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Brunet, M.*; Podolyk, Zs.*; Berry, T. A.*; Brown, B. A.*; Carroll, R. J.*; Lica, R.*; Sotty, Ch.*; Andreyev, A. N.; Borge, M. J. G.*; Cubiss, J. G.*; et al.
Physical Review C, 103(5), p.054327_1 - 054327_13, 2021/05
被引用回数:2 パーセンタイル:58.42(Physics, Nuclear)The structure of Po populated through the EC/ decay of At is investigated using -ray spectroscopy at the ISOLDE Decay Station. The presented level scheme contains 27 new excited states and 43 new transitions, as well as a further 50 previously observed rays which have been (re)assigned a position. Through the analysis using the shell model calculations approximately half of the -decay strength of At is found to proceed via allowed decay and half via first-forbidden decay. The first-forbidden transitions predominantly populate core excited states at high excitation energies, which is qualitatively understood using shell model considerations.
Berry, T. A.*; Podolyk, Zs.*; Carroll, R. J.*; Lic, R.*; Grawe, H.*; Timofeyuk, N. K.*; Alexander, T.*; Andreyev, A. N.; Ansari, S.*; Borge, M. J. G.*; et al.
Physics Letters B, 793, p.271 - 275, 2019/06
被引用回数:5 パーセンタイル:48.53(Astronomy & Astrophysics)Gamow-Teller decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This = 0 requirement plays a major role in the decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical -process pathway below both = 50 (for 82) and = 82 (for 126). The level of forbiddenness of the = 1 10 transition has been investigated from the decay of the ground state of Hg into the single-proton-hole nucleus Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible -ray transitions depopulating the 0 state in Tl, an upper limit of 3.910 % was obtained for the probability of this decay, corresponding to log 8.8 within a 95% confidence limit. This is the most stringent test of the = 0 selection rule to date.
Andel, B.*; Andreyev, A. N.; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; Elseviers, J.*; Fedorov, D. V.*; et al.
Physical Review C, 96(5), p.054327_1 - 054327_11, 2017/12
被引用回数:3 パーセンタイル:27.8(Physics, Nuclear)A detailed -decay spectroscopy study of Tl has been performed at ISOLDE (CERN). Z-selective ionization by the Resonance Ionization Laser Ion Source (RILIS) coupled to mass separation provided a high-purity beam of Tl. Fine-structure decays to excited levels in the daughter Au were identified and an -decay scheme of Tl was constructed based on an analysis of - and - - coincidences. Multipolarities of several -ray transitions deexciting levels in Au were determined. Based on the analysis of reduced -decay widths, it was found that all decays are hindered, which signifies a change of configuration between the parent and all daughter states.
Jentschel, M.*; Blanc, A.*; de France, G.*; Kster, U.*; Leoni, S.*; Mutti, P.*; Simpson, G.*; Soldner, T.*; Ur, C.*; Urban, W.*; et al.
Journal of Instrumentation (Internet), 12(11), p.P11003_1 - P11003_33, 2017/11
被引用回数:34 パーセンタイル:84.59(Instruments & Instrumentation)A highly efficient array of high-purity germanium (HPGe) detectors was developed and operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of -rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 10nscm at the target position and negligible neutron halo. The target was surrounded by an array of eight to ten anti-Compton shielded EXOGAM Clover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr:(Ce) detectors from the FATIMA collaboration.
Lund, M. V.*; Andreyev, A. N.; 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
被引用回数:16 パーセンタイル:75.97(Physics, Nuclear)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.
Lic, R.*; Mach, H.*; Fraile, L. M.*; Gargano, A.*; Borge, M. J. G.*; Mrginean, N.*; Sotty, C. O.*; Vedia, V.*; Andreyev, A. N.; Benzoni, G.*; et al.
Physical Review C, 93(4), p.044303_1 - 044303_7, 2016/04
被引用回数:5 パーセンタイル:39.74(Physics, Nuclear)The levels in Sn populated from the decay of In isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station. The lowest 1/2 state and the 3/2 ground state in Sn are expected to have configurations dominated by the neutron (=0) and (=2) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow -forbidden transition. Using fast-timing spectroscopy we have measured the half-life of the 1/2 315.3-keV state, = 19(10) ps, which corresponds to a moderately fast transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured value by the renormalization of the effective operator for neutron holes.
Rgis, J.-M.*; Jolie, J.*; Saed-Samii, N.*; Warr, N.*; Pfeiffer, M.*; Blanc, A.*; Jentschel, M.*; Kster, U.*; Mutti, P.*; Soldner, T.*; et al.
Physical Review C, 90(6), p.067301_1 - 067301_4, 2014/12
被引用回数:23 パーセンタイル:80.47(Physics, Nuclear)A smooth onset of collectivity in Kr has been determined from reported and E(2) values. This is in contrast to the sudden onset in even-even Zr, Mo, and Sr isotopes. Our objective was to complete the systematics by determining the value in Kr, which was produced by cold-neutron-induced fission of U. The lifetime of the 2 state in Kr was measured via the electronic timing technique using the EXILL and FATIMA spectrometers. Based on the measured mean lifetime of = 15(10) ps, the value of 13 W.u. in Kr is determined for the first time and the smooth onset of deformation in the even-even Kr isotopes beyond neutron number N=50 is confirmed.
Elseviers, J.*; Andreyev, A. N.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.
Physical Review C, 88(4), p.044321_1 - 044321_13, 2013/10
被引用回数:38 パーセンタイル:89(Physics, Nuclear)The detailed analysis of the -delayed fission data of Tl is presented. The experiment was performed by producing a pure beam of Tl by means of highly selective resonance laser ionization followed by mass separation with the ISOLDE isotope separator. A surprising asymmetric mass distribution of fission fragments from Hg, the daughter of Tl decays, was obtained. Here, the energy calibration of the silicon detectors, which is crucial for a proper determination of the fission fragments' energy and mass split, is presented and the total kinetic energy and its dependence on the mass split ratio is discussed. A more precise -delayed fission probability of 3.2(2)10 was deduced.
Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; Khuyagbaatar, J.*; Ackermann, D.*; Antalic, S.*; Barth, B.*; Block, M.*; Burkhard, H. G.*; et al.
European Physical Journal A, 48(5), p.62_1 - 62_23, 2012/05
被引用回数:157 パーセンタイル:98.92(Physics, Nuclear)The synthesis of element 116 in the reactions of Ca+Cm was studied at the GSI-SHIP. Four decay chains from the isotope 116 and one decay 116 were detected at the reaction leading to the excitation energy of 40.9 MeV. The cross sections were 3.4 and 0.9 pb, respectively. The decay character reproduced the reported data at FLNR, Russia. In the decay chain, we observed the higher -particle energy in the decay of 114, which suggested the population and the decay of a quasiparitcle state.
Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.
Physical Review Letters, 105(25), p.252502_1 - 252502_5, 2010/12
被引用回数:181 パーセンタイル:97.19(Physics, Multidisciplinary)A very exotic process of -delayed fission of Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post--decay daughter nucleus Hg (/ = 1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two Zr fragments, with magic = 50 and semi-magic = 40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly-measured branching ratio for -delayed fission of Tl is 3.6(7)10 %.
Dia, C.*; 高木 久徳*; 小嶋 智*; 大谷 具幸*; 天野 健治
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土岐花崗岩体の西端と中心部に掘削された1,000m級の2本の深層ボーリング孔(DH-8, DH-9号孔)のデータを用いて岩芯地質観察並びに孔壁画像(BTV)観察を組合せた解析を行い、割れ目の頻度や方位,形状,割れ目充填物を指標とした割れ目系統区分を試みた。その結果、調査対象となったDH-8, DH-9号孔周辺の土岐花崗岩においては、(1)平滑な割れ目面の形状を示す高角な東西,北西-南東走向の割れ目と(2)不規則な割れ目面の形状を示す低角度な割れ目に二分されるとともに、高角度な割れ目にはスメクタイトと緑泥石が特徴的な割れ目充填物として存在していることが明らかとなった。
西尾 勝久; Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; et al.
no journal, ,
陽子過剰な原子核Hgの低励起エネルギー核分裂を測定した。CERN-ISOLDEにおいてTlをアイソトープ分離し、このベータ崩壊によって娘核Hgを励起さることで、この核分裂を観測した(ベータ崩壊遅延核分裂)。核分裂特性を調べたところ、中性子数50の閉殻を有するZr原子核は生成されず、質量数80と100に収率の最大を有する非対称な核分裂を示した。また、原子力機構タンデム加速器において、陽子過剰原子核のインビーム核分裂実験を行った。この結果、ウランなど従来の核分裂と異なり、励起エネルギーが増加しても質量非対称度が変化しないことがわかった。