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論文

Measurement of radiative decay of $$Lambda$$(1405) by using hyperon spectrometer at J-PARC

Hwang, S.; 今井 憲一

JPS Conference Proceedings (Internet), 17, p.033010_1 - 033010_2, 2017/07

The electromagnetic transitions rates of excited baryons to their ground baryon state are a clean probe to see the structure of the baryons. However the radiative decay has a very small branching ratio, which is of the order of 1%. While the radiative decay of the $$Sigma$$(1385) and the $$Lambda$$(1520) were reported, there are no direct measurements of the radiative decay of the $$Lambda$$(1405). Recent theoretical calculation showed that the KN compositeness of the $$Lambda$$(1405) relates with the radiative decay width of v(1405)$$rightarrow$$ $$Lambda gamma$$. The Hyperon-Time- Projection (HypTPC) is being built at the J-PARC hadron experimental facility to explore an existence of the H-dibaryon and the 3-body hadronic nucleon resonances. The HypTPC is suitable to measure the radiative decay of the $$Lambda$$(1405) due to the large acceptance and high resolution. Additionally, we are developing a $$gamma$$-array counter for improving the detection of the radiative decay. In this presentation, we will discuss the detector R&D and the expected results of a new experiment to measure the radiative decay of the $$Lambda$$(1405) with the HypTPC at J-PARC.

論文

Study of baryon excited states in $$(pi,2pi)$$ reactions at J-PARC

佐甲 博之

JPS Conference Proceedings (Internet), 17, p.063004_1 - 063004_2, 2017/07

N*, $$Delta *$$のバリオン励起状態は長年研究されているが、依然として多くの高質量の励起状態が見つかっていない。最近の理論研究で$$pipi N$$が高質量バリオン励起状態の崩壊チャンネルとして大きな寄与を持っていることが分かってきた。このため、$$(pi,2pi)$$生成反応を測定する実験(J-PARC E45)を提案した。本発表ではこの実験の概要と検出器の開発状況について発表する。

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

Kaonic-atom X-ray spectroscopy with superconducting microcalorimeters

橋本 直; 谷田 聖; 他45名*

JPS Conference Proceedings (Internet), 17, p.072001_1 - 072001_4, 2017/07

We will measure kaonic helium X-rays using transition-edge-sensor microcalorimeters, TES, in the JPARC hadron experimental facility. To demonstrate the feasibility of the experiment, we performed a measurement of pionic carbon X-rays at PSI, where an excellent FWHM energy resolution of 7 eV at 6.4 keV was achieved. We also evaluated the expected TES performance in the kaon beam at J-PARC. The simulation results show that the TES spectrometer would work with a good energy resolution, and clear peaks of kaonic helium X-rays would be observed on a reasonably suppressed background.

論文

Spectroscopic study of hyperon resonance below $$bar{K}N$$ threshold via the $$d(K^-,n)$$ reaction

井上 謙太郎*; 橋本 直; 谷田 聖; 他69名*

JPS Conference Proceedings (Internet), 17, p.072003_1 - 072003_4, 2017/07

We have taken the data of the $$(K^-,n)$$ reaction on the $$D_2$$ target in May, 2015. In this reaction, it is expected that the $$K^-$$ kicks a neutron and produces the $$Lambda(1405)$$ in a backward angle. We identify the final state of $$K^- d to npi^+pi^-n$$ by detecting the forward neutron, $$pi^+$$ and $$pi^-$$ and obtain the $$d(K^-,n)pi^{mp}Sigma^{pm}$$ spectrum excluded $$K^0$$ and forward-going $$Sigma$$ productions. We observed few hundred events in the region below the $$bar{K}N$$ threshold.

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.

口頭

Scattered proton detection system for $$Sigma p$$ scattering experiment with the cylindrical scintillating fiber tracker and BGO calorimeters

中田 祥之; 長谷川 勝一; 早川 修平

no journal, , 

J-PARC K1.8ビームラインにおいてシグマ陽子散乱実験を計画している。本実験では散乱された陽子の飛跡とエネルギーと生成したK中間子の運動量から運動学を計算することで、散乱事象を再構成する手法を用いる。このため、高い散乱事象検出効率を達成するために、散乱された陽子の飛跡とエネルギーを高い精度で測定する必要がある。現在、散乱陽子の飛跡とエネルギーを高精度で測定するための散乱陽子検出システムを開発中であり、この散乱陽子検出システムのテストを2014年秋に80MeV陽子とポリエチレン標的を用いて東北大学サイクロトロンラジオアイソトープセンターで行った。そこで得られた結果についての講演を行う。

口頭

Development of PID method in nuclear emulsion

金原 慎二; 谷田 聖

no journal, , 

我々の到達点はダブルハイパー核から放出される娘粒子の核種を同定する方法を開発することである。この方法を開発するために理化学研究所にて8つの粒子を原子核乾板に光軸に対してあらゆる角度で照射した。本講演では電荷1$$sim$$5の粒子に適用させた結果を報告する。

口頭

The Result of the test experiment for the double lambda hypernuclei experiment with the emulsion

佐藤 進; 早川 修平

no journal, , 

J-PARC K1.8ビームラインにおいて、原子核乾板を用いたダブルラムダハイパー核探索実験を計画している。2015年5月、K中間子ビームの調整や飛跡検出器と原子核乾板の飛跡の整合性などの確認のためのテスト実験を行った。本会議ではその結果について発表する。

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