Increasing Octupole Collectivity across the Z=64 Isotopic Chain: B(E3) Values in ^{150}Gd.

Area of Science:

• Nuclear Physics
• Atomic and Molecular Physics

Background:

• Octupole collectivity, a nuclear shape characterized by pear-like deformations, is a key phenomenon in nuclear structure physics.
• Investigating enhanced octupole transitions provides insights into the underlying nuclear interactions and symmetries.

Purpose of the Study:

• To measure the electric octupole (E3) strength for the 3⁻→0⁺ transition in the ^{150}Gd nucleus.
• To provide direct experimental evidence for significant octupole collectivity in ^{150}Gd.
• To analyze the systematics of E3 strength across the Gadolinium (Gd) isotopic chain.

Main Methods:

• Measurement of the mean lifetime of the J^π=3⁻ level in ^{150}Gd.
• Determination of the weak E3 decay branch from the 3⁻ level directly to the ground state.
• Systematic analysis of E3 strengths across Gd isotopes.

Main Results:

• An enhanced electric octupole (E3) strength of 45(5) W.u. was measured for the 3⁻→0⁺ transition in ^{150}Gd.
• Direct experimental evidence for large octupole collectivity was established in ^{150}Gd.
• Systematic trends indicate enhanced octupole collectivity specifically in ^{150}Gd within the Gd isotopic chain.

Conclusions:

• The findings confirm significant octupole collectivity in ^{150}Gd, supported by experimental data.
• Theoretical analysis using five state-of-the-art models, particularly quasiparticle random phase approximation calculations, best reproduces the observed trends.
• This study enhances the understanding of octupole collectivity in the rare-earth nuclear region.