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論文

Development of TPC Trigger Hodoscope for J-PARC E42/E45 hadron experiment

Jung, W.*; Ahn, J. K.*; 長谷川 勝一; Hicks, K.*; Hwang, S.*; 市川 裕大; Kim, S.*; 佐甲 博之; 佐藤 進; 谷田 聖

JPS Conference Proceedings (Internet), 27, p.011007_1 - 011007_6, 2019/11

https://doi.org/10.7566/JPSCP.27.011007

We have developed HypTPC consists of TPC and the trigger hodoscope for the J-PARC hadron experiments. The TPC Hodoscope has large scintillators of 80 $$times$$ 7 $$times$$ 1 cm$$^3$$ to cover the TPC. Especially, we have developed a readout circuit for multiple MPPCs to detect photons generated over a large area of the scintillator. A general methods of applying voltage to multiple MPPCs are parallel and series connections. In the case of parallel connections, a signal has a long tail due to the large sensor capacitance. MEG collaboration used four MPPC segments as a serial connection. However, in the case of a series connection, the requiring bias voltage is very high, and the gain is low. To avoid this problem, we have developed a new individual biasing method with a summing amplifier for stable multiple MPPC readouts. We also made prototype detectors and performed a cosmic-ray test. Brief descriptions of our prototypes and preliminary results of the cosmic-ray test are presented in this article.

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.

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

https://doi.org/10.7566/JPSCP.26.023015

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

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

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

High-rate performance of a time projection chamber for an H-dibaryon search experiment at J-PARC

Kim, S. H.*; 市川 裕大; 佐甲 博之; 長谷川 勝一; 早川 修平*; 七村 拓野*; 佐藤 進; 谷田 聖; 吉田 純也; 他11名*

Nuclear Instruments and Methods in Physics Research A, 940, p.359 - 370, 2019/10

https://doi.org/10.1016/j.nima.2019.06.050
 被引用回数：2 パーセンタイル：34.3(Instruments & Instrumentation)

We have developed a gas electron multiplier (GEM)-based time projection chamber (TPC) for the H-dibaryon search experiment at J-PARC. High-rate $$K^-$$ beam particles enter a TPC gas volume of approximately 0.2 m$$^3$$, in a direction perpendicular to the electric field. A long-rectangular hollow section is located inside the TPC volume to accommodate a diamond target. We commissioned the TPC using 230 MeV protons with beam rates of up to 1 MHz. The TPC data acquisition system collected 5768 pad signals in full readout mode, with almost 100% efficiency, at a preset trigger rate of 230 Hz. We operated the TPC in an Ar/CH$$_4$$ gas mixture (90/10) without a magnetic field. The spatial resolutions on the pad plane are measured to be 400-700 $$mu$$m, which correspond to 230-300 $$mu$$m in a magnetic field of 1 T. We confirmed high tracking capability at beam rates of up to 1 MHz.

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

https://doi.org/10.1063/1.5118379
 被引用回数：0 パーセンタイル：100

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

https://doi.org//10.1063/1.5118383

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

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

https://doi.org/10.1093/ptep/pty149
 被引用回数：1 パーセンタイル：100(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

First determination of the level structure of an $$sd$$-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; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; et al.

Physical Review Letters, 120(13), p.132505_1 - 132505_5, 2018/03

https://doi.org/10.1103/PhysRevLett.120.132505
 被引用回数：5 パーセンタイル：35.7(Physics, Multidisciplinary)

We report on the first observation of $$gamma$$ rays emitted from an $$sd$$-shell hypernucleus, $$^{19}_{Lambda}$$F. The energy spacing between the ground state doublet, $$1/2^+$$ and $$3/2^+$$ states, of $$^{19}_{Lambda}$$F is determined to be $$315.5pm0.4({rm stat.})^{+0.6}_{-0.5}({rm syst.})$$ keV by measuring the $$gamma$$-ray energy of the $$M1(3/2^+ to 1/2^+)$$ transition. In addition, three $$gamma$$-ray peaks are observed and assigned as $$E2(5/2^+ to 1/2^+)$$, $$E1(1/2^- to 1/2^+)$$, and $$E1(1/2^- to 3/2^+)$$ transitions. The excitation energies of the $$5/2^+$$ and $$1/2^-$$ states are determined to be $$895.2pm0.3({rm stat.})pm0.5({rm syst.})$$ keV and $$1265.6pm1.2({rm stat.})^{+0.5}_{-0.7}({rm syst.})$$ keV, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing $$s$$- and $$p$$-shell hypernuclear data.

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

https://doi.org/10.7566/JPSCP.18.011031

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

$$gamma$$-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

https://doi.org/10.7566/JPSCP.17.011004

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

https://doi.org/10.7566/JPSCP.17.012009

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

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

https://doi.org/10.7566/JPSCP.17.012004

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.

論文

Missing-mass spectroscopy with the $$^6$$Li$$(pi^-,K^+)X$$ reaction to search for $$^6_Lambda$$H

本多 良太郎*; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 永宮 正治; 佐甲 博之; 佐藤 進; 杉村 仁志; et al.

Physical Review C, 96(1), p.014005_1 - 014005_23, 2017/07

AA2017-0465.pdf:1.08MB

https://doi.org/10.1103/PhysRevC.96.014005
 被引用回数：9 パーセンタイル：22.36(Physics, Nuclear)

We searched for the bound state of the neutron-rich $$Lambda$$-hypernucleus $$^6_Lambda$$H, using the $$^6$$Li$$(pi^-,K^+)X$$ double charge-exchange reaction at a $$pi^-$$ beam momentum of 1.2 GeV/$$c$$ at J-PARC. A total of $$1.4 times 10^{12}$$ $$pi^-$$ was driven onto a $$^6$$Li target of 3.5 g/cm$$^2$$ thickness. No event was observed below the bound threshold, i.e., the mass of $$^4_Lambda$$H+$$2n$$, in the missing-mass spectrum of the $$^6$$Li$$(pi^-,K^+)X$$ reaction in the $$2^{circ} < theta_{pi K} <20^{circ}$$ angular range. Furthermore, no event was found up to 2.8 MeV/c$$^2$$ above the bound threshold.

論文

Baryon spectroscopy in $$(pi,2pi)$$ reactions with 10$$^{6}$$Hz pion beams at J-PARC

佐甲 博之; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一; Hicks, K.*; Ahn, J. K.*; Kim, S. H.*; Lee, J. W.*; Hwang, S. H.*

Proceedings of Science (Internet), 5 Pages, 2017/05

https://pos.sissa.it/archive/conferences/281/266/INPC2016_266.pdf

バリオン励起状態(N$$^{*}$$,$$Delta^{*}$$)は長年にわたって研究されてきたが、その性質や質量スペクトルに関する我々の知見は大変限られている。最近、Dynamical-Couple Channel (DCC)模型の発展により、$$(pi,2pi)$$反応がこれらの励起状態に大きく寄与することが分かってきた。しかしながら、$$(pi,2pi)$$反応データは1970年代に測定された24万事象に限られており、決定的に不足している。そのため、我々はJ-PARCにおいて統計を二桁上げるE45実験を提案した。この実験においては、$$10^6$$Hzの$$pi$$ビームを用いて超電導Helmholtz型双極磁石に設置したTime Projection Chamberでこれらの反応を測定する。これらの測定をビーム運動量を細かく変えながら高統計で測定する。本発表では実験の設計と準備状況、シミュレーションの結果を報告する。

論文

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

永江 知文*; 江川 弘行; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 杉村 仁志; 谷田 聖; et al.

Proceedings of Science (Internet), 7 Pages, 2017/05

https://pos.sissa.it/archive/conferences/281/038/INPC2016_038.pdf

We have carried out a pilot data taking of the J-PARC E05 experiment to search for the bound state peaks of $$^{12}_{Xi}$$Be in the $$^{12}$$C$$(K^-,K^+)X$$ reaction at 1.8 GeV/$$c$$. The measurement was performed at the K1.8 beam line of the J-PARC hadron experimental hall with a typical $$K^-$$ beam intensity of $$6 times 10^5$$ every six seconds. So far the best energy resolution of about 6 MeV FWHM was achieved with the existing SKS spectrometer. With a reasonable statistics, we have succeeded to observe peak structures in the bound region, which seems to suggest that the potential depth of $$Xi$$ would be deeper than 14 MeV estimated in the previous measurements.

報告書

Verification of alternative dew point hygrometer for CV-LRT in MONJU; Short- and long-term verification for capacitance-type dew point hygrometer (Translated document)

市川 正一; 千葉 悠介; 大野 史靖; 羽鳥 雅一; 小林 孝典; 上倉 亮一; 走利 信男*; 犬塚 泰輔*; 北野 寛*; 阿部 恒*

JAEA-Research 2017-001, 40 Pages, 2017/03

JAEA-Research-2017-001.pdf:5.19MB

日本原子力研究開発機構は、高速増殖原型炉もんじゅのプラント工程への影響を低減するため、現在、原子炉格納容器全体漏えい率試験で用いている塩化リチウム式露点検出器の代替品として、静電容量式露点検出器の検証試験を実施した。原子炉格納容器全体漏えい率試験(試験条件: 窒素雰囲気、24時間)における静電容量式露点検出器の測定結果は、既存の塩化リチウム式検出器と比較して有意な差は無かった。また、長期検証試験(試験条件:空気雰囲気、2年間)においては、静電容量式露点検出器は、高精度鏡面式露点検出器との比較の結果、「電気技術規程(原子力編)」の「原子炉格納容器の漏えい試験規定」に基づく使用前検査時に要求される機器精度(精度:$$pm$$2.04$$^{circ}$$C)を長期間にわたり有することを確認した。

報告書

「もんじゅ」の原子炉格納容器全体漏えい率試験に対する代替露点検出器の実証試験

市川 正一; 千葉 悠介; 大野 史靖; 羽鳥 雅一; 小林 孝典; 上倉 亮一; 走利 信男*; 犬塚 泰輔*; 北野 寛*; 阿部 恒*

JAEA-Research 2016-021, 32 Pages, 2017/02

JAEA-Research-2016-021.pdf:5.0MB

日本原子力研究開発機構は、高速増殖原型炉もんじゅのプラント工程への影響を低減するため、現在、原子炉格納容器全体漏えい率試験で用いている塩化リチウム式露点検出器の代替品として、静電容量式露点検出器の検証試験を実施した。原子炉格納容器全体漏えい率試験(試験条件: 窒素雰囲気、24時間)における静電容量式露点検出器の測定結果は、既存の塩化リチウム式検出器と比較して有意な差は無かった。また、長期検証試験(試験条件: 空気雰囲気、2年間)においては、静電容量式露点検出器は、高精度鏡面式露点検出器との比較の結果、「電気技術規程(原子力編)」の「原子炉格納容器の漏えい率試験規程」に基づく使用前検査時に要求される機器精度(精度: $$pm$$2.04$$^{circ}$$C)を長期間にわたり有することを確認した。

論文

Study of the $$overline{K}$$-nucleus interaction by using the $$^{12}$$C(K$$^{-}$$, p) reaction at J-PARC

市川 裕大; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; 今井 憲一; 金原 慎二; 中田 祥之; 佐甲 博之; 佐藤 進; et al.

JPS Conference Proceedings (Internet), 13, p.020007_1 - 020007_5, 2017/02

https://doi.org/10.7566/JPSCP.13.020007

これまで反K中間子と原子核の間の相互作用はK中間子原子(K-中間子と原子核の電磁相互作用による束縛状態)のX線を用いて研究が行われてきた。しかし、このK中間子原子のX線測定では理論モデルの種類によって結果が大きく依存するという問題がため、X線測定だけでは相互作用を決定することが困難である。そこで、われわれは$$^{12}$$C(K$$^{-}$$, p)反応におけるエネルギースペクトルを測定し、理論計算と比較する手法を用いて反K中間子と原子核の間の相互作用を決定しようとしている。この手法は既にKEK E548実験で行われているが、実験セットアップ上の問題点が指摘されているため、過去の高エネルギー加速器研究機構での実験では不十分である。そこで、われわれはJ-PARCにおいて再実験を行い、正しく$$^{12}$$C(K$$^{-}$$, p)のスペクトルを取得することに成功した。

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