Sublet, J.-Ch.*; Bondarenko, I. P.*; Bonny, G.*; Conlin, J. L.*; Gilbert, M. R.*; Greenwood, L. R.*; Griffin, P. J.*; Helgesson, P.*; 岩元 洋介; Khryachkov, V. A.*; et al.
European Physical Journal Plus (Internet), 134(7), p.350_1 - 350_50, 2019/07
核データを用いた原子核反応については、放射線照射を受けた材料のカスケード損傷による欠陥生成の起点となる。そのため、欠陥生成の指標となる一次はじき出し原子(PKA)、PKAの損傷エネルギー及び原子あたりのはじき出し数(DPA値)の導出において、原子核反応を正確に考慮することが重要となる。ここで、原子核反応を考慮した欠陥生成の評価手法(メトリクス)を用いることで、照射材料中の個々の欠陥やクラスタ化した欠陥のマクロな挙動をシミュレーションすることが可能となる。より具体的には、原子炉, 核融合, 加速器, 核医学, 宇宙分野等の様々な分野において、照射条件(入射粒子, 入射エネルギー, 材料等)に対応した損傷評価が可能となる。本論文は、核反応及び損傷エネルギーに関する最近の理論と進展をレビューするとともに、欠陥生成量を導出する際の核データにおける誤差の伝播、分子動力学に基づいた損傷計算等について述べる。
Panikkath, P.*; 大塚 直彦*; 岩元 洋介; Mohanakrishnan, P.*
European Physical Journal A, 55(6), p.91_1 - 91_9, 2019/06
Devaraja, H. M.*; Heinz, S.*; Beliuskina, O.*; Hofmann, S.*; Hornung, C.*; Mnzenberg, G.*; Ackermann, D.*; Gupta, M.*; Gambhir, Y. K.*; Henderson, R. A.*; et al.
European Physical Journal A, 55(2), p.25_1 - 25_9, 2019/02
The results for nuclei above curium, produced in multi-nucleon transfer reactions of Ca+Cm at the velocity filter SHIP of GSI Darmstadt, are presented. Spontaneous fission and activities have been used to study the population of nuclei with lifetimes ranging from few milliseconds to several days. We observed several, relatively neutron-rich isotopes with atomic numbers Z 98; among them a weak 224 millisecond activity which we tentatively attributed to No. The measured cross-sections of the observed nuclei give hope that multi-nucleon transfer reactions are a way to reach new neutron-rich heavy and superheavy nuclei, which are not accessible in other reactions. We compare our results with data from earlier experiments and discuss limitations and future perspectives of the method.
Mastromarco, M.*; Manna, A.*; Aberle, O.*; Andrzejewski, J.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他116名*
European Physical Journal A, 55(1), p.9_1 - 9_20, 2019/01
Neutron capture cross section measurements on Gd and Gd were performed using the time-of-flight technique at the n_TOF facility at CERN on isotopically enriched samples. The measurements were carried out in the n TOF experimental area EAR1, at 185m from the neutron source, with an array of 4 CD liquid scintillation detectors. At a neutron kinetic energy of 0.0253eV, capture cross sections of 62.2(2.2) and 239.8(8.4) kilobarn have been derived for Gd and Gd, respectively, with up to 6% deviation relative to values presently reported in nuclear data libraries, but consistent with those values within 1.6 standard deviations. A resonance shape analysis has been performed in the resolved resonance region up to 181eV and 307eV, respectively for Gd and Gd, where on average, resonance parameters have been found in good agreement with evaluations. Above these energies and up to 1keV, the observed resonance-like structure of the cross section has been analysed and characterised. From a statistical analysis of the observed neutron resonances we deduced: neutron strength function of 2.01(28) 10 and 2.17(41) 10; average total radiative width of 106.8(14)meV and 101.1(20)meV and s-wave resonance spacing 1.6(2)eV and 4.8(5)eV for n + Gd and n + Gd systems, respectively.
Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他175名*
European Physical Journal C, 78(11), p.928_1 - 928_8, 2018/11
We report evidence for the charged charmed-strange baryon with a signal significance of 3.9 with systematic errors included. The charged is found in its decay to in the substructure of decays. The measured mass and width are ~MeV/ and ~MeV, respectively, and the product branching fraction is . We also measure with greater precision than previous experiments, and present the results of a search for the charmonium-like state and its spin partner, , in the invariant mass spectrum. No clear signals of the or are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of pairs collected at the resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
岩元 大樹; Stankovskiy, A.*; Fiorito, L.*; Van den Eynde, G.*
European Physical Journal; Nuclear Sciences & Technologies (Internet), 4, p.42_1 - 42_7, 2018/11
Tamponi, U.*; 谷田 聖; Belle Collaboration*; 他174名*
European Physical Journal C, 78(8), p.633_1 - 633_10, 2018/08
We study bottomonium production in association with an meson in annihilations near the , at a center of mass energy of GeV. The results are based on the fb data sample collected by the Belle experiment at the asymmetric energy KEKB collider. Only the meson is reconstructed and the missing-mass spectrum of candidates is investigated. We observe the process and find evidence for the process, while no significant signals of , , nor are found. Cross sections for the studied processes are reported.
Li, Y. B.*; 谷田 聖; Belle Collaboration*; 他178名*
European Physical Journal C, 78(3), p.252_1 - 252_8, 2018/03
We report the first observation of the charmed-strange baryon with a significance greater than 5. The is found in its decay to in decays. The measured mass and width are MeV/ and MeV, respectively, and the product branching fraction is =. We also measure with improved precision, and search for the charmonium-like state and its spin partner, , in the invariant mass spectrum. No clear signals of the nor its spin partner are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of pairs collected at the resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
Lund, M. V.*; Andreyev, A.; Borge, M. J. G.*; Cederkll, J.*; De Witte, H.*; Fraile, L. M.*; Fynbo, H. O. U.*; Greenlees, P. T.*; Harkness-Brennan, L. J.*; Howard, A. M.*; et al.
European Physical Journal A, 52(10), p.304_1 - 304_14, 2016/10
Beta-delayed proton emission from Mg has been measured at ISOLDE, CERN, with the ISOLDE Decay Station setup including both charged-particle and -ray detection capabilities. A total of 27 delayed proton branches were measured including seven so far unobserved. An updated decay scheme, including three new resonances above the proton separation energy in Na and more precise resonance energies, is presented. Beta-decay feeding to two resonances above the Isobaric Analogue State in Na is observed. This may allow studies of the 4032.9(2.4) keV resonance in Ne through the beta decay of Mg, which is important for the astrophysically relevant reaction O(,)Ne. Beta-delayed protons were used to obtain a more precise value for the half-life of Mg, 91.4(1.0) ms.
Gunsing, F.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他141名*
European Physical Journal Plus (Internet), 131(10), p.371_1 - 371_13, 2016/10
Nuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. CERN's neutron time-of-flight facility, n_TOF, has produced a considerable amount of experimental data since it has become fully operational with the start of the scientific measurement program in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at n_TOF will be presented.
Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; Mnzenberg, G.*; Antalic, S.*; Barth, W.*; Burkhard, K. G.*; Dahl, L.*; Eberhardt, K.*; et al.
European Physical Journal A, 52(6), p.180_1 - 180_34, 2016/06
The reaction Cr+Cm was investigated at the velocity filter SHIP at GSI with the intention to study production and decay properties of isotopes of element 120. Three correlated signals were measured, which occurred within a period of 279 ms. The heights of the signals correspond with the expectations for a decay sequence starting with an isotope of element 120. However, a complete decay chain cannot be established, since a signal from the implantation of the evaporation residue cannot be identified unambiguously. Measured properties of the event chain are discussed in detail. The result is compared with theoretical predictions. Previously measured decay properties of even element super-heavy nuclei were compiled in order to find arguments for an assignment from the systematics of experimental data. In the course of this review, a few tentatively assigned data could be corrected. New interpretations are given for results which could not be assigned definitely in previous studies. The discussion revealed that the cross-section for production of element 120 could be high enough so that a successful experiment seems possible with presently available techniques. However, a continuation of the experiment at SHIP for a necessary confirmation of the results obtained in a relatively short irradiation of five weeks is not possible at GSI presently. In the summary and outlook section we also present concepts for the continuation of research in the field of super-heavy nuclei.
Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; Mnzenberg, G.*; Antalic, S.*; Barth, W.*; Dahl, L.*; Eberhardt, K.*; Grzywacz, R.*; et al.
European Physical Journal A, 52(4), p.116_1 - 116_12, 2016/04
Shell-correction energies of super-heavy nuclei are approximated by using Q values of measured decay chains. Five decay chains were analyzed, which start at the isotopes Fl, 118, Lv, Lv and Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far.
木村 敦; 原田 秀郎; 中村 詔司; 岩本 修; 藤 暢輔; 小泉 光生; 北谷 文人; 古高 和禎; 井頭 政之*; 片渕 竜也*; et al.
European Physical Journal A, 51(12), p.180_1 - 180_8, 2015/12
In order to improve the data accuracy of neutron-capture cross sections of minor actinides (MAs) and long-lived fission products (LLFPs), a new experimental instrument named "Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI)" has been constructed in the Materials and Life science experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), and measurements of neutron-capture cross sections of MAs, LLFPs and some stable isotopes with high intensity pulsed neutrons have been started. The analyses for Cm, Cm, Am and Np were finished; those for I, Pd, Tc, Zr and some stable isotopes are in progress. These results will make significant contributions in the field of developing innovative nuclear systems.
渡部 創; 佐野 雄一; 野村 和則; 駒 義和; 岡本 芳浩
European Physical Journal; Nuclear Sciences & Technologies (Internet), 1, p.9_1 - 9_8, 2015/12
In the extraction chromatography system, accumulation of hydrogen gas in the chromatography column is suspected to lead to fire or explosion. In order to prevent the hazardous accidents, it is necessary to evaluate behaviors of gas radiolytically generated inside the column. In this study, behaviors of gas inside the extraction chromatography column were investigated through experiments and Computation Fluid Dynamics (CFD) simulation. N gas once accumulated as bubbles in the packed bed was hardly discharged by the flow of mobile phase. However, the CFD simulation and X-ray imaging on -ray irradiated column revealed that during operation the hydrogen gas generated in the column was dissolved into the mobile phase without accumulation and discharged.
Steiger, K.*; 西村 俊二*; Li, Z.*; Gernhuser, R.*; 宇都野 穣; Chen, R.*; Faestermann, T.*; Hinke, C.*; Krcken, R.*; 西村 美月*; et al.
European Physical Journal A, 51(9), p.117_1 - 117_9, 2015/09
Sambi, S.*; Raabe, R.*; Borge, M. J. G.*; Caamano, M.*; Damoy, S.*; Fernndez-Domnguez, B.*; Flavigny, F.*; Fynbo, H.*; Gibelin, J.*; Grinyer, G. F.*; et al.
European Physical Journal A, 51(3), p.25_1 - 25_7, 2015/03
In a proof-of-principle experiment, the Maya active target detector was employed to study the C(p,p) resonant elastic scattering reaction in inverse kinematics. The excitation energy region from 0 to 3 MeV above the proton-breakup threshold in N was investigated in a single experiment. The excitation spectrum of N was fitted using R-matrix formalism. The level parameters extracted are in good agreement with previous studies. The active target proved its potential for the study of resonant elastic scattering in inverse kinematics with radioactive beams, when detection efficiency is of primary importance.
Zhao, Y.; 小泉 智; 山口 大輔; 近藤 哲男*
European Physical Journal E, 37(12), p.129_1 - 129_12, 2014/12
We present a time-resolved investigation of the natural drying process of microbial cellulose (MC) by means of simultaneous small-angle neutron scattering (SANS), intermediate-angle neutron scattering (IANS) and weighing techniques. SANS was used to elucidate the microscopic structure of the MC sample. The coherent scattering length density of the water penetrating amorphous domains varied with time during the drying process to give a tunable scattering contrast to the water-resistant cellulose crystallites, thus the contrast variation was automatically performed by simply drying.
Grassi, A.*; Fedeli, L.*; Macchi, A.*; Bulanov, S. V.; Pegoraro, F.*
European Physical Journal D, 68(6), p.178_1 - 178_8, 2014/06
The relativistic Vlasov equation is integrated numerically in order to investigate the phase space development of the wave break of a relativistic Langmuir wave in a thermal plasma. Relativistic effects lead to a differential retardation in the time required by the electrons to evolve in phase space, the largest momentum electron staking the longest time. This leads to the formation of long lasting spikes in momentum space at the wave break position that propagates with a velocity close to the speed of light and to extremely steep density jumps in coordinate space.
羽島 良一; 早川 岳人; 静間 俊行; Angell, C.; 永井 良治; 西森 信行; 沢村 勝; 松葉 俊哉; 小菅 淳*; 森 道昭; et al.
European Physical Journal; Special Topics, 223(6), p.1229 - 1236, 2014/05
Generation of energy-tunable -rays via laser Compton scattering is of great interest for applications of MeV photons -which interact with nuclei- and scientific studies. One of the promising applications of such energy-tunable -rays is the nondestructive detection and assay of nuclides, which are necessary for nuclear security and safeguards. We are developing technologies relevant to -ray nondestructive detection and assay, which include a high-brightness -ray source based on modern laser and accelerator technologies, and -ray measurement methods optimized for highly radioactive samples.
Becker, B.*; Kopecky, S.*; 原田 秀郎; Schillebeeckx, P.*
European Physical Journal Plus (Internet), 129(4), p.58_1 - 58_9, 2014/04
A measurement of the uncollided neutron flux passing through a sample containing a stochastic mixture of tungsten and sulfur grains has been performed using neutron resonance transmission analysis in the 3-200 eV energy region. The impact of the heterogeneous characteristic of the sample is shown based on a comparison of the measurement with a calculated transmission spectrum of a homogeneous sample, which was verified by a measurement with a homogeneous metallic disc. By using a single strong resonance of tungsten, the particle self-shielding factor between 0.2-0.9 was directly measured. The experimental data have been compared with model calculations using the Markovian Levermore-Pomraning model. The measured transmission has been used to determine the effective characteristic chord length and volume fraction of the tungsten grains within the sample.