Coulomb excitation of 73Ga

TL;DR

This study measured B(E2) transition strengths in 71Ga and 73Ga via Coulomb excitation, revealing a shift in nuclear collectivity and evidence for a near-degenerate 1/2-; 3/2- doublet in 73Ga, indicating structural changes around N=40.

Contribution

It provides new Coulomb excitation data for 73Ga, showing a shift in E2 collectivity and evidence for a near-degenerate doublet, advancing understanding of nuclear structure in this region.

Findings

Shift of E2 collectivity to lower energy with added neutrons

Evidence for a 1/2-; 3/2- doublet near the ground state in 73Ga

Confirmation of structural change between N=40 and N=42

Abstract

The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.