Evolution of quadrupole collectivity in N=80 isotones toward the Z=64 subshell gap: The B(E2; 2(1)(+) -> 0(1)(+)) value of Sm-142

It was shown that the evolution of the B(E2; 2+1 → 0+1 ) values in N = 80 isotones from Te to Nd is affected by the underlying subshell structure. This manifests itself in the observation of the local suppression of the B(E2) value at Z = 58 with respect to the neighboring nuclei 136Ba and 140Nd. To investigate this shell sensitivity toward the Z = 64 subshell gap, the B(E2; 2+1 → 0+1 ) value of the unstable nucleus 142Sm was measured utilizing the projectile Coulomb excitation technique. The radioactive ion beam (RIB) experiment was performed at the REX-ISOLDE facility at CERN. The B(E2) value of 32 (4) W.u. reflects the impact of the π(1g7/2 2d5/2) subshell closure at Z = 64 with respect to a linear scaling of collectivity with valence proton number.status: publishe

Coulomb excitation of re-accelerated Rn-208 and Po-206 beams

In the present study, B(E2; 2+ → 0+) values have been measured in the 208Rn and 206Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. The resulting B(E2; 2+ → 0+) in 208Rn is ∼0.08 e2b2. These nuclei lie in, or at the boundary of the region where seniority scheme should persist. However, contributions from collective excitations may be present when mov- ing away from the N = 126 shell closure. To date, surprisingly little is known of the transition probabilities between the low-spin states in this region.status: publishe

Do nuclei go pear-shaped? Coulomb excitation of Rn-220 and Ra-224 at REX-ISOLDE (CERN)

The IS475 collaboration conducted Coulomb-excitation experiments with post-accelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam: 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted ‹3−||E3||0+› matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. This finding has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nuclei.status: publishe