J-PARC E07; Systematic study of double strangeness system with hybrid emulsion method

Yoshida, Junya; Akaishi, Takaya; Fujita, Manami; Hasegawa, Shoichi; Hashimoto, Tadashi; Hosomi, Kenji; Ichikawa, Masaya; Ichikawa, Yudai; Imai, Kenichi*; Kim, S.; et al.

JPS Conference Proceedings (Internet), 33, p.011112_1 - 011112_8, 2021/03

https://doi.org/10.7566/JPSCP.33.011112

Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment

Ekawa, Hiroyuki; Ashikaga, Sakiko; Hasegawa, Shoichi; Hashimoto, Tadashi; Hayakawa, Shuhei; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Kimbara, Shinji*; Nanamura, Takuya; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.021D02_1 - 021D02_11, 2019/02

https://doi.org/10.1093/ptep/pty149

Charge identification of low-energy particles for double-strangeness nuclei in nuclear emulsion

Kimbara, Shinji*; Ekawa, Hiroyuki; Hayakawa, Shuhei; Yoshida, Junya; 12 of others*

Progress of Theoretical and Experimental Physics (Internet), 2019(1), p.011H01_1 - 011H01_9, 2019/01

https://doi.org/10.1093/ptep/pty137

A development has been achieved in the identification method of the charges 1 to 5 of nuclides from the decay of double hypernuclei to be uniquely recognized by their nuclear species. The method is basically the measurement of track volume by the widths, depths, and angles of tracks of exposed nuclei of H, He, Li, Be, and B in nuclear emulsion at Riken Projectile-fragment Separator of RIKEN Radioactive Isotope Beam Factory. After their calibration by particles, we obtained a quadric function to present a unified recognition of tracks with volume ratios of five nuclei to the particles. The function in the emulsion has been applied to a candidate event of a hypernucleus for identification of the production and decay processes. We succeeded in recognizing a daughter nuclear fragment of a single- hypernucleus as He with a likelihood ratio of 0.9; the process was then uniquely identified as + N Be + He + .

Survey of radiation protection creiteria following the accident at the Fukushima Dai-ichi Nuclear Power Plant

Yamada, Katsunori; Fujii, Katsutoshi; Kanda, Hiroshi; Higashi, Daisuke; Kobayashi, Toshiaki; Nakagawa, Masahiro; Fukami, Tomoyo; Yoshida, Keisuke; Ueno, Yumi; Nakajima, Junya; et al.

JAEA-Review 2013-033, 51 Pages, 2013/12

JAEA-Review-2013-033.pdf:2.73MB

After the accident at Fukushima Dai-ichi Nuclear Power Plant, various numerical criteria relevant to radiation protection were defined. We surveyed these criteria through internet. As a result of survey, the following 13 items were identified: (1) criteria for taking stable iodine tablets, (2) criteria for the screening of surface contamination, (3) evacuation area, sheltering area, etc., (4) activity concentrations in food, drinking water, etc., (5) dose limit for radiation workers engaged in emergency work, (6) guideline levels of radioactive substances in bathing areas, (7) criteria for use of school buildings and schoolyards, (8) restriction on planting rice, (9) acceptable activity concentrations in feedstuff, (10) acceptable activity concentrations in compost, (11) criteria for export containers and ships, (12) criteria for contaminated waste, (13) standards for radiation workers engaged in decontamination work. In this report, the basis of and issues on these criteria are summarized.

J-PARC E07, systematic study of double strangeness nuclei with hybrid emulsion method

Yoshida, Junya

no journal, , 

The studies of double strangeness nuclei play an important role for modern hadron physics because they have been providing information about Lambda-Lambda and Xi-Nucleon interaction as extensions of nuclear force. J-PARC E07 is a unique experiment at J-PARC to investigate double strangeness nuclei with hybrid emulsion method. This experiment was designed to obtain ten times more double strangeness nuclei than that obtained by previous experiments. Moreover, it aims the first measurement of X-ray from Xi-atom by Germanium detector. The beam exposure of E07 was successfully completed in 2016 and 2017. New double strangeness nuclear events will be detected in the near future through the analysis of emulsion sheet. I will report the present status and the future prospect of the experiment.

J-PARC E07, systematic study of doublestrangeness nuclei with hybrid emulsion method

Yoshida, Junya

no journal, , 

J-PARC E07 is a unique experiment at J-PARC to investigate double hypernuclei with the hybrid emulsion method. It is designed to detect 10 times higher statistics of double hypernuclei compared to the past experiments. Moreover, this experiment aims the first measurement of X-ray from Xi-atom by a Germanium detector array. These experimental data will provide essential information on Lambda-Lambda and Xi-nucleon interactions. Beam exposure of J-PARC E07 has been completed in 2017 with 118 emulsion modules containing 1.5k emulsion sheets. Photographic developing of all emulsion sheets has been completed. These emulsion sheets are presently being analyzed with dedicated microscope systems. About 10 double hypernuclear events have been observed in nearly ten percent of total statistics as of June 2018. I will report the latest information about our experiment: status of searching work, analysis of found events, and the prospect of the analysis.

Analysis status of scattering events in the J-PARC E40 experiment

Nanamura, Takuya; Ichikawa, Yudai; Hayakawa, Shuhei; Yoshida, Junya; Miwa, Koji*; Honda, Ryotaro*; Akazawa, Yuya*; Yamamoto, Takeshi

no journal, , 

Hyperon-nucleon scattering experiment is one of the powerful methods for studying YN interaction. However, it is difficult due to short lifetime of hyperon. scattering experiments were performed as KEK E251 and KEK E289 in order to measure the differential cross sections. In these experiments, statistics were limited to less than 100 events and differential cross section had too large statistical errors to restrict baryon-baryon interaction models. J-PARC E40 experiment aims for measuring cross sections of scatterings with high statistics (10000 events) by overcoming difficulties of hyperon-nucleon scattering experiment. By using high rate ( 19M /spill) beam and large acceptance spectrometer, we can produce and tag large amount of beam. LH target and surrounding detector system CATCH enable us to reconstruct reactions from two body kinematics. Our experimental group completed data taking and about half of data taking by 2019 Apr. Left data taking will be performed in the end of this fiscal year.

Study of -N interaction by measurement of twin hypernuclei with hybrid emulsion method at J-PARC

Hayakawa, Shuhei; Yoshida, Junya

no journal, , 

The studies of hyperon-nucleon and hyperon-hyperon interactions are necessary for the understanding of general baryon-baryon interaction. Even in the = -1 sector such as and , the available data is limited. As for the = -2 sector such as and , there are few experimental data. The J-PARC E07 experiment was performed to investigate = -2 hypernuclei at J-PARC K1.8 beam line. Using a K- meson beam with the momentum of 1.81 GeV/c, - hyperons are produced in the quasi-free , K- reaction at a diamond target. A method using combined information between two spectrometers and nuclear emulsion, called hybrid emulsion method, was conducted by using silicon-strip detectors and one hundred eighteen emulsion modules. A twin hypernuclear event, named IBUKI event, was observed with a newly developed scanning system. At the - capture point, two hypernuclei of Be and He were the most likely to be produced by the conservation laws of energy and momentum. The reaction process of the IBUKI event was identified as - + N Be + He. The binding energy of - + N system was determined to be 1.27 0.21 MeV. From the consideration of an excited state, the energy level for Be was interpreted to be the ground state (2-) or the other state of the spin doublet (1-). The IBUKI event was the first event whose binding energy was determined with a little ambiguity. The binding energy indicates a bound state of the -N system by an attractive interaction. In this talk, we would like to report the above result of the IBUKI event.

Production of Double-Lambda hypernuclei at JPARC

Yoshida, Junya

no journal, , 

J-PARC E07, the largest experiment with Double Lambda hypernucleus thus far at J-PARC was designed and performed. Double hypernuclei, rare nuclei containing 2 Lambda particles is one of the important subjects in modern hadron nuclear physics. The experiment is unique in that photographic emulsion sheets are employed as the main detector for Double hypernuclei. We performed the physics-run in the J-PARC hadron facility in 2016-17. One of the observed events was identified as a beryllium 11 double Lambda. We measured the strength of Lambda-Lambda interaction through the event. Moreover, we detected several hypernuclei events which suggest multiple bound levels of particle in the nucleus. Further event search is ongoing.

Working Group Session "IRPA Practical Guidance for Engagement with the Public on Radiation and Risk"

Yoshida, Hiroko*; Nomura, Naoki*; Kono, Takahiko; Sakoda, Akihiro; Kuroda, Yujiro*; Naito, Wataru*; Hirota, Seiko*; Kudo, Shinichi*; Etani, Reo*; Chikamoto, Kazuhiko*; et al.

no journal, , 

This working group has been translating into Japanese the publication "Practical Guidance for Engagement with the Public on Radiation and Risk" by IRPA in 2020. This publication was made with the theme of public understanding, which was one of key issues that the consultation by IRPA to its member societies identified as most necessary in the radiation protection system. The translated guidance is supposed to be distributed to radiation protection experts and relevant communities in Japan who may be interested in public understanding. The purpose of this symposium is to share the working progress and important points of the guidance.