Measurement of lifetimes for high spin states in 152Sm, 154Gd and 156Gd by the Doppler broadened lineshape method

doi:10.1016/0375-9474(77)90331-1

Nuclear Physics A

Volume 291, Issue 2, 14 November 1977, Pages 443-458

https://doi.org/10.1016/0375-9474(77)90331-1 Get rights and content

Abstract

Lifetimes of the ground band levels up to spin 10⁺ in ¹⁵²Sm, ¹⁵⁴Gd and ¹⁵⁶Gd have been measured by the Doppler broadened lineshape (DBLS) analysis of peaks observed following Coulomb excitation of enriched metallic targsts by 132–143 MeV ³⁵Cl beams. The γ-ray lineshapes were measured in time coincidence with backscattered ions and were analyzed with a computer program incorporating tabulated electronic stopping powers. The nuclear stopping power of Lindhard et al and multiple scattering treatment by Blaugrund were assumed. Renormalization of the electronic stopping powers given by Northclifie and Schilling was found necessary to reproduce the accurately known lifetime of the 6⁺ state in ¹⁵²Sm. Stopping powers for Sm in Sm inferred from the tabulated ⁴He stopping power of Ziegler and Chu support this renormalization. The stretching parameter a derived from the lifetimes of the ground band are (2.0 ± 0.6) × 10⁻³, (1.85 ± 0.40) × 10⁻³ and (0.0 ± 0.45) × 10⁻³, in ¹⁵²Sm, ¹⁵⁴Gd and ¹⁵⁶Gd, respectively.

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Nuclear Data Sheets for A = 152
2013, Nuclear Data Sheets
Detailed level schemes, decay schemes, and the experimental data on which they are based are presented for all nuclei with mass number A=152. The experimental data are evaluated; inconsistencies and discrepancies are noted; and adopted values for level and γ–ray energies, γ intensities, as well as for other nuclear properties are given. This evaluation replaces the A=152 evaluation published by Agda Artna–Cohen in Nuclear Data Sheets 79, 1 (1996) and the evaluation for 152Dy prepared by Balraj Singh and published in Nuclear Data Sheets 95, 995 (2002).
Nuclear Data Sheets for A = 156
2012, Nuclear Data Sheets
Nuclear Data Sheets for A = 154
2009, Nuclear Data Sheets
Nuclear data sheets for A = 156
2003, Nuclear Data Sheets
General properties of the πh<inf>9/2</inf>[541]1/2- configuration and level scheme of 165Tm
2001, Nuclear Physics A
¹⁶⁵Tm has been studied through the reactions ¹⁵⁰Nd(¹⁹F, 4n), E_beam=85 MeV and ¹⁵⁴Sm (¹⁵N, 4n), E_beam=70 MeV. The level scheme has been extended to spin 71/2⁻ℏ, and four new bands have been added. Two are assigned to the K=17/2, three-quasiparticle configurations, π[523]7/2⁻⊗ν[642]5/2⁺⊗ν[523]5/2⁻ and π[404]7/2⁺⊗ν[642]5/2⁺⊗ν[523]5/2⁻, and the remaining two are assigned to γ-vibrations coupled to an h_9/2 proton. Lifetimes of high-spin states in the [541]1/2⁻ and [411]1/2⁺ bands have been measured using DSAM techniques, allowing transition quadrupole moments to be deduced. Furthermore, crossings between the [541]1/2⁻ and [523]7/2⁻ bands and between the [411]1/2⁺ and [404]7/2⁺ bands are analysed with a band-mixing calculation to obtain the quadrupole moments of the [523]7/2⁻ and [404]7/2⁺ bands. While the [523]7/2⁻, [411]1/2⁺ and [404]7/2⁺ bands all have similar deformations, the [541]1/2⁻ band has a quadrupole moment approximately 15% larger. The relative deformations are in good agreement with diabatic potential energy surface calculations performed using the code “Ultimate Cranker”. The experimental crossing frequency, due to the alignment of i_13/2 neutrons, is found to be delayed in the [541]1/2⁻ band compared to the other bands. This is a universal feature in the rare-earth region, and extensive systematic Cranked Shell Model calculations have been performed to predict deformations and crossing frequencies for nuclei in the region. The model is unable to reproduce the full delay in crossing frequency, confirming that deformation alone is not responsible for the shift.
Precise DSAM lifetime measurements in 48Cr and 50Cr as a test of large scale shell model calculations
1998, Nuclear Physics A
Precise DSAM lifetime values have been obtained for the positive parity yrast bands of ⁴⁸Cr and ⁵⁰Cr, populated with the reaction ²⁸Si+²⁸Si at 115 MeV bombarding energy using a Au backed target. The obtained precision relies on the well-known stopping power at high velocity and on the use of DSAM analysis procedures which avoid the sidefeeding contribution. The deduced B(E2) and B(M1) values are in very good agreement with those predicted by full fp shell model (SM) calculations. A new procedure named narrow gate on transition below has been applied for the analysis of the lifetimes.
Clear evidence was found in both nuclei for a low-lying negative parity band which has been successfully described by SM in the fp shell extended to include a hole in the $1 d_{32}$ orbital. Also in this case the derived B(E2) and B(M1) values are in good agreement with the SM calculations.

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^†

Work supported by Atomic Energy Control Board of Canada grant.

Present address: Department of Nuclear Physics, The Australian National University, Canberra, ACT, Australia 2600.

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Nuclear Physics A

Abstract

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Nuclear Data Sheets for A = 152

Nuclear Data Sheets for A = 156

Nuclear Data Sheets for A = 154

Nuclear data sheets for A = 156

General properties of the πh<inf>9/2</inf>[541]1/2<sup>-</sup> configuration and level scheme of <sup>165</sup>Tm

Precise DSAM lifetime measurements in <sup>48</sup>Cr and <sup>50</sup>Cr as a test of large scale shell model calculations