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Periez, R.*; Bezhenar, R.*; Maderych, V.*; Brovchenko, I.*; Liptak, L.*; 小林 卓也; Min, B.-I.*; Suh, K. S.*; Little, A.*; Iosjpe, M.*; et al.
IAEA-TECDOC-2060, 55 Pages, 2024/07
IAEAは、2016年から2019年にかけて、放射線影響評価のためのモデリングとデータに関する(MODARIA II)プログラムを組織した。MODARIA IIの第7作業部会「海洋環境に放出された放射性核種の移行挙動の評価」では、拡散モデルを使用した海洋環境における放射性核種のシミュレーションに関する一般情報をまとめた。そして、東京電力福島第一原子力発電所事故シナリオを用いてCs-137の広域シミュレーションと生物への移行について検討するとともに、大西洋シナリオとして、ヨーロッパの核燃料使用済施設からの歴史的な放出について検討した。最後に、ラグランジェモデルにおける補間スキームの試験を実施した。本書は第7作業部会の活動内容について述べたものである。
Schnabel, G.*; 国枝 賢; 今野 力; 中山 梓介; 他27名*
Nuclear Data Sheets, 193, p.1 - 78, 2024/02
被引用回数:1 パーセンタイル:94.19国際原子力機関(IAEA)が中心となり、各国の研究者の協力のもと、核融合研究開発のための国際核データライブラリFENDLの更新を行った。最新ライブラリ(FENDL-3.2b)の構築にあたっては、主に米国のENDF、欧州のJEFF、日本のJENDLの相互比較を行い、積分検証結果も踏まえつつ、現状で最も妥当と考えられるデータを個々の核種毎に採用した。従来のライブラリとの大きな違いは、加速器中性子源やそれを用いる材料研究分野からのニーズに応えるためにこれまでのエネルギー上限を20MeVから最大200MeVに拡張し、中性子データのみならず陽子や重陽子データの収録も新規に行なったことである。また、本ライブラリの品質を検証することを目的として、中性子輸送計算や核発熱シミュレーション等を通じた種々のベンチーマーク解析を実施した。それにより、従来のライブラリに比べ実用性が大きく向上していることを示した。
Sun, L. J.*; Fry, C.*; Davids, B.*; Esker, N.*; Wrede, C.*; Smallcombe, J.; 他27名*
Physics Letters B, 839, p.137801_1 - 137801_8, 2023/04
被引用回数:1 パーセンタイル:59.27(Astronomy & Astrophysics)Motivated primarily by the large uncertainties in the thermonuclear rate of the 30PS reaction that limit our understanding of classical novae, we carried out lifetime measurements of S excited states using the Doppler Shift Lifetimes (DSL2) facility at the TRIUMF Isotope Separator and Accelerator (ISAC-II) facility.
相川 脩*; 橋本 直; 谷田 聖; 他73名*
Physics Letters B, 837, p.137637_1 - 137637_8, 2023/02
被引用回数:2 パーセンタイル:47.44(Astronomy & Astrophysics)We measured a set of , , and invariant mass spectra below and above the mass threshold in -induced reactions on deuteron. We deduced the -wave and scattering amplitudes in the isospin 0 channel in the framework of a and coupled channel. We find that a resonance pole corresponding to is located at 1417.7(fitting errors)(systematic errors) + (fitting errors)(systematic errors)] MeV/, closer to the mass threshold than the value determined by the Particle Data Group.
飯村 俊*; Rosenbusch, M.*; 高峰 愛子*; 角田 佑介*; 和田 道治*; Chen, S.*; Hou, D. S.*; Xian, W.*; 石山 博恒*; Yan, S.*; et al.
Physical Review Letters, 130(1), p.012501_1 - 012501_6, 2023/01
被引用回数:6 パーセンタイル:93.39(Physics, Multidisciplinary)The atomic masses of Sc, Ti, and V have been determined using the high-precision multireflection time-of-flight technique. The radioisotopes have been produced at RIKEN's Radioactive Isotope Beam Factory (RIBF) and delivered to the novel designed gas cell and multireflection system, which has been recently commissioned downstream of the ZeroDegree spectrometer following the BigRIPS separator. For Ti and V, the mass uncertainties have been reduced down to the order of 10 keV, shedding new light on the shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species Ti and V. With the new precision achieved, we reveal the nonexistence of the empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap above the occupied p orbit is identified as a feature unique to Ca. We perform new Monte Carlo shell model calculations including the d and g orbits and compare the results with conventional shell model calculations, which exclude the g and the d orbits. The comparison indicates that the shell gap reduction in Ti is related to a partial occupation of the higher orbitals for the outer two valence neutrons at .
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
被引用回数:1 パーセンタイル:28.09(Physics, Nuclear)The neutron-deficient Bi and Po isotopes have been studied by -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 rays have been established on top of the (10) -decaying isomer in Bi. The first excited (2) state in Po was identified, its excitation energy of 242(2) keV continues the nearly constant trend for the first 2 states in 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 = 104. In this mass region, a reduction in the prompt -ray yield obtained with recoil decay tagging was observed for a few nuclides, and the possible reasons are presented.
Adriani, O.*; 谷田 聖; RHICf Collaboration*; 他17名*
Journal of Instrumentation (Internet), 16(10), p.P10027_1 - P10027_16, 2021/10
被引用回数:0 パーセンタイル:0.00(Instruments & Instrumentation)In the RHIC forward (RHICf) experiment, an operation with collisions was performed at 510 GeV from 24-27 June 2017. The performances, energy and position resolutions, trigger efficiency, stability, and background during the operation, have been studied using data and simulations, which revealed that the requirements for production cross-section and transverse single-spin asymmetry measurements of very forward photons, s, and neutrons were satisfied. In this paper, we describe the details of these studies.
Tonev, D.*; De Angelis, G.*; Deloncle, I.*; Orlandi, R.; 他27名*
Physics Letters B, 821, p.136603_1 - 136603_6, 2021/10
被引用回数:5 パーセンタイル:62.78(Astronomy & Astrophysics)The mirror nuclei P and S, produced via the Ne+C reaction at 33 MeV, were studied at Legnaro Laboratory using the EUCLIDES Si array coupled with the GASP Ge array. The observed B(E1) strengths of mirror E1 transitions, provide strong evidence for breaking of isospin symmetry in the A=31 mass region. The new finding are supported and explained by state-of-the-art beyond-mean-field calculations including 2- and 3-body forces. According to these findings, the breaking of isospin symmetry originate from violation of charge symmetry in the 2- and 3-body parts of the Coulomb potential.
Li, L. K.*; 谷田 聖; Belle Collaboration*; 他187名*
Journal of High Energy Physics (Internet), 2021(9), p.75_1 - 75_21, 2021/09
被引用回数:1 パーセンタイル:9.61(Physics, Particles & Fields)We measure the branching fractions and asymmetries for the singly Cabibbo-suppressed decays , , and , using 980 fb of data from the Belle experiment at the KEKB collider. We obtain where the third uncertainty () is from the uncertainty in the branching fraction of the reference mode . The color-suppressed decay is observed for the first time, with very high significance. The results for the asymmetries are The results for are a significant improvement over previous results. The branching fraction and results for , and the result for , are the first such measurements. No evidence for violation is found in any of these decays.
Nisar, N. K.*; 谷田 聖; Belle Collaboration*; 他197名*
Physical Review D, 104(3), p.L031101_1 - L031101_8, 2021/08
被引用回数:1 パーセンタイル:9.61(Astronomy & Astrophysics)We report the results of the first search for the decay using of data collected at the resonance with the Belle detector at the KEKB asymmetric-energy collider. We observe no significant signal and set a 90% confidence-level upper limit of on the branching fraction of this decay.
Dubey, S.*; 谷田 聖; Belle Collaboration*; 他171名*
Physical Review D, 104(1), p.012007_1 - 012007_11, 2021/07
被引用回数:1 パーセンタイル:9.61(Astronomy & Astrophysics)We report the first search for the penguin-dominated process using a semi-inclusive method. A 121.4 integrated luminosity data set collected by the Belle experiment, at the KEKB asymmetric-energy collider, is used. We observe no statistically significant signal and including all uncertainties, we set a 90% confidence level upper limit on the partial branching fraction at 1.4 10 for 2.4 GeV/.
Juhsz, M. M.*; 吉田 数貴; 他77名*
Physical Review C, 103(6), p.064308_1 - 064308_9, 2021/06
被引用回数:4 パーセンタイル:54.40(Physics, Nuclear)Vの準位構造を陽子非弾性散乱およびノックアウト反応によって初めて明らかにした。新たに観測された696(8)keVおよび889(16)keV状態の線による遷移とLenzi-Nowacki-Poves-Sieja相互作用を用いた殻模型計算との比較によって、これらの励起状態は第一11/2と9/2状態であることが確立された。陽子非弾性散乱断面積は、純粋な四重極変形と四重極+十六重極変形を仮定したチャネル結合計算によって解析された。これらの分析によって大きな変形パラメータが得られ、VはNi下方の逆転の島に含まれることが明らかになった。
Park, S.-H.*; 谷田 聖; Belle Collaboration*; 他217名*
Journal of High Energy Physics (Internet), 2021(4), p.191_1 - 191_15, 2021/04
被引用回数:0 パーセンタイル:0.01(Physics, Particles & Fields)We present a search for the dark photon in the decays, where subsequently decays to , , and . The search is performed by analyzing events collected by the Belle detector at the KEKB energy-asymmetric collider at the resonance. No signal is found in the dark photon mass range , and we set upper limits of the branching fraction of at the 90% confidence level. The products of branching fractions, and , have limits of the order of depending on the mass. Furthermore, considering decay rate to each pair of charged particles, the upper limits of are of the order of -. From the upper limits of , we obtain the Higgs portal coupling for each assumed dark photon and dark Higgs mass. The Higgs portal couplings are of the order of - at and - at .
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
被引用回数:44 パーセンタイル:96.61(Physics, Multidisciplinary)A new -emitting isotope U, produced by the fusion-evaporation reaction W(Ar,4n)U, was identified by employing the gas-filled recoil separator SHANS and the recoil- correlation technique. More precise -decay properties of even-even nuclei U were also measured in the reactions of Ar, Ca beams with W targets. By combining the experimental data, improved -decay reduced widths for the even-even Po-Pu nuclei in the vicinity of the magic neutron number = 126 are deduced. Their systematic trends are discussed in terms of the scheme in order to study the influence of proton-neutron interaction on decay in this region of nuclei. It is strikingly found that the reduced widths of U are significantly enhanced by a factor of two as compared with the systematics for the 84 90 and 126 even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the 1 and 1 spin-orbit partner orbits, which is supported by the large-scale shell model calculation.
Wehle, S.*; 谷田 聖; Belle Collaboration*; 他179名*
Physical Review Letters, 126(16), p.161801_1 - 161801_8, 2021/04
被引用回数:20 パーセンタイル:87.96(Physics, Multidisciplinary)We present a measurement of , the branching fraction ratio / , for both charged and neutral mesons. The ratio for the charged case, , is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass, . The analysis is based on a data sample of , containing events, recorded at the resonance with the Belle detector at the KEKB asymmetric-energy collider. The obtained results are consistent with Standard Model expectations.
Acharya, U.*; 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397名*
Physical Review C, 102(6), p.064905_1 - 064905_13, 2020/12
被引用回数:5 パーセンタイル:51.18(Physics, Nuclear)The PHENIX experiment at the Relativistic Heavy Ion Collider measured and mesons at midrapidity in UU collisions at GeV in a wide transverse momentum range. Measurements were performed in the decay modes. A strong suppression of and meson production at high transverse momentum was observed in central UU collisions relative to binary scaled results. Yields of and mesons measured in UU collisions show similar suppression pattern to the ones measured in AuAu collisions at GeV for similar numbers of participant nucleons. The / ratios do not show dependence on centrality or transverse momentum, and are consistent with previously measured values in hadron-hadron, hadron-nucleus, nucleus-nucleus, and collisions.
Acharya, U.*; 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572名*
Physical Review C, 102(5), p.054910_1 - 054910_11, 2020/11
被引用回数:3 パーセンタイル:35.09(Physics, Nuclear)We present direct photon-hadron correlations in 200 GeV/A AuAu, Au and collisions, for direct photon from 5 - 12 GeV/, collected by the PHENIX Collaboration in the years from 2006 to 2011. We observe no significant modification of jet fragmentation in Au collisions, indicating that cold nuclear matter effects are small or absent. Hadrons carrying a large fraction of the quark's momentum are suppressed in AuAu compared to and Au. As the momentum fraction decreases, the yield of hadrons in AuAu increases to an excess over the yield in collisions. The excess is at large angles and at low hadron and is most pronounced for hadrons associated with lower momentum direct photons. Comparison to theoretical calculations suggests that the hadron excess arises from medium response to energy deposited by jets.
Jungclaus, A.*; Keatings, J. M.*; Simpson, G. S.*; Orlandi, R.; 他47名*
Physical Review C, 102(3), p.034324_1 - 034324_11, 2020/09
被引用回数:5 パーセンタイル:51.18(Physics, Nuclear)The decay of Sn was investigated at RIBF, RIKEN. For Sb the first information on excited states was obtained. In the case of Sb and Sb, new gamma-rays were observed. The new experimental results, in combination with state-of-the-art shell-model calculations, provide the first information on the evolution of the 0gand 1d proton single-particle states with increasing neutron number beyond =84.
Jia, S.*; 谷田 聖; Belle Collaboration*; 他175名*
Physical Review D, 101(9), p.091101_1 - 091101_8, 2020/05
被引用回数:11 パーセンタイル:60.41(Astronomy & Astrophysics)We report the measurement of via initial-state radiation using a data sample of an integrated luminosity of 921.9 fb collected with the Belle detector at the and nearby. We find evidence for an enhancement with a 3.4 significance in the invariant mass of The measured mass and width are and , respectively. The mass, width, and quantum numbers of this enhancement are consistent with the charmonium-like state at 4626 MeV/ recently reported by Belle in The product of the cross section and the branching fraction of is measured from threshold to 5.6 GeV.
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.