A microscopic description of the collective bands in 75–77Kr
Abstract
The collective states projected from the Hartree-Fock intrinsic states with maximum prolate deformation generated self-consistently within the valence space by Kuo's effective interaction for this space provide a fair description of the spectra and a good description of the E2 transition probabilities recently measured for these nuclei. A modification of the Kuo interaction significantly improves the agreement with the experimental spectra.
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Cited by (25)
Nuclear data sheets for A = 75
2013, Nuclear Data SheetsThe experimental nuclear spectroscopic data for known nuclides of mass number 75 (Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr) have been evaluated and presented together with Adopted properties for levels and γ rays. New high-spin data are available for 75Ga, and 75Rb; and lifetime data for high-spin states in 75Br and 75Kr. For ΔJ =1, M1+E2 transitions in two rotational bands in 75Kr, several B(E2)(W.u.) values are anomalously high, deviating by 2–3 σ values from currently accepted RUL(E2) = 300. In the opinion of the evaluators, there is need to remeasure level lifetimes and multipole mixing ratios in 75Kr to resolve this serious discrepancy. New precise single-particle transfer cross section data are available for 75Ga, 75Ge, 75As and 75Se from several different reactions (2009Ka06,2008Sc03); these data give information for occupancy of valence neutron orbitals in the ground states of target nuclides: 76Ge, 76Se and 78Se. No significant new data since the 1999 NDS for A = 75 have been reported for 75As and 75Se. No data are yet available for excited states in 75Co, 75Ni and 75Sr. For 75Fe, only the isotopic identification is made with one observed event. The radioactive decay schemes of 75Co and 75Ni are unknown while those for 75Rb and 75Sr are incomplete. This work supersedes the data presented in the previous NDS evaluation of A = 75 published by 1999Fa05.
Nuclear Data Sheets for A = 77
2012, Nuclear Data SheetsThe experimental nuclear spectroscopic data for known nuclides of mass number 77 (Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y) have been evaluated and presented together with adopted properties for levels and γ rays. New high-spin data are available for 77Ga, 77Br and 77Kr. New precise single-particle transfer cross section data are available for 77Ge, 77As, 77Se and 77Br from eight different reactions (2009Ka06,2008Sc03); these data give information for occupancy of valence neutron orbitals in the ground states of target nuclides: 76Ge, 76Se and 78Se. No significant new data since the 1997 NDS for A = 77 (1997Fa12) have been reported for 77Rb and 77Sr. No data are yet available for excited states in 77Ni, 77Cu and 77Y. Level schemes from the radioactive decays of 77Ni to 77Cu and 77Y to 77Sr are unknown, while those for the decays of 77Cu to 77Zn and 77Ga to 77Ge are incomplete. Detailed gamma-ray data for 77Ge from thermal-neutron capture in 76Ge, together with extensive gamma-ray data from 77Ge decay to 77As have become available from 2012Me04. This work benefited from earlier evaluations (1997Fa12,1989Fa07,1980Si05,1973Ur02) of A = 77 nuclides, however, the data presented here supersede those in above evaluations.
Nuclear data sheets for A = 75
1999, Nuclear Data SheetsThe experimental nuclear spectroscopic data for known nuclides of mass number 75 (Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr) have been evaluated and presented together with adopted properties for levels and γ rays. No data are yet available for excited states in75Co,75Ni,75Cu,75Zn and75Sr. Since the 1990 evaluation (90Fa07), new high-spin data are available for75Se,75Br,75Kr and75Rb; and new nuclides of75Co,75Ni and75Sr are now identified. No significant new data, since 1990, have been reported for75Ga and75As. The nuclide75Fe has not yet been identified but half-life calculations are reported by 85Bu27 (also 71Pe16 and 97Mo25). This evaluation supersedes earlier evaluations (90Fa07,81Ek02,75Ho17) of A = 75.
Shape coexistence phenomena in medium mass nuclei
1999, Progress in Particle and Nuclear PhysicsWe review the theoretical interpretation of experimental results on low and high spin states in some even mass A=60−80 nuclei within the complex versions of the Excited Vampir and Fed Vampir variational approaches. The coexistence of oblate and prolate deformed configurations and their mixing at low spin are found to be responsible for the irregular sequences of states and the isomeric decays identified at low excitation energy in even-even nuclei. This behaviour is determined essentially by the isoscalar neutron-proton interaction. At higher spins the coexistence of states with different deformations causes complicated multiple band structures and strong fragmentation of the B(E2) strengths. It also influences the occurence of almost identical bands at normal deformation in some even mass nuclei. In some odd-odd nuclei the shape coexistence furthermore suggests a possible mechanism to populate high spin isomeric states. For the ground state properties of N=Z nuclei the competition between neutron-proton and like-nucleon isovector pairing plays an important role. With increasing angular momentum the neutron-proton alignment dominates the like-nucleon one in the ground bands of odd-odd N=Z nuclei while in the doubly even N=Z nuclei both types of alignment are of comparable importance.
Nuclear data sheets for A = 77
1997, Nuclear Data SheetsAbstract:The experimental nuclear spectroscopic data for known nuclides of mass number 77 (Nl, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y) have been evaluated and presented together with adopted properties for levels and γ rays. New high-spin data are available for77As,77Se,77Br,77Kr,77Rb and77Sr. No significant new data (since the 1989 Nuclear Data Sheets for A=77) have been reported for77Zn,77Ga, and77Ge. No data are yet available for excited states in77Nl,77Cu and77Y. This work supersedes earlier evaluations (89Fa07,80Si05,73Ur02) of A=77 nuclides.Cutoff Date:Literature available up to July 15, 1997, has been consulted.General Policies and Organization of Material:See the January issue of Nuclear Data Sheets.Acknowledgments:The evaluators are indebted to Prof. Ali Al-Shamlan and Prof. Adnan Al-Ageel for their help and encouragement. We thank A. Kestelman for mending data on77Ge β−decay (52.9 s) prior to publication, K.P. Lieb and A. Jungelaus for sending a preprint of their high-spin study of77Rb, and M.J. Martin for a detailed and constructive review of this evaluation.General Comments:The statistical analysis of γ-ray data and deduced level schemes is carried out through computer codes available at data centers in Berkeley and Brookhaven. The methodology and procedures for some of these codes are described by 86BrZQ and 86Br21. A general 3% uncertainty is assumed in quoted theoretical internal conversion coefficients taken mainly from 68Ha53.
Shape coexistence and shape transition in N ≃ Z nuclei from krypton to molybdenum
1996, Nuclear Physics AThe recent investigations of the shape coexistence phenomena dominating the structure of even-even and odd-odd nuclei in the A ∼ 70 mass region are extended to nuclei ranging from krypton to molybdenum. Positive-parity states with even angular momenta in 72Kr, 76Sr, 78Sr, 80Zr and 84Mo are investigated within the EXCITED VAMPIR approximation using essentially complex Hartree-Fock-Bogoliubov transformations and a relatively large model space. The results are compared with the available experimental data. We obtain an oblate ground band and strong oblate-prolate mixing for N = Z = 36, almost pure prolate and oblate bands, with the yrast one being prolate in 76Sr, maximum prolate deformation in 76,78Sr and 80Zr with very high-lying non-yrast bands and decreased prolate quadrupole deformation for the N = Z = 42 system. Predictions for the electromagnetic properties of the investigated states are presented, too.
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On leave of absence from Institut de Physique, USTHB BP9, Dar el Beida, Alger, Algeria.
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On leave of absence from Physical Research Laboratory, Ahmedabad, 380 009 India at CRN Strasbourg.