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Cubiss, J. G.*; Andreyev, A. N.; Barzakh, A. E.*; Manea, V.*; Al Monthery, M.*; Althubiti, N. A.*; Andel, B.*; Antalic, S.*; 他39名*
Physical Review C, 102(4), p.044332_1 - 044332_12, 2020/10
A comprehensive study of the isotope Au has been made at the CERN-ISOLDE facility, using resonance laser ionization. Two long-lived states in
Au were identified - a low-spin ground state and a high-spin isomer - each of which were produced as pure beams. Using the ISOLTRAP precision Penning trap, the excitation energy of the isomeric state in
Au was determined to be
189(14) keV. The
-decay fine structure patterns of the two states were studied using the Windmill decay station, providing information on the low-lying states in the daughter nucleus
Ir. Nuclear spin assignments of
Au
and
Au
are made based on the observed
-decay feeding and hyperfine structure intensity patterns.
Stryjczyk, M.*; Andel, B.*; Andreyev, A. N.; Cubiss, J.*; Pakarinen, J.*; 他43名*
Physical Review C, 102(2), p.024322_1 - 024322_9, 2020/08
Decay spectroscopy of the long-lived states in Tl has been performed at ISOLDE, CERN. The
decay from the low-spin (2
) state in
Tl was observed for the first time and a half-life was determined. Based on the
-decay energy, the relative positions of the long-lived states were fixed, with the (2
) state as the ground state, the 7
state at 77(56) keV, and the 10
state at 451(56) keV. The level scheme of the internal decay of the
Tl(10
) state, which was known to decay solely through emission of 374-keV
-ray transition, was extended and a lower limit for the
-decay branching b
5.9(3)% was determined. The extracted retardation factors for the
decay of the 10
state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the
d
shell in the isomeric decay and significant structure differences between
Tl and
Tl.
Andel, B.*; Andreyev, A. N.; Antalic, S.*; Al Monthery, M.*; Barzakh, A.*; Bissell, M. L.*; Chrysalidis, K.*; 他29名*
Physical Review C, 102(1), p.014319_1 - 014319_12, 2020/07
-delayed fission (
DF) decay of a low-spin (ls) and a high-spin (hs) isomer in
Bi was studied at the ISOLDE facility at CERN. Their
DF partial half-lives were determined:
,
DF(
Bi
)= 5.6(8)
10
s and
,
DF(
Bi
)=1.7(6)
10
s. This work is the first
DF study of two states in one isotope and allows the spin dependence of low-energy fission to be explored. The fission fragment mass distribution of a daughter nuclide
Pb, following the
decay of the high-spin isomer, was deduced and indicates a mixture of symmetric and asymmetric fission modes.
Barzakh, A. E.*; Atanasov, D.*; Andreyev, A. N.; Al Monthery, M.*; Althubiti, N. A.*; Andel, B.*; Antalic, S.*; Blaum, K.*; 他34名*
Physical Review C, 101(6), p.064321_1 - 064321_7, 2020/06
Hyperfine-structure parameters and isotope shift of the isomeric state in
Au relative to
Au for the 267.6-nm atomic transition have been measured for the first time using the in-source resonance-ionization spectroscopy technique. The magnetic dipole moment and change in the mean-square charge radius for this
isomer have been deduced. The observed large isomer shift relative to the
ground state in
Au confirms the occurrence of the shape coexistence in
Au proposed earlier from the analysis of the nuclear spectroscopic data and particle plus triaxial rotor calculations. The analysis of the magnetic moment supports the previously proposed
,
[541] assignment at moderate prolate deformation for
Au
.
Barzakh, A. E.*; Atanasov, D.*; Andreyev, A. N.; Al Monthery, M.*; Althubiti, N. A.*; Andel, B.*; Antalic, S.*; Blaum, K.*; 他39名*
Physical Review C, 101(3), p.034308_1 - 034308_9, 2020/03
Hyperfine-structure constants for the = 11/2
gold isomers
Au
have been measured at CERN-ISOLDE, using the in-source laser resonance-ionization spectroscopy technique. From the measured hyperfine constants the differences between hyperfine anomalies have been deduced. These differential hyperfine anomaly values have been used to determine the hyperfine anomaly relative to the stable
Au with advanced atomic calculations. Magnetic dipole moments for the gold isomers in question have been deduced, taking into account the corresponding relative hyperfine-anomaly values. It has been shown that the commonly used prescription for the extraction of the magnetic moment values for the gold isotopes should be reconsidered. The magnetic moments calculated by this prescription have been reevaluated by properly accounting for the hyperfine anomaly, which is as large as 10% for several gold isotopes.
Cubiss, J. G.*; Harding, R. D.*; Andreyev, A. N.; Althubiti, N.*; Andel, B.*; Antalic, S.*; Barzakh, A. E.*; Cocolios, T. E.*; Day Goodacre, T.*; Farooq-Smith, G. J.*; et al.
Physical Review C, 101(1), p.014314_1 - 014314_4, 2020/01
被引用回数:3 パーセンタイル:6.71(Physics, Nuclear)Ptの基底状態から娘核
Osの基底状態への
崩壊分岐比を0.52(5)%と、過去の値と比較してより高精度で再決定した。
PtはCERN-ISOLDE実験施設において
Hgを単離し、その
崩壊孫核種として生成した。今回の結果を用いて導出した
崩壊の換算崩壊幅は、中性子欠損Pt同位体の
崩壊幅の系統性について新しい描像を与えることとなった。
Cubiss, J. G.*; Andreyev, A. N.; Barzakh, A. E.*; Andel, B.*; Antalic, S.*; Cocolios, T. E.*; Day Goodacre, T.*; Fedorov, D. V.*; Fedosseev, V. N.*; Ferrer, R.*; et al.
Physical Review C, 99(6), p.064317_1 - 064317_6, 2019/06
被引用回数:3 パーセンタイル:27.46(Physics, Nuclear)Atの
崩壊について、CERN-ISOLDE施設においてレーザーイオン化法を使うことで研究した。
-
同時計数データを初めて取得し、より精度の良い半減期の値として1.27(6)秒を得た。
崩壊の微細構造を基に新しい
崩壊図式を構築した。それらの結果から、
Atの基底状態のスピン・パリティは(3
)がより確からしいことが解ったが、(2)
の可能性も完全には否定しきれない。
Barzakh, A. E.*; Cubiss, J. G.*; Andreyev, A. N.; Seliverstov, M. D.*; Andel, B.*; Antalic, S.*; Ascher, P.*; Atanasov, D.*; Beck, D.*; Biero, J.*; et al.
Physical Review C, 99(5), p.054317_1 - 054317_9, 2019/05
被引用回数:3 パーセンタイル:27.46(Physics, Nuclear)Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in At have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope
At has been found to be larger than the average.
Andel, B.*; Andreyev, A.; 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:0 パーセンタイル:100(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.
Wilson, G. L.*; 武山 美麗*; Andreyev, A.; Andel, B.*; Antalic, S.*; Catford, W. N.*; Ghys, L.*; 羽場 宏光*; Heberger, F. P.*; Huang, M.*; et al.
Physical Review C, 96(4), p.044315_1 - 044315_7, 2017/10
被引用回数:3 パーセンタイル:57.42(Physics, Nuclear)The exotic decay process of -delayed fission has been studied in the neutron-deficient isotope
Am at RIKEN, Japan. The
Am nuclei were produced in the complete fusion reaction
Pb(
Al,4n)
Am and separated by using the GARIS gas-filled recoil ion separator. A lower limit for the
-delayed fission probability larger than 0.30 was deduced, which so far is the highest value among all known nuclei exhibiting this decay mode.
erovnik, G.*; Schillebeeckx, P.*; Cano-Ott, D.*; Jandel, M.*; 堀 順一*; 木村 敦; Rossbach, M.*; Letourneau, A.*; Noguere, G.*; Leconte, P.*; et al.
EPJ Web of Conferences, 146, p.11035_1 - 11035_4, 2017/09
被引用回数:4 パーセンタイル:2.78There is a serious gap between required accuracy and current accuracy on nuclear data for developing innovative nuclear reactor systems. To bridge this gap, an international joint activity entitled Improving Nuclear Data Accuracy of Am and
Np capture cross sections (INDA) has being performed under WPEC. In this joint study, the forefront knowledge of energy dependent cross section measurements, spectrum averaged experiments, relevant nuclear structure data, and evaluations are intended to be integrated on the capture cross sections of
Am and
Np. From the joint study, it was shown that integration of knowledge from the independent specialities enables us not only to crosscheck between data obtained by different techniques but also to improve the measurement accuracy of each other.
Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Kahler, A. C.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Pigni, M.*; Dunn, M.*; Leal, L.*; et al.
EPJ Web of Conferences, 146, p.02001_1 - 02001_9, 2017/09
被引用回数:5 パーセンタイル:1.55CIELO共同研究では中性子断面積データの改善及びこれまでの評価で見られた断面積の不一致を解決することを目的として、原子力の臨界性に大きな影響を与える5核種(O,
Fe,
U,
Pu)の中性子断面積を評価している。この国際パイロットプロジェクトでは、経済協力開発機構・原子力機関・核データ評価国際協力ワーキングパーティに設置されたサブグループ40の下でIAEAからのサポートを受けて、実験並びに理論的な研究を活発に実施している。これらの研究を通じて測定データを精度よく反映し、さらに臨界性に関する積分テストで良い結果を示す新しい評価済ライブラリを開発している。
Truesdale, V. L.*; Andreyev, A.; Ghys, L.*; Huyse, M.*; Van Duppen, P.*; Sels, S.*; Andel, B.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; et al.
Physical Review C, 94(3), p.034308_1 - 034308_11, 2016/09
被引用回数:7 パーセンタイル:37.47(Physics, Nuclear)A nuclear-decay spectroscopy study of the neutron-deficient isotope At is reported where an isotopically pure beam was produced using the selective Resonance Ionization Laser Ion Source and On-Line Isotope Mass Separator (CERN). The fine-structure
decay of
At allowed the low-energy excited states in the daughter nucleus
Bi to be investigated. A
-delayed fission study of
At was also performed. A mixture of symmetric and asymmetric fission-fragment mass distributions of the daughter isotope
Po (populated by
decay of
At) was deduced based on the measured fission-fragment energies. A
DF probability
(
At) = 9(1)
10
was determined.
Hota, S.*; Tandel, S.*; Chowdhury, P.*; Ahmad, I.*; Carpenter, M. P.*; Chiara, C. J.*; Greene, J. P.*; Hoffman, C. R.*; Jackson, E. G.*; Janssens, R. V. F.*; et al.
Physical Review C, 94(2), p.021303_1 - 021303_5, 2016/08
被引用回数:5 パーセンタイル:48.22(Physics, Nuclear)Puにおける
= 8
アイソマーからの崩壊と集団的バンド構造が
Tiと
Pbのビームによる深部非弾性散乱実験によって調べられた。バンド内の正確な
分岐比の測定によって、偶
,
=150アイソトーンにおける
= 8
二準中性子アイソマーが9/2
[734]
7/2
[624]
の配位であることを確かめた。
=152における変形シェルギャップ近傍のこれらのアイソマーは、超重核の一粒子エネルギーの理論的な予言において重要なベンチマークとなる。
Andel, B.*; Andreyev, A.; Antalic, S.*; Heberger, F. P.*; Ackermann, D.*; Hofmann, S.*; Huyse, M.*; Kalaninov
, Z.*; Kindler, B.*; Kojouharov, I.*; et al.
Physical Review C, 93(6), p.064316_1 - 064316_12, 2016/06
被引用回数:0 パーセンタイル:100(Physics, Nuclear)Isomeric states in Po and
Po were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions
Pr(
Fe,
)
Po and
Sm(
V,
)
Po. Several new
-ray transitions were attributed to the isomers and
-
coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in
Po, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (11
) to (10
). The de-excitation of the (11
) isomeric level in
Po by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV (E3) transition to (8
) level of the ground-state band was suggested. Moreover, side feeding to the (4
) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting 11
isomers in neighboring Po and Pb isotopes.
Chadwick, M. B.*; Dupont, E.*; Bauge, E.*; Blokhin, A.*; Bouland, O.*; Brown, D. A.*; Capote, R.*; Carlson, A. D.*; Danon, Y.*; De Saint Jean, C.*; et al.
Nuclear Data Sheets, 118, p.1 - 25, 2014/04
被引用回数:90 パーセンタイル:1.18(Physics, Nuclear)CIELO(Collaborative International Evaluated Library Organization)は核反応データの評価作業を国際協力により実施するためのワーキンググループである。CIELOでは国際的な核データコミュニティから専門家を集め、既存の評価済ライブラリや測定データ、モデル計算の間にある矛盾を明らかにし、その原因を取り除き、より信頼性の高いデータを開発することを目的としている。最初の取り組みとして、最重要核種であるH,
O,
Fe,
U,
Puを対象とする予定である。この論文ではこれらの最重要核種の評価済データ及び積分結果をレビューし、評価間の矛盾を調査する。また、この枠組みで実施する核データ評価に関する作業計画をまとめている。
Robinson, A. P.*; Khoo, T. L.*; Seweryniak, D.*; Ahmad, I.*; 浅井 雅人; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; Davids, C. N.*; Greene, J.*; et al.
Physical Review C, 83(6), p.064311_1 - 064311_7, 2011/06
被引用回数:25 パーセンタイル:16.32(Physics, Nuclear)104番元素Rfの励起状態に半減期17
秒の核異性体があることを実験的に明らかにした。実験はアルゴンヌ国立研究所の反跳核分離装置を用いて行い、検出器に打ち込まれた
Rfと同時計数する内部転換電子を測定することで同定した。核異性体の生成率から、この核異性体は中性子数152の原子核で通常観測される2準粒子状態の
核異性体ではなく、4準粒子状態の
核異性体であると考えられる。2準粒子状態の核異性体が観測されなかった理由は、その核異性体が核分裂によって崩壊し、その半減期が
Rfの基底状態の半減期に近いと考えれば説明できる。あるいは、原子核の4重極変形度が104番元素から突然小さくなり、2準粒子状態の核異性体がまったく存在しない、という可能性も考えられる。
Seweryniak, D.*; Khoo, T. L.*; Ahmad, I.*; Kondev, F. G.*; Robinson, A.*; Tandel, S. K.*; 浅井 雅人; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; et al.
Nuclear Physics A, 834(1-4), p.357c - 361c, 2010/03
被引用回数:7 パーセンタイル:48.54(Physics, Nuclear)陽子数100,中性子数152近傍の原子核における一粒子軌道エネルギーの実験値は、超重核領域の殻構造を予測する理論計算の検証に重要な役割を果たす。われわれはNo及び
Noに2準粒子状態の高K核異性体を観測し、それらのエネルギーから陽子数100近傍における陽子の一粒子軌道エネルギーを評価することに成功した。また
Rfに3準粒子状態の高K核異性体を発見し、
Rfの
崩壊の実験データから中性子の一粒子軌道エネルギーも評価した。得られた実験値をさまざまな理論計算の予測値と比較した結果、Woods-Saxonポテンシャルを用いた計算が最もよく実験値を再現することを見いだした。
Robinson, A. P.*; Khoo, T. L.*; Ahmad, I.*; Tandel, S. K.*; Kondev, F. G.*; 中務 孝*; Seweryniak, D.*; 浅井 雅人; Back, B. B.*; Carpenter, M. P.*; et al.
Physical Review C, 78(3), p.034308_1 - 034308_6, 2008/09
被引用回数:42 パーセンタイル:9.44(Physics, Nuclear)Cm及び
Noの励起準位に、量子数
を持ち、
の八重極振動回転バンドを経由して崩壊する核異性体を発見した。これらの中性子数
核における
及び2
準位は、原子番号
102の範囲においてほぼ一定の励起エネルギーを持つことから、中性子の励起に起因する準位と考えられる。ただし
Cmの2
準位だけは例外的に低い励起エネルギーを持ち、中性子の励起に加えて陽子の配位の影響を受けていると考えられる。