4,304 research outputs found

    Quantum critical behavior of the hyperkagome magnet Mn3CoSi

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    β-Mn-type family alloys Mn3TX (T = Co, Rh, and Ir; X = Si and Ge) have a three-dimensional antiferromagnetic (AF) corner-shared triangular network, i.e., the hyperkagome lattice. The antiferromagnet Mn3RhSi shows magnetic short-range order over a wide temperature range of approximately 500 K above the Néel temperature TN of 190 K. In this family of compounds, as the lattice parameter decreases, the long-range magnetic ordering temperature decreases. Mn3CoSi has the smallest lattice parameter and the lowest TN in the family. The quantum critical point (QCP) from AF to the quantum paramagnetic state is expected near a cubic lattice parameter of 6.15 Å. Although the Néel temperature of Mn3CoSi is only 140 K, the emergence of the quantum critical behavior in Mn3CoSi is discussed. We study how the magnetic short-range order appears in Mn3CoSi by using neutron scattering, μSR, and bulk characterization such as specific heat capacity. According to the results, the neutron scattering intensity of the magnetic short-range order in Mn3CoSi does not change much at low temperatures from that of Mn3RhSi, although the μSR short-range order temperature of Mn3CoSi is largely suppressed to 240 K from that of Mn3RhSi. Correspondingly, the volume fraction of the magnetic short-range order regions, as shown by the initial asymmetry drop ratio of μSR above TN, also becomes small. Instead, the electronic-specific heat coefficient γ of Mn3CoSi is the largest in this Mn3T Si system, possibly due to the low-energy spin fluctuation near the quantum critical point

    UJI MIKRODOSIMETRI DARI BERKAS NEUTRON DOUBLE LAYER BAM SHAPING ASSEMBLY MENGGUNAKANMETODE MONTE CARLO

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    Double Layer Beam Shaping Assembly (DLBSA) adalah sistem pengolah berkas neutron cepat menjadi neutron epitermal. DLBSA telah menghasilkan berkas neutron epitermal sesuai standar IAEA. Namun DLBSA belum dilakukan uji mikrodosimetri guna mengetahui efek dan respon biologi pada tingkat sel. Penelitian ini bertujuan  untuk menentukan parameter mikrodosimetri  yaitu Linear Energy Transfer (LET)  dan  Relative Biological Effectiveness (RBE). Uji paremeter mikrodosimetri dilakukan menggunakan model mikrosel yang diinteraksikan dengan neutron dari DLBSA. Perhitungan parameter mikrodosimetri dilakukan menggunakan program berbasis monte carlo yaitu Particle Heavy Ion Transport System ( PHITS). Hasil uji mikrodosimetri diperoleh nilai LET dari berkas neutron DLBSA sebesar 100  KeV dan nilai RBE 2,56

    Two superconducting states with broken time-reversal symmetry in FeSe1-xSx

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    Iron-chalcogenide superconductors FeSe1x_{1-x}Sx_x possess unique electronic properties such as non-magnetic nematic order and its quantum critical point. The nature of superconductivity with such nematicity is important for understanding the mechanism of unconventional superconductivity. A recent theory suggested the possible emergence of a fundamentally new class of superconductivity with the so-called Bogoliubov Fermi surfaces (BFSs) in this system. However, such an {\em ultranodal} pair state requires broken time-reversal symmetry (TRS) in the superconducting state, which has not been observed experimentally. Here we report muon spin relaxation (μ\muSR) measurements in FeSe1x_{1-x}Sx_x superconductors for 0x0.220\le x \le 0.22 covering both orthorhombic (nematic) and tetragonal phases. We find that the zero-field muon relaxation rate is enhanced below the superconducting transition temperature TcT_{\rm c} for all compositions, indicating that the superconducting state breaks TRS both in the nematic and tetragonal phases. Moreover, the transverse-field μ\muSR measurements reveal that the superfluid density shows an unexpected and substantial reduction in the tetragonal phase (x>0.17x>0.17). This implies that a significant fraction of electrons remain unpaired in the zero-temperature limit, which cannot be explained by the known unconventional superconducting states with point or line nodes. The time-reversal symmetry breaking and the suppressed superfluid density in the tetragonal phase, together with the reported enhanced zero-energy excitations, are consistent with the ultranodal pair state with BFSs. The present results reveal two different superconducting states with broken TRS separated by the nematic critical point in FeSe1x_{1-x}Sx_x, which calls for the theory of microscopic origins that account for the relation between the nematicity and superconductivity.Comment: 8 pages, 4 figures, typos corrected. Accepted for publication in PNA

    高速炉燃料の再処理工程における燃料集合体の解体技術に関する研究

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    東京都市大学博士(工学)2022年度(令和4年)doctoral thesi

    鉄標的を用いたΞ原子X線測定の研究

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    Tohoku University田村裕和課

    Proceedings of the Specialists' Meeting on “Nuclear Spectroscopy and Condensed Matter Physics Using Short-Lived Nuclei IX”

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    令和5年1月11日開催 (January, 11, 2023)編集 : 小林義男、柴田理尋、谷口秋洋Edited by: Y. Kobayashi, M. Shibata, and A. Taniguchi原子炉や加速器を利用することで、多様な不安定原子核や素粒子を生成できる。これらの不安定原子核や素粒子は、宇宙核物理や原子核物理の研究対象であるばかりでなく、その静的な電磁気性質を用い、超微細相互作用を介して、電子物性の研究にも広く利用されている。これらの研究に携わる者にとって、定期的に互いの研究分野の新しい動向を知ることは非常に有意義なことであり、令和5(2023)年1月11日、「短寿命RIを用いた核分光と核物性研究IX」専門研究会がオンライン形式で開催された。物性研究においては、1)メスバウアー分光法や摂動角相関測定法を用いた研究や新たなプローブ核の開拓、2)β-NMR法とμ-SR法を用いた研究やβ-MRIの開発、原子核物理においては、3)不安定原子核生成装置の開発、4)核分光実験などの講演が提供された。各講演において活発な議論があり、多様な研究分野における最新の動向や技術的ノウハウを知る場として十分機能した。また、大学院生に対する成果発表の場ともなった。最後に、講演者の方々、さらに、お忙しい中原稿をお寄せいただいた執筆者に、お礼を申し上げるとともに、この報告書が今後の各研究の進展に貢献すれば幸いである。A wide variety of unstable nuclei and elementary particles can be produced by using nuclear reactors and accelerators. These unstable nuclei and elementary particles are not only the targets of research in nuclear astrophysics and nuclear physics but are al so widely used to study electromagnetic properties of condensed materials through the hyperfine interactions using their static electromagnetic properties. For those involved in these studies, it is very meaningful to regularly learn about new trends in each other's research fields. The specialist meeting on “Nuclear Spectroscopy and Nuclear Properties Using Short-Lived RI (IX)” was held online on January 11, 2023, with 11 presentations given on the following themes: in the field of material science, 1) Mössbauer spectroscopy and TDPAC, the development of new probe nuclei, 2) β-NMR and μ-SR methods, and the development of β-MRI, and in the field of nuclear physics, 3) the development of the radioactive ion beam techniques, 4) nuclear spectroscopy experiments, and so on. Lively discussions followed each talk, which served as an opportunity to know about the latest trends and technical know-how in the research field, as well as to provide graduate students with a great opportunity to present their research results. Finally, the editors would like to thank all the speakers and the authors who contribute to the manuscripts, and we hope that this report will be useful for the progress of the related research fields in the future.1) 酸化グラフェン --鉄酸化物複合体のメスバウアースペクトル/ 中島覚(広島大N-BARD; 広島大院先進理工)、ヌグロホ バングン サトリオ(広島大N-BARD) [1]2) 3次元シアノ層状高分子錯体のNi-61メスバウアー分光による研究/ 北清航輔(東邦大理)、北澤孝史(東邦大理; 東邦大複合物性センター)、岡田浩明(東邦大理)、上田大生(東邦大理)、小林康浩(京都大学複合原子力科学研究所)、北尾真司(京都大学複合原子力科学研究所)、窪田卓見(京都大学複合原子力科学研究所)、瀬戸誠(京都大学複合原子力科学研究所) [4]3) Biを添加したYIGのCEMS/ 吉田実生(電通大院)、渡辺裕夫(電通大院)、小林義男(電通大院; 理研仁科センター) [9]4) アンモニアボランH₃BNH₃にイオン注入した⁵⁷Fe/⁵⁷Mnインビーム・メスバウアースペクトル/ 木本周平(電通大 III類)、吉田実生(電通大院)、伊藤史菜(電通大院)、小林義男(電通大院; 理研仁科セ)、渡辺裕夫(電通大院)、久保謙哉(ICU)、三原基嗣(阪大院)、佐藤渉(金沢大院)、宮崎淳(東京電機大)、長友傑(理研仁科セ)、佐藤眞二(QST HIMAC)、北川敦志(QST HIMAC) [13]5) Cd₀.₇₅Fe₂.₂₅O₄の磁性とその時間変動/ 佐藤渉(金沢大理工)、伊東泰佑(金沢大院自然) [17]6) β線核磁気共鳴法を用いたイメージング法の開発/ 木村容子(大阪大理; Open-it)、杉崎尭人(大阪大理; Open-it)、高山元(大阪大理)、田中聖臣(理研; Open-it)、溝井浩(大阪電通大; Open it)、三原基嗣(大阪大理; Open-it)、福田光順(大阪大理)、大谷優里花(大阪大理; Open-it)、福留美樹(大阪大理)、田口諒(大阪大理)、S. Chen(大阪大理)、石谷壮史(大阪大理)、宮原里菜(大阪大理)、渡辺薫(大阪大理)、泉川卓司(新潟大研究推進機構)、野口法秀(新潟大自然科学)、高津和哉(新潟大自然科学)、大坪隆(新潟大自然科学)、西村太樹(東京都市大)、高橋弘幸(東京都市大)、矢野朝陽(筑波大)、関響咲(埼玉大; Open-it)、松多健策(大阪大理)、北川敦志(QST)、佐藤眞二(QST)、百田佐多生(高知工科大) [20]7) 放射光によるGd-155の核励起/ 筒井智嗣(高輝度光科学研究センター; 茨城大学院理工)、金友拓哉(東京理科大学)、谷合亮祐(東京理科大学)、榎本真哉(東京理科大学)、石田尚行(電気通信大学)、門脇瑞斗(茨城大学院理工)、伊賀文俊(茨城大学院理工)、本多史憲(東北大学金属材料研究所(現九州大学アイソトープ総合センター))、永澤延元(高輝度光科学研究センター)、依田芳卓(高輝度光科学研究センター)、小林義男(電気通信大学; 理化学研究所仁科加速器研究センター) [26]8) ミュオン原子核吸収反応による生成核準位測定/ 二宮和彦(阪大)、浅利駿介(阪大)、I-Huan Chiu(阪大)、吉村崇(阪大)、佐藤朗(阪大)、Alex Amato(PSI)、Sayani Biswas(PSI)、Lars Frieder Gerchow(PSI)、Carlos Vigo(PSI)、Chennan Wang(PSI)、Charles Hillis Mielke III(PSI)、Debarchan Das(PSI)、Fabian Hotz(PSI)、Thomas Prokscha(PSI)、Toni Shiroka(PSI)、Zaher Salman(PSI)、Zurab Guguchia(PSI)、Hubertus Luetkens(PSI)、Katharina von Schoeler(PSI)、新倉潤(理研)、Gianluca Janka(ETH Zurich)、Narongrit Ritjoho(SUT) [31]9) KISSでの核分光研究/ 渡辺裕(高エネ研和光センター)、平山賀一(高エネ研和光センター)、向井もも(理研仁科センター)、Peter Schury(高エネ研和光センター)、庭瀬暁隆(高エネ研和光センター)、Jun Young Moon(基礎科学院)、橋本尚志(基礎科学院)、Marco Rosenbusch(高エネ研和光センター)、石山博恒(理研仁科センター)、木村創大(理研仁科センター)、飯村俊(立教大)、小柳津充広(高エネ研和光センター)、鄭淳讃(高エネ研和光センター)、谷口秋洋(京大複合研)、宮武宇也(高エネ研和光センター)、和田道治(高エネ研和光センター)、KISSコラボレーション [32]10) JAEA-ISOLにおけるPIN diodeを用いた²³⁴[m]Npの内部転換電子測定/ 宮澤達也(名大院工)、柴田理尋(名大院工; 名大RIセンター)、浅井雅人(JAEA)、塚田和明(JAEA)、佐藤哲也(JAEA)、伊藤由太(JAEA)、青木涼太(茨城大院理工) [39]11) H₂O中に入射した窒素イオンが形成する化学種の分析/ 三原基嗣(阪大理)、木村容子(阪大理)、大谷優里花(阪大理)、杉﨑尭人(阪大理)、福留美樹(阪大理)、高山元(阪大理)、田口諒(阪大理)、松多健策(阪大理)、福田光順(阪大理)、南園忠則(阪大理)、石谷壮史(阪大理)、宮原里菜(阪大理)、渡辺薫(阪大理)、S. Chen(阪大理)、高橋弘幸(東京都市大)、西村太樹(東京都市大)、泉川卓司(新潟大研究推進機構)、野口法秀(新潟大理)、大坪隆(新潟大理)、小沢顕(筑波大)、矢野朝陽(筑波大)、長友傑(理研仁科セ)、北川敦志(量子科学研究開発機構)、佐藤眞二(量子科学研究開発機構)、百田佐多生(高知工科大)、久保謙哉(国際基督教大)、A. D. Pant(高エネ研)、下村浩一郎(高エネ研)、幸田章宏(高エネ研)、竹下聡史(高エネ研) [44]1) Mössbauer Spectra of Graphene Oxide --Iron oxide Composites/ S. Nakashima(Natural Science Center for Basic Research and Development, Hiroshima Univ.; Graduate School of Advanced Science and Engineering, Hiroshima Univ.), and B. S. Nugroho(Natural Science Center for Basic Research and Development, Hiroshima Univ.) [1]2) ⁶¹Ni Mössbauer Spectroscopy for 3D Coordination Polymers/ K. Kitase(Faculty of Science, Toho Univ.), T. Kitazawa(Faculty of Science, Toho Univ.; Research Centre for Materials with Integrated Properties, Toho Univ.), H. Okada(Faculty of Science, Toho Univ.), D. Ueda(Faculty of Science, Toho Univ.), Y. Kobayashi(Institute for Integrated Radiation and Nuclear Science, Kyoto Univ.), S. Kitao(Institute for Integrated Radiation and Nuclear Science, Kyoto Univ.), T. Kubota(Institute for Integrated Radiation and Nuclear Science, Kyoto Univ.), and M. Seto(Institute for Integrated Radiation and Nuclear Science, Kyoto Univ.) [4]3) Conversion electron Mössbauer spectroscopy (CEMS) of Bi-doped YIG/ M. Yoshida(Grad. Sch. Eng. Sci., Univ. Electro Comm.), Y. Watanabe(Grad. Sch. Eng. Sci., Univ. Electro Comm.), and Y. Kobayashi(Grad. Sch. Eng. Sci., Univ. Electro Comm.; RIKEN Nishina Center) [9]4) In-beam Mössbauer Spectra of ⁵⁷Fe Obtained After ⁵⁷Mn Implantation into Ammonia Borane/ S. Kimoto(Cluster III, Dept. Engi. Sci, Univ. Electro Commun.), M. Yoshida(Grad. Sch. Engi. Sci, Univ. Electro Commun.), M. Ito(Grad. Sch. Engi. Sci, Univ. Electro Commun.), Y. Kobayashi(Grad. Sch. Engi. Sci, Univ. Electro Commun.; RIKEN Nishina Center), Y. Watanabe(Grad. Sch. Engi. Sci, Univ. Electro Commun.), M. K. Kubo(Div. Arts Sci., Int. Christ. Univ.), M. Mihara(Grad. Sch. Sci., Osaka Univ.), W. Sato(Grad. Sch. Nat. Sci. Tech., Kanazawa Univ.), J. Miyazaki(Tokyo Denki Univ.), T. Nagatomo(RIKEN Nishina Center), S. Sato(QST HIMAC), and A. Kitagawa(QST HIMAC) [13]5) Magnetism and Its Time Variation of Cd₀.₇₅Fe₂.₂₅O₄/ W. Sato(Institute of Science and Engineering, Kanazawa Univ.) and T. Ito(Graduate School of Natural Science and Technology, Kanazawa Univ.) [17]6) Development of imaging method using β-ray nuclear magnetic resonance/ Y. Kimura(Dept. Phys., Osaka Univ.; Open-it), T. Sugisaki(Dept. Phys., Osaka Univ.; Open-it), G. Takayama(Dept. Phys., Osaka Univ.), M. Tanaka(RIKEN; Open-it), Y. Mizoi(OECU; Open-it), M. Mihara(Dept. Phys., Osaka Univ.; Open-it), M. Fukuda(Dept. Phys., Osaka Univ.), Y. Otani(Dept. Phys., Osaka Univ.; Open-it), M. Fukutome(Dept. Phys., Osaka Univ.), R. Taguchi(Dept. Phys., Osaka Univ.), S. Chen(Dept. Phys., Osaka Univ.), S. Ishitani(Dept. Phys., Osaka Univ.), R. Miyahara(Dept. Phys., Osaka Univ.), K. Watanabe(Dept. Phys., Osaka Univ.), T. Izumikawa(IRP Niigata Univ.), N. Noguchi(Dept. Fundamental Sciences Niigata Univ.), K. Takatsu(Dept. Fundamental Sciences Niigata Univ.), T. Otsubo(Dept. Fundamental Sciences Niigata Univ.), D. Nishimura(Tokyo City Univ.), H. Takahashi(Tokyo City Univ.), A. Yano(Univ. of Tsukuba), H. Seki(Saitama Univ.; Open-it), K. Matsuta(Dept. Phys., Osaka Univ.), A. Kitagawa(QST), S. Sato(QST), and S. Momota(KUT) [20]7) Nuclear Excitation of Gd-155 Isotope with Synchrotron Radiation/ S. Tsutsui(Japan Synchrotron Radiation Research Institute (JASRI), SPring-8; Graduate School of Science and Engineering, Ibaraki Univ.), T. Kanetomo(Tokyo Univ. of Science), R. Taniai(Tokyo Univ. of Science), M. Enomoto(Tokyo Univ. of Science), T. Ishida(The Univ. of Electro Communications), M. Kadowaki(Graduate School of Science and Engineering, Ibaraki Univ.), F. Iga(Graduate School of Science and Engineering, Ibaraki Univ.), F. Honda(Institute for Material Research, Tohoku Univ.), N. Nagasawa(Japan Synchrotron Radiation Research Institute (JASRI), SPring-8), Y. Yoda(Japan Synchrotron Radiation Research Institute (JASRI), SPring-8), Y. Kobayashi(The Univ. of Electro Communications; Nishina Center for Accelerator Based Science, RIKEN) [26]8) Measurement of excitation level of nuclei generated by muon nuclear absorption reaction/ K. Ninomiya(Osaka University), S. Asari(Osaka University), I. Chiu(Osaka University), T. Yoshimura(Osaka University), A. Sato(Osaka University), A. Amato(Paul Scherrer Institute), S. Biswas(Paul Scherrer Institute), L. Gerchow(Paul Scherrer Institute), C. Vigo(Paul Scherrer Institute), C. Wang(Paul Scherrer Institute), C. Mielke(Paul Scherrer Institute), D. Das(Paul Scherrer Institute), F. Hotz(Paul Scherrer Institute), T. Prokscha(Paul Scherrer Institute), T. Shiroka(Paul Scherrer Institute), Z. Salman(Paul Scherrer Institute), Z. Guguchia(Paul Scherrer Institute), H. Luetkens(Paul Scherrer Institute), K. Schoeler(Paul Scherrer Institute), M. Niikura(RIKEN), G. Janka(ETH Zurich), and N. Ritjoho(Suranaree University of Technology) [31]9) Nuclear Spectroscopy Experiments at KISS/ Y.X. Watanabe(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), Y. Hirayama(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), M. Mukai(RIKEN Nishina Center for Accelerator Based Science), P. Schury(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), T. Niwase(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), J.Y. Moon(Institute for Basic Science (IBS)), T. Hashimoto(Institute for Basic Science (IBS)), M. Rosenbusch(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), H. Ishiyama(RIKEN Nishina Center for Accelerator Based Science), S. Kimura(RIKEN Nishina Center for Accelerator Based Science), S. Iimura(Rikkyo Univ.), M. Oyaizu(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), S.C. Jeong(Wako Nuclear Science Center (WNSC), Institute of Particle and N uclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), A. Taniguchi(Institute for Integrated Radiation and Nuclear Science, Kyoto Univ. (KURNS), H. Miyatake(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), M. Wada(Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)), and KISS collaboration [32]10) Measurement of internal conversion electron of ²³⁴[m]Np using PIN diode at JAEA-ISOL/ T. Miyazawa(Graduate School of Engineering, Nagoya Univ.), M. Shibata(Graduate School of Engineering, Nagoya Univ.; Radioisotope Research Center, Nagoya Univ.), M. Asai(Japan Atomic Energy Agency (JAEA)), K. Tsukada(Japan Atomic Energy Agency (JAEA)), T. K. Sato(Japan Atomic Energy Agency (JAEA)), Y. Ito(Japan Atomic Energy Agency (JAEA)), and R. Aoki(Graduate School of Science and Engineering, Ibaraki Univ.) [39]11) Analysis of Chemical Species Formed by Nitrogen Ions injected into H₂O/ M. Mihara(Department of Physics, Osaka University), Y. Kimura(Department of Physics, Osaka University), Y. Otani(Department of Physics, Osaka University), T. Sugisaki(Department of Physics, Osaka University), M. Fukutome(Department of Physics, Osaka University), G. Takayama(Department of Physics, Osaka University), R. Taguchi(Department of Physics, Osaka University), K. Matsuta(Department of Physics, Osaka University), M. Fukuda(Department of Physics, Osaka University), T. Minamisono(Department of Physics, Osaka University), S. Ishitani(Department of Physics, Osaka University), R. Miyahara(Department of Physics, Osaka University), K. Watanabe(Department of Physics, Osaka University), S. Chen(Department of Physics, Osaka University), H. Takahashi(Tokyo City University), D. Nishimura(Tokyo City University), T. Izumikawa(Institute for Research Promotion, Niigata University), N. Noguchi(Graduate School of Science and Technology, Niigata University), T. Ohtsubo(Graduate School of Science and Technology, Niigata University), A. Ozawa(University of Tsukuba), A. Yano(University of Tsukuba), T. Nagatomo(RIKEN Nishina Center for Accelerator-Based Science), A. Kitagawa(National Institute for Quantum and Radiological Science and Technology (QST)), S. Sato(National Institute for Quantum and Radiological Science and Technology (QST)), S. Momorta(Kochi University of Technology), M.K. Kubo(International Christian University), A.D. Pant(High Energy Accelerator Research Organization (KEK)), K. Shimomura(Graduate School of Science and Technology, Niigata University), A. Koda(High Energy Accelerator Research Organization (KEK)), and S. Takeshita(High Energy Accelerator Research Organization (KEK)) [44

    Overview of the dissemination of n_TOF experimental data and resonance parameters

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    The n_TOF neutron time-of-flight facility at CERN is used for nuclear data measurements. The n_TOF Collaboration works closely with the Nuclear Reaction Data Centres (NRDC) network to disseminate the experimental data through the international EXFOR library. In addition, the Collaboration helps integrate the results in the evaluated library projects. The present contribution describes the dissemination status of n_TOF results, their impact on evaluated libraries and ongoing efforts to provide n_TOF resonance parameters in ENDF-6 format for further use by evaluation projects

    Measurement of the 14N(n, p) 14C cross section at the CERN n_TOF facility from subthermal energy to 800 keV

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    Background: The 14N(n, p) 14C reaction is of interest in neutron capture therapy, where nitrogen-related dose is the main component due to low-energy neutrons, and in astrophysics, where 14N acts as a neutron poison in the s process. Several discrepancies remain between the existing data obtained in partial energy ranges: thermal energy, keV region, and resonance region. Purpose: We aim to measure the 14N(n, p) 14C cross section from thermal to the resonance region in a single measurement for the first time, including characterization of the first resonances, and provide calculations of Maxwellian averaged cross sections (MACS). Method: We apply the time-of-flight technique at Experimental Area 2 (EAR-2) of the neutron time-of-flight (n_TOF) facility at CERN. 10B(n, & alpha;) 7Li and 235U(n, f ) reactions are used as references. Two detection systems are run simultaneously, one on beam and another off beam. Resonances are described with the R-matrix code SAMMY. Results: The cross section was measured from subthermal energy to 800 keV, resolving the first two resonances (at 492.7 and 644 keV). A thermal cross section was obtained (1.809 & PLUSMN; 0.045 b) that is lower than the two most recent measurements by slightly more than one standard deviation, but in line with the ENDF/B-VIII.0 and JEFF-3.3 evaluations. A 1/v energy dependence of the cross section was confirmed up to tens of keV neutron energy. The low energy tail of the first resonance at 492.7 keV is lower than suggested by evaluated values, while the overall resonance strength agrees with evaluations. Conclusions: Our measurement has allowed determination of the 14N(n, p) cross section over a wide energy range for the first time. We have obtained cross sections with high accuracy (2.5%) from subthermal energy to 800 keV and used these data to calculate the MACS for kT = 5 to kT = 100 keV.p>Instituto de Salud Carlos III Spanish Government PID2020-117969RB-I00Junta de Andalucia (FEDER Andalucia 2014-2020) P20-00665 B-FQM-156UGR20UK Science and Facilities Council ST/M006085/1 ST/P004008/1European Research Council (ERC) 677497Spanish Ministry of Science, Innovation and Universities under the FPU Grant FPU17/0230

    New perspectives for neutron capture measurements in the upgraded CERN-n_TOF Facility

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    This work has been carried out in the framework of a project funded by the European Research Council (ERC) under the European Union ' s Horizon 2020 research and innovation programme (ERC Consolidator Grant project HYMNS, with grant agreement No. 681740). This work was supported by grant FJC2020-044688-I funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGenerationEU/PRTR. The authors acknowledge support from the Spanish Ministerio de Ciencia e Innovacion under grants PID2019-104714GB-C21, FPA2017-83946-C2-1-P, FIS2015-71688-ERC, CSIC for funding PIE-201750I26.The n_TOF facility has just undergone in 2021 a major upgrade with the installation of its third generation spallation target that has been designed to optimize the performance of the two n_TOF time-of-flight lines. This contribution describes the key features and limitations for capture measurements in the two beam lines prior to the target upgrade and presents first results of (n,gamma) measurements carried out as part of the commissioning of the upgraded facility. In particular, the energy resolution, a key factor for both increasing the signal-to background ratio and obtaining accurate resonance parameters, has been clearly improved for the 20 m long vertical beam-line with the new target design while keeping the remarkably high resolution of the long beamline n_TOF-EAR1. The improvements in the n_TOF neutron beam-lines need to be accompanied by improvements in the instrumentation. A review is given on recent detector R&D projects aimed at tackling the existing challenges and further improving the capabilities of this facility.European Research Council (ERC)European Union's Horizon 2020 research and innovation programme HYMNS 681740MCIN/AEI FJC2020-044688-IEuropean Union (EU)Instituto de Salud Carlos III Spanish Government PID2019-104714GB-C21, FPA2017-83946-C2-1-P, FIS2015-71688-ERCCSIC PIE-201750I2
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