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Chen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; 角田 佑介*; 大塚 孝治*; 茶園 亮樹*; Hagen, G.*; Holt, J. D.*; et al.
Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08
Scからの1陽子ノックアウト反応を用いて、
Caと
Caのガンマ崩壊を観測した。
Caでは1456(12)keVの
線遷移が、
Caでは1115(34)keVの遷移が観測された。どちらの遷移も暫定的に
と割り当てられた。有効核子間相互作用をわずかに修正した広い模型空間での殻模型計算では、
準位エネルギー、2中性子分離エネルギー、反応断面積が実験とよく一致し、N=34閉殻の上に新しい殻が形成されていることを裏付けた。その構成要素である
と
軌道はほぼ縮退しており、これは
Caが二重魔法核である可能性を排除し、Ca同位体のドリップラインを
Caあるいはそれ以上にまで広げる可能性がある。
Wang, H.*; 安田 昌弘*; 近藤 洋介*; 中村 隆司*; Tostevin, J. A.*; 緒方 一介*; 大塚 孝治*; Poves, A.*; 清水 則孝*; 吉田 数貴; et al.
Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08
Neからの1中性子除去反応を用いて、
Neの詳細な
線分光を行った。平行運動量分布の解析に基づき、
Neの準位構造とスピンパリティを決定し、初めて負のパリティ状態を同定した。測定された断面積と運動量分布から、N=20とN=28のシェルギャップの消失の証拠となる有意なintruder p-wave強度が明らかになった。束縛状態については、弱いf-waveの可能性のある強度が観測された。いくつかの有効相互作用を用いた大規模殻模型計算では、実験的に観測された大きなp-wave強度と小さなf-wave強度は再現されず、Ne同位体に沿った反転の島への遷移の完全な理論的記述への挑戦が続いていることを示している。
Rossi, F.; 小泉 光生; Rodriguez, D.; 高橋 時音
Proceedings of INMM & ESARDA Joint Annual Meeting 2023 (Internet), 5 Pages, 2023/05
Since 2015, the Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) of the Japan Atomic Energy Agency has been working on the development of the Delayed Gamma-ray Spectroscopy non-destructive assay technique for the quantification of fissile-nuclide content in mixed nuclear materials. Thanks to the efforts and lessons learned from past experiments, the ISCN has successfully designed and fabricated a final integrated instrument. The instrument is composed of a moderator and dose shield where different neutron sources, like Cf-252 and neutron generators, can be inserted to irradiate the sample. Within the moderator, a series of neutron detectors are installed for perform prompt neutron analysis and continuous monitoring of the neutron source emission. Thanks to an innovative transfer system, the sample is then moved to the gamma-ray detector in less than 1.5s providing a fast and reliable movement while being safe from possible contamination. In this work, we will describe the design details of this new instrument. This work is supported by the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT) under the subsidy for the "promotion for strengthening nuclear security and the like".
Elekes, Z.*; Juhsz, M. M.*; Sohler, D.*; Sieja, K.*; 吉田 数貴; 緒方 一介*; Doornenbal, P.*; Obertelli, A.*; Achouri, N. L.*; 馬場 秀忠*; et al.
Physical Review C, 106(6), p.064321_1 - 064321_10, 2022/12
被引用回数:0 パーセンタイル:0.02(Physics, Nuclear)Vと
Vの低励起準位構造を初めて探索した。
Vについては中性子ノックアウト反応と陽子非弾性散乱が、
Vについては中性子ノックアウト反応データが得られた。
Vについては4つ、
Vについては5つの新たな遷移が確認された。Lenzi-Nowacki-Poves-Sieja (LNPS)相互作用に基づく殻模型計算との比較によって、それぞれの同位体について確認されたガンマ線のうち3つが、first 11/2
状態とfirst 9/2
状態からの崩壊と決定された。
Vについては、(
,
)非弾性散乱断面積は四重極変形と十六重極変形を想定したチャネル結合法により解析されたが、十六重極変形の影響により、明確に反転の島に属するとは決定できなかった。
Enciu, M.*; Liu, H. N.*; Obertelli, A.*; Doornenbal, P.*; Nowacki, F.*; 緒方 一介*; Poves, A.*; 吉田 数貴; Achouri, N. L.*; 馬場 秀忠*; et al.
Physical Review Letters, 129(26), p.262501_1 - 262501_7, 2022/12
被引用回数:0 パーセンタイル:0(Physics, Multidisciplinary)230MeV/nucleonでの
Caからの中性子ノックアウト反応が
線分光と行われ、
と
軌道からの中性子ノックアウト反応の運動量分布が測定された。断面積は
の閉殻と整合し、Ca同位体での
と
閉殻と同程度に強い閉殻であることが確認された。運動量分布の分析から
と
軌道の平均二乗根半径の差は0.61(23)fmと決定され、これはmodified-shell-modelによる予言の0.7fmと整合した。これは、中性子過剰なCa同位体での
軌道半径が大きいことが、中性子数にしたがって線形的に荷電半径が増える意外な現象の原因であることを示唆している。
Rossi, F.; 小泉 光生; Rodriguez, D.; 高橋 時音
Proceedings of INMM 63rd Annual Meeting (Internet), 5 Pages, 2022/07
With the initial goal of fissile-nuclide content quantification in small samples containing uranium and plutonium, the Integrated Support Center for Nuclear Nonproliferation and Nuclear Security of the Japan Atomic Energy Agency is developing the Delayed Gamma-ray Spectroscopy non-destructive assay technique. For this, while in the past years several experiments were conducted to prove the feasibility of the technique, a new instrument was designed considering the previous lessons learned. It includes a modular insertion for different neutron sources, like radioisotopes or neutron generators; a gamma-ray detector with improved data acquisition system allowing for real-time dead-time correction; and a full new mechanism for the sample transfer between irradiation and measurement. Together with this, neutron detectors are integrated to supplement the DGS mass analysis and monitor the source intensity. In this work, we will describe the new instrument and the preliminary results obtained from instrument characterization compared to previous experiments. This work is supported by the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT) under the subsidy for the "promotion for strengthening nuclear security and the like". This work was done under the agreement between JAEA and EURATOM in the field of nuclear material safeguards research and development.
小岩井 拓真*; Wimmer, K.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Duguet, T.*; Holt, J. D.*; 宮城 宇志*; Navrtil, P.*; 緒方 一介*; et al.
Physics Letters B, 827, p.136953_1 - 136953_7, 2022/04
被引用回数:2 パーセンタイル:66.35(Astronomy & Astrophysics)中性子過剰核Caでは、新魔法数34が発見されて以来、その構造を知るために多くの実験がなされてきたが、それを超える中性子過剰核の情報は全く知られてこなかった。本論文では、理化学研究所RIBFにて
K,
Ca,
Caの励起状態から脱励起するガンマ線を初めて観測した結果を報告した。それぞれ1つのガンマ線しか得られなかったものの、
Kおよび
Caのデータは、それぞれ、陽子の
と
軌道間のエネルギー差、中性子の
と
軌道間のエネルギー差を敏感に反映し、両方とも最新の殻模型計算によって200keV程度の精度で再現できることがわかった。また、1粒子状態の程度を特徴づける分光学的因子を実験データと歪曲波インパルス近似による反応計算から求め、その値も殻模型計算の値と矛盾しないことがわかった。
Rodriguez, D.; Abbas, K.*; 小泉 光生; Nonneman, S.*; Rossi, F.; 高橋 時音
Nuclear Instruments and Methods in Physics Research A, 1014, p.165685_1 - 165685_10, 2021/10
被引用回数:2 パーセンタイル:41.25(Instruments & Instrumentation)Under the MEXT subsidy on research for improving nuclear security related development, we designed the Delayed Gamma-ray Californium Test (DGCT) instrument. From He-3 count-rate experiments performed in collaboration with the European Commission Joint Research Centre, we show the effective neutron flux entering the sample space. Further, we show delayed gamma-ray spectra of both U and Pu samples as well as a comparison to the background from Cf activation of the environment. Finally, we make comparisons to earlier spectra obtained using PUNITA, including relative fission capability, spectral signature, and mass correlations.
Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; Gmez-Ramos, M.*; et al.
Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10
被引用回数:3 パーセンタイル:54.62(Physics, Nuclear)理化学研究所のRIビームファクトリーにて中性子過剰Clの励起状態を
Arからのノックアウト反応によって生成し、脱励起ガンマ線からそのエネルギー準位を測定した。また、陽子ノックアウトの運動量分布から
Clの基底状態が
であることがわかった。その結果を大規模殻模型計算およびいくつかの第一原理計算と比較した。
Cl同位体の基底状態および第一励起状態は、計算で用いた相互作用に敏感であることがわかった。それは、陽子の一粒子エネルギーと四重極集団運動との複雑な結合によるためであると考えられる。
Rossi, F.; Abbas, K.*; 小泉 光生; Lee, H.-J.; Rodriguez, D.; 高橋 時音
Proceedings of INMM & ESARDA Joint Virtual Annual Meeting (Internet), 7 Pages, 2021/08
The Japan Atomic Energy Agency is developing the Delayed Gamma-ray Spectroscopy (DGS) non-destructive assay technique to quantify the fissile-nuclide content in small samples of mixed nuclear materials. One of our primary goals is to develop a compact and efficient DGS instrument to be easily installable into analytical laboratories. The instrument should include an external neutron source and a gamma-ray detection system along with other supporting systems like sample transfer and neutron monitoring. One of the challenges is to design a compact and efficient moderator for commercial neutron sources (e.g. neutron generators or sealed radioactive sources) that emit neutrons with high energy. However, to be able to enhance the gamma-ray signal from fissile materials, thermal neutrons are best due to their higher fission cross-sections. The choice of viable neutron source (neutron spectrum and strength) depends on several considerations (e.g. sample type and interrogation pattern), but also affect the gamma-ray measurement and the consequence analysis. In this work, we will first describe the evaluation results of our Delayed Gamma-ray Test Spectrometer using a Cf source (DGTS-C) from the first experiment carried out in PERLA in collaboration with the European Commission, Joint Research Centre. In association, we will describe how it provided guidance for our demonstration irradiator. Further, we will present our final moderator design concept for a deuterium-deuterium (D-D) neutron generator and present the latest results of data-model comparisons, including those with our PUNITA results. This work is supported by the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT) under the subsidy for the "promotion for strengthening nuclear security and the like". This work was done under the agreement between JAEA and EURATOM in the field of nuclear material safeguards research and development.
Tohamy, M.*; Abbas, K.*; Nonneman, S.*; Rodriguez, D.; Rossi, F.
Applied Radiation and Isotopes, 173, p.109694_1 - 109694_7, 2021/07
被引用回数:5 パーセンタイル:72.97(Chemistry, Inorganic & Nuclear)An experiment to evaluate a neutron flux for an irradiator using Cf was performed by the EC-JRC by applying the Westcott method to indium and gold activation foils. ISCN DG members subsequently developed an MCNP model for a flux comparison within the MEXT subsidiary budget for the promotion of applications related to nuclear security. The flux values are able to show values within 10% for the thermal evaluation with larger differences in the resonance peak energies. Contrarily, there are differences in the reaction rate and peak-count data-model comparisons that could provide new opportunities of basic science research.
Browne, F.*; Chen, S.*; Doornenbal, P.*; Obertelli, A.*; 緒方 一介*; 宇都野 穣; 吉田 数貴; Achouri, N. L.*; 馬場 秀忠*; Calvet, D.*; et al.
Physical Review Letters, 126(25), p.252501_1 - 252501_7, 2021/06
被引用回数:8 パーセンタイル:75.01(Physics, Multidisciplinary)理化学研究所RIビームファクトリーにて、中性子過剰核Scからの1陽子ノックアウト反応によって
Caを生成し、そのエネルギー準位と反応断面積をガンマ線分光および不変質量分光によって得た。その結果を歪曲波インパルス近似による核反応計算と大規模殻模型による核構造計算を組み合わせた理論値と比較した。実験の準位と断面積は理論計算によってよく再現された。
Caの正パリティ状態については、基底状態の生成断面積が励起状態のものに比べて圧倒的に大きいという結果が得られた。これは、
Scでは中性子魔法数34が消滅し
Caではその魔法数が存在するというこれまでの知見と一見矛盾するが、対相関による分光学的因子のコヒーレンスから理解することができる。
Rodriguez, D.; Bogucarska, T.*; 小泉 光生; Lee, H.-J.; Pedersen, B.*; Rossi, F.; 高橋 時音; Varasano, G.*
Nuclear Instruments and Methods in Physics Research A, 997, p.165146_1 - 165146_13, 2021/05
被引用回数:1 パーセンタイル:23.07(Instruments & Instrumentation)Under the MEXT subsidy to strengthen nuclear security related research, the ISCN is developing delayed gamma-ray spectroscopy (DGS) for nuclear safeguards. Here we present results from experiments using the PUNITA instrument in collaboration with JRC-Ispra to evaluate the gamma-ray spectral dependence on interrogation time patterns and number of cycles. Specifically, we investigated the observable gamma rays useful to quantify the Pu and
U contributions. Of the time patterns tested in this study, we determined that irradiating the sample for 60-
followed by a gamma-ray measurement of 60-
was the best for a comparable one-hour total interrogation time.
Rossi, F.; 小泉 光生; Rodriguez, D.
Journal of Nuclear Science and Technology, 58(3), p.302 - 314, 2021/03
被引用回数:5 パーセンタイル:58.88(Nuclear Science & Technology)The Japan Atomic Energy Agency is evaluating delayed gamma-ray spectroscopy as an active interrogation nondestructive assay technique to quantify the fissile composition of nuclear materials for improved safeguards verification in nuclear fuel cycle facilities. In this paper, we optimize a moderator to thermalize the 2.5 MeV neutrons emitted from a deuterium-deuterium (D-D) neutron generator. The moderator is optimized to maximize the thermal neutron flux, maintain a high moderator quality factor, and be compact for easy installation in the analytical laboratories of reprocessing facilities. With the objective of applying our system to high-radioactivity nuclear materials (e.g. spent fuel solution), we applied this moderator's flux to an interrogation using delayed gamma-ray spectroscopy for various sample sizes and timing patterns. The results indicate that our 78-cm system is sufficiently able to use commercially available D-D neutron generators with neutron emission rates less than 10
n/s for 25- and 100-ml solutions under specific interrogations. This work is supported by the subsidy for the "promotion of strengthening nuclear security and the like" from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.
Juhsz, M. M.*; Elekes, Z.*; Sohler, D.*; 宇都野 穣; 吉田 数貴; 大塚 孝治*; 緒方 一介*; Doornenbal, P.*; Obertelli, A.*; 馬場 秀忠*; et al.
Physics Letters B, 814, p.136108_1 - 136108_8, 2021/03
被引用回数:3 パーセンタイル:54.62(Astronomy & Astrophysics)(,
)反応と
線分光を用いて
Arの束縛状態と非束縛状態の核構造研究を行った。実験結果と殻模型計算を比較することで、2つの束縛状態と6つの非束縛状態を決定した。
Arの束縛状態を生成する反応断面積が小さいことから、これは中性子数32, 34の顕著なsub-shell closureが存在している確かな証拠と解釈できる。
Rossi, F.; 小泉 光生; Lee, H.-J.; Rodriguez, D.; 高橋 時音; Abbas, K.*; Bogucarska, T.*; Crochemore, J.-M.*; Pedersen, B.*; Varasano, G.*
61st Annual Meeting of the Institute of Nuclear Materials Management (INMM 2020), Vol.2, p.907 - 911, 2021/00
Delayed Gamma-ray Spectroscopy (DGS) is a nondestructive assay technique with the capability to quantify the fissile composition of small nuclear material samples from reprocessing plants. In recent years, the Japan Atomic Energy Agency in collaboration with the Joint Research Centre performed several experiments using uranium and plutonium standard samples. In this paper, we present some of our recent experiment results showing the feasibility of DGS for fissile mass estimation. In particular, we interrogate uranium samples of different enrichment and we are showing that we were able to qualify significant peaks even for a depleted uranium sample above 2.7 MeV. Applying correction factors for neutron self-shielding and gamma self-absorption, we obtained a mass linear correlation when considering total integrated counts above 3.3 MeV as well as specific individual peak counts. This work is supported by the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT) under the subsidy for the "promotion for strengthening nuclear security and the like". This work was done under the agreement between JAEA and EURATOM in the field of nuclear material safeguards research and development.
Corts, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Men
ndez, J.*; 緒方 一介*; Schwenk, A.*; 清水 則孝*; Simonis, J.*; et al.
Physical Review C, 102(6), p.064320_1 - 064320_9, 2020/12
被引用回数:9 パーセンタイル:77.94(Physics, Nuclear)理化学研究所RIBFにおいて、=32同位体である
Arの低励起構造を陽子・中性子ノックアウト反応,多核子剥離反応,陽子非弾性散乱と
線分光によって調査した。すでに知られていた2つに加えて、3
状態の候補を含む5つの状態を新たに確認した。
coincidenceによって得られた準位図は
模型空間での殻模型計算やカイラル2体・3体力による第一原理計算と比較した。陽子・中性子ノックアウト反応断面積の理論との比較により、新たに発見された2つの状態は2
状態であり、また以前に4
とされていた状態も2
であることが示唆された。
Rossi, F.; Bogucarska, T.*; 小泉 光生; Lee, H.-J.; Pedersen, B.*; Rodriguez, D.; 高橋 時音; Varasano, G.*
Nuclear Instruments and Methods in Physics Research A, 977, p.164306_1 - 164306_7, 2020/10
被引用回数:2 パーセンタイル:29.04(Instruments & Instrumentation)The Japan Atomic Energy Agency and the European Commission Joint Research Centre are collaborating to develop delayed gamma-ray spectroscopy (DGS) for nuclear materials for safeguards verification in reprocessing plants. In this paper, we describe DGS interrogation using the Pulsed Neutron Interrogation Test Assembly with standard samples of different U enrichments. By analyzing gamma-ray spectra, we reveal a linear correlation between the sample mass and both the total counts above 3.3 MeV and the peak counts of specific high-energy gamma-ray. We were able to observe, qualify and quantify specific gamma rays peak down to the depleted uranium (0.5 g
U) mass sample. Based on this, we demonstrate that our technique is able to estimate the total fissile mass with a statistical uncertainty
2% when taking into account self-shielding and gamma self-absorption corrections. Using integrated counts above 3.3 MeV we were able to reduce the mass-dependent bias for the higher enrichments (
3 to 4%) to 4%. This work is supported by the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT) under the subsidiary for the "promotion for strengthening nuclear security and the like". This work was done under the agreement between JAEA and EURATOM in the field of nuclear materials safeguards research and development.
Rodriguez, D.; Abbas, K.*; Crochemore, J.-M.*; 小泉 光生; Nonneman, S.*; Pedersen, B.*; Rossi, F.; 瀬谷 道夫*; 高橋 時音
EPJ Web of Conferences, 239, p.17005_1 - 17005_5, 2020/09
被引用回数:0 パーセンタイル:0.1While nondestructive assay techniques would improve the efficiency and time to quantify high-radioactivity nuclear material, there are no passive NDA techniques available to directly verify the U and Pu content. The JAEA and JRC are collaboratively developing the Delayed Gamma-ray Spectroscopy to evaluate the fissile composition from the unique fission product yield distributions. We are developing an Inverse Monte Carlo method that simulates the interrogation and evaluates the individual contributions to the composite spectrum. While the current nuclear data affects the ability to evaluate the composition, the IMC analysis method can be used to determine the systematic uncertainty contributions and has the potential to improve the nuclear data. We will present the current status of the DGS collaborative work as it relates to the development of the DGS IMC analysis.
Rodriguez, D.; 小泉 光生; Rossi, F.; 瀬谷 道夫; 高橋 時音; Bogucarska, T.*; Crochemore, J.-M.*; Pedersen, B.*; 高峰 潤
Journal of Nuclear Science and Technology, 57(8), p.975 - 988, 2020/08
被引用回数:3 パーセンタイル:39.99(Nuclear Science & Technology)Present safeguards verification methods of high-radioactivity nuclear material use destructive analysis techniques since passive nondestructive techniques are incapable of determining the nuclear material content. To improve this verification process, the JAEA and EC-JRC Ispra, Italy have been collaborating to develop delayed gamma-ray spectroscopy for composition analysis of the fissile nuclides as an aspect of the MEXT subsidy for improving nuclear security and the like. Multiple experiments were performed over three years using PUNITA to interrogate U and Pu samples to determine the signature from the short-lived fission products. We observed many gamma rays useful to determine the composition of a mixed nuclear material sample. Presented here are the results of these measurements with correlations to the interrogation, mass, volume, and sample homogeneity.