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HK: Fachverband Physik der Hadronen und Kerne

HK 30: Structure and Dynamics of Nuclei VII

HK 30.2: Vortrag

Dienstag, 12. März 2024, 18:00–18:15, HBR 19: C 5b

Coulomb excitation of ¹²⁴Te: persisting seniority structure in the 6₁⁺ level — •Martha Reece^1,2, Ben Coombes², AJ Mitchell², Andrew Stuchbery², Greg Lane², Angela Gargano³, Nathan Spinks², and Jack Woodside² — ¹GSI, Darmstadt, Germany — ²ANU, Canberra, Australia — ³INFN, Napoli, Italy

A new research program at the Australian Heavy Ion Accelerator Facility is examining the nature of near-spherical nuclei using Coulomb-excitation measurements. To facilitate these measurements, a new silicon photodiode particle detector system has been developed and integrated into the CAESAR array of Compton-suppressed γ-ray detectors. The first experiments studied ¹²⁴Te, a nucleus that lies in a transitional region between single-particle and collective behaviour just beyond the Z = 50 proton shell. The value B(E2; 6₁⁺→4₁⁺) = 25(7) W.u. was measured for the first time in this nucleus; this is significantly below the collective limits of the previously proposed spherical-vibrator and triaxial-rotor models. The experimental results are compared to shell-model calculations for ^120−128Te, which show remarkable agreement for the known B(E2; 6₁⁺ → 4₁⁺) values. It appears that, despite approaching mid-shell, ¹²⁴Te retains single-particle structure in the 6₁⁺ level. This is in contrast to other B(E2) values in ¹²⁴Te, and neighboring ^120,122Te, in which collectivity becomes enhanced as more neutrons are removed.

Keywords: Coulomb excitation; Nuclear shell model; Nuclear collectivity; Nuclear structure