Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Pb, the heaviest 
-process; Only isotope in the solar systemCasanovas-Hoste, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 133(5), p.052702_1 - 052702_8, 2024/07
被引用回数：3 パーセンタイル：75.95(Physics, Multidisciplinary)Tl(n, 
) cross section was measured at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of Tl produced at the Institute Laue Langevin high flux reactor. At the -process temperatures of kT 
8 keV and kT 30 keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new Tl MACS, the uncertainty arising from the Tl(n, ) cross section on the -process abundance of Pb has been reduced from 
30% down to +8%/-6%, and the -process calculations are in agreement with the latest solar system abundance of Pb reported by K. Lodders in 2021.
nuclei constrain element abundancesXian, W.*; 伊藤 由太; 他30名*
Physical Review C, 109(3), p.035804_1 - 035804_10, 2024/03
被引用回数：1 パーセンタイル：0.00(Physics, Nuclear)Atomic masses of the neutron-rich isotopes 
Ga, 
Ge, 
As, 
Se, 
Br, 
Kr, and 
Rb have been measured with high precision and accuracy using the multi-reflection time-of-flight mass spectrograph at the RIBF facility. The masses of 
As were measured for the first time and the mass uncertainties of 
Ge and 
Se were significantly reduced from several hundred keV to below the 10 keV scale. Investigation of shell evolution and potential subshell closures are proceeded by analysis of two-neutron separation energy systematics. As a result of the precise mass measurements, no prominent change on the slope of the two-neutron separation energy beyond 
is observed in Se isotopes, indicating the subshell closure effect at of Se does not exist. Also, various leading mass models are compared with the measurements. The impact of the more precisely known data on r-process nucleosynthesis calculations is investigated in light of these new mass measurements, showing a remarkable reduction of reaction-rate uncertainties.
Ce(n, ) cross section at n_TOF and its astrophysical implications for the chemical evolution of the universeAmaducci, S.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 132(12), p.122701_1 - 122701_8, 2024/03
被引用回数：5 パーセンタイル：82.50(Physics, Multidisciplinary)Ce(n,) is a key reaction for slow neutron-capture (-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty 5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
Patronis, N.*; 木村 敦; 他130名*
EPJ Techniques and Instrumentation (Internet), 10, p.13_1 - 13_10, 2023/05
During the second long shutdown period of the CERN accelerator complex (LS2, 2019-2021), several upgrade activities took place at the n_TOF facility. The most important have been the replacement of the spallation target with a next generation nitrogen-cooled lead target. Additionally, a new experimental area, at a very short distance from the target assembly (the NEAR Station) was established. In this paper, the core commissioning actions of the new installations are described. The improvement in the n_TOF infrastructure was accompanied by several detector development projects. All these upgrade actions are discussed, focusing mostly on the future perspectives of the n_TOF facility. Furthermore, some indicative current and future measurements are briefly reported.
Moreno-Soto, J.*; 木村 敦; 他130名*
Physical Review C, 105(2), p.024618_1 - 024618_14, 2022/02
被引用回数：2 パーセンタイル：31.55(Physics, Nuclear)The -ray spectra from neutron-capture reactions on the 
U, 
U, and 
U nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated s-wave resonances up to about 140 eV. The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions (PSFs) and nuclear level density (NLD). No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) E1 PSF, which match the experimental spectra as well as the total radiative widths.
collisions at 
GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他306名*
Physical Review D, 105(3), p.032003_1 - 032003_8, 2022/02
被引用回数：2 パーセンタイル：19.58(Astronomy & Astrophysics)In 2015, the PHENIX collaboration has measured single-spin asymmetries for charged pions in transversely polarized proton-proton collisions at the center of mass energy of GeV. The pions were detected at central rapidities of 
. The single-spin asymmetries are consistent with zero for each charge individually, as well as consistent with the previously published neutral-pion asymmetries in the same rapidity range. However, they show a slight indication of charge-dependent differences which may suggest a flavor dependence in the underlying mechanisms that create these asymmetries.
, Al, and Au collisions at 
= 200 GeV as a function of transverse and longitudinal momentaAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他305名*
Physical Review D, 105(3), p.032004_1 - 032004_13, 2022/02
被引用回数：4 パーセンタイル：36.52(Astronomy & Astrophysics)In 2015 the PHENIX collaboration at the Relativistic Heavy Ion Collider recorded , Al, and Au collision data at center of mass energies of 
GeV with the proton beam(s) transversely polarized. At very forward rapidities 
relative to the polarized proton beam, neutrons were detected either inclusively or in (anti)correlation with detector activity related to hard collisions. The resulting single spin asymmetries, that were previously reported, have now been extracted as a function of the transverse momentum of the neutron as well as its longitudinal momentum fraction 
. The explicit kinematic dependence, combined with the correlation information allows for a closer look at the interplay of different mechanisms suggested to describe these asymmetries, such as hadronic interactions or electromagnetic interactions in ultra-peripheral collisions, UPC. Events that are correlated with a hard collision indeed display a mostly negative asymmetry that increases in magnitude as a function of transverse momentum with only little dependence on . In contrast, events that are not likely to have emerged from a hard collision display positive asymmetries for the nuclear collisions with a kinematic dependence that resembles that of a UPC based model. Because the UPC interaction depends strongly on the charge of the nucleus, those effects are very small for collisions, moderate for Al collisions, and large for Au collisions.
Ge(n,) cross section at the n_TOF facility at CERNGawlik, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review C, 104(4), p.044610_1 - 044610_7, 2021/10
被引用回数：5 パーセンタイル：51.13(Physics, Nuclear)The Ge(n,) reaction has been measured at the n_TOF facility at CERN via the time-of-flight technique. Neutron capture cross sections on Ge are of interest to a variety of low-background experiments, such as neutrinoless double 
decay searches, and to nuclear astrophysics. We have determined resonance capture kernels up to 52 keV neutron energy and used the new data to calculate Maxwellian-averaged neutron capture cross sections for k
T values of 5 to 100 keV.
collisions at 
=200 GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他306名*
Physical Review Letters, 127(16), p.162001_1 - 162001_8, 2021/10
被引用回数：9 パーセンタイル：61.41(Physics, Multidisciplinary)Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in collisions at =200 GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a fifty-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.
s isomeric states in the odd-odd nucleus 
AuGillespie, S. A.*; Stott, A.*; Andreyev, A. N.; 他30名*
Physical Review C, 103(4), p.044307_1 - 044307_9, 2021/04
被引用回数：1 パーセンタイル：13.22(Physics, Nuclear)Proton-rich Au isotopes are an excellent laboratory to study shape coexistence and isomerism at low excitation energies. In this work, two new isomeric states were found in the odd-odd nuclide Au in an experiment at RITU in JYFL, Jyvaskyla. These two isomers significantly extend the current knowledge of this nucleus and pave the way to future in beam studies where they will be used to tag new gamma rays. Possible spin assignments for the new isomeric states are proposed. Finally, the new data will help clarify the poorly known 
-decay scheme of two long-lived states in the 
Tl to Au decay chain.
and 
mesons in polarized collisions at GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他309名*
Physical Review D, 103(5), p.052009_1 - 052009_10, 2021/03
被引用回数：5 パーセンタイル：32.63(Astronomy & Astrophysics)We present a measurement of the transverse single-spin asymmetry for and mesons in 
collisions in the pseudorapidity range 
and at a center-of-mass energy of 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. In comparison with previous measurements in this kinematic region, these results have a factor of 3 smaller uncertainties. As hadrons, and mesons are sensitive to both initial- and final-state nonperturbative effects for a mix of parton flavors. Comparisons of the differences in their transverse single-spin asymmetries have the potential to disentangle the possible effects of strangeness, isospin, or mass. These results can constrain the twist-3 trigluon collinear correlation function as well as the gluon Sivers function.
collisions at GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他308名*
Physical Review D, 103(3), p.032007_1 - 032007_8, 2021/02
被引用回数：3 パーセンタイル：20.40(Astronomy & Astrophysics)In 2015, the PHENIX collaboration has measured very forward () single-spin asymmetries of inclusive neutrons in transversely polarized proton-proton and proton-nucleus collisions at a center of mass energy of 200 GeV. A previous publication from this data set concentrated on the nuclear dependence of such asymmetries. In this measurement the explicit transverse-momentum dependence of inclusive neutron single spin asymmetries for proton-proton collisions is extracted using a bootstrapping-unfolding technique on the transverse momenta. This explicit transverse-momentum dependence will help improve the understanding of the mechanisms that create these asymmetries.
伊藤 好孝*; 谷田 聖; 他30名*
EPJ Web of Conferences, 208, p.05004_1 - 05004_8, 2019/05
被引用回数：0 パーセンタイル：0.00(Astronomy & Astrophysics)The Large Hadron Collider forward and the Relativistic Heavy Ion Collider forward experiments measured forward particles produced in high-energy hadron collisions at the LHC and RHIC. Using compact calorimeters neutral particles produced in pseudorapidities 
and 
are observed by the respective experiments. Because the collision energies ranging from 0.51 TeV to 13 TeV correspond to the cosmic-ray equivalent energies of 
to 
eV, the measurements are important to understand the hadronic interaction relevant to extensive air shower measurements. This paper reviews recent results of LHCf and initial performance of RHICf that took data in the 2017 RHIC operation.
collisions at GeVAidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他309名*
Physical Review Letters, 120, p.022001_1 - 022001_9, 2018/01
被引用回数：10 パーセンタイル：56.13(Physics, Multidisciplinary)During 2015 the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized 
collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in collisions predicts only a moderate atomic-mass-number () dependence. In contrast, the asymmetries observed at RHIC in 
collisions showed a surprisingly strong dependence in inclusive forward neutron production. The observed asymmetry in +Al collisions is much smaller, while the asymmetry in + Au collisions is a factor of three larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed dependence.
Chen, Y. H.*; Tassan-Got, L.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他130名*
EPJ Web of Conferences, 146, p.03020_1 - 03020_4, 2017/09
被引用回数：1 パーセンタイル：58.02(Nuclear Science & Technology)CERNの中性子飛行時間測定施設において、長い中性子飛行距離を有する第1実験室に加え、短い中性子飛行距離位置に第2実験室を設計・建設した。パラレル・プレート・アバランチェ・カウンター(PPAC)を用いて、第2実験室における中性子ビームの空間的広がり及びエネルギー分布を測定した。また、第1実験室で観測され時間校正に使用されてきた線フラッシュは観測されないという知見が得られ、本観測結果に基づき、線フラッシュの物理的起源に関する考察結果を示した。
+ Au collisions at 
GeVAidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他304名*
Physical Review C, 95(3), p.034910_1 - 034910_10, 2017/03
被引用回数：40 パーセンタイル：92.29(Physics, Nuclear)We present measurements of long-range angular correlations and the transverse momentum dependence of elliptic flow 
in high-multiplicity + Au collisions at GeV. A comparison of these results to previous measurements in high-multiplicity 
+ Au and 
He + Au collisions demonstrates a relation between and the initial collision eccentricity 
, suggesting that the observed momentum-space azimuthal anisotropies in these small systems have a collective origin and reflect the initial geometry. Good agreement is observed between the measured and hydrodynamic calculations for all systems, and an argument disfavoring theoretical explanations based on initial momentum-space domain correlations is presented. The set of measurements presented here allows us to leverage the distinct intrinsic geometry of each of these systems to distinguish between different theoretical descriptions of the long-range correlations observed in small collision systems.
