International Symposium on
Clustering as a Window on the Hierarchical Structure of Quantum Systems(CLUSHIQ2022)

Experimental studies ofnuclear systems with double strangenessusing nuclear emulsion
Junya Yoshida
Tohoku University1

Hypernuclei: nuclear systems with strangeness

LifeMolecule

AtomNucleus

Image: The Nobel Prize in Physics 2008

Nucleons (N)ProtonNeutronduduud

HyperonsΛ hyperon Ξ- hyperonss sdud

Only up- and down-quarks

Contain strange-quark(s)• Baryon-baryon interaction as an extension of the nuclear force• Contributions of quark for nuclear force at short range• Introducing the 3rd quark, strange, is an effective way
Single Λ hypernucleus

Double strangeness nucleiΛ ΛΛHypertriton (3ΛH)

Double Λ hypernucleus• Precise measurement of hyperon in the core nucleus• Information source of ΛN, ΛΛ and ΞN interactions

ΞΞ hypernucleus

2

Production and decay of a double strangeness nuclei
Solid material
K- Beam particle~1.8 GeV/c
K-

Targetp K+Ξ

K+ particle

3

Production and decay of a double strangeness nuclei
Solid material
K- Beam particle~1.8 GeV/c

TargetK+K-K+ particle
Ξ-Ξ-Ξ- atomΞ-Double Λ hypernucleus
NucleusΛ Λ
Ξ- + p → Λ + Λ + Energy~10µm scale~ a few %Ξ-~ a few %Ξ- hypernucleus

4Production and decay of a double strangeness nuclei

K- Beam particle~1.8 GeV/c

Photographic emulsion sheetswith µm precision resolution

TargetK+K-

ΞParticle tracking detector

Ξ- atomΞ-~ a few %Double Λ hypernucleus
NucleusΛ Λ
Ξ- + p → Λ + Λ + Energy~10µm scale

Ξ-~ a few %Ξ- hypernucleus

5Evolution of experiments with hybrid emulsion method for double strangeness
KEK-PS E176 (1988-89)

Number of Ξ- stop events#10-09-06

Nuclear Physics A 828 (2009) 191–232#14-03-35#13-11-14~80#15-03-37* Existence of double Λ hypernucleus

X10 scale

KEK-PS E373 (1998-2000)
Nagara~650

PHYSICAL REVIEW C 88, 014003 (2013)

MikageHida

Demachiyanagi

PTEP 2019, 021D01

Ξ-Ξ-

Ξ-

Ξ-

* Identification of ΛΛ6He and Ξ hypernucleus

X10 scale~104

J-PARC E07 (2016-17)

KEK-PS E373
J-PARC E07Emulsion gel

K- purity

Beam intensity

2.1 tons~82%

3*105/spill

0.8 tons

25%

1*104/spill

6Experimental apparatus of E07
2016-2017
K1.8 beamline, J-PARC

7

K- beamline(180 cm above the floor)

Emulsion module

BeamTarget

K+K-Ξtracking detector
Emulsion module

88Emulsion module
Tracking detector (SSD)

beam direction
Emulsion sheets
0.4 mm Thickness * 2
1.0 mm Thickness * 11

Emulsion module

Air pressure
SUS 100 µm

x118 modules
9Track following for Ξ- stop event searchwith dedicated image processing

volume for readout~(+-200 µm)2emulsion module (13 emulsion sheets)0.4 mm Thin-type~(+-10 µm)2

~440 predictions of Ξ- tracks
per module

1.0 mm Thick-type

1.0 mm Thick-type

Beam direction
Automated Track Following
https://youtu.be/3fiWI5tDx2U

10Detected double strangeness events:

14 events in the former experiments
33 events in J-PARC E07

Ξ15C

K. Nakazawa, et al.,Prog. Theor. Exp. Phys.
2015, 033D02 (2015)

10 µm

Double Λ hypernuclear eventsΛΛBe

H. Ekawa, et al.,Prog. Theor. Exp. Phys.
2019, 021D02 (2019)

Ξ hypernuclear eventsΛΛ

8Li orΛΛ

10BeNyaw, A. N. L. et al.,Bull. Soc. Photogr. Imag. Japan30, 22– 25 (2020)

M. Yoshimoto, et al.,Prog. Theor. Exp. Phys. 2021, 073D02 (2021)

S. H. Hayakawa, et al.,Phys. Rev. Let., 126, 062501 (2021)

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Systematic analysis of double strangeness system using multiple eventsΛΛΞ

Double Λ hypernucleus

Nyaw, A. N. L. et al.,Bull. Soc. Photogr. Imag. Japan 30, 22– 25 (2020)

M. Yoshimoto, et al.,Prog. Theor. Exp. Phys. 2021, 073D02 (2021)

The most likely cases

A-dependence of BΛΛ can be discussed.

Ξ hypernucleus

Atomic3D state
p-states-stateCombining experimental data and theoretical calculation,• p-state: ~1 MeV• s-state: ~6 MeV
12seem likely

List of twin Λ hypernuclear events

Ξ hypernuclei

Although the ratio of the C, N, and O in emulsion is 0.55 : 0.16 : 0.29, Ξ--14N event predominates

E176 #10-9-6 (2p?)
E176 #13-11-14 (2p?)
T008, atomic
T009, atomic
T004, atomic
E373 - 1, atomic
T002, atomic
T007, atomic
T011, atomic
E176 #14-03-35 (2p?)
T013 (2p?)
E373 : KISO
T006 : IBUKI
E373 : KINKA
T010 : IRRAWADDYΞ – captured by…
121416CNO
●
●
●
●

○●
●
●
●
○○●
●
●
●
Excess?

••
•

H

4H
4Ht

●

○(t)

He
2Λ5He
5
Λ He
5
Λ He
2Λ5He,α5
Λ He
5
Λ He
2Λ5He, α2Λ5He, (α)
5
Λ He
5
Λ He
5
Λ He
2Λ5He, αdaughter nuclei
LiBeB
9Be
9Be

nNucl. Phys. A 828 (2009) 191–232
Nucl. Phys. A 828 (2009) 191–232

8
Λ LiΛ9Λ Be
9Λ Be10Be10Λ Be
9Λ BeΛC●: Uniquely identified○: Multiple interpretations

12B

1
1
1
1

AIP Conf. Proc. 2130, 020016 (2019)
Phys. Lett. B 500 (2001) 37.
EPJ A, volume 58, 190 (2022)
PTEP 2021, 073D02 (2021)
PTEP 2021, 073D02 (2021)
Nucl. Phys. A 828 (2009) 191–232

(1)
1
1

PTEP 2015, 033D02 (2015)
Phys. Rev. Lett., 126, 062501 (2021)
PTEP 2021, 073D02 (2021)
PTEP 2021, 073D02 (2021)

alpha cluster structure?

Nature of Ξ- capture process? or biases caused by our analytical methods?
These identified events are a small fraction of the total.
Charge identification of daughter particles based on track boldness is important.

13The first Ξ− atomic X-ray spectroscopy measurementn-Ξ Ag atomic level

M. Fujita et al., NIM-A 1042 (2022) 167439≈l≈ΞX-ray8J
absorption

ΓΔE

7I (Last orbit)

X-ray

X-ray

absorption
Coulomb
Coulomb + strong interaction••

X-ray energy may be shifted and/or broadened due tothe strong interaction
X-ray spectroscopy is one of the most useful methods•••

Dedicated germanium (Ge) detector array, Hyperball-X
Continuous in-beam calibration
Background suppression using Bi4Ge3O12 (BGO)

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X-ray measurement using the hybrid method
Ge detector

Synchronized

K-SSDEmulsion sheetsK+Ξ-Ξ- track identification byangle and position consistency

Peak search

Br (8→7)
206 keV•••ρ-stop: Stop without nuclear fragment(It can be a proton)
Not used

σ-stop: Stop with nuclear fragment(almost Ξ-)
UsedStop confirmation inemulsion sheets

Ag (9→8)
255 keVBr (7→6)
316 keVAg (8→7) Expected energy only Coulomb
370 keV• w/ BGO suppression• Fit method : log likelihood• Fit function : Gaussian + constant(BG)• MeanGauss = Emean• σGauss = fixed to σGe (0.8 keV)
• Peak significance ≡ 𝐴𝐴𝑚𝑚𝑝𝑝𝑔𝑔𝑎𝑎𝑢𝑢𝑠𝑠𝑠𝑠/𝐴𝐴𝑚𝑚𝑝𝑝𝑔𝑔𝑎𝑎𝑢𝑢𝑠𝑠𝑠𝑠 𝐸𝐸𝑟𝑟𝑟𝑟𝑜𝑜𝑟𝑟

No evident peak using current dataset.
An upper limit of the probability that Ξ- reaches the last orbit was evaluated.
A paper reporting this result is in review. (PTEP)

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Overall scanning method: a technique to search for untriggered events
An upgraded scanning stage developed by Gifu Univ.
The Field of view of the microscopeused track following

100 μmThe Field of view of the developed microscope

New scanning system (2021)

Objective lens
Focal depth
Area of Field of view [µm2]
Frame rate [fps]Dead time ratio
scanning speed/day
To scan the all E07 sheets

x20
6 µm
530*530
4Mpix CMOS sensor
160by a piezo actuator
0.2
540 cm2
16 years ( 4 years using 4 stages )1000cm2×both_side×1000 sheets, 250 days operation per year

100 μmThis work has been supported by this project (KAKEN JP19H05147)

16

Image recognition using machine learning led by RIKEN
Vertex detection

Classifier based on Convolutional Neural Network
CNNResNet50

J. Yoshida, et al.,N.I.M A, 847 (2017) 86-92

Purity: 0.081 ± 0.006
Efficiency: 0.788 ± 0.056

J. Yoshida et al.,N.I.M. A 989 (2021) 164930

Thresholding

Noise Signal
Purity: 0.547 ± 0.025
Efficiency: 0.788

Mask R-CNN

Object detection using Region based CNN
Modified
Mask R-CNN

50 µm

Training data is generated using a style transfer modeltrained by Generative Adversarial Networks.

https://github.com/multimodallearning/pytorch-mask-rcnn
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“Pix2pix”

Generation of training images using a style transfer techniqueLayered binarized image

Simulated image

https://arxiv.org/abs/1611.07004

Transform

Simulated Hypertriton events
p50 µmα decay chain

RGB color = depth

3 HΛ

π-π-dTracks generated by Monte Carlo simulations••

simulated

3He3 HΛ•

A simulated Double Λ hypernuclear
α decay chain
event decayed like Nagara
Stop and decay of Hypertriton (3ΛH)Ξ• 2-body decayα• 3-body decayt 6Production and decay of Double Λ hypernucleus etc.
HeΛΛ

20 μm

5 HeΛ
18Toward precise measurement of binding energies of hypernuclei
Simulated

Binding energy of Λ in 3ΛH and 4ΛHAyumi Kasagi for his Ph.D. thesis
Gifu Univ., RIKEN
Simulated

Detection of 3-body decays of Hypertritons

Shohei Sugimoto for his Master thesis
Saitama Univ., RIKEN
Simulated

Detection of double Λ Hypernuclei

The 1st hypertriton event detected in an emulsion sheet using ML“New direction of hypernuclear physics”
T.R Saito et.al., Nature Reviews Physics
https://doi.org/10.1038/s42254-021-00371-w

Yan He for her Ph.D. thesisLanzhou Univ., RIKEN

Applications to hypernuclear physics is ongoing.

19Analysis of a twin Λ hypernuclei event using X-ray microscopy at SPring-8 (BL47XU)
Ξ- + 14N → Λ10Be + Λ5He + n
Optical microscopy?

A. Kasagi et al., EPJ A 58, 190 (2022)

X-ray microscopy (+ stereo method)

20 µm
Uncertainty;
position: 3 µm
BΞ-:3 MeV

Uncertainty;
position: 0.04 µm
BΞ-: 0.86 MeV••

BΞ- : −1.23 ± 0.86 MeVIt indicates that a Ξ− atomic state is produced.

•This technique will be applied to charge identification of daughter particles based on track boldness measurement.

20Summary:• Emulsion experiments have been pioneering nuclear systems with double strangeness.
• 47 events of double strangeness including 33 in J-PARC E07 are observed, thus far.
• Some of them are uniquely identified successfully.
• A-dependence of BΛΛ can be discussed using data of multiple double Λ hypernuclides.
• Multiple levels of Ξ− in a 14N nucleus deeper than the atomic 3D level have been observed.
• The first Ξ- atomic X-ray spectroscopy was conducted, and the probability that Ξ- reaches the lastorbit was evaluated.

Prospects:• Overall scanning method is being developed to detect untriggered events.
• Upgrade of scanning systems to readout 103 emulsion sheets.
• Development of image recognition using machine learning techniques.
• This technique is applying to precise measurement of hypernuclei.
• X-ray microscopy is applied to resolve vertices and charge identification of daughter particles.
21E07 Collaboration (Author list of PTEP 2019, 021D02)
H. Ekawa1,2, K. Agari3, J. K. Ahn4, T. Akaishi5, Y. Akazawa3, S. Ashikaga1,2, B. Bassalleck6, S. Bleser7, Y. Endo8,
Y. Fujikawa1, N. Fujioka9, M. Fujita9, R. Goto8, Y. Han10, S. Hasegawa2, T. Hashimoto2, S. H. Hayakawa2,5,T. Hayakawa5, E. Hayata1, K. Hicks11, E. Hirose3, M. Hirose1, R. Honda9, K. Hoshino8, S. Hoshino5,
K. Hosomi2, S. H. Hwang12, Y. Ichikawa2, M. Ichikawa1,13, M. Ieiri3, K. Imai2, K. Inaba1, Y. Ishikawa9,A. Iskendir5, H. Ito8, K. Ito14, W. S. Jung4, S. Kanatsuki1, H. Kanauchi9, A. Kasagi8, T. Kawai15, M. H. Kim4,S. H. Kim4, S. Kinbara2,8, R. Kiuchi16, H. Kobayashi8, K. Kobayashi5, T. Koike9, A. Koshikawa1, J. Y. Lee17,J. W. Lee4, T. L. Ma18, S. Y. Matsumoto1,13, M. Minakawa3, K. Miwa9, A. T. Moe19, T. J. Moon17,M. Moritsu3, Y. Nagase8, Y. Nakada5, M. Nakagawa5, D. Nakashima8, K. Nakazawa8, T. Nanamura1,2,M. Naruki1,2, A. N. L. Nyaw8, Y. Ogura9, M. Ohashi8, K. Oue5, S. Ozawa9, J. Pochodzalla7,20, S. Y. Ryu21,H. Sako2, Y. Sasaki9, S. Sato2, Y. Sato3, F. Schupp7, K. Shirotori21, M. M. Soe22, M. K. Soe8, J. Y. Sohn23,H. Sugimura24, K. N. Suzuki1,2, H. Takahashi3, T. Takahashi3, Y. Takahashi1, T. Takeda1, H. Tamura2,9,K. Tanida2, A. M. M. Theint8, K. T. Tint8, Y. Toyama9, M. Ukai3, E. Umezaki1, T. Watabe14, K. Watanabe1,T. O. Yamamoto2, S. B. Yang4, C. S. Yoon23, J. Yoshida2, M. Yoshimoto8, D. H. Zhang18, and Z. Zhang18
1Department of Physics, Kyoto University, 2Advanced Science Research Center, Japan Atomic Energy Agency, 3Institute of Particle andNuclear Study (IPNS), High Energy Accelerator Research Organization (KEK), 4Department of Physics, Korea University, 5Department ofPhysics, Osaka University, 6Department of Physics and Astronomy, University of New Mexico, 7Helmholtz Institute Mainz, 8Physics
Department, Gifu University, 9Department of Physics, Tohoku University, 10Institute of Nuclear Energy Safety Technology, Chinese Academyof Sciences, 11Department of Physics & Astronomy, Ohio University, 12Korea Research Institute of Standards and Science, 13RIKEN Clusterfor Pioneering Research, 14Department of Physics, Nagoya University, 15RIKEN Nishina Center, 16Institute of High Energy Physics,
17Department of Physics, Seoul National University, 18Institute of Modern Physics, Shanxi Normal University, 19Department of Physics,Lashio University, 20Institut für Kernphysik, Johannes Gutenberg-Universität, 21Research Center for Nuclear Physics, Osaka University,
22Department of Physics, University of Yangon, 23Research Institute of Natural Science, Gyeongsang National University, 24AcceleratorLaboratory, High EnergyAccelerator Research Organization (KEK)22Collaboration on machine learning for nuclear physics
Manami Nakagawa1, Ayumi Kasagi1,2, Enqiang Liu1,3,4, Hiroyuki Ekawa1, Junya Yoshida5,Wenbo Dou1,6, Yan He1,11, Abdul Muneem1,7, Kazuma Nakazawa1,8, Christophe Rappold9,
Nami Saito1, Takehiko R. Saito1,10,11, Shohei Sugimoto1,6, Masato Taki12, Yoshiki K. Tanaka1,He Wang1, Yiming Gao1,3,4, Ayari Yanai1,6, and Masahiro Yoshimoto13
1High Energy Nuclear Physics Laboratory, Cluster for Pioneering Research, RIKEN
2Graduate School of Engineering, Gifu University

3Institute of Modern Physics, Chinese Academy of Sciences

4School of Nuclear Science and Technology, University of Chinese Academy of Sciences
5Department of physics, Tohoku University

6Department of Physics, Saitama University

7Faculty of Engineering Sciences, Ghulam Ishaq Khan Institute of Engineering Sciences and Technology
8Faculty of Education, Gifu University

9Instituto de Estructura de la Materia, CSIC

10GSI Helmholtz Centre for Heavy Ion Research

11School of Nuclear Science and Technology, Lanzhou University

12Graduate School of Artificial Intelligence and Science, Rikkyo University
13RIKEN Nishina Center for Accelerator-Based Science, RIKEN

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My current work: construction of a new synchrotron radiation facility, Nano Terasu
Sendai Sta.

International center for Synchrotron Radiation Innovation Smart

Tohoku-U. Aobayama campus

HereNano Terasu

Google Map
https://www.sris.tohoku.ac.jp/1km• Development of the control systems for• X-ray optics devices• Light sources in the electron storage ring
• It will be ready in Apr. 2024

• I would like to pioneer new science across various
research fields. I look forward to working with you again
in the future.
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