoki Kojima2, Hironao Sakaki1,2, Haruya
Matsumoto1,2, Thanh-Hung Dinh2, Masayasu Hata2, Masaharu Nishikino2,
Kotaro Kondo2, Mamiko Nishiuchi2, Yukinobu Watanabe1, Yoshiyuki Iwata3,
Toshiyuki Shirai3, Masaki Kando2, Kiminori Kondo2
Interdisciplinary Graduate School of Engineering Sciences, Kyushu
University, Japan
2
KPSI, Institutes for Quantum and Radiological Science and Technology,
Japan
3
NIRS, Institutes for Quantum and Radiological Science and Technology,JapanE-mail: miyatake.tatsuhiko.640@s.kyushu-u.ac.jp
1

Keywords: Laser-driven ion acceleration, TNSA, Ion beams, Emittance, PIC simulation
In Target Normal Sheath Acceleration (TNSA), one of the best-known laser-plasma ion acceleration
mechanisms, an ultra-intense laser is focused onto a thin foil target, accelerating electrons to relativistic
levels and generating a charge separation field gradient of ~TV/m on the rear side of the target. This field
accelerates ions on the rear side of the target at multi-MeV kinetic energies [1]. The ion beams produced in
TNSA have high quality with small transverse emittance and short bunch widths. According to Cowan etal., the transverse emittance of the proton beam at 10 MeV is 0.004 mm-mrad (normalized RMS value) [2].
From these characteristics, this acceleration mechanism is suitable for various applications such as theminiaturization of particle accelerators, FLASH therapy [3], and physical property experiments including
PIXE [4]. In the development of this novel laser accelerator, one of the most important works is to generatea high-brightness beam, but the laser irradiation conditions have not been sufficiently optimized.
In this study, the correlation between the beam quality and the laser irradiation conditions is observed tocontrol the ion beam for the realization of a laser accelerator. A two-dimensional particle-in-cellsimulation: EPOCH 2D was performed to optimize the ion beam quality with the target thickness and laser
spot diameter as parameters. The beam brightness determined from the emittance and current is evaluatedto optimize these parameters.
This work was supported by JST-MIRAI R&D Program No. JPMJMI17A1 and JSPS KAKENHI Grant
Number JP21J22132.
References[1] R. A. Snavely et al., Phys. Rev. Lett., 85, 2945 (2000).
[2] T.E. Cowan et al., Phys. Rev. Lett., 92, 204801 (2004).
[3] F. Kroll et al., Nature Physics, 18, 316–322 (2022).
[4] M. Barberio and P. Antici, Scientific Reports, 9, 6855, (2019).

57

PO-17
Temporal measurement of laser wakefield electrons via electro-optic sampling
K. Huang1,2, H. Kotaki1, M. Mori1, T. Esirkepov1, J. K. Koga1, Y. Hayashi1, N.
Nakanii1,2, Z. Jin2,3, T. Hosokai2,3, M. Kando1,2
Kansai Photon Science Institute, National Institutes for Quantum Science andTechnology (QST), 8-1-7 Umemidai, Kizugawa-city, Kyoto 619-0215, Japan
2
Laser Accelerator R&D, Innovative Light Sources Division, RIKEN SPring-8
Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
3
SANKEN, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
E-mail: huang.kai@qst.go.jp; kando.masaki@qst.go.jp
1

Keywords: Ultra-short pulse laser, electron acceleration, beam diagnostics, EO
Temporal diagnostics on electron bunches from laser wakefield acceleration [1] via single-shot
electro-optic spatial decoding. We established electro-optic (EO) [2] sampling techniques adequate for the
diagnostics of electron temporal information in laser wakefield acceleration (LWFA). For the investigationof electron timing jitter and injection process, EO spatial decoding on the electron Coulomb field was
performed. The spherical wavefront of the Coulomb field [3,4] and plasma-density-dependent electron
emission timing were discovered. For the determination of electron bunch durations, EO spatial decoding
on the coherent transition radiation (CTR) produced when electrons passing through a metal foil was
conducted. Electron beam timing fluctuation of 7 fs [5] and bunch durations of few tens of femtoseconds
had been demonstrated.
This research not only showed the capability of EO sampling serving as a real-time electron temporal
diagnostic for laser-driven sources but also demonstrated the ultra-fast and high-brightness nature oflaser-driven electron sources for various applications.
References[1] T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979).
[2] J. Shan et al., Optics letters 25, 426 (2000).
[3] K. Huang et al., Sci. Rep. 8, 2938 (2018).
[4] K. Huang et al., Phys. Rev. Accel. Beams 22, 121301 (2019).
[5] K. Huang et al., Applied Physics Express 15, 036001 (2022).

This work was funded by the JST-Mirai Program Grant No. JPMJMI17A1, Japan, the Grant-in-Aid for
Early-Career Scientists (No. JP21K17998, No. 23K17152) from JSPS KAKENHI, Japan and the QST
President's Strategic Grant (Exploratory Research), Japan.

58

PO-18Development of a high-power terahertz source baced onlaser-produced plasma for electron acceleration
Yuta Suzuki, Takamitsu P. Otsuka, Ren Kashihara, Hidetoshi Ito,
Souki Takeda, Daichi Ueda, Noboru Yugami
Graduate School of Regional development and Creativity,
Utsunomiya University, Japan
E-mail: y.suzuki2022@lwfa.oe.utsunomiya-u.ac.jp
Keywords: Plasma, Terahertz
Acceleration gradient of conventional accelerator is limited by the breakdown threshold of accelerationtube, and it has been experimentally confirmed that use of the electromagnetic wave (EM wave) with higher
frequency and shorter pulse length can solve the problem of breakdown threshold. Terahertz (THz) is acandidate of the future radio-frequency acceleration. E. A. Nanni et al. demonstrated that THz-driven linear
electron accelerator with a radially polarized THz pulse produced via optical rectification of a laser pulse [1].
In practical use, it is necessary to make high-power THz source like conventional radio-frequency sources,
such as klystron. N. Yugami et al. reported that laser generated plasma emits radially polarized THz wave[2], furthermore, when applied a static electric field along the laser propagation axis, the THz intensity isenhanced proportionately to square of the applied electric field [3]. This is expected as a high-power THz
source, but the mechanism of radiation source is still unclear.
To develop high-power THz source, we plan to carry out experiment with Ti:Sapphire laser system which
deliver 800 nm, 120 mJ and 120 fs (full width at half maximum) pulse at 10 Hz repetition rate. Electric field
applied to the plasma is approximately 30 kV/cm. Figure 1 shows the diagram of the experimental setup. We
plan to measure the THz using single-shot time-domain spectroscopy. And we will measure spectra of lightfrom plasma to study the state of plasma. In our presentation, we plan to discuss about a model of radiationand experimental plan.
(a)

(b)

Fig.1 Experimental setup. (a) Setup of THz measurement. (b) Top view of the setup. Emitted light from plasma isobserved by using a CMOS camera and spectrometer.

References[1] E. A. Nanni et al., Nat. Communication, 6, 8486 (2015).
[2] N. Yugami et al., Jpn. J. Appl. Phys. 45, 39 (2006).
[3] Yi Liu et al., Appl. Phys. Lett. 93, 051108 (2008). T. Fukuda et al., Jpn. J. Appl. Phys. 58, 070909 (2019).

59

PO-19Laser peening with microchip laser mounted
on a controlled robotic arm

Yoshio Mizuta1, Satoshi Tamaki1, Kiyotaka Masaki2, Tomoharu Kato3,
Yoshihiro Sakino3, Tomonao Hosokai1 and Yuji Sano 1,4,5
SANKEN, Osaka University, Japan
Saitama Institute of Technology, Japan
3
Kindai University, Japan
4
Institute for Molecular Science, Japan
5
LAcubed Co., Ltd., Japan
E-mail: y.mizuta@sanken.osaka-u.ac.jp
Keywords: Microchip laser, Material processing, Laser peening, residual stress, fatigue properties

Presenting
Author’s photo12

Laser peening (LP) or laser shock peening (LSP) introduces compressive residual stresses on the surface of
metallic components covered with water by irradiating them with successive high-intensity laser pulses.1-3
The advantage of LP is the possibility of fine execution management and the capability to introduce deep
compressive residual stresses on the material surfaces. It is well known to be highly effective in inhibitingstress corrosion cracking and fatigue cracking on material surfaces. In addition, LP has an excellent effecton improving the fatigue strength of welds, which compensates for the disadvantage of high strength steels
when welded. LP has a high potential for enhancing material surface, but the high-power laser usedrequires clean room facilities, large equipment and severe operating conditions. Therefore, the applicationof the LP has been limited to high cycle fatigue of jet engine fan blades and stress corrosion cracking of
nuclear reactor structures. If microchip lasers, which are small and easy to handle, could be used as a lightsource for LP, it would be possible to apply them not only to production processes in factories but also toexisting steel structures such as bridges, to which conventional lasers have been difficult to apply for theabove reasons. In this presentation, we report the results of the LP treatment of A7075 (aluminum alloy)
and HT780 (high strength steel) with the laser pulse energy of less than 10 mJ. Even at such a low pulse
energy, compressive residual stress was imparted (Fig.1) and fatigue properties were improved.

Fig.1 Experimental setup and surface residual stress of HT780(High strength steel) after laser peening

References[1] Sano, Y., “Quarter Century Development of Laser Peening without Coating”, Metals, Vol. 10 (2020),
152.
[2] Clauer, A.H., “Laser Shock Peening, the Path to Production”, Metals, Vol. 9 (2019), 626.
[3] See, D.W., Dulaney, J.L., Clauer, A.H., and Tenaglia, R.D., “The Air Force Manufacturing
Technology Laser Peening Initiative”, Surf. Eng., Vol. 18 (2002), pp. 32-36.

60

PO-20

Undulator light source with a compact, slender and lightweight frame
based on a magnet technology developed for very-short-period
undulators
Shigeru Yamamoto1, ,Presenting
Author’s photo1

Institute of Materials Structure Science,High Energy Accelerator Research Organization,
KEK, Tsukuba, Japan
E-mail: shigeru.yamamoto@kek.jp

Keywords: Undulator, Short period lengths, Synchrotron light source, FEL
We have been exploring a novel method to fabricate undulator magnets having a very short period
length of a few mm. Plate monolithic magnets (PMM) made of Nd-Fe-B, 100mm long with 4-mm period
length have been successfully fabricated[1-3]. The 4-mm period length allows us to obtain 12-keVradiation with the first harmonic of this undulator in the 2.5-GeV light source accelerator. A connection
method of these magnet plates has also been successfully developed to fabricate longer undulator
magnets[4-5].
As a next step of the development, we are developing a magnetic cancellation method of an attractive
force produced by the undulator main magnets by using repulsion magnets. The attractive force iseffectively cancelled out by them placed outward in the magnet gap. We found that the repulsion magnets
made of PMM were easily optimized in the present system where the main magnets were also made of
PMM in contrast to the previous work[6].
We are also developing a compact undulator frame, in which magnetic attractive force between the main
undulator magnets is effectively cancelled out by the above cancellation method using repulsion magnets.
This undulator is designed as a light source for an XUV-FEL development which has been undertaken in
the experimental plat-form at SP-8 for the JST-MIRAI project. Target parameters of the undulator for thisexperiment are: period length, λu=25mm, field strength K=1.4 at the gap=5mm or larger, and number of
period=80. The magnet array is divided into two segments 1m long each, gap of which can be controlled
independently.
References[1] S. Yamamoto, Journal of Phys.: Conf. Ser. 425 032014, 2013.
[2] S. Yamamoto, WEOAA02, Proc. IPAC2014, 1845-1857, Dresden, Germany, 2014.
[3] S. Yamamoto, Synchrotron Radiation News 28 No.3, 19-22, 2015.
[4] S. Yamamoto, AIP Conf. Proc. 1741, 020029, 2016, doi: 10.1063/1.4952808.
[5] S. Yamamoto, WEXGBD1, Proc. IPAC2018, 1735-1739, Vancouver, BC, Canada, 2018, doi:10.18429/
JACoW-IPAC2018-WEXGBD1.
[6] R.Kinjo, et al., S.Yamamoto, T.Tanaka, Review Scientific Instrum. 88, 073302 (2017), doi:http://dx.doi.org/
10.1063/1.4991652.

61

PO-21

Current status and prospect of RLQBS in SANKEN
Yoshihide Honda, Sachiko Tojo, Kazuya Furukawa, Yuhei Fukui,
Jinfeng Yang and Tomonao Hosokai
SANKEN, Osaka University, Japan
E-mail: honda@sanken.osaka-u.ac.jp

Keywords: electron linac, cobalt-60, pulse radiolysis
The Research Laboratory for Quantum Beam Science (RLQBS) was established in 2009 as a successor of
Radiation Laboratory [1]. The representative facilities are L-band electron linac, 150 MeV S-band linac,
photocathode RF-gun equipped S-band electron linac and Co-60 γ-ray irradiation facility as shown in Fig.1.
These machines are available not only for the users in Osaka University, but also for the collaborators in
the world. Relating with the electron linacs, the unique studies about such as time-evolved chemical
reaction triggered by energetic electron beam using pulse radiolysis system and pursuing the achievementof ultimate short-pulsed-electron-beam have been carried out in addition to the many radiation-related
studies. Furthermore, so far the developments and applications of THz FEL and slow positron beam havebeen promoted. However, these linacs have been aged and maintenance becomes difficult despite thereplacement of partial equipment with new one, especially 150 MeV S-band linac was stopped working
and will be removed soon. Thus, a new project to promote linacs and quantum beam science are desired.
Recently, a C-band electron linac is due to shift to our laboratory, after discarding the old 150 MeV linac.
This accelerator is compact and has good enough beam-quality.

We are also planning to develop alaser-driven electron accelerator, meanwhile, the C-band linac is thought to turn to be a useful alternativeelectron source for developing not only a new FEL source but also a new pharmaceutical approach, whichis also presented in this conference. To exploit new themes, it is necessary to prepare the spaces forresearchers to work creatively with each other. Thus, the second floor of linac building is scheduled to beout of restriction area for radiation hazard, so that the new spaces will be located in there.
The recent results of our laboratory and the future plans are presented.

Fig.1 Facilities in RLQBS

References[1] see https://www.sanken.osaka-u.ac.jp/labs/rl/English/index.html.

62

PO-22Development of a compact 50 TW laser for energetic quantum beam
generation toward practical applications
Thanh-Hung Dinh, Michiaki Mori, Keisuke Nagashima, Sadaoki Kojima,
Noboru Hasegawa, Hajime Okada, Yoichi Yamamoto, Fuyumi Ito,
Masahiko Ishino, Tatsuhiko Miyatake, Hiranao Sakaki,
Masaharu Nishikino, Masaki Kando, Toshiyuki Shirai, and Kiminori Kondo
National Institutes for Quantum and Radiological Science and Technology
Umemidai 8-1-7, Kizugawa, Kyoto 619-0215, Japan
E-mail: dinh.thanhhung@qst.go.jp
Keywords: Ultra-short pulse laser, High power laser, Laser ion acceleration, Quantum beams,
Recently several petawatt-class lasers have been constructed worldwide, thanks to the invention of chirpedpulse amplification (CPA) together with titanium-doped sapphire (Ti:sapphire) media. Such laser facilities
provide opportunities for experimental investigation of the behavior of matter in ultra-high electromagnetic
fields. Apart from that, there has been a keen demand of reliable TWs laser system for practical applications.
Here, the laser development for energetic quantum beam generation ongoing at QST will be reported. The
schematic setup of our laser system is shown in Fig. 1. We combine a double CPA with cross-polarized wave
generation (XPW) technique to improve the temporal contrast. Figure 2 shows typical beam properties after
the XPW pulse cleaner. A nearly diffraction-limited beam quality (Fig. 2(a)) and a highly stable operation(Fig. 2(b)) was achieved. At such condition, the laser contrast after 2nd CPA was better than 1010 at 100 ps
before main pulse.
Oscillator

Grating
Stretcher

Grating Compressor~0.8 J (~2.2 J), 40 fs

Multi-pass
Amplifier

AOPDF

Multi-pass Amplifier~1.5J (3.2 J) /10 Hz

Grating Compressor~200 µJ / 100 Hz

Multi-pass Amplifier~40 mJ / 100 Hz

Pulse cleaner (XPW)~20 µJ / 100 Hz

Multi-pass Amplifier& Assist compressor

Grating
StretcherFig.1 Schematic of the laser system.

Near-field(b)
Far-field

Angular movement α_X [µrad](a)50

α_X (µrad)4030

2σ = 7.5 µrad

20
10
0
-10
-20
-30
-40
-50
0

1

2

3

4

Time [hours]

Fig.2 Typical beam profile (a) and pointing stability (b) at the output of pulse cleaner.

Acknowledgements
This work is supported by JST-MIRAI R & D Program #JPMJ17A1. The authors (T.-H.D., N.H., M.I.,
M.N.) acknowledges support from Japan Society for the Promotion of Science (JP21H03750)

63

PO-23
Plasma Effects on Electron Beam Bunching in External Periodic Fields
Alexei Zhidkov1,2, Naveen Pathak1,2, Driss Oumbarek Espinos1,2, James K. Koga2,3,
Masaki Kando2,3, Tomonao Hosokai1,21Institute of Scientific and Industrial Research, Osaka University,

8-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan
2

Laser Accelerator R&D, Innovative Light Sources Division, RIKEN SPring-8 Center,

1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
3

Kansai Photon Science Institute, National Institutes for Quantum and Radiological

Science and Technology, 8-1, Umemi-dai, Kizugawa, Kyoto 619-0215, Japan

Abstract
Low density plasma focusing and modulation of high energy electron beams can result inessential increasing of beam brightness and, therefore, the free electron laser (FEL) gain in
undulators. However, strong coupling between the transverse beam focusing and modulation byplasma and longitudinal electron bunching in the undulator field can affect the radiation both
positively and negatively. Here, the interaction of electron beams with plasma and an external
periodic magnetic field is studied by particle-in-cell simulations in a booster reference framewith the resolution allowing direct evaluation of beam bunching and FEL radiation. To obtaincharacteristics of forward radiation, the booster reference frame is chosen with a large relativistic
factor R to achieve a necessary resolution for radiation, with the wavelength x=uR/B2, ofelectrons with the energy mc2B in an undulator with the period u. The non-resonance plasmacases with rather long plasma wavelengths p>xR1/2 are considered.

64

PO-24Focusing and reduction of correlated energy spread of chirped electron
beams in passive plasma lens.
N. Pathak1,3, A. Zhidkov1,3, D. Oumbarek Espinos1,3, Y. Mizuta1, Z. Jin1,2,3 and Hosokai1,2,3
1

SANKEN, Osaka University, Japan
Graduate School of Engineering, Osaka University, Japan
3
Laser Accelerator R&D Team, RIKEN SPring-8 Center, Japan
E-mail: naveenpathak@sanken.osaka-u.ac.jp
2

Keywords: LWFA, Plasma lens, PIC

For the next generation of the particle accelerators, including laser wakefield acceleration (LWFA), applicaPresenting
tion of plasma based focusing of electron beams is an area of active research. This approach will pave a path
Author’s photofor the miniaturization of the beam transportation line in particle accelerators. In the context of LWFA
scheme, this approach will open the opportunity to realize an extremely small setups of multi-GeV and brightsource of electron beams. We will present numerical results of passive plasma lens of an electron beam via
self-consistent and relativistic particle-in-cell (PIC) simulations. The focusing of an electron beam by a passive plasma lens is a non-linear and dynamic process, which strongly depends on the space charge induced
evacuation of the plasma electrons in the vicinity of the propagating electron beam. An initially negative
energy chirp is essential in suppressing the unwanted growth in the relative energy spread of the electron
beam during the passive lensing. A passive plasma element is useful for both a single as well as multi-stage
laser wakefield acceleration configuration.
References[1] J. B. Johnson, J. Opt. Soc. A. 6, 701 (1922).
[2] W. H. Bennett, Phys. Rev. 98, 1584 (1955).
[3] S. Kuschel, D. Hollatz, et. al., Phys. Rev. Accel. Beams 19, 7101 (2016).
[4] N. Pathak, A. Zhidkov, D. Oumbarek Espinos, T. Hosokai (Submitted Phys. Plasmas).

65PO-25

Study of gas jet stability for LWFA in the context of shock injection
Y. J. Gu1, Z. Lei1, Z. Jin1, A. Zhidkov1, and T. Hosokai 1
1

SANKEN, Osaka University, Japan

E-mail: gu_yanjun@sanken.osaka-u.ac.jp

Keywords: LWFA, shock injection, supersonic nozzle, CFD, PIC
Presenting Author’s
Shock-front injection becomes a promising and controllable electron injection mechanism in
photolaser-wakefield-acceleration (LWFA). Supersonic gas jets are widely employed to produce shockwaves via the interaction with a blade. The stabilization of the gas flow is critical to control the
injection process and the electron beam quality. In this work, we focused on the role of theConverging-Diverging nozzle to improve the stability of the gas jets. By the Computational Fluid
Dynamics (CFD) simulations and the Mach-Zehnder interferometric measurements, theinstabilities originated from the nonlinear eddies and the mechanism to suppress them are
discussed. Both the numerical and experimental results prove that a nozzle with a stillingchamber can reduce perturbation by more than 10%.

Fig.1 Experimental setup66

PO-26

An Overview of Laser Wakefield Acceleration Platform in Spring-8
Z. Jin1, 2, Y. J. Gu1, Z. Lei1, Y. Mizuta1, D. Oumbarek Espinos1,
N. Pathak1, A. Rondpierre1, S. Sato1, A. Zhidkov1,
K. Huang3, M. Kando3, and T. Hosokai1, 2
SANKEN, Osaka University, Japan
2
RIKEN SPring-8 Center
3
Kansai Photon Science Institute, QST
1E-mail: jin@sanken.osaka-u.ac.jp
Keywords: Laser wakefield accleration
Laser-wakefield acceleration (LWFA), providing potentially jitter-free sources of radiation andelectrons, is one of the rapidly developed scientific fields [1]. Staging LWFA is considered to be anecessary technique for developing full-optical high energy electron accelerators. Splitting of theacceleration length into several technical parts and with independent laser drivers allows not only thegeneration of stable, reproducible acceleration fields but also overcoming the dephasing length while
maintaining an overall high acceleration gradient and a compact footprint [2, 3].

Figure 1 Experimental setup of staging LWFA and electron beam transportation.
The Laser Acceleration Platform is a unique experimental platform specially designed for laser
wake-field acceleration research, which is located in the RIKEN SPring-8 center, Harima, Hyogo
Prefecture, next to the 8 GeV storage ring and SACLA linear accelerator and XFEL. In thispresentation, we will give an overview of our recent progress in this platform.
References[1] T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43 (1979) 267.
[2] S. Steinke et. al., Nature 530 (2016) 190.
[3] Z. Jin et. al., Scientific Reports 9 (2019) 20045.

67

PO-27

Title: Characterization of Plasma Targets for Electron Beam
Generation in Laser Wakefield Acceleration Systems
Shingo Sato1,2,3, Zhenzhe Lei1,2,3, Zhan Jin1,2,3, Tomonao Hosokai1,2,3
1

SANKEN, Osaka University, Japan
Graduate School of Science, Osaka University, Japan
3
Laser Accelerator R&D Team, RIKEN SPring-8 Center, Japan
E-mail: s.sato25@sanken.osaka-u.ac.jp
2

Keywords:
shock injection, schlieren image, supersonic gas jet, Mach-Zehnder interferometryting
Author’s
photo
Plasma targets play a crucial role in electron beam generation within Laser Wakefield Acceleration(LWFA) systems, particularly for non-external injection schemes where the plasma target properties
significantly impact electron injection and acceleration. In our current experiment, we employ the sharp
density down ramp injection (shock injection) for electron beam generation, where the precise control ofposition and intensity of the shock are essential for achieving high-quality electrons. To characterize theshock, we investigate the use of a Schlieren imaging system at Osaka University.
The post-shock plasma profile greatly influences the electron beam acceleration. For our experiment, we
aim to achieve a relatively flat density distribution in the plasma following the shock. We have
implemented a Mach-Zehnder interferometer in our system at the Harima facility to measure the plasma
density in the corresponding region. Additionally, we utilize another Mach-Zehnder interferometer setup at
Osaka University to investigate the overall profile of our supersonic gas jet.
Here we discuss our experimental setup and the characterization techniques for plasma targets in LWFA
systems to improve the electron beam generation and beam quality.

68PO-28The electron beam diagnostics system for MeV range high repetition
rate LWFA sources

Presenting
Author’s photo

I. Zymak1, M. Favetta2, G. Grittani1, C. M. Lazzarini1,3, L. Goncalves1, V.
Sluková1,3, V. Sobr1, W. Szuba1, R. Versaci1, S. Lorenz1,3, M. Nevrkla1,3, F.
Vitha1,3, F. I. M. Fucilli2, L. Lapadula2, N. Hafz4, C. Kamperidis4, D. Papp4,
S. Mondal4, P. Bakule1 and S. V. Bulanov1,5

ELI Beamlines, ELI ERIC, Za Radnicí 835, 252 41 Dolní Břežany, Czech Republic
2U.O.S.D. Fisica Sanitaria Azienda Ospedaliero Universitaria Consorziale Policlinico, Piazza
Giulio Cesare 11, 70124 Bari, Italy
3Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague,
Brehova 7, Prague 11519, Czech Republic
4ELI-ALPS, The Extreme Light Infrastructure ERIC, Za Radnicí 835, 252 41 Dolní Břežany,Czech Republic
5Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science andTechnology, Umemidai 8-1-7, Kizugawa, Kyoto 619-0215, Japan
E-mail: illia.zymak@eli-beams.eu
1

Keywords: LPA, LWFA, Electron beam diagnostic, Ultra-short electron beam, Ultra-high dose rate
Electron accelerators are widely used as a source of relativistic electrons for medical applications(FLASH and very high electron energy therapy), material science, secondary photons sources [1,2]and as a laboratory analogue of space radiation environment for radiation effects to electronics(R2E) [3] research. Conventional particle acceleration technologies (e.g. linear accelerators,
LINAC) are limited by a maximal acceleration gradient of about 100 MeV/m due to the breakdown[4]. Laser-plasma acceleration (LPA) devices [5] overcome this value with the potentiallyachievable 100 MeV/mm range [6]. The use of the high laser repetition rate allows achieving aaverage dose rates reasonable for irradiation experiments. One of such device, a recently
constructed by the ELI-Beamlines electron accelerator group Allegra Laser For Acceleration(ALFA) [7,8] electron beam accelerator is developed to prove a concept of using Laser Wakefield
Acceleration (LWFA) devices for irradiation experiments and real-life application. Electron beamdiagnostics for compact LWFA device with short focal distance optics, high repetition rate andminimal required laser intensity is a technical challenge due to probability of the interaction of thelaser and electron beams with components of the device. It may result in damage of the opticalsystem, reducing of the vacuum quality and affect the electron beam properties. The proposed
electron beam diagnostic system (EBDS) includes energy, beam profile and delivered dose
measurement. The calibrated phosphor screen charge density [9] and orthogonal magnetic fieldenergy [10] measurement techniques has been used for the beam diagnostics. A relatively small
dipole magnet with a distance between poles higher than width and length of magnets has beenused to optimize the dimensions of the device and increase the electron beam acceptance angle.
Proposed geometry of the beam diagnostic setup is efficient for the optimization of broad electron69

beams with variable pointing and also it minimizes risks of damage to the system by a high-power
laser. A numerical electron trajectories simulation and Monte Carlo models were developed to
improve accuracy of the spectrometer, which is strongly dependent on the definition of themagnetic field geometry. This technique is designed for ultra-short, unstable, diverged electron
pulses with the 1 kHz repetition rate.
Theoretical results have been verified by the experiment in the range of 6 – 20 MeV. The accuracyof energy measurement is better than 10%. The beam imaging system is cross-calibrated to measureelectron charge density and available dose. The experiment confirms linearity and average accuracyof the measurement better than 2% for electron radiation dose available for the water target andbeam charge density in the measurement range of mGy/pulse and pC/cm2/pulse respectively. The
electron energy spectrometer is also proposed to be used as a high-pass energy filter and for beam
pointing manipulation for irradiation experiments.

Fig.1 Scheme of the experimental setup

References[1] Michel, P. in 2008 IEEE Nuclear Science Symposium Conference Record 3078–3080 (2008)[2] Sampath, A. et al. "Extremely Dense Gamma-Ray Pulses in Electron Beam-Multifoil Collisions" Phys. Rev. Lett.
126, 64801 (2021) DOI: 10.1103/PhysRevLett.126.064801[3] Zymak, I. et al. in 2021 21th European Conference on Radiation and Its Effects on Components and Systems(RADECS) 1–4 (2021)[4] Descoeudres, A. et al. "Investigation of the dc vacuum breakdown mechanism" Phys. Rev. Spec. Top. - Accel. Beams
12, 92001 (2009) DOI: 10.1103/PhysRevSTAB.12.092001[5] Hubbard, R. F. et al. "Scaling of accelerating gradients and dephasing effects in channel-guided laser wakefield
accelerators" IEEE Trans. plasma Sci. 28, 1122–1132 (2000)[6] Gschwendtner, E. et al. "Plasma wakefield accelerators" Nat. Rev. Phys. 1, 246–248 (2019) DOI: 10.1038/s42254019-0049-z[7] Lazzarini, C. M. et al. in Beam Acceleration in Crystals and Nanostructures 153–170 (WORLD SCIENTIFIC2020)[8] Costa, G. et al. "Characterization of self-injected electron beams from LWFA experiments at SPARC_LAB" Nucl.
Instruments Methods Phys. Res. Sect. A Accel. Spectrometers, Detect. Assoc. Equip. 909, 118–122 (2018) DOI:
https://doi.org/10.1016/j.nima.2018.02.008[9] Buck, A. et al. "Absolute charge calibration of scintillating screens for relativistic electron detection" Rev. Sci.
Instrum. 81, 33301 (2010) DOI: 10.1063/1.3310275[10] Cha, H. J. et al. "Absolute energy calibration for relativistic electron beams with pointing instability from a laserplasma accelerator" Rev. Sci. Instrum. 83, 63301 (2012) DOI: 10.1063/1.4725530

70PO-29The electronic structure of the solvated electron
investigated by pulse radiolysis

Presenting
Author’s photo

Masao Gohdo1, Ryoya Tamaki1, Koichi Kan1, Jinfeng Yang1,
Seiichi Tagawa1, Yoichi Yoshida1
SANKEN, Osaka University, Japan
E-mail: mgohdo@sanken.osaka-u.ac.jp
1

Keywords: Electron beam, Radiation chemistry, solvated electron, Radiation induced reaction
We are trying to understand radiation induced reaction in condensed phase using pulse radiolysis
technique with pulsed electron beam. In this study, we focus on solvated electrons (esol) in alcohol,

especially on the electronic structure of solvated electrons. Because the esol is an important active reaction
intermediate which is the starting material for ionizing radiation induce chemical reactions in polar fluid
solution. It is also known that the pre-solvated electron (epre) as precursor of esol. Both transients has been
well known, though there are still two open questions, “Whether is epre an excited state of esol, or not?” and“How to understand the absorption spectra of esol?” In this study, the electronic structure of the solvatedelectron in 1-pentanol was studied by ns-pulse radiolysis and the electron-photon double-excitation pulse
radiolysis.
The esol photo-excitation experiments showed the bleach of the esol absorption due to the photo-excitation.
And the bleach was not recovered at all. The epre formation due to the photo-excitation was not observed.
The photo-excitation of esol formed by electron beam irradiation results in the charge recombination via theconduction band, which is distorted by the Coulomb potential of the parent radical cation. This observation
was quite different from the similar experimental result conducted on e sol formed by photo-ionization by
Silva et. al [1] which has been good evidence supporting “epre is the excited states of esol” story.
The absorption bands due to the esol were observed forthe binary mixture of 1-pentanol and THF with theconcentration range of 0 to 100 vol.% with every 10
vol.% separation. The absorption maxima were graduallyshifted from ~640 nm to ~1200 nm according to the
1-pentanol concentration decreased. Thus, the absorption
band can be assigned to the electronic transition to the
conduction band, because this observation can beunderstood by the conduction band energy level
perturbation due to mixing of solvents.
Two series of experiments suggests the absorption
band of the esol can be assigned to the electronictransition to the conduction band described in Fig. 1.

Fig.1 Experimental setup

References[1] Silva, C.; Walhout, P.K.; Reid, P.J.; Barbara, P.F. J. Phys. Chem. A, 102, No.28, 5701–5707 (1998).

71

PO-30Beam pointing control of laser wakefield accelerator
by shaping near field profile of laser pulse
Nobuhiko Nakanii1,2, Kai Huang1,2, Zhan Jin2,3, Kotaro Kondo1,
Izuru Daito1, Hiromitsu Kiriyama1, Tomonao Hosokai2,3, Masaki Kando1,2,3Presenting
Author’s photo

1

2

Kaisai Photon Science Institute, QST, Japan
Laser Accelerator R&D Team, RIKEN SPring-8 Center, Japan
3
SANKEN, Osaka University, Japan
E-mail: nakanii.nobuhiko@qst.go.jp

Keywords: Laser wakefield accelerator, Beam manipulation, Ultra-short pulse laser
A laser wakefield accelerator (LWFA) with an acceleration gradient three orders of magnitude higher
than conventional accelerators is expected to be a next-generation compact accelerator. For the practicaluses of the LWFA such as a free electron laser (FEL)[1,2], the stability and directional control of theelectron beams is crucially important. If the pointing of the beams is unstable, the electron beam cannot betransported in a beamline and emit. The stability of the LWFA beams has been improved by thestabilization of the laser system and the choice of injection methods. However, still typical pointing
fluctuations of the electron beams observed in experiments are three times larger than those of the driving
laser pulses. The cause of the instability of the LWFA electron beams needs to be clarified.
We have stabilized the electron beams by putting an aperture in the laser transport line before an
off-axis parabolic mirror. Shaping of near field profile of the laser pulse with the aperture removes theouter part of the laser pulse with unstable wavefront and intensity. That improves the quality and stabilityof the focusing laser pulse, so the electron beam generated by this laser pulse also becomes stable.
Moreover, the direction of the beam can be controlled by just moving this aperture perpendicularly to thelaser pulse propagation [3]. This simple method could expect to be one of the key techniques to realize an
ultra-compact accelerator with LWFA in the future.

References[1] W. Wang et al., Nature 595, 519 (2021).
[2] M. Labat et al., Nat. Photon. 17, 150 (2023).
[3] N. Nakanii, K. Huang, K. Kondo, H. Kiriyama, and M. Kando, Appl. Phy. Express 16, 026001 (2023).

72

PO-31

Picosecond pump-probe study on radiation-induced primary reaction
processes of solutions at extreme conditions
Yusa Muroya1, Yosuke Katsumura2, Shinichi Yamashita2,
Mingzhang Lin3, Takahiro Kozawa1
SANKEN, Osaka University, Japan
School of Engineering, University of Tokyo, Japan
3
University of Science and Technology of China, P.R. China
E-mail: muroya@sanken.osaka-u.ac.jp
1

2

Keywords: Picosecond pump-probe, Radiation-induced reaction kinetics, High temperature highpressure solution, supercritical solution
To understand fundamental processes of beam-material interactions is basically of great importance foradvanced application fields of ionizing radiation. In nuclear engineering field, radiolysis of water (fromroom temperature up to subcritical regime) has been paid much attention as it seriously affects onsustainability of nuclear structural materials in nuclear power plants.
In order to study the radiolysis process experimentally, novel techniques have been developed andpractically applied, such as steady-state beta/gamma radiolysis (non time-resolved), picosecond- andnanosecond- pulse radiolysis (time-resolved) etc. Among them, to investigate reaction mechanisms, highly
time-resolved techniques will be the most powerful because transient behaviors of short-lived
intermediates can be directly traced. For room temperature solutions, the techniques have been successfully
adopted and have revealed various radiation-induced physical, physicochemical, and chemical phenomena.
However, it has been difficult for high temperature / high pressure solutions (HTHP).
In this work, aiming to characterize the radiation-induced fast process in solutions at HTHP conditions,picosecond electron pulse radiolysis technique for HTHP study will be introduced. Moreover, someexperimental results by using the system, such as shallowing potential well of solvated electron, electron

0.12

0.07 7.09730E+2
7.09730E+2

0.1

0.06

0.08
0.06
o

at 710 nm

24 C

0.04

pH : neutral
pH = 11.4

0.02
0
0

500

AbsorbanceAbsorbancesolvation process, and inhomogeneous reaction scheme at elevated temperatures will also be presented.
Avee-aq + OH
Ave

0.05
0.04
0.03

300 oC

0.02
0.01
0
0

1000 1500 2000 2500

Time /ps500

at 900 nm

e-aq + H3O+

pH : neutral
pH = 11.4

1000 1500 2000 2500

Time /ps

Figure 6. Direct observation of radiation-induced primary reactions of solvated electron in waterat different pH and temperature.

References[1] Y. Muroya, Y. Katsumura, J.-P. Jay-Gerin et al., Phys. Chem. Chem. Phys., 14, 14325-14333, 2012.
[2] Y. Muroya, Y. Katsumura et al., Phys. Chem. Chem. Phys., 19, 30834-30841, 2017.

73