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論文

亀裂性堆積岩を対象とした地下水流動解析における有効間隙率の与え方; 北海道幌延に分布する声問層と稚内層浅部の事例

宮川 和也; 石井 英一; 今井 久*; 平井 哲*; 大野 宏和; 中田 弘太郎*; 長谷川 琢磨*

原子力バックエンド研究(CD-ROM), 31(2), p.82 - 95, 2024/12

https://doi.org/10.3327/jnuce.31.2_82

高レベル放射性廃棄物の処分地の選定過程における概要調査では、地下水の涵養域から流出域までを包含する数km-数十kmの広域を対象とした地下水流動解析により、地下水の移行時間・経路が評価される。亀裂の発達する岩盤中の地下水の移行時間を解析的に求める上で、岩盤の水理学的有効間隙率は感度の高いパラメータである。堆積岩ではボーリング調査における原位置水理試験から得られた亀裂の透水性を岩盤の透水性として扱う一方で、コア試料を用いて浮力法などの室内試験から得られた健岩部の間隙率を水理学的有効間隙率として扱うなど、有効間隙率の考え方が明確ではない。本研究では亀裂の発達する堆積岩である声問層および稚内層浅部を例として、亀裂の開口幅を基に推定した有効間隙率を用いた場合の移行時間を、観測結果と比較することで、有効間隙率の推定方法を検討した。その結果、亀裂の開口幅を基に推定した有効間隙率を用いた場合、観測結果と整合的な移行時間が得られた。その時の有効間隙率は、健岩部の間隙率と比較して1-3桁小さい値であった。多孔質な健岩部と割れ目からなる水みちネットワークを有する堆積岩の場合、亀裂の開口幅を基に有効間隙率を推定することが有効であることが示された。

論文

Missing-mass measurement of the $$^{12}$$C$$(K^-,K^+)$$ reaction at 1.8 GeV/$$c$$ with the Superconducting Kaon spectrometer

市川 裕大; 藤田 真奈美; 長谷川 勝一; 今井 憲一*; 七村 拓野; 成木 恵; 佐藤 進; 佐甲 博之; 田村 裕和; 谷田 聖; et al.

Progress of Theoretical and Experimental Physics (Internet), 2024(9), p.091D01_1 - 091D01_13, 2024/09

https://doi.org/10.1093/ptep/ptae133
 被引用回数：1 パーセンタイル：49.52(Physics, Multidisciplinary)

We conducted a measurement of the inclusive missing-mass spectrum in the $$^{12}$$C$$(K^-, K^+)$$ reaction at an incident beam momentum of 1.8 GeV/$$c$$. This measurement was carried out utilizing the Superconducting Kaon Spectrometer (SKS) and the K1.8 beamline spectrometer at the Hadron Experimental Hall in J-PARC. Remarkably, our experimental setup yielded an exceptionaly good energy resolution of 8.2 MeV (FWHM), enabling us to observe significant enhancements in the vicinity of the $$^{12}_{Xi}$$Be threshold region. In order to estimate the spectrum information, we employed several fitting parameters assumptions. The best agreement with the spectrum shape was obtained with combining quasi-free (QF) component and two-Gaussian functions, with the experimental resolution $$sigma$$ being held constant. The peak positions were obtained to be $$B_{Xi} = 8.9 pm 1.4$$ (stat.) $$^{+3.8}_{-3.1}$$ (syst.) MeV and $$B_{Xi} = -2.4 pm 1.3$$ (stat.) $$^{+2.8}_{-1.2}$$ (syst.) MeV. Another model assumption, utilizing quasi-free (QF) and one Breit-Wigner function with $$B_{Xi} = -2.7 pm 2.2$$ (stat.) $$^{+0.5}_{-0.7}$$ (syst.) MeV and $$Gamma = 4.1 pm 2.1$$ (stat.) $$^{+1.2}_{-0.7}$$ (syst.) MeV, also yielded a similar $$chi^2$$ value.

論文

$$Xi^-$$ atomic X-ray spectroscopy using a counter-emulsion hybrid method

藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 真也; 市川 裕大; Kim, S.; 七村 拓野; 佐甲 博之; 田村 裕和; 山本 剛史; et al.

Progress of Theoretical and Experimental Physics (Internet), 2022(12), p.123D01_1 - 123D01_17, 2022/12

https://doi.org/10.1093/ptep/ptac156
 被引用回数：1 パーセンタイル：13.66(Physics, Multidisciplinary)

$$Xi^-$$ atomic X-ray spectroscopy is one of the most useful methods for investigation of the $$Xi$$-nucleus strong interaction. Since the X-ray energy is shifted and/or broadened due to the $$Xi$$-nucleus strong interaction compared to those calculated from electromagnetic interaction alone, the measurement of the energy shift, $$Delta$$E, and the width, $$Gamma$$, give us information on the $$Xi$$-nucleus potential. A serious problem in the measurement is the significant background derived from in-flight $$Xi^-$$ decay. A novel method of identifying stopped $$Xi^-$$ events using the nuclear emulsion was developed to realize the first $$Xi^-$$ atomic X-ray spectroscopy experiment as the J-PARC E07 experiment, which also aimed at searching for $$LambdaLambda$$ and $$Xi^-$$ hypernuclei in the emulsion. The X-rays emitted from $$Xi^-$$ Br and $$Xi^-$$ Ag atoms were measured using germanium detectors. No clear peaks were observed in the obtained spectra. However, we succeeded in reducing the background to 1/170 by this method employing coincidence measurements using nuclear emulsion and X-ray detectors.

論文

Strangeness physics programs by S-2S at J-PARC

後神 利志*; 江端 健悟; 藤田 真奈美; 原田 健志; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一*; Kim, S.; 七村 拓野; et al.

EPJ Web of Conferences, 271, p.11002_1 - 11002_7, 2022/11

https://doi.org/10.1051/epjconf/202227111002

In the K1.8 beam-line at Hadron Experimental Facility of J-PARC, a new magnetic spectrometer S-2S is being installed. S-2S was designed to achieve a high momentum resolution of $$Delta p/p = 6 times 10^{-4}$$ in FWHM. Several strangeness-physics programs which require the high resolution will be realized by S-2S. The present article introduces J-PARC E70 (missing-mass spectroscopy of $$_{Xi}^{12}$$Be) and E94 (missing-mass spectroscopy of $$_{Lambda}^7$$Li, $$_{Lambda}^{10}$$B, and $$_{Lambda}^{12}$$C) experiments.

論文

Recent progress and future prospects of hyperon nucleon scattering experiment

三輪 浩司*; 藤田 真奈美; 原田 健志; 長谷川 勝一; 細見 健二; 市川 真也; 今井 憲一*; 佐甲 博之; 佐藤 進; 田村 裕和; et al.

EPJ Web of Conferences, 271, p.04001_1 - 04001_7, 2022/11

https://doi.org/10.1051/epjconf/202227104001

A new hyperon-proton scattering experiment, dubbed J-PARC E40, was performed to measure differential cross sections of the $$Sigma^+ p$$, $$Sigma^- p$$ elastic scatterings and the $$Sigma^- p to Lambda n$$ scattering by identifying a lot of $$Sigma $$ particles in the momentum ranging from 0.4 to 0.8 GeV/$$c$$ produced by the $$pi^{pm}p to K^+Sigma^{pm}$$ 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 $$Lambda$$ beam for providing quantitative information on the $$Lambda N$$ interaction. The results of three $$Sigma p$$ channels and future prospects of the $$Lambda p$$ scattering experiment are described.

論文

Estimation of children's thyroid equivalent doses in 16 municipalities after the Fukushima Daiichi Nuclear Power Station accident

鈴木 元*; 石川 徹夫*; 大葉 隆*; 長谷川 有史*; 永井 晴康; 宮武 裕和*; 義澤 宣明*

Journal of Radiation Research (Internet), 63(6), p.796 - 804, 2022/11

https://doi.org/10.1093/jrr/rrac058
 被引用回数：3 パーセンタイル：29.95(Biology)

2011年の福島第一原子力発電所事故による被ばく線量と甲状腺がんの関係を明らかにするために、小児の甲状腺等価線量(TED)を評価する必要がある。これまでに、行動調査データと大気拡散モデルにより構築した放射性物質の時空間分布データベースを組み合わせたTED再構築手法について報告した。本研究では、この手法をさらに精緻化し、原発周辺16市町村における3256人の行動調査データに基づき、小児のTEDを評価した。TED評価結果は、いわき市,川俣町,飯舘村,南相馬市の小児1080人の測定データと近い値であった。1歳児のTEDの平均値は伊達市の1.3mSvから南相馬市小高地区の14.9mSvの範囲であり、95パーセンタイル値は伊達市の2.3mSvから浪江町の28.8mSvの範囲であった。本研究成果は、今後の甲状腺がんの調査に有効活用される。

論文

Measurement of differential cross sections for $$Sigma^+ p$$ elastic scattering in the momentum range 0.44-0.80 GeV/c

七村 拓野; 藤田 真奈美; 長谷川 勝一; 市川 真也; 市川 裕大; 今井 憲一*; 成木 恵; 佐藤 進; 佐甲 博之; 田村 裕和; et al.

Progress of Theoretical and Experimental Physics (Internet), 2022(9), p.093D01_1 - 093D01_35, 2022/09

https://doi.org/10.1093/ptep/ptac101
 被引用回数：16 パーセンタイル：81.16(Physics, Multidisciplinary)

We performed a novel $$Sigma^+p$$ scattering experiment at the J-PARC Hadron Experimental Facility. Approximately 2400 $$Sigma^+p$$ elastic scattering events were identified from $$4.9 times 10^7$$ tagged $$Sigma^+$$ particles in the $$Sigma^+$$ momentum range 0.44 - 0.80 GeV/c. The differential cross sections of the $$Sigma^+p$$ 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 $$^3S_1$$ and $$^1P_1$$ 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 to be $$20^circ<|delta_{^3S_1}|<35^circ$$. 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.

論文

Precise measurement of differential cross sections of the $${Sigma}^- p to {Lambda} n$$ reaction in momentum range 470-650 MeV/$$c$$

三輪 浩司*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 裕大*; 今井 憲一*; 七村 拓野; 佐甲 博之; 佐藤 進; 田村 裕和; et al.

Physical Review Letters, 128(7), p.072501_1 - 072501_6, 2022/02

https://doi.org/10.1103/PhysRevLett.128.072501
 被引用回数：20 パーセンタイル：86.62(Physics, Multidisciplinary)

The differential cross sections of the $${Sigma}^- p to {Lambda} n$$ reaction were measured accurately for the $${Sigma}^-$$ momentum $$(p_{{Sigma}})$$ ranging from 470 to 650 MeV/$$c$$ at the J-PARC Hadron Experimental Facility. Precise angular information about the $${Sigma}^- p to {Lambda} n$$ reaction was obtained for the first time by detecting approximately 100 reaction events at each angular step of $${Delta}cos{theta} = 0.1$$. The obtained differential cross sections show slightly forward-peaking structure in the measured momentum regions. The cross sections integrated for $$-0.7 < cos{theta} < 1.0$$ were obtained as $$22.5 pm 0.68 (stat.) pm 0.65 (syst.)$$ mb and $$15.8 pm 0.83(stat.) pm 0.52 (syst.)$$ mb for $$470 < p_{{Sigma}}$$ (MeV/c) $$<550$$ and $$550 < p_{{Sigma}}$$ (MeV/c)$$<650$$, respectively. These results show a drastic improvement compared to past measurements of the hyperon-proton scattering experiments. They will play essential roles in updating the theoretical models of the baryon-baryon interactions.

論文

Measurement of the differential cross sections of the $$Sigma^- p$$ elastic scattering in momentum range 470 to 850 MeV/$$c$$

三輪 浩司*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; 佐藤 進; et al.

Physical Review C, 104(4), p.045204_1 - 045204_20, 2021/10

https://doi.org/10.1103/PhysRevC.104.045204
 被引用回数：20 パーセンタイル：88.44(Physics, Nuclear)

A high statistics $$Sigma p$$ scattering experiment is performed at the J-PARC Hadron Experimental Facility. Momentum-tagged $$Sigma^-$$s running in a liquid hydrogen target are accumulated by detecting the reaction with a high intensity $$pi^-$$ beam of 20 M/spill. The differential cross sections of the $$Sigma^- p$$ elastic scattering were derived with a drastically improved accuracy by identifying approximately 4,500 events from 1.72 $$times$$ 10$$^7$$ $$Sigma^-$$. The derived differential cross section shows a clear forward-peaking angular distribution for a $$Sigma^-$$ momentum range from 470 to 850 MeV/$$c$$. The accurate data will impose a strong constraint on the theoretical models of the baryon-baryon interactions.

論文

Establishment of a modern experimental technique of a $$Sigma p$$ scattering experiment at J-PARC

赤澤 雄也*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.

JPS Conference Proceedings (Internet), 33, p.011134_1 - 011134_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011134

We are performing a scattering experiment between a $$Sigma$$ hyperon and a proton (J-PARC E40) at the K1.8 beamline in the J-PARC Hadron Hall. The purpose of this experiment is to investigate the $$Sigma N$$ interaction by measuring the differential cross sections of the $$Sigma^+ p$$, $$Sigma^- p$$ elastic scatterings and $$Sigma^- p to Lambda n$$ inelastic scattering. The experimental data gives a strong constraint on the theoretical models of the $$Sigma N$$ interaction. The identification of $$Sigma p$$ scattering event with a high statistics is important by overcoming the difficulties in the hyperon proton scattering experiment. We have introduced a new identification method of the $$Sigma p$$ scattering event, which does not need to detect $$Sigma$$ particles directly. We used a new detector system called CATCH and two spectrometer systems installed at the upstream and the downstream of a liquid hydrogen target. A high intensity $$pi$$ beam of 20 M/spill was used to produce $$Sigma$$ particle. The momenta of $$pi$$ beam and scattered $$K^+$$ were measured by the spectrometers to reconstruct the momentum of a $$Sigma$$ beam produced via the $$pi p to Sigma K^+$$ reactions. The scattering angle and the kinetic energy of recoil protons from the $$Sigma p$$ scattering were measured by CATCH for the identification of the $$Sigma p$$ scattering events by checking the kinematic consistency. A part of the experiment was performed in 2018 and 2019 in J-PARC. As a result of analyzing the collected data, the $$Sigma^-$$ production and the $$Sigma^- p$$ scattering reaction have been identified. It means that our new measurement and analysis method are successfully working well. Analysis for deriving the differential cross section of the $$Sigma p$$ scattering is on going.

論文

Study of $$Lambda$$ identification method by the $$pi^-p to K^0Lambda$$ reaction for a $$Lambda p$$ scattering experiment at J-PARC

坂尾 珠和*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.

JPS Conference Proceedings (Internet), 33, p.011133_1 - 011133_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011133

The $$pi^-p to K^0Lambda$$ reaction is an important elementary process to produce $$Lambda$$ from a proton target and is a key for a $$Lambda p$$ scattering experiment where the momentum of $$Lambda$$ should be tagged from the missing momentum of the $$(pi^-,K^0)$$ reaction. However, the $$(pi^-,K^0)$$ spectroscopy method has not been established yet due to the difficulty of the $$K^0$$ detection. Therefore, we have proposed a new $$K^0$$ detection method where $$pi^+$$ and $$pi^-$$ from the $$K^0$$ decay are measured by a forward magnetic spectrometer and a detector cluster surrounding the target, respectively. The feasibility of the $$K^0$$ detection method was confirmed by analyzing the J-PARC E40 data taken with such a detector system. In the analysis, $$Lambda$$'s were successfully identified in the missing mass spectrum of the $$pi^-p to K^0 X$$ reaction.

論文

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

吉田 純也; 赤石 貴也; 藤田 真奈美; 長谷川 勝一; 橋本 直; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; Kim, S.; et al.

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

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

J-PARC E07 is the most ambitious and complex emulsion experiment to date investigating double hypernuclei with Hybrid emulsion method. The physics run at the K1.8 beam line in the J-PARC hadron experimental facility have been completed in 2017. The emulsion sheets are presently being analyzed with dedicated optical microscopes. Current statistics are estimated to be more 3 times than that of previous experiments. Quantitative data on the $$Lambda Lambda$$ and $$Xi N$$ interaction are being accumulated successfully via analysis of double $$Lambda$$ and $$Xi$$ hypernuclei. Multiple $$Xi$$ hypernucleus candidates suggests several features about $$Xi$$ hypernucleus that the identification efficiency of $$^{15}_Xi$$C is significantly higher than other mode, many daughters of $$^{15}_Xi$$C are identified as He or Be, and multiple bound states of $$Xi^-$$ exist in the $$^{14}$$N nucleus. An analysis of X-ray spectroscopy of $$Xi^-$$ hyperatoms are ongoing.

論文

Observation of Coulomb-assisted nuclear bound state of $$Xi^-$$-$$^{14}$$N system

早川 修平; 藤田 真奈美; 長谷川 勝一; 橋本 直; 細見 健二; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.

Physical Review Letters, 126(6), p.062501_1 - 062501_6, 2021/02

https://doi.org/10.1103/PhysRevLett.126.062501
 被引用回数：46 パーセンタイル：93.42(Physics, Multidisciplinary)

In an emulsion-counter hybrid experiment performed at J-PARC, a $$Xi^-$$ absorption event was observed which decayed into twin single-$$Lambda$$ hypernuclei. Kinematic calculations enabled a unique identification of the reaction process as $$Xi^{-} + ^{14}$$N$$ rightarrow ^{10}_Lambda$$Be + $$^5_Lambda$$He. For the binding energy of the $$Xi^{-}$$ hyperon in the $$Xi^-$$-$$^{14}$$N system a value of $$1.27 pm 0.21$$ MeV was deduced. The energy level of $$Xi^-$$ is likely a nuclear $$1p$$ state which indicates a weak $${Xi}N$$-$$LambdaLambda$$ coupling.

論文

Study of $$Sigma N$$ interaction from the $$Sigma p$$ scattering experiment at J-PARC

三輪 浩司*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.

Journal of Physics; Conference Series, 1643, p.012174_1 - 012174_6, 2020/12

BB2022-0024.pdf:1.14MB

https://doi.org/10.1088/1742-6596/1643/1/012174
 被引用回数：2 パーセンタイル：77.44(Astronomy & Astrophysics)

A high statistics $$Sigma p$$ scattering experiment has been performed at the K1.8 beamline in the J-PARC Hadron Experimental Facility. Data for momentum-tagged $$Sigma^-$$ beam running in a liquid hydrogen target were accumulated by detecting the $$pi^{-}p to {K}^{+}{Sigma}^{-}$$ reaction with a high intensity $$pi^-$$ beam of 20 M/spill. The number of the $$Sigma^-$$ beam was about $$1.7 times 10^7$$ in total. The $$Sigma^- p$$ elastic scattering and the $$Sigma^- p to Lambda n$$ inelastic scattering events were successfully observed with about 100 times larger statistics than that in past experiments.

論文

Study on the baryon interaction by $$Xi$$ hypernuclear spectroscopy with the $$(K^-, K^+)$$ reaction

後神 利志*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 今井 憲一*; 市川 裕大; 七村 拓野; 成木 恵; 佐甲 博之; 佐藤 進; et al.

Journal of Physics; Conference Series, 1643, p.012133_1 - 012133_6, 2020/12

BB2021-0622.pdf:0.71MB

https://doi.org/10.1088/1742-6596/1643/1/012133
 被引用回数：2 パーセンタイル：77.44(Astronomy & Astrophysics)

We performed $$Xi$$ hypernuclear spectroscopy with the $$(K^-, K^+)$$ reaction at J-PARC to investigate the $$Xi N$$ interaction (J-PARC E05). A new experiment (J-PARC E70) in which a better energy resolution could be achieved is now being prepared. In this article, an analysis status of J-PARC E05 and a preparation status of J-PARC E70 are described.

論文

An Event excess observed in the deeply bound region of the $$^{12}$$C$$(K^-,p)$$ missing-mass spectrum

市川 裕大*; 藤田 真奈美; 長谷川 勝一; 早川 修平; 佐甲 博之; 佐藤 進; 田村 裕和; 谷田 聖; 山本 剛史; 他36名*

Progress of Theoretical and Experimental Physics (Internet), 2020(12), p.123D01_1 - 123D01_34, 2020/12

https://doi.org/10.1093/ptep/ptaa139
 被引用回数：9 パーセンタイル：52.11(Physics, Multidisciplinary)

We have measured, for the first time, the inclusive missing-mass spectrum of the $$^{12}$$C$$(K^-,p)$$ reaction at an incident kaon momentum of 1.8 GeV/c at the J-PARCK 1.8 beamline. We observed a prominent quasi-elastic peak ($$K^-,p)$$ $$rightarrow$$ $$(K^-,p)$$ in this spectrum. In the quasi-elastic peak region, the effect of secondary interaction is apparently observed as a peak shift, and the peak exhibits a tail in the bound region. We compared the spectrum with a theoretical calculation based on the Green's function method by assuming different values of the parameters for the $$bar{K}$$-nucleus optical potential. We found that the spectrum shape in the binding-energy region -300 MeV $$<$$ $$B_{K}$$ $$<$$ 40 MeV is best reproduced with the potential depths $$V_{0}$$ = -80 MeV (real part) and $$W_{0}$$ = -40 MeV(imaginary part). On the other hand, we observed a significant event excess in the deeply bound region around $$B_{K}$$ $$sim$$ 100 MeV, where the major decay channel of $$K^{-}NN$$ $$rightarrow$$ $$pi Sigma$$$$N$$ is energetically closed, and the non-mesonic decay modes ($$K^{-}NN$$ $$rightarrow$$ $$Lambda$$$$N$$ and $$Sigma$$$$N$$) should mainly contribute. The enhancement is fitted well by a Breit-Wigner function with a kaon-binding energy of 90 MeV and width 100 MeV. A possible interpretation is a deeply bound state of a $$gamma*$$-nucleus system.

論文

Bromine-isotope selective ionization using field-free alignment of IBr isotopologues with a switched nanosecond laser pulse

赤木 浩*; 熊田 高之; 乙部 智仁*; 板倉 隆二*; 長谷川 宗良*; 大島 康裕*

Chemistry Letters, 49(4), p.416 - 418, 2020/04

https://doi.org/10.1246/cl.200024
 被引用回数：1 パーセンタイル：3.27(Chemistry, Multidisciplinary)

We demonstrate isotope selective ionization of I$$^{79}$$Br and I$$^{81}$$Br isotopologues using field-free alignment induced by a linearly-polarized nanosecond laser pulse with rapid turn off at the maximum. Following the switched nanosecond pulse irradiation, a 60-fs laser pulse ionizes one of the isotopologues preferentially. The ion yield ratio $$I$$(I$$^{81}$$Br$$^+$$)/$$I$$(I$$^{79}$$Br$$^+$$) varies in the range of 0.93-1.06, depending on time delay between the pulses. This is the first demonstration of laser isotope separation of heavy elements using field-free alignment and angular dependent ionization.

論文

Search for excited state of $$_{Sigma }^{4}{rm He}$$ hypernucleus in the J-PARC E13 experiment

中川 真菜美*; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 田村 裕和; 谷田 聖; et al.

JPS Conference Proceedings (Internet), 26, p.023005_1 - 023005_3, 2019/11

https://doi.org/10.7566/JPSCP.26.023005

The $$Sigma N$$ interaction is not much studied than the $$Lambda N$$ interaction. To understand the $$Sigma N$$ interaction, we study $$Sigma$$ hypernuclei. As for the $$Sigma$$ hypernucleus, only the ground state of $$_{Sigma }^{4}{rm He}$$ has been observed. To obtain more information about the $$Sigma N$$ interaction, the excited state should be studied. Therefore, we measure the missing-mass of the $$^4$$He$$(K^-,pi^-)$$ reaction at $$p_{K^-} = 1.5$$ GeV/$$c$$ and $$theta_{rm Lab} =$$ 2-14$$^{circ}$$ at the J-PARC K1.8 beam line. The ground state of $$_{Sigma }^{4}{rm He}$$ is observed whereas a peak of the excited states is not observed. We also observe suppression of the $$Sigma$$ quasi-free process at smaller angles.

論文

Study of $$Y^*$$ in nuclei through C$$(K^-, pi^+)X$$ spectrum at 1.8 GeV/$$c$$ in the J-PARC E05 experiment

本多 良太郎*; 長谷川 勝一; 早川 修平; 細見 健二; 今井 憲一; 市川 裕大; 七村 拓野; 成木 恵; 佐甲 博之; 佐藤 進; et al.

JPS Conference Proceedings (Internet), 26, p.023014_1 - 023014_4, 2019/11

https://doi.org/10.7566/JPSCP.26.023014

We measured the $$(K^-,pi^+)$$ reaction spectra at 1.8 GeV/$$c$$ for the graphite and the polyethylene targets in the J-PARC E05 pilot experiment. By comparing the spectra for these two targets, it was found that $$Sigma^{*-}(1385)$$ in the $$^{11}$$B nucleus is quite broadened. Furthermore, we also compared broadness of $$Sigma^{*-}(1385)$$ with $$K^*(892)$$ obtained in the $$(K^-,p)$$ spectrum. $$Sigma^{*-}(1385)$$ seems to be much more broadened in nuclei than $$K^*(892)$$. We gave a possible interpretation, which is related to compositeness of decuplet baryons, for this situation.

論文

A $$Sigma p$$ scattering experiment at J-PARC and the analysis status

中田 祥之*; 長谷川 勝一; 早川 修平*; 細見 健二; 市川 裕大; 今井 憲一; 七村 拓野*; 成木 恵*; 佐甲 博之; 佐藤 進; et al.

JPS Conference Proceedings (Internet), 26, p.023024_1 - 023024_5, 2019/11

https://doi.org/10.7566/JPSCP.26.023024

J-PARC E40 aims to measure the differential cross sections of the $$Sigma^{pm}p$$ elastic scatterings and the $$Sigma^-p to Lambda n$$ conversion. A clear peak of $$Sigma^-$$ was observed in a missing mass spectrum of the $$pi^-pto K^+X$$ reaction and recoil protons from the $$pi p$$ elastic scattering were successfully observed in the data taken in the summer 2018. The rest of data taking is coming in the spring 2019.

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