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論文

Neutron-induced damage simulations; Beyond defect production cross-section, displacement per atom and iron-based metrics

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。

論文

Measurement of thermal neutron capture cross section of $$^{71}$$Ga with dual monitor foils and covariance analysis

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

ENDF/B-VIIIなど多くの評価済データライブラリで$$^{71}$$Gaの熱中性子捕獲断面積を4.7b前後と評価している一方、JENDL-4.0では約20%低い値の3.71bと評価している。これらの断面積データの多くは、絶対値を決定するモニター箔を用いた放射化測定で得られたものであるが、古い年代のものが多く、結果は採用されるモニター箔に依存している可能性がある。そこで、$$^{71}$$Gaの熱中性子捕獲断面積を複数のモニター箔を用いて再測定した。本実験では、コンクリートで減速したAm-Be線源からの中性子を、$$^{71}$$Ga箔と$$^{197}$$Au及び$$^{55}$$Mnのモニター箔を組み合わせた試料に照射し、放射化した箔から放出される$$gamma$$線をゲルマニウム検出器で測定した。ここで、試料中の中性子の自己遮蔽効果を粒子・重イオン輸送計算コードPHITSを用いて計算したところ、0.1%以下と寄与が小さいことが分かった。この結果も参照して、AuとMnの測定結果から共分散行列の非対角化成分を導出し、これを用いて$$^{71}$$Gaの熱中性子断面積の重みつき平均とその不確かさを導出した。その結果、$$^{71}$$Gaの熱中性子断面積として4.05$$pm$$0.27bとなり、JENDL-4.0の値3.71bに近い値を得た。

論文

Population of nuclides with Z$$ge$$98 in multi-nucleon transfer reactions of $$^{48}$$Ca+$$^{248}$$Cm

Devaraja, H. M.*; Heinz, S.*; Beliuskina, O.*; Hofmann, S.*; Hornung, C.*; M$"u$nzenberg, 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

 被引用回数:1 パーセンタイル:14.11(Physics, Nuclear)

The results for nuclei above curium, produced in multi-nucleon transfer reactions of $$^{48}$$Ca+$$^{248}$$Cm at the velocity filter SHIP of GSI Darmstadt, are presented. Spontaneous fission and $$alpha$$ 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 $$ge$$ 98; among them a weak 224 millisecond activity which we tentatively attributed to $$^{260}$$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.

論文

Cross section measurements of $$^{155,157}$$Gd(n,$$gamma$$) induced by thermal and epithermal neutrons

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 $$^{155}$$Gd and $$^{157}$$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 C$$_6$$D$$_6$$ 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 $$^{155}$$Gd and $$^{157}$$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 $$^{155}$$Gd and $$^{157}$$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) $$times$$ 10$$^{-4}$$ and 2.17(41) $$times$$ 10$$^{-4}$$; 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 + $$^{155}$$Gd and n + $$^{157}$$Gd systems, respectively.

論文

Evidence of a structure in $$bar{K}^{0} Lambda _{c}^{+}$$ consistent with a charged $$Xi _c(2930)^{+}$$, and updated measurement of $$bar{B}^{0} rightarrow bar{K}^{0} Lambda _{c}^{+} bar{Lambda }_{c}^{-}$$ at Belle

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 $$Xi_{c}(2930)^+$$ with a signal significance of 3.9$$sigma$$ with systematic errors included. The charged $$Xi_{c}(2930)^+$$ is found in its decay to $$K_{S}^{0} Lambda_{c}^+$$ in the substructure of $$bar{B}^{0} to K^{0}_{S} Lambda_{c}^{+} bar{Lambda}_{c}^{-}$$ decays. The measured mass and width are $$[2942.3 pm 4.4 (rm stat.) pm 1.5(rm syst.)]$$~MeV/$$c^{2}$$ and $$[14.8 pm 8.8(rm stat.) pm 2.5(rm syst.)]$$~MeV, respectively, and the product branching fraction is $${cal B}(bar{B}^{0} to Xi_c(2930)^{+} bar{Lambda}_{c}^{-})$$ $${cal B}(Xi_c(2930)^{+}to bar{K}^{0} Lambda_{c}^{+})=[2.37 pm 0.51 (rm stat.)pm 0.31(rm syst.)]times 10^{-4}$$. We also measure $${cal B}(bar{B}^{0} to bar{K}^{0} Lambda_{c}^{+} bar{Lambda}_{c}^{-}) = [3.99 pm 0.76(rm stat.) pm 0.51(rm syst.)] times 10^{-4}$$ with greater precision than previous experiments, and present the results of a search for the charmonium-like state $$Y(4660)$$ and its spin partner, $$Y_{eta}$$, in the $$Lambda_{c}^{+}bar{Lambda}_{c}^{-}$$ invariant mass spectrum. No clear signals of the $$Y(4660)$$ or $$Y_{eta}$$ 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 $$(772pm11)times 10^{6} Bbar{B}$$ pairs collected at the $$Upsilon(4S)$$ resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.

論文

Sensitivity and uncertainty analysis of $$beta_{rm eff}$$ for MYRRHA using a Monte Carlo technique

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

実効遅発中性子割合$$beta_{rm eff}$$は、原子炉の核設計において最も重要な安全パラメータの一つであり、その値は核データに起因する不確かさを含めて評価することが求められている。本研究では、モンテカルロ粒子輸送計算コードMCNPを用いて、鉛ビスマス冷却核変換研究炉MYRRHA臨界炉心及び未臨界炉心の$$beta_{rm eff}$$に対する感度解析及び不確かさ解析を実施した。感度解析では、千葉により提案された「修正中性子増倍率比法」を用いて$$beta_{rm eff}$$の感度係数を求めた。$$beta_{rm eff}$$の感度係数に対する本手法で導入されたスケーリング因子の依存性を統計的不確かさ低減の観点から調査した結果、感度解析および不確かさ解析に対するスケーリング因子の最適な値は$$20$$であることがわかった。このスケーリング因子を用いて求めた$$beta_{rm eff}$$の感度係数及びJENDL-4.0を一部修正したJENDL-4.0uの共分散データを用いて、MYRRHA臨界炉心及び未臨界炉心の核データに起因する不確かさを求めた。それらの値はそれぞれ2.2$$pm$$0.2%および2.0$$pm$$0.2%と評価され、その大部分は$$^{239}$$Pu及び$$^{238}$$Uの遅発中性子収率に起因することがわかった。

論文

Inclusive study of bottomonium production in association with an $$eta $$ meson in $$e^+e^-$$ annihilations near $$Upsilon (5S)$$

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 $$eta$$ meson in $$e^+e^-$$ annihilations near the $$Upsilon(5S)$$, at a center of mass energy of $$sqrt{s}=10.866,$$GeV. The results are based on the $$121.4,$$fb$$^{-1}$$ data sample collected by the Belle experiment at the asymmetric energy KEKB collider. Only the $$eta$$ meson is reconstructed and the missing-mass spectrum of $$eta$$ candidates is investigated. We observe the $$e^+e^-toetaUpsilon_J(1D)$$ process and find evidence for the $$e^+e^-toetaUpsilon(2S)$$ process, while no significant signals of $$Upsilon(1S)$$, $$h_b(1P)$$, nor $$h_b(2P)$$ are found. Cross sections for the studied processes are reported.

論文

Observation of $$Xi_{c}(2930)^0$$ and updated measurement of $$B^{-} to K^{-} Lambda_{c}^{+} bar{Lambda}_{c}^{-}$$ at Belle

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 $$Xi_{c}(2930)^0$$ charmed-strange baryon with a significance greater than 5$$sigma$$. The $$Xi_{c}(2930)^0$$ is found in its decay to $$K^- Lambda_{c}^+$$ in $$B^{-} to K^{-} Lambda_{c}^{+} bar{Lambda}_{c}^{-}$$ decays. The measured mass and width are $$[2928.9 pm 3.0(rm stat.)^{+0.9}_{-12.0}(rm syst.)]$$ MeV/$$c^{2}$$ and $$[19.5 pm 8.4(rm stat.) ^{+5.9}_{-7.9}(rm syst.)]$$ MeV, respectively, and the product branching fraction is $${cal B}(B^{-} to Xi_{c}(2930)^0 bar{Lambda}_{c}^{-})$$$$ {cal B}(Xi_{c}(2930)^0 to K^- Lambda_{c}^{+})$$=$$[1.73 pm 0.45(rm stat.) pm 0.21(rm syst.)] times 10^{-4}$$. We also measure $${cal B}(B^{-} to K^{-} Lambda_{c}^{+} bar{Lambda}_{c}^{-}) = [4.80 pm 0.43(rm stat.) pm 0.60(rm syst.)] times 10^{-4}$$ with improved precision, and search for the charmonium-like state $$Y(4660)$$ and its spin partner, $$Y_{eta}$$, in the $$Lambda_{c}^{+}bar{Lambda}_{c}^{-}$$ invariant mass spectrum. No clear signals of the $$Y(4660)$$ 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 $$(772pm11)times 10^{6} Bbar{B}$$ pairs collected at the $$Upsilon(4S)$$ resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.

論文

Beta-delayed proton emission from $$^{20}$$Mg

Lund, M. V.*; Andreyev, A.; Borge, M. J. G.*; Cederk$"a$ll, 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

 被引用回数:8 パーセンタイル:22.35(Physics, Nuclear)

Beta-delayed proton emission from $$^{20}$$Mg has been measured at ISOLDE, CERN, with the ISOLDE Decay Station setup including both charged-particle and $$gamma$$-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 $$^{20}$$Na and more precise resonance energies, is presented. Beta-decay feeding to two resonances above the Isobaric Analogue State in $$^{20}$$Na is observed. This may allow studies of the 4032.9(2.4) keV resonance in $$^{19}$$Ne through the beta decay of $$^{20}$$Mg, which is important for the astrophysically relevant reaction $$^{15}$$O($$alpha$$,$$gamma$$)$$^{19}$$Ne. Beta-delayed protons were used to obtain a more precise value for the half-life of $$^{20}$$Mg, 91.4(1.0) ms.

論文

Nuclear data activities at the n_TOF facility at CERN

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

 被引用回数:9 パーセンタイル:45.56(Physics, Multidisciplinary)

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.

論文

Review of even element super-heavy nuclei and search for element 120

Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; M$"u$nzenberg, 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

 被引用回数:59 パーセンタイル:7.58(Physics, Nuclear)

The reaction $$^{54}$$Cr+$$^{248}$$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.

論文

Remarks on the fission barriers of super-heavy nuclei

Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; M$"u$nzenberg, 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

 被引用回数:14 パーセンタイル:10.27(Physics, Nuclear)

Shell-correction energies of super-heavy nuclei are approximated by using Q$$_{alpha}$$ values of measured decay chains. Five decay chains were analyzed, which start at the isotopes $$^{285}$$Fl, $$^{294}$$118, $$^{291}$$Lv, $$^{292}$$Lv and $$^{293}$$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.

論文

Current activities and future plans for nuclear data measurements at J-PARC

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

 パーセンタイル:100(Physics, Nuclear)

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 $$^{244}$$Cm, $$^{246}$$Cm, $$^{241}$$Am and $$^{237}$$Np were finished; those for $$^{129}$$I, $$^{107}$$Pd, $$^{99}$$Tc, $$^{93}$$Zr and some stable isotopes are in progress. These results will make significant contributions in the field of developing innovative nuclear systems.

論文

Safety operation of chromatography column system with discharging hydrogen radiolytically generated

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$$_{2}$$ 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 $$gamma$$-ray irradiated column revealed that during operation the hydrogen gas generated in the column was dissolved into the mobile phase without accumulation and discharged.

論文

Nuclear structure of $$^{37,38}$$Si investigated by decay spectroscopy of $$^{37,38}$$Al

Steiger, K.*; 西村 俊二*; Li, Z.*; Gernh$"a$user, R.*; 宇都野 穣; Chen, R.*; Faestermann, T.*; Hinke, C.*; Kr$"u$cken, R.*; 西村 美月*; et al.

European Physical Journal A, 51(9), p.117_1 - 117_9, 2015/09

 被引用回数:5 パーセンタイル:45.25(Physics, Nuclear)

中性子数20領域の中性子過剰核では、魔法数20が消滅することが知られ、殻構造の変化が起きていると考えられている。この論文では、この領域の殻構造をより直接的に調べるため、$$^{37,38}$$Si核の準位構造を$$^{37,38}$$Al核のベータ崩壊によって調べた結果を報告する。$$^{37,38}$$Alを理化学研究所RIBFを用いて生成し、そこからのベータ崩壊後の$$gamma$$線を観測することによって、$$^{37,38}$$Si核の低励起状態の準位構造を得た。$$^{37}$$Siの717keVと1270keVに強く遷移することから、これらの準位は正パリティ状態と同定された。実験で得られた準位構造は殻模型計算によってよく再現され、717keVと1270keVはそれぞれ$$3/2^+$$, $$5/2^+$$に対応することがわかった。この結果は、最近の殻模型相互作用が与える殻構造変化を確かめるものである。

論文

$$^{12}$$C + p resonant elastic scattering in the Maya active target

Sambi, S.*; Raabe, R.*; Borge, M. J. G.*; Caamano, M.*; Damoy, S.*; Fern$'a$ndez-Dom$'i$nguez, 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

 被引用回数:5 パーセンタイル:45.25(Physics, Nuclear)

In a proof-of-principle experiment, the Maya active target detector was employed to study the $$^{12}$$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 $$^{13}$$N was investigated in a single experiment. The excitation spectrum of $$^{13}$$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.

論文

Hierarchical structure in microbial cellulose; What happens during the drying process

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

 被引用回数:5 パーセンタイル:64.81(Chemistry, Physical)

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.

論文

Phase space dynamics after the breaking of a relativistic Langmuir wave in a thermal plasma

Grassi, A.*; Fedeli, L.*; Macchi, A.*; Bulanov, S. V.; Pegoraro, F.*

European Physical Journal D, 68(6), p.178_1 - 178_8, 2014/06

 被引用回数:6 パーセンタイル:51.09(Optics)

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.

論文

Application of laser Compton scattered $$gamma$$-ray beams to nondestructive detection and assay of nuclear material

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

 被引用回数:9 パーセンタイル:55.89(Physics, Multidisciplinary)

Generation of energy-tunable $$gamma$$-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 $$gamma$$-rays is the nondestructive detection and assay of nuclides, which are necessary for nuclear security and safeguards. We are developing technologies relevant to $$gamma$$-ray nondestructive detection and assay, which include a high-brightness $$gamma$$-ray source based on modern laser and accelerator technologies, and $$gamma$$-ray measurement methods optimized for highly radioactive samples.

論文

Measurement of the direct particle transport through stochastic media using neutron resonance transmission analysis

Becker, B.*; Kopecky, S.*; 原田 秀郎; Schillebeeckx, P.*

European Physical Journal Plus (Internet), 129(4), p.58_1 - 58_9, 2014/04

 被引用回数:11 パーセンタイル:28.13(Physics, Multidisciplinary)

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.

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