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
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.
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.
Harding, R. D.*; Andreyev, A. N.; Barzakh, A. E.*; Atanasov, D.*; Cubiss, J. G.*; Van Duppen, P.*; 他40名*
Physical Review C, 102(2), p.024312_1 - 024312_16, 2020/08
A detailed nuclear spectroscopy study of Au was performed. An -decay branching ratio of % and a half-life of s have been derived. The first measurement of the hyper fine structure for atomic transitions has been also performed, from which the magnetic dipole moment has been extracted. A spin assignment of is proposed for the ground state of Au, with a  configuration.
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.
Chrysalidis, K.*; Barzakh, A. E.*; Ahmed, R.*; Andreyev, A. N.; Ballof, J.*; Cubiss, J. G.*; Fedorov, D. V.*; Fedosseev, V. N.*; Fraile, L. M.*; Harding, R. D.*; et al.
Nuclear Instruments and Methods in Physics Research B, 463, p.472 - 475, 2020/01
放射壊変によって生成された多数のジスプロシウム同位体について、ISOLDEのレーザー共鳴イオン源(RILIS)を用いてイオン源内レーザー分光法によって研究した。Dyに対する相対的な同位体シフトを (gs) 共鳴遷移を用いて測定した。電子的因子Fとマスシフト因子Mを導出し、それらを使ってDyとDyの平均自乗荷電半径の変化を初めて決定した。
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
Ghys, L.*; Andreyev, A. N.; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; Cocolios, T. E.*; Cubiss, J.*; Derkx, X.*; et al.
Physical Review C, 100(5), p.054310_1 - 054310_13, 2019/11
The aim of this work was to investigate the -decay properties of Fr and daughter products. Neutron-deficient francium nuclei are produced at ISOLDE-CERN bombarding a UCx target with 1.4 GeV protons. Due to the very high statistics and the high beam purity, improved decay data for Fr and its daughters were obtained. The observation of crossover transitions positioned the isomeric high-spin level of At at an excitation energy of 265(3) keV. Half-life values of 4.47(5) s and 1.28(10) s were extracted for the ground state and isomeric state of At and 52(3) ms for the ground-state decay of Fr.
Gillespie, S. A.*; Andreyev, A. N.; Al Monthery, M.*; Barton, C. J.*; Antalic, S.*; Auranen, K.*; Badran, H.*; Cox, D.*; Cubiss, J. G.*; O'Donnell, D.*; et al.
Physical Review C, 99(6), p.064310_1 - 064310_6, 2019/06
An experiment has been performed to study excited states in the neutron-deficient nucleus Ir via the use of the JUROGAM II high-purity germanium detector array and the RITU gas-filled separator at JYFL, Jyvskyl. By using isomer tagging, an isomeric state with a half-life of 6.58(15) s has been observed in Ir for the first time. It has been established that the isomer decays via a 45.2 () - 26.1 () keV cascade to new states below the previously reported ground state in Ir with . We now reassign this state to the isomeric state discovered in this study.
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
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
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.
Cubiss, J. G.*; Barzakh, A. E.*; Andreyev, A. N.; 他57名*
Physics Letters B, 786, p.355 - 363, 2018/11
The first accurate measurements of the -decay branching ratio and half-life of the I=1/2 ground state in Tl have been made, along with the first determination of the magnetic moments and I=1/2 spin assignments of the ground states in Au. The results are discussed within the complementary systematics of the reduced -decay widths and nuclear g factors of low-lying, I=1/2states in the neutron-deficient lead region. The findings shed light on the unexpected hindrance of the 1/2 1/2, Tl Au decay, which is explained by a mixing of 3sand 2d configurations in Au, whilst Tl remains a near-pure 3s. This conclusion is inferred from the g factor of Au which has an intermediate value between those of 3s and 2d states. A similar mixed configuration is proposed for the I=1/2 ground state of Au. This mixing may provide evidence for triaxial shapes in the ground states in these nuclei.
Cubiss, J.*; Andreyev, A. N.; 光岡 真一*; 永目 諭一郎; 西尾 勝久; 太田 周也*; 若林 泰生*; 他60名*
Physical Review C, 97(5), p.054327_1 - 054327_19, 2018/05
Hyperfine-structure parameters and isotope shifts of At have been measured for the first time at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy method. The hyperfine structures of isotopes were recorded using a triad of experimental techniques for monitoring the photo-ion current. The Multi-Reflection Time-of-Flight Mass Spectrometer, in connection with a high-resolution electron multiplier, was used as an ion-counting setup for isotopes that either were affected by strong isobaric contamination or possessed a long half-life; the ISOLDE Faraday cups were used for cases with high-intensity beams; and the Windmill decay station was used for short-lived, predominantly -decaying nuclei. The electromagnetic moments and changes in the mean-square charge radii of the astatine nuclei have been extracted from the measured hyperfine-structure constants and isotope shifts. This was only made possible by dedicated state-of-the-art large-scale atomic computations of the electronic factors and the specific mass shift of atomic transitions in astatine that are needed for these extractions. By comparison with systematics, it was possible to assess the reliability of the results of these calculations and their ascribed uncertainties. A strong deviation in the ground-state mean-square charge radii of the lightest astatine isotopes, from the trend of the (spherical) lead isotopes, is interpreted as the result of an onset of deformation. This behavior bears a resemblance to the deviation observed in the isotonic polonium isotopes. Cases for shape coexistence have been identified in At, for which a significant difference in the charge radii for ground (9/2) and isomeric (1/2) states has been observed.