Sudden shape change from spherical to maximally deformed for A⋍100 nuclei

doi:10.1016/0375-9474(90)90573-5

Nuclear Physics A

Volume 507, Issue 1, 29 January 1990, Pages 141-148

https://doi.org/10.1016/0375-9474(90)90573-5 Get rights and content

Abstract

One of the unusual features of neutron-rich $A ⋍100$ nuclei is the sudden change of nuclear shape. The analysis of B(E2) and B(M1) values from recent level lifetime measurements indicates that Sr nuclei (and perhaps also Y) nuclei obtain maximal deformations for the nuclei at the onset of deformation, which suggests a “phase change” from a spherical to a maximally deformed nuclear shape.

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Cited by (20)

Nuclear Data Sheets for A=100
2021, Nuclear Data Sheets
Evaluated experimental data are presented for 15 known nuclides of mass 100 (Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn). Recommended values are given for level parameters, γ and β radiations, and other spectroscopic information. No excited states are known in ¹⁰⁰Rb and ¹⁰⁰Sn. Except for isotopic identification, no information is available for the decay of the ¹⁰⁰Kr isotope, and limited information is known about the decay properties of the ¹⁰⁰Sn isotope. According to Fig. 2 (A/Q versus counts plot) and as mentioned in the text in 2021Su01, ¹⁰⁰Br isotope was not observed, although, discovery of ¹⁰¹Br was claimed in this work. In the case of ¹⁰⁰Pd, the agreement in the orderings of the γ-ray cascades and γ-ray inventory between various studies of high-spin structures remains poor at high excitation energies (>9 MeV). For ¹⁰⁰Y, the assignments of the two previously known half-lives to the respective states (g.s. and the 145-keV isomer) remain to be established. This work supersedes earlier full evaluations of A=100 by 2008Si01, 1997Si09, 1990Si05 and 1974Ko37.
Nuclear Data Sheets for A=98
2020, Nuclear Data Sheets
Experimental spectroscopic data on nuclear structure and decay are evaluated for known nuclides of mass 98 (Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In). Detailed evaluation results of individual reactions and decays are presented together with the Adopted values that are recommended for level properties, γ and β radiations, and other spectroscopic information. ⁹⁸Mo remains as the most extensively studied nuclide via various reactions and decays. Level schemes of Sr, Y, Zr, Tc, and Pd nuclides in this mass chain are also well established to date; while Kr, Rb, Nb, Ag and Cd are amongst the least-studied ones for excited states, with only limited data available for each. On the neutron-rich side, ⁹⁸Br has been identified in the ⁹Be(²³⁸U,F) reaction, but no spectroscopic data are yet available, while for ⁹⁸In on the proton-rich side, only the ground state and an isomer are known with half-lives measured but their spin-parities and the absolute level energy of the isomer yet to be determined. While ⁹⁸Ru and ⁹⁸Rh have also been extensively studied, large discrepancies exist between the high-spin sections of the proposed level schemes in different measurements, and these need to be clarified and resolved with further experimental investigations to improve the currently-adopted ones, which have been selected from the measurements with higher statistics, considering no other criteria of preference. This work supersedes all the earlier evaluations of A=98 (2003Si07, 1998Si18, 1992Si21, 1983Mu21, 1974Me34).
Nuclear Data Sheets for A = 99
2017, Nuclear Data Sheets
Coexistence and B(E2)'s in 98Sr
2017, Nuclear Physics A
Nuclear Data Sheets for A = 99
2011, Nuclear Data Sheets
The first observation of a deformed Kπ = 1+ ground-state band in 100Nb and the high-spin level scheme of its 4n fission partner 148La
2009, Nuclear Physics A
The high-spin level schemes of odd–odd ¹⁰⁰Nb ( $Z = 41$ , $N = 59$ ) and ¹⁴⁸La ( $Z = 57$ , $N = 91$ ) were identified from $γ – γ – γ$ coincidence studies of prompt γ rays in the spontaneous fission of ²⁵²Cf with Gammasphere. Spin/parity assignments for the levels in these two nuclei were made based on the low-lying levels assigned in decay work, on the internal conversion coefficient (ICC) measurements and the level systematics of the neighboring isotopes. A $K^{π} = 1^{+}$ deformed ground-state band was identified in ¹⁰⁰Nb. The onset of ground-state deformation in Nb isotopes is found to take place at $N = 59$ , in contrast to $N = 60$ for Sr ( $Z = 38$ ), Y ( $Z = 39$ ) and Zr ( $Z = 40$ ) isotopes. Unlike the observation in ⁹⁹Nb, the $N = 56$ subshell closure seems to be no longer dominant in ¹⁰⁰Nb. The bands observed in ¹⁴⁸La are interpreted as aligned coupling of ${[π h_{11 / 2} υ h_{9 / 2}]}_{low J}$ to the deformed core rotor.

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Nuclear Physics A

Abstract

References (15)

Nucl. Instrum. Methods

Nucl. Phys.

Phys. Rev. C

Phys. Scr.

Phys. Rev. C

Cited by (20)

Nuclear Data Sheets for A=100

Nuclear Data Sheets for A=98

Nuclear Data Sheets for A = 99

Coexistence and B(E2)'s in <sup>98</sup>Sr

Nuclear Data Sheets for A = 99

The first observation of a deformed K<sup>π</sup> = 1<sup>+</sup> ground-state band in <sup>100</sup>Nb and the high-spin level scheme of its 4n fission partner <sup>148</sup>La