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論文

Identification of excited states in $$^{188}$$Bi and $$^{188}$$Po

Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Huang, H.*; 他37名*

Physical Review C, 106(2), p.024317_1 - 024317_11, 2022/08

https://doi.org/10.1103/PhysRevC.106.024317
 被引用回数：1 パーセンタイル：58.8(Physics, Nuclear)

The neutron-deficient $$^{188}$$Bi and $$^{188}$$Po isotopes have been studied by $$gamma$$-ray spectroscopy using the recoil-decay tagging technique with the Argonne Gas-Filled Analyzer. A new 0.25(5)-micro second isomeric state and a prompt cascade formed by 319-, 366-, and 462-keV $$gamma$$ rays have been established on top of the (10$$^{-}$$) $$alpha$$-decaying isomer in $$^{188}$$Bi. The first excited (2$$^{+}$$) state in $$^{188}$$Po was identified, its excitation energy of 242(2) keV continues the nearly constant trend for the first 2$$^{+}$$ states in $$^{190,192,194}$$Po. The state is most likely a member of a prolate rotational band built on the ground state, albeit mixing with other coexisting configurations cannot be excluded. The new results obtained in the present work provide new information to shape coexistence in bismuth and polonium isotopes near the neutron midshell at $$N$$ = 104. In this mass region, a reduction in the prompt $$gamma$$-ray yield obtained with recoil decay tagging was observed for a few nuclides, and the possible reasons are presented.

論文

New $$alpha$$-emitting isotope $$^{214}$$U and abnormal enhancement of $$alpha$$-particle clustering in lightest uranium isotopes

Zhang, Z. Y.*; Yang, H. B.*; Andreyev, A. N.; Liu, M. L.*; Ma, L.*; 他37名*

Physical Review Letters, 126(15), p.152502_1 - 152502_6, 2021/04

https://doi.org/10.1103/PhysRevLett.126.152502
 被引用回数：27 パーセンタイル：96.94(Physics, Multidisciplinary)

A new $$alpha$$-emitting isotope $$^{214}$$U, produced by the fusion-evaporation reaction $$^{182}$$W($$^{36}$$Ar,4n)$$^{214}$$U, was identified by employing the gas-filled recoil separator SHANS and the recoil-$$alpha$$ correlation technique. More precise $$alpha$$-decay properties of even-even nuclei $$^{216,218}$$U were also measured in the reactions of $$^{40}$$Ar, $$^{40}$$Ca beams with $$^{180,182,184}$$W targets. By combining the experimental data, improved $$alpha$$-decay reduced widths $$delta$$$$^{2}$$ for the even-even Po-Pu nuclei in the vicinity of the magic neutron number ${it N}$ = 126 are deduced. Their systematic trends are discussed in terms of the ${it N}$ $$_{it p}$$ ${it N}$ $$_{it n}$$ scheme in order to study the influence of proton-neutron interaction on $$alpha$$ decay in this region of nuclei. It is strikingly found that the reduced widths of $$^{214,216}$$U are significantly enhanced by a factor of two as compared with the ${it N}$ $$_{it p}$$ ${it N}$ $$_{it n}$$ systematics for the 84 $$leq$$ ${it Z}$ $$leq$$ 90 and ${it N}$ $$<$$ 126 even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the $$pi$$1${it f}$ $$_{7/2}$$ and $$nu$$1${it f}$ $$_{5/2}$$ spin-orbit partner orbits, which is supported by the large-scale shell model calculation.

論文

Erratum; The Belle II physics book

Kou, E.*; 谷田 聖; Belle II Collaboration*; 他537名*

Progress of Theoretical and Experimental Physics (Internet), 2020(2), p.029201_1 - 029201_6, 2020/02

https://doi.org/10.1093/ptep/ptaa008
 被引用回数：155 パーセンタイル：100(Physics, Multidisciplinary)

In the original version of this manuscript, an error was introduced on pp.352. "2.7nb:1.6nb" has been corrected to "2.4nb:1.3nb" in the current online and printed version.

論文

The Belle II physics book

Kou, E.*; 谷田 聖; Belle II Collaboration*; 他537名*

Progress of Theoretical and Experimental Physics (Internet), 2019(12), p.123C01_1 - 123C01_654, 2019/12

https://doi.org/10.1093/ptep/ptz106
 被引用回数：311 パーセンタイル：99.97(Physics, Multidisciplinary)

We present the physics program of the Belle II experiment, located on the intensity frontier SuperKEKB $$e^+e^-$$ collider. Belle II collected its first collisions in 2018, and is expected to operate for the next decade. It is anticipated to collect 50/ab of collision data over its lifetime. This book is the outcome of a joint effort of Belle II collaborators and theorists through the Belle II theory interface platform (B2TiP), an effort that commenced in 2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II program, which includes a wide scope of physics topics: B physics, charm, tau, quarkonium, electroweak precision measurements and dark sector searches. It is composed of nine working groups (WGs), which are coordinated by teams of theorist and experimentalists conveners: Semileptonic and leptonic B decays, Radiative and Electroweak penguins, $$phi_1$$ and $$phi_2$$ (time-dependent CP violation) measurements, $$phi_3$$ measurements, Charmless hadronic B decay, Charm, Quarkonium(-like), tau and low-multiplicity processes, new physics and global fit analyses. This book highlights "golden- and silver-channels", i.e. those that would have the highest potential impact in the field. Theorists scrutinised the role of those measurements and estimated the respective theoretical uncertainties, achievable now as well as prospects for the future. Experimentalists investigated the expected improvements with the large dataset expected from Belle II, taking into account improved performance from the upgraded detector.

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

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

AA2018-0124.pdf:0.62MB

https://doi.org/10.1103/PhysRevLett.120.132505
 被引用回数：7 パーセンタイル：54.46(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

Observation of the "$$K^-pp$$"-like structure in the $$d(pi^+, K^+)$$ reaction at 1.69 GeV/$$c$$

市川 裕大; 長谷川 勝一; 細見 健二; 今井 憲一; 佐甲 博之; 佐藤 進; 杉村 仁志; 他37名*

Progress of Theoretical and Experimental Physics (Internet), 2015(2), p.021D01_1 - 021D01_8, 2015/02

https://doi.org/10.1093/ptep/ptv002
 被引用回数：67 パーセンタイル：93.49(Physics, Multidisciplinary)

1.69GeV/$$c$$の$$pi^+$$ビームによる$$d(pi^+, K^+)$$反応の測定から"$$K^-pp$$"-like structureを観測した。この反応では、$$Lambda^*prightarrow K^-pp$$のように$$Lambda$$(1405)を中間状態として$$K^-pp$$束縛状態が形成されると考えられる。しかしながら、大部分の$$Lambda(1405)$$は上記のような二次反応を行わず重水素外に放出されてしまう。そこで、250MeV/$$c$$以上の運動量で大角度($$39^circ<theta_{rm lab.}<122^circ$$)に放出される陽子を同時検出することで、シグナル-バックグラウンド比を向上させ、2.27GeV/$$c^2$$付近に幅の広い構造を観測した。この構造は$$K^-pp$$の束縛エネルギー・崩壊幅において、それぞれ95$$^{+18}_{-17}$$(stat.)$$^{+30}_{-21}$$(syst.)MeV、162$$^{+87}_{-45}$$(stat.)$$^{+66}_{-78}$$(syst.)MeVに相当する。

論文

Inclusive spectrum of the $$d(pi^{+}, K^{+})$$ reaction at 1.69 GeV/$$c$$

市川 裕大; 長谷川 勝一; 細見 健二; 今井 憲一; 佐甲 博之; 佐藤 進; 杉村 仁志; 他37名*

Progress of Theoretical and Experimental Physics (Internet), 2014(10), p.101D03_1 - 101D03_8, 2014/10

https://doi.org/10.1093/ptep/ptu128
 被引用回数：14 パーセンタイル：67.01(Physics, Multidisciplinary)

質量分解能2.7$$pm$$0.1MeV/$$c^2$$(FWHM)の精度で、1.69GeV/$$c$$の$$pi^{+}$$ビームを用いて、$$d(pi^+, K^+)$$の包括的な質量欠損スペクトルを測定した。そこで、おおむね得られたスペクトルを単純な準自由過程のシミュレーションで再現することができたが、以下にあげる二つの逸脱が見られた。すなわち、2.13GeV/$$c^2$$付近における$$Sigma N$$ cusp起因と考えられる過剰事象と$$Lambda(1405)$$や$$Sigma(1385)^{+/0}$$の生成領域におけるバンプ構造の中心値が低い質量側に22.4$$pm$$0.4(stat.)$$^{+2.7}_{-1.7}$$(syst.)MeV/$$c^2$$ずれていることを見出した。

論文

Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in $$vec{p}$$ + $$vec{p}$$ collisions at $$sqrt{s}$$ = 200 GeV

今井 憲一; 谷田 聖; PHENIX Collaboration*; 他378名*

Physical Review D, 90(1), p.012007_1 - 012007_19, 2014/07

AA2014-0582.pdf:1.66MB

https://doi.org/10.1103/PhysRevD.90.012007
 被引用回数：52 パーセンタイル：87.98(Astronomy & Astrophysics)

RHIC PHENIX実験において、重心エネルギー200GeVにおける偏極陽子-陽子衝突での$$pi^0$$および$$eta$$中間子生成の二重スピン非対称測定の2009年のデータを報告する。この新しい2009年のデータを最近の偏極散乱データのグローバル解析に加えたときの結果を示す。それによると$$Delta G$$の値は、0.05$$<x<$$0.2の範囲の積分値で0.06 $$_{-0.15}^{+0.11}$$となる。

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