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Andel, B.*; Andreyev, A. N.; Antalic, S.*; Al Monthery, M.*; Barzakh, A.*; Bissell, M. L.*; Chrysalidis, K.*; 他29名*
Physical Review C, 102(1), p.014319_1 - 014319_12, 2020/07
被引用回数:6 パーセンタイル:57.61(Physics, Nuclear)-delayed fission (
DF) decay of a low-spin (ls) and a high-spin (hs) isomer in
Bi was studied at the ISOLDE facility at CERN. Their
DF partial half-lives were determined:
,
DF(
Bi
)= 5.6(8)
10
s and
,
DF(
Bi
)=1.7(6)
10
s. This work is the first
DF study of two states in one isotope and allows the spin dependence of low-energy fission to be explored. The fission fragment mass distribution of a daughter nuclide
Pb, following the
decay of the high-spin isomer, was deduced and indicates a mixture of symmetric and asymmetric fission modes.
Aidala, C.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他297名*
Physical Review C, 101(3), p.034910_1 - 034910_16, 2020/03
被引用回数:16 パーセンタイル:87.31(Physics, Nuclear)The PHENIX experiment has studied nuclear effects in Al and
Au collisions at
GeV on charged hadron production at forward rapidity (
,
-going direction) and backward rapidity (
,
-going direction). Such effects are quantified by measuring nuclear modification factors as a function of transverse momentum and pseudorapidity in various collision multiplicity selections. In central
Al and
Au collisions, a suppression (enhancement) is observed at forward (backward) rapidity compared to the binary scaled yields in
+
collisions. The magnitude of enhancement at backward rapidity is larger in
Au collisions than in
Al collisions, which have a smaller number of participating nucleons. However, the results at forward rapidity show a similar suppression within uncertainties. The results in the integrated centrality are compared with calculations using nuclear parton distribution functions, which show a reasonable agreement at the forward rapidity but fail to describe the backward rapidity enhancement.
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 reaction spectra at 1.8 GeV/
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
in the
B nucleus is quite broadened. Furthermore, we also compared broadness of
with
obtained in the
spectrum.
seems to be much more broadened in nuclei than
. We gave a possible interpretation, which is related to compositeness of decuplet baryons, for this situation.
Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他296名*
Physical Review Letters, 123(12), p.122001_1 - 122001_9, 2019/09
被引用回数:10 パーセンタイル:61.49(Physics, Multidisciplinary)We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively-charged hadrons in polarized ,
Al and
Au collisions at
GeV. The measurements have been performed at forward rapidity (
) over the range of
GeV
and
. We observed a positive asymmetry
for positively-charged hadrons in
collisions, and a significantly reduced asymmetry in
+
collisions. These results reveal a nuclear dependence of charged hadron
in a regime where perturbative techniques are relevant. These results provide new opportunities to use
A collisions as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions and to use TSSA as a new handle in studying small-system collisions.
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
被引用回数:12 パーセンタイル:98.06(Physics, Nuclear)For the full understanding of baryon-baryon interactions in flavor , the
interaction is the last missing piece of information. So far, we have revealed the
interaction to be attractive (
MeV), and
interaction to be repulsive in the medium to heavy mass-number region. The
bonding energy is weakly attractive. While we have a few experimental observations suggesting the
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
hypernuclei by observing bound-state peaks are strongly awaited. In this report, a new preliminary result on the missing-mass spectrum of a
C
reaction, which strongly suggests the existence of
-hypernuclear bound states, is presented.
Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他296名*
Physical Review D, 99(9), p.092003_1 - 092003_21, 2019/05
被引用回数:7 パーセンタイル:39.85(Astronomy & Astrophysics)Measurements of the differential production of electrons from open-heavy-flavor hadrons with charm- and bottom-quark content in collisions at
GeV are presented. The measurements proceed through displaced-vertex analyses of electron tracks from the semileptonic decay of charm and bottom hadrons using the PHENIX silicon-vertex detector. The relative contribution of electrons from bottom decays to inclusive heavy-flavor-electron production is found to be consistent with fixed-order-plus-next-to-leading-log perturbative-QCD calculations within experimental and theoretical uncertainties. These new measurements in
collisions provide a precision baseline for comparable forthcoming measurements in A
A collisions.
Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他293名*
Physical Review C, 99(4), p.044912_1 - 044912_10, 2019/04
被引用回数:5 パーセンタイル:46.65(Physics, Nuclear)The PHENIX collaboration has measured high- dihadron correlations in
,
Al, and
Au collisions at
GeV. The correlations arise from inter- and intra-jet correlations and thus have sensitivity to nonperturbative effects in both the initial and final states. The distributions of
, the transverse momentum component of the associated hadron perpendicular to the trigger hadron, are sensitive to initial and final state transverse momenta. These distributions are measured multi-differentially as a function of
, the longitudinal momentum fraction of the associated hadron with respect to the trigger hadron. The near-side
widths, sensitive to fragmentation transverse momentum, show no significant broadening between
Au,
Al, and
. The away-side nonperturbative
widths are found to be broadened in
Au when compared to
; however, there is no significant broadening in
Al compared to
collisions. The data also suggest that the away-side
broadening is a function of
, the number of binary nucleon-nucleon collisions, in the interaction. The potential implications of these results with regard to initial and final state transverse momentum broadening and energy loss of partons in a nucleus, among other nuclear effects, are discussed.