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論文

The $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross section from the surrogate ratio method and its effect on the $$^{60}$$Fe nucleosynthesis

Yan, S. Q.*; Li, X. Y.*; 西尾 勝久; Lugaro, M.*; Li, Z. H.*; 牧井 宏之; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; 廣瀬 健太郎; et al.

Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10

 被引用回数:0

The long-lived $$^{60}$$Fe (with a half-life of 2.62 Myr) is a crucial diagnostic of active nucleosynthesis in the Milky Way galaxy and in supernovae near the solar system. The neutron-capture reaction $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe on $$^{59}$$Fe (half-life=44.5 days) is the key reaction for the production of $$^{60}$$Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the E1 $$gamma$$-ray strength function but a negligible constraint on the M1 and E2 components. In this work, for the first time, we use the surrogate ratio method to experimentally determine the $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.5$$pm$$3.5 mb at $$kT$$ = 30 keV and 13.4$$pm$$1.7 mb at $$kT$$ = 90 keV, roughly 10%-20% higher than previous estimates. We analyzed the impact of our new reaction rates in nucleosynthesis models of massive stars and found that uncertainties in the production of $$^{60}$$Fe from the $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe rate are at most 25$$%$$. We conclude that stellar physics uncertainties now play a major role in the accurate evaluation of the stellar production of $$^{60}$$Fe.

論文

Mesoporous alumina-titania composites with enhanced molybdenum adsorption towards medical radioisotope production

Benu, D. P.*; Earnshaw, J.*; Ashok, A.*; 土谷 邦彦; Saptiama, I.*; Yuliarto, B.*; Suendo, V.*; Mukti, R. R.*; 福光 延吉*; 有賀 克彦*; et al.

Bulletin of the Chemical Society of Japan, 94(2), p.502 - 507, 2021/02

本研究は、TiO$$_{2}$$含有量を変化させたメソポーラスAl$$_{2}$$O$$_{3}$$-TiO$$_{2}$$複合材料の製造開発及び医療用放射性同位元素の製造のためのMo吸着剤の性能向上のために行った。TiO$$_{2}$$の含有量の増加は、元の形態を変えることなく、Al$$_{2}$$O$$_{3}$$表面へのより多くのTiO$$_{2}$$ナノ粒子の形成を促進する。開発したAl$$_{2}$$O$$_{3}$$-2.5%Ti及びAl$$_{2}$$O$$_{3}$$-5%Tiのアルミナ試料はアモルファスであったが、Al$$_{2}$$O$$_{3}$$-10%Tiでは、TiO$$_{2}$$がAl$$_{2}$$O$$_{3}$$表面に被覆されていた。一方、TiO$$_{2}$$の添加により、比表面積はAl$$_{2}$$O$$_{3}$$の177m$$^{2}$$/gからAl$$_{2}$$O$$_{3}$$-5%Ti試料では982m$$^{2}$$/gまで大幅に増加した。これにより、Mo吸着量は、Al$$_{2}$$O$$_{3}$$で37.1mg/g、Al$$_{2}$$O$$_{3}$$-2.5%Tiで39.0mg/g、Al$$_{2}$$O$$_{3}$$-10%Tiで40.5mg/gであったが、Al$$_{2}$$O$$_{3}$$-5%Tiはよりも高い44.5mg/gを示した。これにより、従来のAl$$_{2}$$O$$_{3}$$の吸着能力と比較して、Al$$_{2}$$O$$_{3}$$-TiO$$_{2}$$複合材料の吸着能力の向上に見通しを得た。

論文

Non-destructive analysis of samples with a complex geometry by NRTA

Ma, F.; Kopecky, S.*; Alaerts, G.*; 原田 秀郎; Heyse, J.*; 北谷 文人; Noguere, G.*; Paradela, C.*; $v{S}$alamon, L.*; Schillebeeckx, P.*; et al.

Journal of Analytical Atomic Spectrometry, 35(3), p.478 - 488, 2020/03

AA2019-0356.pdf:2.54MB

 被引用回数:1 パーセンタイル:34.45(Chemistry, Analytical)

The use of Neutron Resonance Transmission Analysis to characterize homogeneous samples not fulfilling good transmission geometry conditions is discussed. Analytical expressions for such samples have been derived and implemented in the resonance shape analysis code REFIT. They were validated by experiments at the time-of-flight facility GELINA using a set of metallic natural copper samples. The expressions were used to derive sample characteristics by a least squares adjustment to experimental transmission data. In addition, the resonance parameters of Cu for energies below 6 keV, which are reported in the literature and recommended in evaluated data libraries, were verified. This research was implemented under the subsidiary for nuclear security promotion of MEXT.

論文

Shell structure of the neutron-rich isotopes $$^{69,71,73}$$Co

Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; 緒方 一介*; 吉田 数貴; Authelet, G.*; et al.

Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03

 被引用回数:4 パーセンタイル:79.36(Physics, Nuclear)

中性子過剰核である$$^{69,71,73}$$Coに対する($$p,2p$$)ノックアウト反応が理化学研究所RIBFで測定された。$$gamma-gamma$$ coincidenceの方法で準位構造が決定され、測定された包括的断面積および排他的断面積から暫定的ではあるがスピン・パリティが決定された。殻模型計算との比較により、$$^{69,71,73}$$Coの低励起状態には球形核と変形核が共存することが示唆された。

論文

IRDFF-II; A New neutron metrology library

Trkov, A.*; Griffin, P. J.*; Simakov, S. P.*; Greenwood, L. R.*; Zolotarev, K. I.*; Capote, R.*; Aldama, D. L.*; Chechev, V.*; Destouches, C.*; Kahler, A. C.*; et al.

Nuclear Data Sheets, 163, p.1 - 108, 2020/01

 被引用回数:23 パーセンタイル:99.09(Physics, Nuclear)

60MeVまでの核分裂炉、核融合炉の中性子計測のための核データであるIRDFF-IIが公開された。このライブラリは、(a)研究炉応用、(b)商業炉の安全性応用、(c)核融合材料開発のための損傷研究、をサポートしている。本論文は、ライブラリの内容、検証プロセスについて述べ、幅広い中性子場でのベンチマークデータを提供している。このライブラリは様々な応用のための中性子計測における国際的な基準データとなることが期待される。

論文

Biosurface properties and lead adsorption in a clone of ${it Sphagnum palustre}$ (Mosses); Towards a unified protocol of biomonitoring of airborne heavy metal pollution

Di Palma, A.; Gonz$'a$lez, A. G.*; Adamo, P.*; Giordano, S.*; Reski, R.*; Pokrovsky, O. S.*

Chemosphere, 236, p.124375_1 - 124375_9, 2019/12

 被引用回数:3 パーセンタイル:29.49(Environmental Sciences)

In this work we used field- and laboratory-grown S. palustre moss treated by EDTA and devitalized by oven drying, to elaborate a consistent procedure of metal and proton adsorption on moss surfaces and a biomonitoring protocol using cloned moss. Devitalization and EDTA treatments did not produce any measurable difference in terms of H$$^{+}$$ and Pb$$^{2+}$$ adsorption capacities of moss surfaces. Therefore, in view of the use of S. palustre clone for biomonitoring purposes, we recommend devitalization as unique treatment to perform with the aim to preserve the biomaterial before and after its exposure in bags.

論文

Comparison of heavy-ion transport simulations; Collision integral with pions and $$Delta$$ resonances in a box

小野 章*; Xu, J.*; Colonna, M.*; Danielewicz, P.*; Ko, C. M.*; Tsang, M. B.*; Wang, Y,-J.*; Wolter, H.*; Zhang, Y.-X.*; Chen, L.-W.*; et al.

Physical Review C, 100(4), p.044617_1 - 044617_35, 2019/10

AA2019-0025.pdf:2.76MB

 被引用回数:29 パーセンタイル:98.33(Physics, Nuclear)

2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究では、辺の長さが20fmの直方体に320個の中性子と陽子をランダム配置し、それらが70fm/cの間に起こす散乱の回数やエネルギーを計算した。ここでは、特にパイオンやその前駆体であるデルタ共鳴の生成に注目して比較を行った。参加コードは、個々の粒子の時間発展を追うQMD型コードと、粒子の位置や運動量の確率分布を決めておき、散乱や崩壊が発生したときそれらを乱数サンプリングするBUU型コードがあり、発表者が用いたJQMDは前者に属する。本研究により、計算における時間刻みが各コードによる結果の差の主な原因であることが分かった。さらに、今後のJQMDの改良方針の策定に有益な知見を得ることができた。

論文

Evidence for singular-phonon-induced nematic superconductivity in a topological superconductor candidate Sr$$_{0.1}$$Bi$$_{2}$$Se$$_{3}$$

Wang, J.*; Ran, K.*; Li, S.*; Ma, Z.*; Bao, S.*; Cai, Z.*; Zhang, Y.*; 中島 健次; 河村 聖子; $v{C}$erm$'a$k, P.*; et al.

Nature Communications (Internet), 10, p.2802_1 - 2802_6, 2019/06

 被引用回数:12 パーセンタイル:83.95(Multidisciplinary Sciences)

Superconductivity mediated by phonons is typically conventional, exhibiting a momentum-independent $$s$$-wave pairing function, due to the isotropic interactions between electrons and phonons along different crystalline directions. Here, by performing inelastic neutron scattering measurements on a superconducting single crystal of Sr$$_{0.1}$$Bi$$_{2}$$Se$$_{3}$$, a prime candidate for realizing topological superconductivity by doping the topo-logical insulator Bi$$_{2}$$Se$$_{3}$$, we found that there exist singular phonons, with the linewidths of the acoustic phonons increasing substantially at long wavelengths, but only for those along the [001] direction. This observation indicates a large and singular electron-phonon coupling at small momenta, which we propose to give rise to the exotic $$p$$-wave nematic superconducting pairing in the MxBi$$_{2}$$Se$$_{3}$$ (M = Cu, Sr, Nb) superconductor family. Therefore, we show that these superconductors may be the first examples where electron-phonon interaction can induce more exotic superconducting pairing than the $$s$$-wave.

論文

Emergence of a complete heavy-quark spin symmetry multiplet; Seven molecular pentaquarks in light of the latest LHCb analysis

Liu, M.-Z.*; Pan, Y.-W.*; Peng, F.-Z.*; S$'a$nchez-S$'a$nchez, M.*; Geng, L.-S.*; 保坂 淳; Valderrama, M. P.*

Physical Review Letters, 122(24), p.242001_1 - 242001_5, 2019/06

 被引用回数:106 パーセンタイル:99.61(Physics, Multidisciplinary)

A recent analysis by the LHCb Collaboration suggests the existence of three narrow pentaquarklike states-the $$P_c$$(4312), $$P_c$$(4440), and $$P_c$$(4457)-instead of just one in the previous analysis [the $$P_c$$(4450)]. The closeness of the $$P_c$$(4312) to the $$bar{D}^{*}Sigma_c$$ threshold and the $$P_c$$(4440) and $$P_c$$(4457) to the $$bar{D}^{*}Sigma_c$$ threshold suggests a molecular interpretation of these resonances. We show that these three pentaquarklike resonances can be naturally accommodated in a contact-range effective field theory description that incorporates heavy-quark spin symmetry. This description leads to the prediction of all the seven possible $$S$$-wave heavy antimeson-baryon molecules [that is, there should be four additional molecular pentaquarks in addition to the $$P_c$$(4312), $$P_c$$(4440), and $$P_c$$(4457)], providing the first example of a heavy-quark spin symmetry molecular multiplet that is complete. If this is confirmed, it will not only give us an impressive example of the application of heavy-quark symmetries and effective field theories in hadron physics, it will also uncover a clear and powerful ordering principle for the molecular spectrum, reminiscent of the SU(3)-flavor multiplets to which the light hadron spectrum conforms.

論文

Sample shape effect on nuclear material quantification with neutron resonance transmission analysis

土屋 晴文; Ma, F.; 北谷 文人; Paradella, C.*; Heyse, J.*; Kopecky, S.*; Schillebeeckx, P.*

Proceedings of 41st ESARDA Annual Meeting (Internet), p.374 - 377, 2019/05

From a viewpoint of nuclear safeguards and nuclear security, non-destructive assay (NDA) techniques are needed to quantify special nuclear materials (SNMs) in nuclear fuels such as spent fuels and fuel debris. Neutron Resonance Transmission Analysis (NRTA) is an NDA technique and it measures the amount of U isotopes in a U$$_{3}$$O$$_{8}$$ sample within 1% accuracy and Pu isotopes in a PuO$$_{2}$$ sample within 5% accuracy. However, NRTA measurements done so far were mainly applied to homogeneous samples with a constant thickness. Spent fuel and especially debris have irregular shapes that affect the NRTA measurements. In order to investigate the influence of irregular-shaped samples, NRTA experiments were done with a copper bar sample with different rotation angles with respect to neutron beams, at a neutron Time-Of-Flight (TOF) facility GELINA (Belgium). Analytical models for irregular shaped samples proposed by Harada et al. (JNST, 2015) were applied to the experimental data. It has been found that the experimental data can be well reproduced by the proposed models. In this presentation, we report how analytical models are applied to a real NRTA experiment with a Cu bar sample and discuss a future prospect of a compact NRTA system for SNM quantification. This research was implemented under the subsidiary for nuclear security promotion of MEXT.

論文

Mechanism of hardening and damage initiation in oxygen embrittlement of body-centred-cubic niobium

Yang, P.-J.*; Li, Q.-J.*; 都留 智仁; 尾方 成信*; Zhang, J.-W.*; Sheng, H.-W.*; Shan, Z.-W.*; Sha, G.*; Han, W.-Z.*; Li, J.*; et al.

Acta Materialia, 168, p.331 - 342, 2019/04

 被引用回数:17 パーセンタイル:90.93(Materials Science, Multidisciplinary)

ニオブなどの体心立方構造をもつ金属材料は低濃度の酸素固溶によって脆化しやすいことが知られているが、酸素誘起の硬化や損傷の機構は明らかになっていない。我々は、実験、および第一原理計算と分子動力学計算を用いて詳細な機構を検討した。その結果、酸素の格子間原子はらせん転位と引力相互作用を生じ、それによって転位運動でクロスキンクが生成され、同時に多くの空孔が生成されることを明らかにした。これらの空孔はさらに酸素と転位の三体間の硬化によって転位の運動を阻害することで、著しい硬化を生じることを明らかにした。

論文

Nuclear structure of $$^{76}$$Ni from the ($$p$$,$$2p$$) reaction

Elekes, Z.*; Kripk$'o$, $'A$*; Sohler, D.*; Sieja, K.*; 緒方 一介*; 吉田 数貴; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; 馬場 秀忠*; et al.

Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01

 被引用回数:7 パーセンタイル:80.58(Physics, Nuclear)

($$p$$,$$2p$$)反応による$$^{76}$$Niの核構造の探索実験を行った。Lenzi, Nowacki, Poves, Sieja相互作用を用いた殻模型計算では実験結果を説明しうる陽子空孔状態が得られており、理論的な断面積計算は実験値とよい一致を与えた。実験で得られたすべての状態を理論的に一意に決定することはできなかったが、過去の実験結果と同様にNi同位体でのZ = 28の大きなshell gapを示す結果が得られた。

論文

Comparison of heavy-ion transport simulations; Collision integral in a box

Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; 小野 章*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.

Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03

 被引用回数:63 パーセンタイル:99.37(Physics, Nuclear)

2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究はモデル間の共通点と差異を明らかにし、各モデルの問題点を明らかにした。比較において、辺の長さが20fmの直方体に320個の中性子と320個の陽子をランダム配置し、それらが時間発展に伴って起こす散乱の回数や散乱時のエネルギーなどを計算する条件が設定された。また、結果以外にも、理論モデルを構成するアルゴリズムについても比較を行った。発表者は重イオン核反応モデルJQMD(JAERI Quantum Molecular Dynamics)を用いて計算を行い、世界で開発されている15の計算コードによる計算結果と比較した。コードアルゴリズムの比較では、JQMDは必ず陽子から 優先的に衝突確率を計算し、その後に中性子の衝突を計算するため、物理描像の妥当性が指摘された。一方、JQMDは他のモデルとほぼ同じ計算結果を出すことも判明した。衝突回数や運動量の計算値が平均から2倍以上乖離するモデルもある中で、JQMDは本計算条件で安定した性能を発揮することが確認された。

論文

Shell evolution beyond $$Z$$=28 and $$N$$=50; Spectroscopy of $$^{81,82,83,84}$$Zn

Shand, C. M.*; Podoly$'a$k, Zs.*; G$'o$rska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.

Physics Letters B, 773, p.492 - 497, 2017/10

 被引用回数:18 パーセンタイル:88.47(Astronomy & Astrophysics)

Low-lying states in neutron-rich $$^{81,82.83.84}$$Zn nuclei were measured for the first time via in-beam $$gamma$$-ray spectroscopy at RIKEN. These include the 4$$_1^+$$ to 2$$_1^+$$ in $$^{82}$$Zn and the 2$$_1^+$$ to 0$$_1^+$$ and 4$$_1^+$$ to 2$$_1^+$$ in $$^{84}$$Zn. The reduced E($$2^+$$) energies and increased E(4$$^+$$)/E(2$$^+$$) ratios at $$N$$=52,54 compared to $$^{80}$$Zn attest that the magicity is confined just on the neutron number $$N$$=50 only. The levels observed in $$^{84}$$Zn suggest the onset of deformation towards heavier Zn isotopes. The data were compared to state-of-the-art shell model calculations.

論文

Shape evolution in neutron-rich krypton isotopes beyond N=60; First spectroscopy of $$^{98,100}$$Kr

Flavigny, F.*; Doornenbal, P.*; Obertelli, A.*; Delaroche, J.-P.*; Girod, M.*; Libert, J.*; Rodriguez, T. R.*; Authelet, G.*; 馬場 秀忠*; Calvet, D.*; et al.

Physical Review Letters, 118(24), p.242501_1 - 242501_6, 2017/06

 被引用回数:27 パーセンタイル:88.56(Physics, Multidisciplinary)

The first $$gamma$$-ray spectroscopy of very neutron rich $$^{98,100}$$Kr isotopes was carried out at the RIBF at RIKEN Nishina center. Excited states in these isotopes were populated via (p,2p) reactions using radioactive $$^{99,101}$$Rb beams accelerated to 220 MeV/nucleon. The new data show a significant increase in deformation beyond N=60, as well as competing configurations (shape-coexistence) at low energy. The data were compared with beyond-mean-field calculations which predict level energies in good agreement with observation, and suggest oblate-prolate shape coexistence.

論文

$$gamma$$ decay of unbound neutron-hole states in $$^{133}$$Sn

Vaquero, V.*; Jungclaus, A.*; Doornenbal, P.*; Wimmer, K.*; Gargano, A.*; Tostevin, J. A.*; Chen, S.*; N$'a$cher, E.*; Sahin, E.*; 志賀 慶明*; et al.

Physical Review Letters, 118(20), p.202502_1 - 202502_5, 2017/05

 被引用回数:14 パーセンタイル:76.72(Physics, Multidisciplinary)

Excited states in $$^{133}$$Sn were populated following one-neutron knockout reaction from an unstable $$^{134}$$Sn beam at the RIBF laboratory in RIKEN. In addition to the already known $$gamma$$ rays, additional $$gamma$$ strength was observed for the first time in the excitation-energy range 3.5-5.5 MeV. Since the neutron separation energy of $$^{133}$$Sn is low, this observation provides direct evidence for the radioactive decay of neutron-unbound states in this nucleus. The ability of $$gamma$$ decay to compete with neutron emission was attributed to a mismatch between the wave functions of the initial and final states in the neutron emission case. These findings suggest that in the region south-east of $$^{132}$$Sn, nuclear structure effects play a significant role in the decay of unbound states, which are instead usually ignored in the evaluation of neutron-emission probabilities in astrophysical simulations.

論文

Low-lying structure and shape evolution in neutron-rich Se isotopes

Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Rodriguez, T. R.*; Authelet, G.*; 馬場 秀忠*; Calvet, D.*; Ch$^a$teau, F.*; Corsi, A.*; Delbart, A.*; et al.

Physical Review C, 95(4), p.041302_1 - 041302_6, 2017/04

 被引用回数:18 パーセンタイル:88.47(Physics, Nuclear)

Neutron-rich isotopes of selenium, $$^{88,90,92,94}$$Se, where studied via in beam $$gamma$$-ray spectroscopy after nucleon removal reactions at RIBF in RIKEN. The low-energy excitations of these nuclei were investigated using $$gamma$$-$$gamma$$ coincidences, and the first and second excited 2$$^+$$ states were found at remarkably low energies. The analysis and comparison with self-consistent beyond-mean field calculations suggest that both shape coexistence and triaxiality are needed to describe these isotopes.

論文

Type II shell evolution in $$A=70$$ isobars from the $$N geq 40$$ island of inversion

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 角田 佑介*; Otsuka, T.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; et al.

Physics Letters B, 765, p.328 - 333, 2017/02

 被引用回数:28 パーセンタイル:94.69(Astronomy & Astrophysics)

The level schemes of neutron-rich isotopes $$^{70}$$Co and $$^{70}$$Ni were populated in the $$beta$$ decay of $$^{70}$$Fe and studied using $$beta$$-delayed $$gamma$$-ray spectroscopy of the $$beta$$ decay, at the RIBF in RIKEN, Japan. The experimental results were compared to state-of-the-art shell-model calculations, and indicate a dominance of prolate deformation in the low-lying states, coexisting with spherical states. The $$beta$$ decay of the $$A=70$$ isobars is shown to progress in accordance to a new type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.

論文

Are there signatures of harmonic oscillator shells far from stability?; First spectroscopy of $$^{110}$$Zr

Paul, N.*; Corsi, A.*; Obertelli, A.*; Doornenbal, P.*; Authelet, G.*; 馬場 秀忠*; Bally, B.*; Bender, M.*; Calvet, D.*; Ch$^a$teau, F.*; et al.

Physical Review Letters, 118(3), p.032501_1 - 032501_7, 2017/01

 被引用回数:27 パーセンタイル:88.56(Physics, Multidisciplinary)

The first measurement of $$gamma$$ rays emitted by the very neutron rich nuclei $$^{112}$$Mo (Z=42) and $$^{110}$$Zr (Z=40) was carried out at the RIBF facility at RIKEN. These data shine light on the postulated N=70 harmonic oscillator shell. If the spin-orbit splitting which gives rise to the N=82 shell gap is reduced in very neutron-rich nuclei, the harmonic oscillator gap at N=70 should open instead. However, both the measured energy of the first excited state $$^{112}$$Mo and $$^{110}$$Zr, respectively 235(7) keV and 185(11) keV, and their E(4$$^+$$)/E(2$$^+$$) ratio, indicate that these nuclei are good rotors, and exclude the shell stabilization scenario at Z=40 and N=70. These results were compared to state-of-the-art density functional theoretical calculations using Gogny and Skyrme effective interactions.

論文

Low-lying excitations in $$^{72}$$Ni

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; Lorusso, G.*; Patel, Z.*; et al.

Physical Review C, 93(3), p.034328_1 - 034328_14, 2016/03

 被引用回数:19 パーセンタイル:85.24(Physics, Nuclear)

Low-lying excited states in $$^{72}$$Ni have been investigated at RIKEN by studying the $$beta$$ decay of $$^{72}$$Co to $$^{72}$$Ni. $$^{72}$$Co was separated with BigRIPS, implanted into the WaS3ABi Silicon array, and the $$gamma$$ ray measured using the EURICA $$gamma$$ spectrometer. From the analysis, 60 new $$gamma$$-ray transitions and 21 new levels in $$^{72}$$Ni were observed. The new experimental information is compared to shell-model calculations which include neutron excitation across the $$fpg$$ shell. The calculations reproduce rather well the observed states, implying that a clear understanding of these low-lying excitations has been achieved.

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