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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

 被引用回数:6 パーセンタイル:97.77(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 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

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

Negative muonium ion production with a C12A7 electride film

大谷 将士*; 深尾 祥紀*; 二ツ川 健太*; 河村 成肇*; 的場 史郎*; 三部 勉*; 三宅 康博*; 下村 浩一郎*; 山崎 高幸*; 長谷川 和男; et al.

Journal of Physics; Conference Series, 1350, p.012067_1 - 012067_6, 2019/12

 被引用回数:0 パーセンタイル:0.07

負ミューオニウムはそのユニークな性質から様々な科学の分野で応用される可能性がある。1980年代に真空中で初めて生成されて以来、仕事関数の低い物質を用いて負ミューオニウム生成効率を高めることが議論されてきた。アルミナセメントの構成物質であるC12A7は良く知られた絶縁体であるが、電子をドープすることで導体として振舞うことが近年発見された。このC12A7エレクトライドは2.9eVという比較的低い仕事関数を持ち、負イオン生成効率を示すと期待されている。本論文では、従来用いていたアルミニウム、C12A7エレクトライド、さらにステンレスターゲット用いた負ミューオニウムイオン生成効率の比較について述べる。測定された生成率は10$$^{-3}$$/sであり、現状セットアップではエレクトライドにおいても大きな生成率向上は確認されず、表面状態をより注意深く整える必要であることが推定される。また、生成された負ミューオニウムの平均エネルギーに材質依存はなく、0.2$$pm$$0.1keVであった。

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

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.

論文

First $$gamma$$-ray spectroscopy of an $$sd$$-shell hypernucleus, $$^{19}_{Lambda}$$F

Yang, S. B.*; 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.023015_1 - 023015_5, 2019/11

We performed a gamma-ray spectroscopy of $$({}_{Lambda}^{19}{rm F})$$ at J-PARC Hadron Experimental Facility in 2015. It is the first measurement of $$gamma$$ rays emitted from $$sd$$-shell hypernuclei. In this experiment, we determined the energy spacing between the ground state spin doublet, $$3/2^+$$ and $$1/2^+$$ states, as 316 keV. The excitation energies of $$5/2^+$$ and $$1/2^+$$ states are also determined to be 895 and 1266 keV, respectively. The energy spacing is found to be well reproduced by shell-model calculations which describe $$s$$- and $$p$$-shell $$Lambda$$ hypernuclei well. The results show that the present theories of the $$Lambda N$$ interaction describe not only the light hypernuclei but also a heavier hypernucleus.

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

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

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

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

Gamma-ray spectroscopy of single $$Lambda$$-hypernuclei at J-PARC; Results and perspective

小池 武志*; 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; 杉村 仁志; 田村 裕和; et al.

AIP Conference Proceedings 2130, p.020011_1 - 020011_9, 2019/07

 被引用回数:1 パーセンタイル:65.18

Experimental results from the J-PARC E13 experiments are summarized. A new experimental set up of E13 has established a platform for the future $$gamma$$-ray hypernuclear spectroscopy at J-PARC using kaon beams. New $$gamma$$ rays are identified in $$^4_{Lambda}$$He and $$^{19}_{Lambda}$$F. The energy of 1.406 MeV for the $$^4_{Lambda}$$He$$(1^+ to 0^+)$$ transition confirmed a sizable effect of Charge Symmetry Breaking (CSB) in $$Lambda N$$ interaction in the $$A=4$$ hypernuclear system. The identification of four $$gamma$$ rays in $$^{19}_{Lambda}$$F is made for the first time in $$sd$$ shell hypernuclei. Especially, energy spacing of the ground state doublet is found to be 315.5 keV. A good agreement with two theoretical calculations suggests that the theoretical formalism used in $$p$$ shell hypernuclei is also applicable to heavier hypernuclei. Lastly, an overview of the future J-PARC E63 experiment is given.

論文

Observation of a $$Xi$$ bound state in the $$^{12}$$C$$(K^-, K^+)$$ reaction at 1.8 GeV/$$c$$

永江 知文*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 金原 慎二; 七村 拓野*; 成木 恵; et al.

AIP Conference Proceedings 2130, p.020015_1 - 020015_9, 2019/07

For the full understanding of baryon-baryon interactions in flavor $$SU(3)$$, the $$Xi N$$ interaction is the last missing piece of information. So far, we have revealed the $$Lambda N$$ interaction to be attractive ($$U_{Lambda} cong 30$$ MeV), and $$Sigma N$$ interaction to be repulsive in the medium to heavy mass-number region. The $$Lambda Lambda$$ bonding energy is weakly attractive. While we have a few experimental observations suggesting the $$Xi N$$ interaction would be attractive, there still exist large theoretical ambiguities weather it is attractive or not. Experimental determinations on the existence of bound states of $$Xi$$ hypernuclei by observing bound-state peaks are strongly awaited. In this report, a new preliminary result on the missing-mass spectrum of a $$^{12}$$C$$(K^-, K^+)$$ reaction, which strongly suggests the existence of $$Xi$$-hypernuclear bound states, is presented.

論文

Development of an alpha dust monitor using a GPS scintillator plate

森下 祐樹; 金子 純一*; 樋口 幹雄*; 井崎 賢二; 矢島 辰雄*; 松浦 貢*; 田村 健; 鳥居 建男

Radiation Measurements, 122, p.115 - 120, 2019/03

 被引用回数:5 パーセンタイル:75.46(Nuclear Science & Technology)

A dust monitor with a silicon surface barrier detector (SSBD) is introduced at a nuclear fuel facility to detect airborne contamination of $$^{238}$$Pu and $$^{239}$$Pu released by past accidents. However, an SSBD frequently produces false alarms, especially in a room with high humidity. We developed an alpha-particle spectrometer based on a cerium-doped Gd$$_{2}$$Si$$_{2}$$O$$_{7}$$ (GPS) scintillator plate and a photomultiplier tube (PMT). The energy resolution for 5.5-MeV alpha particles was $$sim$$11.9% $$pm$$ 0.2% of the FWHM. The efficiency was 92%, and it had a uniform sensitivity. By applying an energy window, the count-rate of the Rn progeny decreased by 77%. The GPS scintillator plate was able to measure the alpha spectrum even though the GPS scintillator got wet.

論文

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

江川 弘行; 足利 沙希子; 長谷川 勝一; 橋本 直; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 金原 慎二*; 七村 拓野; et al.

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

 被引用回数:13 パーセンタイル:85.21(Physics, Multidisciplinary)

A double-$$Lambda$$ hypernucleus, $${}_{LambdaLambda}mathrm{Be}$$, was observed by the J-PARC E07 collaborationin nuclear emulsions tagged by the $$(K^{-},K^{+})$$ reaction. This event was interpreted as a production and decay of $$ {}_{LambdaLambda}^{;10}mathrm{Be}$$,$${}_{LambdaLambda}^{;11}mathrm{Be}$$, or $${}_{LambdaLambda}^{;12}mathrm{Be}^{*}$$ via $$Xi^{-}$$ capture in $${}^{16}mathrm{O}$$.By assuming the capture in the atomic 3D state, the binding energy of two $$Lambda$$ hyperons$$,$$($$B_{LambdaLambda}$$)of these double-$$Lambda$$ hypernuclei are obtained to be$$15.05 pm 0.11,mathrm{MeV}$$, $$19.07 pm 0.11,mathrm{MeV}$$, and $$13.68 pm 0.11,mathrm{MeV}$$, respectively. Based on the kinematic fitting, $${}_{LambdaLambda}^{;11}mathrm{Be}$$ is the most likely explanation for the observed event.

論文

Dynamic of organic species in organo-clay/polypropyrene composite by quesi-elastic neutron scattering

福嶋 喜章*; 山田 武*; 田村 堅志*; 柴田 薫

Applied Clay Science, 155, p.15 - 19, 2018/04

 被引用回数:4 パーセンタイル:31.92(Chemistry, Physical)

ジオクタデシルジメチルアンモニウムイオン(DODA$$^{+}$$)/ポリプロピレン複合体のために交換されたフルオロマイカ(ME100)カチオンのダイナミクスは、XRDおよびDSC以外に準弾性中性子散乱(QENS)によって分析された。低いQ=2.75nm$$^{-1}$$のDODA-ME100のQENSスペクトルは、DODA$$^{+}$$の融点である445Kより高い温度でも変化しなかった。この結果は、硬質シリケート層とDODA$$^{+}$$とME100との間の強い静電相互作用のために、層間距離における長距離($$>$$2nm)の分子運動が制限されることを示唆している。弾性強度スキャンの結果は、445Kにおける溶融状態においても、複合体中のポリマー鎖の動きが少し制限されていることを示唆した。QENSは、複合材料を研究するための有用なツールの1つであることが期待される。

論文

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

中島 健次; 川北 至信; 伊藤 晋一*; 阿部 淳*; 相澤 一也; 青木 裕之; 遠藤 仁*; 藤田 全基*; 舟越 賢一*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

J-PARC物質・生命科学実験施設の中性子実験装置についてのレビューである。物質・生命科学実験施設には23の中性子ビームポートがあり21台の装置が設置されている。それらは、J-PARCの高性能な中性子源と最新の技術を組み合わせた世界屈指の実験装置群である。このレビューでは、装置性能や典型的な成果等について概観する。

論文

Spectroscopy of nuclei with multi-strangeness by using new S-2S spectrometer at J-PARC

後神 利志*; 江川 弘行; 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; et al.

JPS Conference Proceedings (Internet), 18, p.011031_1 - 011031_6, 2017/11

The missing mass spectroscopy of $$Xi^-$$ hypernuclei is planned at the Japan Proton Accelerator Research Complex (J-PARC) by using the $$(K^-,K^+)$$ reaction. We are constructing a new magnetic spectrometer, S-2S, which has a better momentum resolution [$$Delta p/p = 5 times 10^{-4}$$ (FHWM)] than that of an existing spectrometer (SKS) at J-PARC. S-2S would give us an opportunity to confirm the existence of $$Xi^-$$ hypernuclei as a peak structure owing to both the high momentum resolution and its reasonably large solid angle. Brief descriptions of our experiment and of its preparation status are presentedin this article.

論文

Uplift and denudation history of the Akaishi Range, a thrust block formed by arc-arc collision in central Japan; Insights from low-temperature thermochronometry and thermokinematic modeling

末岡 茂; 池田 安隆*; 狩野 謙一*; 堤 浩之*; 田上 高広*; Kohn, B. P.*; 長谷部 徳子*; 田村 明弘*; 荒井 章司*; 柴田 健二*

Journal of Geophysical Research; Solid Earth, 122(8), p.6787 - 6810, 2017/08

複数の熱年代学的手法とthermo-kinematicモデリングを用いて赤石山脈の削剥史を検討した。熱年代は東に向かって系統的に若返り、赤石山脈北部は東縁に分布する糸魚川-静岡構造線の活動によって隆起した可能性が示唆された。Thermo-kinematicモデリングによって詳細な検討を加えた結果、糸魚川-静岡構造線の変位速度が5-10mm/yr、傾斜が27-45度、デコルマ深度が20-25kmのとき、熱年代測定結果と既存の地形・地球物理データを矛盾なく説明できることが確認できた。隆起速度と削剥速度は約4mm/yrと推定された。一方、赤石山脈南部は、先行研究による少数の熱年代データは北部と異なる値を示しているほか、地形・地質構造等の違いを考慮すると、北部とは別の時期・メカニズムによって隆起している可能性がある。

論文

$$gamma$$-ray spectroscopy of hypernuclei; Recent results and prospect at J-PARC

田村 裕和*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; Hwang, S.; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; et al.

JPS Conference Proceedings (Internet), 17, p.011004_1 - 011004_11, 2017/07

The present status and future prospects of precision $$gamma$$-ray spectroscopy of $$Lambda$$ hypernuclei are described. A new experiment (J-PARC E13) has been performed at the J-PARC K1.8 line employing a newly-developed germanium (Ge) detector array, Hyperball-J, via the $$(K^-,pi^-)$$ reaction on $$^4$$He and $$^{19}$$F targets. This is the first study of $$s$$-shell and $$sd$$-shell $$Lambda$$ hypernuclei with Ge detectors. The $$^4$$He target spectrum exhibited a $$gamma$$-ray peak of $$^4_{Lambda}{rm He}(1^+to 0^+)$$ at $$1.406 pm 0.002 pm 0.002$$ MeV. Compared with the energy ($$1.09 pm 0.02$$ MeV) of the corresponding transition for the mirror hypernucleus, $$^4_{Lambda}{rm H}(1^+to 0^+)$$, the present result clearly indicates a large charge symmetry breaking (CSB) effect. This decisive data for CSB allows a stringent test of baryon-baryon interaction models. As for the $$^{19}$$F target run, a preliminary spectrum shows several $$gamma$$-ray peaks assigned to $$^{19}_{Lambda}{rm F}$$ transitions. Future plans of $$gamma$$-ray spectroscopy are also discussed.

論文

Search for excited state of $$Sigma$$ hypernucleus in the J-PARC E13 experiment

中川 真菜美*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; Hwang, S.; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; et al.

JPS Conference Proceedings (Internet), 17, p.012009_1 - 012009_4, 2017/07

One of the main items of the J-PARC E13 experiment is the search for excited states of the $$^4_{Sigma}$$He hypernucleus via the $$^4$$He$$(K^-,pi^-)$$ reaction at 1.5 GeV/c. The missing-mass spectrum of the $$^4$$He$$(K^-,pi^-)X$$ reaction was obtained in an angular range from 0 to 20 degrees. We show the count-base spectrum of the missing-mass in the angular range from 2 to 14 degrees. The ground state of $$^4_{Lambda}$$He and $$^4_{Sigma}$$He were clearly observed in the missing-mass spectrum. We also show three missing-mass spectra divided by the reaction angle.

論文

High statistics $$Sigma p$$ scattering experiment using high intensity pion beams at J-PARC

三輪 浩司*; 長谷川 勝一; 早川 修平; 細見 健二; 今井 憲一; 近藤 恭弘; 成木 恵; 佐甲 博之; 佐藤 進; 杉村 仁志; et al.

JPS Conference Proceedings (Internet), 17, p.041002_1 - 041002_6, 2017/07

In order to test theoretical frameworks of the Baryon-Baryon ($$BB$$) interactions and to confirm the "Pauli effect between quarks" for the first time, we have proposed an experiment (J-PARC E40) to measure low-energy hyperon-proton scattering cross sections of the $$Sigma^+ p$$, $$Sigma^- p$$ elastic scatterings and the $$Sigma^- p to Lambda n$$ inelastic scattering in the momentum range of $$400 < p ; ({rm MeV}/c) < 700$$ in the laboratory system. Experimentally, we detect two successive reactions of the $$Sigma$$ production $$(pi^{pm}p to K^+Sigma^{pm})$$ and the $$Sigma p$$ scattering ($$Sigma p to Sigma p$$) in the same liquid hydrogen target. The former is measured with two magnetic spectrometers, and the latter with a scattered proton detector (CATCH). By using a high intensity $$pi$$ beam, we estimate that more than 10000 scattering events can be identified. In this experiment, we aim to provide good quality scattering data to test the theoretical models of the $$BB$$ interaction.

論文

The First gamma-ray spectroscopic study of $$sd$$-shell hypernucleus, $$^{19}_{Lambda}$$F

Yang, S. B.*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; Hwang, S.; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; et al.

JPS Conference Proceedings (Internet), 17, p.012004_1 - 012004_4, 2017/07

The first $$gamma$$-ray spectroscopy of $$sd$$-shell hypernucleus, $$^{19}_{Lambda}$$F, is performed in June, 2015 at the J-PARC K1.8 beam line (J-PARC E13). Precise energy levels of $$^{19}_{Lambda}$$F can be revealed by measured $$gamma$$ rays in this experiment. Especially, the strength of $$Lambda N$$ spin-spin interaction in $$sd$$-shell hypernucleus is obtained through the energy spacing of the ground-state doublet of the hypernucleus. By comparing its strength between the $$s$$, $$p$$, and $$sd$$-shell hypernuclei, a radial dependence $$Lambda N$$ interaction is investigated. The hypernucleus is produced through the $$(K^-,pi^-)$$ reaction with the beam momentum of 1.8 GeV/c. In very preliminary results, we observed two $$gamma$$ rays, and their energies are $$315.8 pm 0.4$$ keV and $$ 895.3 pm 0.3$$ keV where the uncertainties are only statistical.

報告書

東濃地科学センターにおける断層ガウジ試料のカリウム-アルゴン(K-Ar)年代測定

田村 肇*; 柴田 健二*; 高橋 直哉; 丹羽 正和

JAEA-Testing 2017-001, 52 Pages, 2017/03

JAEA-Testing-2017-001.pdf:2.36MB

地層処分における地質環境の長期安定性に係る評価のうち、断層の活動性評価に関しては、断層活動時期についての情報を得ることが不可欠である。東濃地科学センターでは、断層活動時期の推定のための年代測定技術の一つとして、断層ガウジのカリウム-アルゴン(K-Ar)年代測定を実施している。測定結果の評価の一助とするため、K-Ar年代測定のための試料処理、分析、および年代計算の手順を本報告書にまとめた。

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