渡邉 寛*; Wang, H. K.*; Lorusso, G.*; 西村 俊二*; Xu, Z. Y.*; 炭竃 聡之*; Orlandi, R.; 他47名*
Physics Letters B, 792, p.263 - 268, 2019/05
The isotopes Pd and Pd, respectively with 79 and 81 neutrons, are key isotopes to understand the evolution of the N=82 shell closure below Pd. These nuclei were studied at RIBF (RIKEN). New isomeric states with half-lives of 144(4) ns and 39(6) s were assigned spins and parities of (23/2) and (19/2) in Pd and Pd, respectively. The assignment was carried out based on the results of the -ray intensity balance analysis and the measured transition strengths with the aid of a shell-model calculation. The isomoer in Pd was ascribed predominantly to three neutron-hole excitations in the N=50-82 shell. The 19/2 state in Pd is expected to involve the coupling of proton and neutron configurations. The new data will provide important benchmarks for a better understanding of -process nucleosynthesis.
Adare, A.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他347名*
Physical Review C, 97, p.064904_1 - 064904_11, 2018/06
We present measurements of the transverse-momentum dependence of elliptic flow for identified pions and (anti)protons at midrapidity (), in 0% - 5% central + Au and He + Au collisions at = 200 GeV. When taken together with previously published measurements in + Au collisions at = 200 GeV, the results cover a broad range of small-collision-system multiplicities and intrinsic initial geometries. We observe a clear mass-dependent splitting of in + Au and He + Au collisions, just as in large nucleus-nucleus ( + ) collisions, and a smaller splitting in + Au collisions. Both hydrodynamic and transport model calculations successfully describe the data at low ( GeV/), but fail to describe various features at higher . In all systems, the values follow an approximate quark-number scaling as a function of the hadron transverse kinetic energy per constituent quark(), which was also seen previously in + collisions.
Gunsing, F.*; Aberle, O.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他147名*
EPJ Web of Conferences, 146, p.11002_1 - 11002_6, 2017/09
Adare, A.*; 今井 憲一; 長谷川 勝一; 永宮 正治; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他477名*
Physical Review Letters, 116(12), p.122301_1 - 122301_9, 2016/03
Jet production rates are measured in and Au collisions at = 200 GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the =0.3 anti- algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multiwire proportional chambers, and the jet transverse momentum () spectra are corrected for the detector response. Spectra are reported for jets with GeV/ within a pseudorapidity acceptance of . The nuclear-modification factor () values and central-to-peripheral ratios () show large, -dependent deviations from unity, challenging the conventional models that relate hard-process rates and soft-particle production in collisions involving nuclei.
Adare, A.*; 長谷川 勝一; 今井 憲一; 永宮 正治; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他477名*
Physical Review C, 92(4), p.044909_1 - 044909_14, 2015/10
The PHENIX Collaboration has measured meson production in + Au collisions at = 200 GeV using the dimuon and dielectron decay channels. The meson is measured in the forward (backward) -going (Au-going) direction, in the transverse-momentum () range from 1-7 GeV/ and at midrapidity in the range below 7 GeV/. The meson invariant yields and nuclear-modification factors as a function of , rapidity, and centrality are reported. An enhancement of meson production is observed in the Au-going direction, while suppression is seen in the -going direction, and no modification is observed at midrapidity relative to the yield in collisions scaled by the number of binary collisions. Similar behavior was previously observed for inclusive charged hadrons and open heavy flavor, indicating similar cold-nuclear-matter effects.
Adare, A.*; 今井 憲一; 谷田 聖; PHENIX Collaboration*; 他477名*
Physical Review C, 91(6), p.064904_1 - 064904_11, 2015/06
The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au+Au collisions at GeV down to . Photons are detected via photon conversions to pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low . We find an excess of direct photons above the -scaled yield measured in collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/ in the range 0.6-2.0 GeV/. While the shape of the distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with , where .