Lifetime Measurements to Test the Coexistence of Spherical and Deformed Shapes inSe72

Abstract

Mean lives of the 4 + to (12 + ) yrast states in 72 Se populated in the reaction 58 Ni( 16 0, 2p) were extracted from a line-shape analysis of the Doppler-broadened lines. The results strongly support the interpretation of the crossing of states built on near-spherical and deformed shapes in the yrast cascade. A least-squares fit of a collective Hamiltonian to the experimental data yielded a potential energy surface with spherical and strongly deformed prolate minima.

Collectivity atN=50:Ge82andGade1, Baugher2, Bazin3 et al. 2010Phys. Rev. C619810View full textAdd to dashboardCite

“…The neutron-rich projectile beams containing 82 Ge and 84 Se were produced in-flight by fragmentation of a 140-MeV/u 86 Kr primary beam provided by the Coupled-Cyclotron Facility at NSCL. 9 Be foils with thicknesses of 432 mg/cm 2 and 329 mg/cm 2 , respectively, served as production targets for the two different secondary beams. The fragments of interest were selected with the A1900 fragment separator [21]; an achromatic 210 mg/cm 2 aluminum wedge degrader located at the midacceptance position of the fragment separator was used.…”

“…Their properties are driven by shape coexistence and rapid shape changes all the way from the N = Z line into the A ≈ 70 mass region [1][2][3][4][5][6][7][8][9][10][11][12][13]. On the other side of the nuclear chart, the most neutron-rich selenium and germanium isotopes accessible for experiments are around the magic neutron number N = 50.…”

“…In the present paper we report the experimental results of the intermediate-energy projectile Coulomb excitation and inelastic scattering on a 9 Be target for the N = 50 isotones 82 Ge and 84 Se. While Coulomb excitation with fast projectile beams allows for the sensitive study of the B(E2; 0 + gs → 2 + 1 ) ≡ B(E2 ↑) excitation strength in even-even nucleia measure of the low-lying quadrupole collectivity- 9 Beinduced inelastic scattering provides access to collective structures beyond the first 2 + state.…”

“…While Coulomb excitation with fast projectile beams allows for the sensitive study of the B(E2; 0 + gs → 2 + 1 ) ≡ B(E2 ↑) excitation strength in even-even nucleia measure of the low-lying quadrupole collectivity- 9 Beinduced inelastic scattering provides access to collective structures beyond the first 2 + state. Measured B(E2 ↑) electric quadrupole excitation strengths along the line of N = 50 isotones are compared to large-scale shell-model calculations with three different effective interactions.…”

“…The evolution of collectivity along the Se and Ge chains is further confronted with mean-field calculations. The population of higher-lying states in the 9 Be-induced inelastic scattering of 84 Se is discussed in comparison to inelastic proton and α scattering on stable selenium isotopes.…”