2022/04/12 更新

写真a

コオリ ヒデキ
郡 英輝
KOHRI Hideki
所属
大学院理学研究科 理学専攻 物理学第二 特任准教授
職名
特任准教授
外部リンク

学位 1

  1. 博士(理学) ( 2000年3月   大阪大学 ) 

研究分野 1

  1. 自然科学一般 / 素粒子、原子核、宇宙線、宇宙物理にする実験  / ハドロン物理学

現在の研究課題とSDGs 1

  1. 偏極核標的の開発と素粒子・原子核物理

経歴 1

  1. 大阪大学   核物理研究センター   特任准教授

    2019年4月 - 現在

学歴 1

  1. 大阪大学   理学研究科   物理専攻

    1997年4月 - 2000年3月

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    備考: 博士後期課程修了

所属学協会 1

  1. 日本物理学会   会員

 

論文 12

  1. Differential Cross Section and Photon-Beam Asymmetry for the gamma p -> Pi(-)Delta(+ +) (1232) Reaction at Forward Pi(-) Angles for E-gamma=1.5-2.95 GeV 査読有り

    Kohri H., Shiu S. H., Chang W. C., Yanai Y., Ahn D. S., Ahn J. K., Chen J. Y., Date S., Ejiri H., Fujimura H., Fujiwara M., Fukui S., Gohn W., Hicks K., Hosaka A., Hotta T., Hwang S. H., Imai K., Ishikawa T., Joo K., Kato Y., Kon Y., Lee H. S., Maeda Y., Mibe T., Miyabe M., Morino Y., Muramatsu N., Nakano T., Nakatsugawa Y., Nam S. I, Niiyama M., Noumi H., Ohashi Y., Ohta T., Oka M., Parker J. D., Rangacharyulu C., Ryu S. Y., Sawada T., Shimizu H., Strokovsky E. A., Sugaya Y., Sumihama M., Tsunemi T., Uchida M., Ungaro M., Wang S. Y., Yosoi M.

    PHYSICAL REVIEW LETTERS   120 巻 ( 20 ) 頁: 202004-1 - 202004-6   2018年5月

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    担当区分:筆頭著者   記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Review Letters  

    Differential cross sections and photon-beam asymmetries for the γ→p→π-Δ++(1232) reaction have been measured for 0.7<cosθπc.m.<1 and Eγ=1.5-2.95 GeV at SPring-8/LEPS. The first-ever high statistics cross-section data are obtained in this kinematical region, and the asymmetry data for 1.5<Eγ(GeV)<2.8 are obtained for the first time. This reaction has a unique feature for studying the production mechanisms of a pure uū quark pair in the final state from the proton. Although there is no distinct peak structure in the cross sections, a non-negligible excess over the theoretical predictions is observed at Eγ=1.5-1.8 GeV. The asymmetries are found to be negative in most of the present kinematical regions, suggesting the dominance of π exchange in the t channel. The negative asymmetries at forward meson production angles are different from the asymmetries previously measured for the photoproduction reactions producing a dd or an ss quark pair in the final state. Advanced theoretical models introducing nucleon resonances and additional unnatural-parity exchanges are needed to reproduce the present data.

    添付ファイル: 1801.07900(1).pdf

    DOI: 10.1103/PhysRevLett.120.202004

    Web of Science

    Scopus

    PubMed

  2. Differential cross section and photon-beam asymmetry for the (gamma) p -> pi(+) n reaction at forward pi(+) angles at E-gamma=1.5-2.95 GeV 査読有り

    Kohri H., Wang S. Y., Shiu S. H., Chang W. C., Yanai Y., Ahn D. S., Ahn J. K., Chen J. Y., Date S., Ejiri H., Fujimura H., Fujiwara M., Fukui S., Gohn W., Hicks K., Hosaka A., Hotta T., Hwang S. H., Imai K., Ishikawa T., Joo K., Kato Y., Kim S. H., Kon Y., Lee H. S., Maeda Y., Mibe T., Miyabe M., Morino Y., Muramatsu N., Nakano T., Nakatsugawa Y., Niiyama M., Noumi H., Ohashi Y., Ohta T., Oka M., Parker J. D., Rangacharyulu C., Ryu S. Y., Sawada T., Shimizu H., Sugaya Y., Sumihama M., Tsunemi T., Uchida M., Ungaro M., Yosoi M.

    PHYSICAL REVIEW C   97 巻 ( 1 ) 頁: 015205-1 - 015205-7   2018年1月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Review C  

    Differential cross sections and photon-beam asymmetries for the γ - p→π+n reaction have been measured for 0.6<cosθπ<1 and Eγ=1.5-2.95GeV at SPring-8/LEPS. The cross sections monotonically decrease as the photon beam energy increases for 0.6<cosθπ<0.9. However, the energy dependence of the cross sections for 0.9<cosθπ<1 and Eγ=1.5-2.2GeV (W=1.9-2.2GeV) is different, which may be due to a nucleon or Δ resonance. The present cross sections agree well with the previous cross sections measured by other groups and show forward peaking, suggesting significant t-channel contributions in this kinematical region. The asymmetries are found to be positive, which can be explained by ρ exchange in the t channel. Large positive asymmetries in the small-|t| region, where the ρ-exchange contribution becomes small, could be explained by introducing π-exchange interference with the s channel.

    添付ファイル: 1708.09574(2).pdf

    DOI: 10.1103/PhysRevC.97.015205

    Web of Science

    Scopus

  3. Photoproduction of Lambda and Sigma(0) hyperons off protons with linearly polarized photons at E-gamma=1.5-3.0 GeV

    Shiu S. H., Kohri H., Chang W. C., Ahn D. S., Ahn J. K., Chen J. Y., Date S., Ejiri H., Fujimura H., Fujiwara M., Fukui S., Gohn W., Hicks K., Hotta T., Hwang S. H., Imai K., Ishikawa T., Joo K., Kato Y., Kon Y., Lee H. S., Maeda Y., Mibe T., Miyabe M., Mizutani K., Morino Y., Muramatsu N., Nakano T., Nakatsugawa Y., Niiyama M., Noumi H., Ohashi Y., Ohta T., Oka M., Parker J. D., Rangacharyulu C., Ryu S. Y., Sawada T., Shimizu H., Sugaya Y., Sumihama M., Tsunemi T., Uchida M., Ungaro M., Yosoi M.

    PHYSICAL REVIEW C   97 巻 ( 1 )   2018年1月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Review C  

    © 2018 American Physical Society. We report the measurement of the γp→K+Λ and γp→K+Σ0 reactions at SPring-8. The differential cross sections and photon-beam asymmetries are measured at forward K+ production angles using linearly polarized tagged-photon beams in the range of Eγ=1.5-3.0 GeV. With increasing photon energy, the cross sections for both γp→K+Λ and γp→K+Σ0 reactions decrease slowly. Distinct narrow structures in the production cross section have not been found at Eγ=1.5-3.0 GeV. The forward peaking in the angular distributions of cross sections, a characteristic feature of t-channel exchange, is observed for the production of Λ in the whole observed energy range. A lack of similar feature for Σ0 production reflects a less dominant role of t-channel contribution in this channel. The photon-beam asymmetries remain positive for both reactions, suggesting the dominance of K∗ exchange in the t channel. These asymmetries increase gradually with the photon energy, and have a maximum value of +0.6 for both reactions. Comparison with theoretical predictions based on the Regge trajectory in the t channel and the contributions of nucleon resonances indicates the major role of t-channel contributions as well as non-negligible effects of nucleon resonances in accounting for the reaction mechanism of hyperon photoproduction in this photon energy regime.

    DOI: 10.1103/PhysRevC.97.015208

    Web of Science

    Scopus

  4. Measurement of nuclear spin relaxation time in lanthanum aluminate for development of polarized lanthanum target

    Ishizaki K., Hotta H., Ide I., Iinuma M., Iwata T., Kitaguchi M., Kohri H., Miura D., Miyachi Y., Ohta T., Shimizu H. M., Yoshikawa H., Yosoi M.

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   1020 巻   2021年12月

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    記述言語:日本語   出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment  

    The nuclear spin–lattice relaxation time (T1) of lanthanum and aluminum nuclei in a single crystal of lanthanum aluminate doped with neodymium ions is studied to estimate the feasibility of the dynamically polarized lanthanum target applicable to beam experiments. The application of our interest is the study of fundamental discrete symmetries in the spin optics of epithermal neutrons. This study requires a highly flexible choice of the applied magnetic field for neutron spin control and favors longer T1 under lower magnetic field and at higher temperature. The T1 of 139La and 27Al was measured under magnetic fields of 0.5–2.5 T and at temperatures of 0.1–1.5 K and found widely distributed up to 100 h. The result suggests that the T1 can be as long as T1∼ 1 h at 0.1 K with a magnetic field of 0.1 T, which partially fulfills the requirement of the neutron beam experiment. Possible improvements to achieve a longer T1 are discussed.

    DOI: 10.1016/j.nima.2021.165845

    Web of Science

    Scopus

  5. Monitoring the build-up of hydrogen polarization for polarized hydrogen-deuteride (HD) targets with nuclear magnetic resonance (NMR) at 17 T 査読有り

    Ohta T., Fujiwara M., Hotta T., Ide I., Ishizaki K., Kohri H., Yanai Y., Yosoi M.

    REVIEW OF SCIENTIFIC INSTRUMENTS   91 巻 ( 9 ) 頁: 095104 - 095104   2020年9月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Review of Scientific Instruments  

    We report on the frozen-spin polarized hydrogen-deuteride (HD) targets for photoproduction experiments at SPring-8/LEPS. Pure HD gas with a small amount of ortho-H2 (∼0.1%) and a very small amount of para-D2 (∼0.001%) was liquefied and solidified by liquid helium. The temperature of the produced solid HD was reduced to about 30 mK with a dilution refrigerator. A magnetic field (17 T) was applied to the HD to grow the polarization with the static method. After the aging of the HD at low temperatures in the presence of a high-magnetic field strength for three months, the polarization froze. Almost all ortho-H2 molecules were converted to para-H2 molecules. Most remaining para-D2 molecules were converted to ortho-D2 molecules. The para-H2 and ortho-D2 molecules exhibited weak spin interactions with the HD. If the concentrations of the ortho-H2 and para-D2 were reduced appropriately at the beginning of the aging process, the aging time can be shortened. We have developed a new nuclear magnetic resonance (NMR) system to measure the relaxation times (T1) of the 1H and 2H nuclei with two frequency sweeps at the respective frequencies of 726 MHz and 111 MHz and succeeded in the monitoring of the polarization build-up at decreasing temperatures from 600 mK to 30 mK at 17 T. Automatic NMR measurements with the frequency sweeps enabled us to omit the use of a manual tuning circuit and to remove magnetic field sweeps with eddy current heat. This technique enables us to optimize the concentration of the ortho-H2 and to efficiently polarize the HD target within a shortened aging time.

    添付ファイル: 17T-NMR-arXiv.pdf

    DOI: 10.1063/5.0005696

    Web of Science

    Scopus

  6. Recent results of charged pion and kaon photoproduction on the proton at SPring-8/LEPS

    Kohri H.

    12TH INTERNATIONAL WORKSHOP ON THE PHYSICS OF EXCITED NUCLEONS (NSTAR 2019)   241 巻   2020年

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    記述言語:日本語  

    DOI: 10.1051/epjconf/202024101010

    Web of Science

  7. Polarized lanthanum target for the t-violation search in slow neutron transmission

    Ishizaki K., Shimizu H.M., Kitaguchi M., Matsushita T., Iinuma M., Kohri H., Yoshikawa H., Yosoi M., Shima T., Iwata T., Miyachi Y., Ishimoto S., Fujita M., Ikeda Y.

    Proceedings of Science   379 巻   2019年

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    記述言語:日本語   出版者・発行元:Proceedings of Science  

    The Nd3+ doped LaAlO3 crystal is a good candidate of a polarized 139La target for the search of the P-odd and T-odd interaction in the low-energy neutron absorption of 139La. As the first step for realizing the polarized 139La target, we grow the undoped LaAlO3 crystal and the La1−xNdxAlO3 (x = 5 ×10−4) crystal by floating-zone method with four halogen lamps. The ESR measurements of Nd3+ in the latter crystal indicated that the linewidth was about 6 gauss, whose value is the same as the crystal in which 50 % 139La polarization was achieved in the previous DNP experiment. As the result, the crystals grown by this method can be applicable to the target study for the T-violation search.

    Scopus

  8. Photoproduction of π-Δ+ + , π+Δ0 , and π+n on the Proton at Eγ= 1.5 –3.0 GeV 査読有り

    H. Kohri, For LEPS collaboration

    Few-Body Systems   59 巻 ( 5 )   2018年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer-Verlag Wien  

    We carry out photoproduction experiments by using linearly polarized photon beams with energies of 1.5–3.0 GeV at SPring-8/LEPS. There is no distinct peak structure due to nucleon or Δ resonances in the preliminary cross sections for the γp→ π-Δ+ +, π+Δ0, and π+n reactions for 0.7&lt
    cos θπ&lt
    1. The cross section ratios σ(π+Δ0)/σ(π-Δ+ +) are close to 1/3, which is expected from the isospin = 1 exchange in the t-channel, at small π angles and become larger than 1/3 at large π angles. The photon beam asymmetries are small negative values, small positive values, and large positive values for the π-Δ+ +, π+Δ0, and π+n reactions, respectively. The asymmetries are sensitive to reaction mechanisms and are found to be largely different among these reactions. The asymmetries are strong constraint in theoretical studies and expected to play an important role in searching for new nucleon resonances.

    DOI: 10.1007/s00601-018-1411-x

    Scopus

  9. First measurement of coherent phi-meson photoproduction from He-4 near threshold

    Hiraiwa T., Yosoi M., Niiyama M., Morino Y., Nakatsugawa Y., Sumihama M., Ahn D. S., Ahn J. K., Chang W. C., Chen J. Y., Date S., Fujimura H., Fukui S., Hicks K., Hotta T., Hwang S. H., Ishikawa T., Kato Y., Kawai H., Kohri H., Kon Y., Lin P. J., Maeda Y., Miyabe M., Mizutani K., Muramatsu N., Nakano T., Nozawa Y., Ohashi Y., Ohta T., Oka M., Rangacharyulu C., Ryu S. Y., Saito T., Sawada T., Shimizu H., Strokovsky E. A., Sugaya Y., Suzuki K., Tokiyasu A. O., Tomioka T., Tsunemi T., Uchida M., Yorita T.

    PHYSICAL REVIEW C   97 巻 ( 3 )   2018年3月

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    記述言語:日本語   出版者・発行元:Physical Review C  

    © 2018 American Physical Society. The differential cross sections and decay angular distributions for coherent φ-meson photoproduction from helium-4 are measured for the first time at forward angles with linearly polarized photons in the energy range Eγ=1.685-2.385GeV. Thanks to the target with spin-parity JP=0+, unnatural-parity exchanges are absent, and thus natural-parity exchanges can be investigated clearly. The decay asymmetry with respect to photon polarization is shown to be very close to the maximal value. This ensures the strong dominance (&gt;94%) of natural-parity exchanges in this reaction. To evaluate the contribution from natural-parity exchanges to the forward cross section (θ=0â) for the γp→φp reaction near threshold, the energy dependence of the forward cross section (θ=0â) for the γHe4→φHe4 reaction is analyzed. The comparison to γp→φp data suggests that enhancement of the forward cross section arising from natural-parity exchanges and/or destructive interference between natural-parity and unnatural-parity exchanges is needed in the γp→φp reaction near threshold.

    DOI: 10.1103/PhysRevC.97.035208

    Web of Science

    Scopus

  10. phi photoproduction on the proton at E-gamma=1.5-2.9 GeV 査読有り

    Mizutani K., Niiyama M., Nakano T., Yosoi M., Nozawa Y., Ahn D. S., Ahn J. K., Chang W. C., Chen J. Y., Date S., Gohn W., Hamano H., Hashimoto T., Hicks K., Hiraiwa T., Hotta T., Hwang S. H., Ishikawa T., Joo K., Jung W. S., Kato Y., Katsuragawa H., Kim M. H., Kim S. H., Kohri H., Kon Y., Lee H. S., Maeda Y., Matsumura Y., Mibe T., Miyabe M., Morino Y., Muramatsu N., Nakatsugawa Y., Noumi H., Ohashi Y., Ohta T., Oka M., Park J. B., Parker J. D., Rangacharyulu C., Ryu S. Y., Sada Y., Sawada T., Shibukawa T., Shiu S. H., Sugaya Y., Sumihama M., Tanaka S., Tokiyasu A. O., Tomida N., Tran H. N., Tsunemi T., Uchida M., Ungaro M., Yanai Y.

    PHYSICAL REVIEW C   96 巻 ( 6 )   2017年12月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Review C  

    Differential cross sections at t=tmin and decay asymmetries for the γp→φp reaction have been measured using linearly polarized photons in the range 1.5 to 2.9 GeV. These cross sections were used to determine the Pomeron strength factor. The cross sections and decay asymmetries are consistently described by the t-channel Pomeron and pseudoscalar exchange model in the Eγ region above 2.37 GeV. In the lower energy region, an excess over the model prediction is observed in the energy dependence of the differential cross sections at t=tmin. This observation suggests that additional processes or interference effects between Pomeron exchange and other processes appear near the threshold region.

    DOI: 10.1103/PhysRevC.96.062201

    Web of Science

    Scopus

  11. Comparison between ūu and d̄d productions by the γp → π−δ++ and π+Δ0 reactions at forward π angles at E γ = 1.5–3.0 GeV 査読有り

    H. Kohri, LEPS collaboration

    Physics of Particles and Nuclei   48 巻 ( 1 ) 頁: 63 - 68   2017年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Maik Nauka-Interperiodica Publishing  

    Photoproduction reactions are dominated by isospin rules. In the case of πΔ photoproduction on the proton at forward π angles, the exchange of isospin = 1 meson(π or ρ) in the t-channel is the most dominant reaction mechanism, which is considered to give a cross section ratio σ(π+Δ0)/σ(π−Δ++) of 1/3. The cross section ratio has not been measured precisely experimentally. We present preliminary results for the cross section ratio at Eγ = 1.5–3.0 GeV. Larger ratios than 1/3 measured by our experiment at LEPS/SPring-8 suggest that the d̄d productions are enhanced compared with the ūu productions in the photoproduction reactions on the proton.

    DOI: 10.1134/S1063779617010129

    Scopus

  12. Development of polarized HD target for SPring-8/LEPS experiment 査読有り

    Yanai Y, Kohri H, Yosoi M, Hotta T, Katsuragawa H, Ohta T, Tanaka S

    Proceedings of Science   324 巻   2017年

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▼全件表示

MISC 2

  1. Recent results of charged pion and kaon photoproduction on the proton at SPring-8/LEPS 査読有り

    H. Kohri  

    EPJ Web of Conference241 巻   頁: 01010 - 01010   2020年9月

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    担当区分:筆頭著者   記述言語:英語  

  2. LEPS実験における円偏光ビーム生成と偏極HD標的開発

    柳井優花, 與曽井優, 郡英輝, 堀田智明, 桂川仁志, 村松憲仁, 住浜水季, 成田龍哉, 太田岳史  

    日本物理学会講演概要集(CD-ROM)75 巻 ( 1 )   2020年

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講演・口頭発表等 1

  1. LEPSの物理と標的

    郡 英輝

    日本のスピン物理学の展望  2021年2月24日 

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    開催年月日: 2021年2月

    会議種別:口頭発表(一般)  

科研費 1

  1. πΔの光生成を用いた陽子と中性子の中の反クォーク構造の研究

    研究課題/研究課題番号:16K05379  2016年4月 - 2019年3月

    科学研究費助成事業  基盤研究(C)

    郡 英輝

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    担当区分:研究代表者 

    配分額:4680000円 ( 直接経費:3600000円 、 間接経費:1080000円 )

    私達はSPring-8/LEPS実験施設において、エネルギー1.5~3GeVの直線偏光フォトンを用いて中間子生成の研究を行った。陽子標的の①γp→π+n、②γp→K+Λ、③γp →π-Δ++、④γp→π+Δ0反応に関して、①と②はPhysical Review C、③はPhysical Review Letters、④はFew-Body Systemsへ結果を発表する事ができた。
    中性子標的の⑤γn→π+Δ-、⑥γn→π-Δ+反応に関しては、ビームタイムの制限により目標の20%程度しかデータ収集を行う事ができなかったが、データの質は良く、2-3年後にはデータ収集を終えて結果を発表する予定である。
    今回発表した中間子光生成反応では、①d-反dクォーク対、②s-反sクォーク対、③u-反uクォーク対、④d-反dクォーク対の生成を分離して研究する事ができる。これは初めての試みであり、高エネルギーフォトンによってどのようなメカニズムでハドロンが生成されるかを解明するために極めて重要な意義が有る。反応③と④の超前方角度断面積の比は、アイソスピンから予測される比とほぼ同じであり、ハドロン生成に関する理解を深める重要な結果になった。大きな角度での断面積は予測より大きな値であり、アイソスピン2の奇妙な粒子の交換か、核子の中の豊富な反dクォークが反応④を促進していると考えられる興味深い結果になった。