Faculty Profiles - YOSHIMURA Koji

Papers - YOSHIMURA Koji

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A method to detect the VUV photons from cooled 229Th:CaF crystals

Ming Guan, Michael Bartokos, Kjeld Beeks, Yuta Fukunaga, Takahiro Hiraki, Takahiko Masuda, Yuki Miyamoto, Ryoichiro Ogake, Koichi Okai, Noboru Sasao, Fabian Schaden, Thorsten Schumm, Kotaro Shimizu, Sayuri Takatori, Akihiro Yoshimi, Koji Yoshimura

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 562 165647 - 165647 2025.5

Characterization of the thorium-229 defect structure in CaF₂ crystals

Sayuri Takatori, Martin Pimon, Stephan Pollitt, Michael Bartokos, Kjeld Beeks, Andreas Grüneis, Takahiro Hiraki, Tetsuo Honma, Niyusha Hosseini, Adrian Leitner, Takahiko Masuda, Ira Morawetz, Kiyofumi Nitta, Koichi Okai, Thomas Riebner, Fabian Schaden, Thorsten Schumm, Oki Sekizawa, Tomas Sikorsky, Yoshio Takahashi, Luca Toscani De Col, Rei Yamamoto, Takumi Yomogida, Akihiro Yoshimi, Koji Yoshimura

New Journal of Physics 2025.4

Publishing type：Research paper (scientific journal) Publisher：IOP Publishing

Abstract

Recent advancements in laser excitation of the low-energy thorium-229 (²²⁹Th) nuclear isomeric state in calcium fluoride (CaF₂) single crystals render this system a promising candidate for a solid-state nuclear clock. Nonetheless, the precise experimental determination of the microscopic ion configuration surrounding the doped ²²⁹Th and its electronic charge state remains a critical challenge. Such characterization is essential for accurately controlling the clock transition and evaluating the performance of this solid-state nuclear clock system. In this study, we use x-ray absorption fine structure spectroscopy of ²²⁹Th:CaF₂ to investigate the charge state and coordination environment of doped ²²⁹Th. The results indicate that ²²⁹Th displays a 4+ oxidation state at the substitutional site of a Ca²⁺ ion, with charge compensated provided by two F^- ions positioned at interstitial sites adjacent to ²²⁹Th.

DOI： 10.1088/1367-2630/adce22

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Other Link： https://iopscience.iop.org/article/10.1088/1367-2630/adce22/pdf

Controlling 229Th isomeric state population in a VUV transparent crystal

Takahiro Hiraki, Koichi Okai, Michael Bartokos, Kjeld Beeks, Hiroyuki Fujimoto, Yuta Fukunaga, Hiromitsu Haba, Yoshitaka Kasamatsu, Shinji Kitao, Adrian Leitner, Takahiko Masuda, Ming Guan, Nobumoto Nagasawa, Ryoichiro Ogake, Martin Pimon, Martin Pressler, Noboru Sasao, Fabian Schaden, Thorsten Schumm, Makoto Seto, Yudai Shigekawa, Kotaro Shimizu, Tomas Sikorsky, Kenji Tamasaku, Sayuri Takatori, Tsukasa Watanabe, Atsushi Yamaguchi, Yoshitaka Yoda, Akihiro Yoshimi, Koji Yoshimura

Nature Communications 15 ( 1 ) 2024.7

Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

The radioisotope thorium-229 (²²⁹Th) is renowned for its extraordinarily low-energy, long-lived nuclear first-excited state. This isomeric state can be excited by vacuum ultraviolet (VUV) lasers and ²²⁹Th has been proposed as a reference transition for ultra-precise nuclear clocks. To assess the feasibility and performance of the nuclear clock concept, time-controlled excitation and depopulation of the ²²⁹Th isomer are imperative. Here we report the population of the ²²⁹Th isomeric state through resonant X-ray pumping and detection of the radiative decay in a VUV transparent ²²⁹Th-doped CaF₂ crystal. The decay half-life is measured to 447(25) s, with a transition wavelength of 148.18(42) nm and a radiative decay fraction consistent with unity. Furthermore, we report a new “X-ray quenching” effect which allows to de-populate the isomer on demand and effectively reduce the half-life. Such controlled quenching can be used to significantly speed up the interrogation cycle in future nuclear clock schemes.

DOI： 10.1038/s41467-024-49631-0

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Other Link： https://www.nature.com/articles/s41467-024-49631-0

Search for Antideuterons of Cosmic Origin Using the BESS-Polar II Magnetic-Rigidity Spectrometer

K. Sakai, H. Fuke, K. Yoshimura, M. Sasaki, K. Abe, S. Haino, T. Hams, M. Hasegawa, K. C. Kim, M. H. Lee, Y. Makida, J. W. Mitchell, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, E. S. Seo, R. E. Streitmatter, N. Thakur, A. Yamamoto, T. Yoshida

Physical Review Letters 132 ( 13 ) 2024.3

Experimental apparatus for detection of radiative decay of $$^{229}$$Th isomer from Th-doped CaF$$_2$$

Takahiro Hiraki, Kjeld Beeks, Michael Bartokos, Hiroyuki Fujimoto, Yuta Fukunaga, Hiromitsu Haba, Yoshitaka Kasamatsu, Shinji Kitao, Adrian Leitner, Takahiko Masuda, Guan Ming, Nobumoto Nagasawa, Ryoichiro Ogake, Koichi Okai, Martin Pimon, Martin Pressler, Noboru Sasao, Fabian Schaden, Thorsten Schumm, Makoto Seto, Yudai Shigekawa, Koutaro Shimizu, Tomas Sikorsky, Kenji Tamasaku, Sayuri Takatori, Tsukasa Watanabe, Atsushi Yamaguchi, Yoshitaka Yoda, Akihiro Yoshimi, Koji Yoshimura

Hyperfine Interactions 245 ( 1 ) 2024.1

Periodic superradiance in an Er:YSO crystal Reviewed

Hideaki Hara, Junseok Han, Yasutaka Imai, Noboru Sasao, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura, Yuki Miyamoto

Physical Review Research 2024.1

The upper limit on antideuteron flux with BESS-Polar II

K.Sakai, K.Abe, H.Fuke, S.Haino, T.Hams, M.Hasegawa, K.C.Kim, M.H.Lee, Y.Makida, J.W.Mitchell, J.Nishimura, M.Nozaki, R.Orito, J.F.Ormes, M.Sasaki, E.S.Seo, R.E.Streitmatter, N.Thakur, A.Yamamoto, T.Yoshida, K.Yoshimura

Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023) 2023.7

Vacuum Tltraviolet Search from Thorium-229 Isomer in Crystal Toward Solid-State Nuclear Clock

S. Takatori, Y. Fukunaga, M. Guan, T. Hiraki, T. Masuda, R. Ogake, K. Okai, N. Sasao, K. Shimizu, S. Uetake, A. Yoshimi, K. Yoshimura, M. Yoshimura, K. Tamasaku, Y. Kasamatsu, Y. Yasuda, K. Beeks, F. Schaden, T. Schumm, S. Kitao, M. Seto, H. Fujimoto, T. Watanabe, K. Konashi, M. Watanabe, H. Haba, Y. Shigekawa, A. Yamaguchi, N. Nagasawa, Y. Yoda

2023 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS) 2023.5

High-sensitivity low-noise photodetector using a large-area silicon photomultiplier

Takahiko Masuda, Ayami Hiramoto, Daniel G. Ang, Cole Meisenhelder, Cristian D. Panda, Noboru Sasao, Satoshi Uetake, Xing Wu, David P. DeMille, John M. Doyle, Gerald Gabrielse, Koji Yoshimura

Optics Express 31 ( 2 ) 1943 - 1943 2023.1

Publishing type：Research paper (scientific journal) Publisher：Optica Publishing Group

The application of silicon photomultiplier (SiPM) technology for weak-light detection at a single photon level has expanded thanks to its better photon detection efficiency in comparison to a conventional photomultiplier tube (PMT). SiPMs with large detection area have recently become commercially available, enabling applications where the photon flux is low both temporarily and spatially. On the other hand, several drawbacks exist in the usage of SiPMs such as a higher dark count rate, many readout channels, slow response time, and optical crosstalk; therefore, users need to carefully consider the trade-offs. This work presents a SiPM-embedded compact large-area photon detection module. Various techniques are adopted to overcome the disadvantages of SiPMs so that it can be generally utilized as an upgrade from a PMT. A simple cooling component and recently developed optical crosstalk suppression method are adopted to reduce the noise which is more serious for larger-area SiPMs. A dedicated readout circuit increases the response frequency and reduces the number of readout channels. We favorably compare this design with a conventional PMT and obtain both higher photon detection efficiency and larger-area acceptance.

DOI： 10.1364/oe.475109

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Other Link： https://opg.optica.org/viewmedia.cfm?URI=oe-31-2-1943&seq=0

Development of Time- and Energy-Resolved Synchrotron-Radiation-Based Mössbauer Spectroscopy

S. Kitao, R. Masuda, T. Fujihara, H. Tajima, N. Nagasawa, Y. Yoda, T. Masuda, K. Yoshimura, M. Seto

Journal of Physics: Conference Series 2380 ( 1 ) 012136 - 012136 2022.12

Publishing type：Research paper (scientific journal) Publisher：IOP Publishing

Abstract

Synchrotron-radiation based Mössbauer spectroscopy has become a useful technique capable for investigating various Mössbauer isotopes. For a typical experimental setup, the information associated with the pulse height (that is, energy) in an avalanche photodiode (APD) detector has not been used effectively. By using a system for simultaneous measurement system of time and energy associated with the APD signal, a system for the time- and energy-resolved Mössbauer spectroscopy has been developed. In this system, the pulse height information was converted to the time information through an amplitude-to-time converter applied to one of the divided signals from the APD. The corresponding time information was processed separately from another one of the divided signals. Both signals are recorded by a multi-channel scaler in an event-by-event data acquisition process. The velocity information from the Mössbauer transducer was also recorded as a tag for each signal event. Thus, the Mössbauer spectra with any time- and energy-window can be reconstructed after the data collection process. This system can be used for many purposes in time- and energy-resolved Mössbauer spectroscopy, and shows significant promise for use with other fast detectors and for various types of experiments.

DOI： 10.1088/1742-6596/2380/1/012136

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Other Link： https://iopscience.iop.org/article/10.1088/1742-6596/2380/1/012136/pdf

Recent progress and future prospects of hyperon nucleon scattering experiment

Koji Miwa, Takuya Nanamura, Tamao Sakao, J. K. Ahn, Y. Akazawa, T. Aramaki, S. Ashikaga, S. Callier, N. Chiga, N. Chiga, S. W. Choi, H. Ekawa, P. Evtoukhovitch, N. Fujioka, M. Fujita, T. Gogami, T. Harada, S. Hasegawa, S. H. Hayakawa, R. Honda, S. Hoshino, K. Hosomi, M. Ichikawa, Y. Ichikawa, M. Ieiri, M. Ikedai, K. Imai, Y. Ishikawa, S. Ishimoto, W. S. Jung, S. Kajikawa, H. Kanauchi, H. Kanda, T. Kitaoka, B. M. Kang, H. Kawai, S. H. Kim, K. Kobayashi, T. Koike, K. Matsuda, Y. Matsumoto, S. Nagao, R. Nagatomi, Y. Nakada, M. Nakagawa, I. Nakamura, M. Naruki, S. Ozawa, L. Raux, T. G. Rogers, A. Sakaguchi, H. Sako, S. Sato, T. Shiozaki, K. Shirotori, K. N. Suzuki, S. Suzuki, M. Tabata, C. d. L. Taille, H. Takahashi, T. Takahashi, T. N. Takahashi, H. Tamura, M. Tanaka, K. Tanida, Z. Tsamalaidze, M. Ukai, H. Umetsu, S. Wada, T. O. Yamamoto, J. Yoshida, K. Yoshimura

EPJ Web of Conferences 271 04001 - 04001 2022.11

Publishing type：Research paper (scientific journal) Publisher：EDP Sciences

A new hyperon-proton scattering experiment, dubbed J-PARC E40, was performed to measure differential cross sections of the Σ⁺p, Σ⁻p elastic scatterings and the Σ⁻p → Λn scattering by identifying a lot of Σ particles in the momentum ranging from 0.4 to 0.8 GeV/c produced by the π^±p → K⁺Σ^± reactions. We successfully measured the differential cross sections of these three channels with a drastically improved accuracy with a fine angular step. These new data will become important experimental constraints to improve the theories of the two-body baryon-baryon interactions. Following this success, we proposed a new experiment to measure the differential cross sections and spin observables by using a highly polarized Λ beam for providing quantitative information on the ΛN interaction. The results of three Σp channels and future prospects of the Λp scattering experiment are described.

DOI： 10.1051/epjconf/202227104001

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SiPM module for the ACME III electron EDM search Reviewed

A. Hiramoto, T. Masuda, D.G. Ang, C. Meisenhelder, C. Panda, N. Sasao, S. Uetake, X. Wu, D. Demille, J.M. Doyle, G. Gabrielse, K. Yoshimura

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 167513 - 167513 2022.10

Measurement of differential cross sections for Σ+p elastic scattering in the momentum range 0.44–0.80 GeV/c

T Nanamura, K Miwa, J K Ahn, Y Akazawa, T Aramaki, S Ashikaga, S Callier, N Chiga, S W Choi, H Ekawa, P Evtoukhovitch, N Fujioka, M Fujita, T Gogami, T K Harada, S Hasegawa, S H Hayakawa, R Honda, S Hoshino, K Hosomi, M Ichikawa, Y Ichikawa, M Ieiri, M Ikeda, K Imai, Y Ishikawa, S Ishimoto, W S Jung, S Kajikawa, H Kanauchi, H Kanda, T Kitaoka, B M Kang, H Kawai, S H Kim, K Kobayashi, T Koike, K Matsuda, Y Matsumoto, S Nagao, R Nagatomi, Y Nakada, M Nakagawa, I Nakamura, M Naruki, S Ozawa, L Raux, T G Rogers, A Sakaguchi, T Sakao, H Sako, S Sato, T Shiozaki, K Shirotori, K N Suzuki, S Suzuki, M Tabata, C d L Taille, H Takahashi, T Takahashi, T N Takahashi, H Tamura, M Tanaka, K Tanida, Z Tsamalaidze, M Ukai, H Umetsu, S Wada, T O Yamamoto, J Yoshida, K Yoshimura

Progress of Theoretical and Experimental Physics 2022 ( 9 ) 2022.8

Publishing type：Research paper (scientific journal) Publisher：Oxford University Press (OUP)

Abstract

We performed a novel Σ+p scattering experiment at the J-PARC Hadron Experimental Facility. Approximately 2400 Σ+p elastic scattering events were identified from 4.9 × 107 tagged Σ+ particles in the Σ+ momentum range 0.44–0.80 GeV/c. The differential cross sections of the Σ+p elastic scattering were derived with much better precision than in previous experiments. The obtained differential cross sections were approximately 2 mb/sr or less, which were not as large as those predicted by the fss2 and FSS models based on the quark cluster model in the short-range region. By performing phase-shift analyses for the obtained differential cross sections, we experimentally derived the phase shifts of the 3S1 and 1P1 channels for the first time. The phase shift of the 3S1 channel, where a large repulsive core was predicted owing to the Pauli effect between quarks, was evaluated as $20^\circ \lt |\delta _{^3S_1}|\lt 35^\circ$. If the sign of $\delta _{^3S_1}$ is assumed to be negative, the interaction in this channel is moderately repulsive, as the Nijmegen extended-sort-core models predicted.

DOI： 10.1093/ptep/ptac101

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Precise Measurement of Differential Cross Sections of the Σ-p → Λn Reaction in Momentum Range 470-650 MeV /c Reviewed

K. Miwa, J. K. Ahn, Y. Akazawa, T. Aramaki, S. Ashikaga, S. Callier, N. Chiga, S. W. Choi, H. Ekawa, P. Evtoukhovitch, N. Fujioka, M. Fujita, T. Gogami, T. Harada, S. Hasegawa, S. H. Hayakawa, R. Honda, S. Hoshino, K. Hosomi, M. Ichikawa, Y. Ichikawa, M. Ieiri, M. Ikeda, K. Imai, Y. Ishikawa, S. Ishimoto, W. S. Jung, S. Kajikawa, H. Kanauchi, H. Kanda, T. Kitaoka, B. M. Kang, H. Kawai, S. H. Kim, K. Kobayashi, T. Koike, K. Matsuda, Y. Matsumoto, S. Nagao, R. Nagatomi, Y. Nakada, M. Nakagawa, I. Nakamura, T. Nanamura, M. Naruki, S. Ozawa, L. Raux, T. G. Rogers, A. Sakaguchi, T. Sakao, H. Sako, S. Sato, T. Shiozaki, K. Shirotori, K. N. Suzuki, S. Suzuki, M. Tabata, C. D.L. Taille, H. Takahashi, T. Takahashi, T. N. Takahashi, H. Tamura, M. Tanaka, K. Tanida, Z. Tsamalaidze, M. Ukai, H. Umetsu, S. Wada, T. O. Yamamoto, J. Yoshida, K. Yoshimura

Physical Review Letters 128 ( 7 ) 072501 2022.2

Measurement of the differential cross sections of the elastic scattering in momentum range 470 to 850 MeV/c Reviewed

K. Miwa, J. K. Ahn, Y. Akazawa, T. Aramaki, S. Ashikaga, S. Callier, N. Chiga, S. W. Choi, H. Ekawa, P. Evtoukhovitch, N. Fujioka, M. Fujita, T. Gogami, T. Harada, S. Hasegawa, S. H. Hayakawa, R. Honda, S. Hoshino, K. Hosomi, M. Ichikawa, Y. Ichikawa, M. Ieiri, M. Ikeda, K. Imai, Y. Ishikawa, S. Ishimoto, W. S. Jung, S. Kajikawa, H. Kanauchi, H. Kanda, T. Kitaoka, B. M. Kang, H. Kawai, S. H. Kim, K. Kobayashi, T. Koike, K. Matsuda, Y. Matsumoto, S. Nagao, R. Nagatomi, Y. Nakada, M. Nakagawa, I. Nakamura, T. Nanamura, M. Naruki, S. Ozawa, L. Raux, T. G. Rogers, A. Sakaguchi, T. Sakao, H. Sako, S. Sato, T. Shiozaki, K. Shirotori, K. N. Suzuki, S. Suzuki, M. Tabata, C. d.L. Taille, H. Takahashi, T. Takahashi, T. N. Takahashi, H. Tamura, M. Tanaka, K. Tanida, Z. Tsamalaidze, M. Ukai, H. Umetsu, S. Wada, T. O. Yamamoto, J. Yoshida, K. Yoshimura

Physical Review C 104 ( 4 ) 2021.10

Estimation of radiative half-life of Th229m by half-life measurement of other nuclear excited states in Th229

Y. Shigekawa, A. Yamaguchi, K. Suzuki, H. Haba, T. Hiraki, H. Kikunaga, T. Masuda, S. Nishimura, N. Sasao, A. Yoshimi, K. Yoshimura

Physical Review C 104 ( 2 ) 2021.8

Suppression of the optical crosstalk in a multi-channel silicon photomultiplier array

Takahiko Masuda, Daniel G. Ang, Nicholas R. Hutzler, Cole Meisenhelder, Noboru Sasao, Satoshi Uetake, Xing Wu, David DeMille, Gerald Gabrielse, John M. Doyle, Koji Yoshimura

Optics Express 29 ( 11 ) 16914 - 16914 2021.5

Simulation Study of Laser Ionization of Muonium by 1S-2S Excitation for the Muon g − 2/EDM Experiment at J-PARC

Ce Zhang, Hideaki Hara, Takahiro Hiraki, Yutaka Ikedo, Yasutaka Imai, Katsuhiko Ishida, Saeid Kamal, Naritoshi Kawamura, Akihiro Koda, Yajun Mao, Takahiko Masuda, Tsutomu Mibe, Yasuhiro Miyake, Yuki Miyamoto, Yu Oishi, Masashi Otani, Patrick Strasser, Koichiro Shimomura, Kazuhito Suzuki, Satoshi Uetake, Takayuki Yamazaki, Shinsuke Yamamoto, Koji Yoshimura, Mitsuhiro Yoshida

Proceedings of the 3rd J-PARC Symposium (J-PARC2019) 2021.3

Establishment of a Modern Experimental Technique of a $\Sigma p$ Scattering Experiment at J-PARC Reviewed

Yuya Akazawa, J. K. Ahn, T. Aramaki, S. Ashikaga, S. Callier, N. Chiga, S. W. Choi, H. Ekawa, P. Evtoukhovitch, N. Fujioka, M. Fujita, T. Gogami, T. Harada, S. Hasegawa, S. Hayakawa, R. Honda, S. Hoshino, K. Hosomi, M. Ichikawa, Y. Ichikawa, M. Ieiri, M. Ikeda, K. Imai, Y. Ishikawa, S. Ishimoto, W. S. Jung, S. Kajikawa, H. Kanauchi, H. Kanda, B. M. Kang, H. Kawai, S. H. Kim, K. Kobayashi, T. Koike, K. Matsuda, Y. Matsumoto, K. Miwa, S. Nagao, R. Nagatomi, Y. Nakada, M. Nakagawa, I. Nakamura, T. Nanamura, M. Naruki, S. Ozawa, L. Raux, T. Rogers, A. Sakaguchi, T. Sakao, H. Sako, S. Sato, T. Shiozaki, K. Shirotori, K. N. Suzuki, S. Suzuki, M. Tabata, C. d. L. Taille, H. Takahashi, T. Takahashi, T. N. Takahashi, H. Tamura, M. Tanaka, K. Tanida, Z. Tsamalaidze, H. Umetsu, M. Ukai, T. O. Yamamoto, J. Yoshida, K. Yoshimura

Proceedings of the 3rd J-PARC Symposium (J-PARC2019) 2021.3

Study of $\Lambda $ Identification Method by the $\pi ^{ - }p \to K^{0}\Lambda $ Reaction for a $\Lambda p$ Scattering Experiment at J-PARC Reviewed

T. Sakao, J. K. Ahn, Y. Akazawa, T. Aramaki, S. Ashikaga, S. Callier, S. W. Choi, P. Evtoukhovitch, N. Fujioka, M. Fujita, T. Gogami, T. Harada, S. Hasegawa, S. H. Hayakawa, R. Honda, S. Hoshino, K. Hosomi, M. Ichikawa, Y. Ichikawa, M. Ikeda, K. Imai, Y. Ishikawa, S. Ishimoto, W. S. Jung, S. Kajikawa, H. Kanauchi, H. Kanda, B. M. Kang, H. Kawai, S. H. Kim, K. Kobayashi, K. Matsuda, Y. Matsumoto, K. Miwa, S. Nagao, R. Nagatomi, Y. Nakada, M. Nakagawa, I. Nakamura, T. Nanamura, M. Naruki, S. Ozawa, L. Raux, T. Rogers, A. Sakaguchi, H. Sako, S. Sato, K. Shirotori, K. N. Suzuki, S. Suzuki, M. Tabata, C. d. L. Taille, H. Takahashi, T. N. Takahashi, T. Takahashi, M. Tanaka, K. Tanida, H. Tamura, Z. Tsamalaidze, M. Ukai, H. Umetsu, T. O. Yamamoto, J. Yoshida, K. Yoshimura

Proceedings of the 3rd J-PARC Symposium (J-PARC2019) 2021.3

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Papers - YOSHIMURA Koji