Electromagnetic properties of the21+state in134Te: Influence of core excitation on single-particle orbits beyond

Abstract

The g factor and B(E2) of the first excited 2 + state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide 134 Te (two protons outside 132 Sn) produced as a radioactive beam. The precision achieved matches related g-factor measurements on stable beams and distinguishes between alternative models. The B(E2) measurement exposes quadrupole strength in the 2 + 1 state beyond that predicted by current large-basis shell-model calculations. This additional quadrupole strength can be attributed to coupling between the two valence protons and excitations of the 132 Sn core. However, the wave functions of the low-excitation positive-parity states in 134 Te up to 6 + 1 remain dominated by the π (g 7/2) 2 configuration.

Nuclear moments and nuclear structure near132Sn

“…The measurements are complementary as the g factor probes single-particle aspects of the wavefunction whereas the B(E2) probes collectivity. This paper will focus on 134 Te [6], which has two valence protons added to 132 Sn. Comparisons will be made with other nuclides that have two valence protons added to a double magic core.…”

Gyromagnetic ratios of excited states and nuclear structure near 132Sn

“…could be produced (perhaps by a batch method), then a combined g-factor and B(E2) measurement could be performed for the 2 + 1 state of 210 Po, similar to the measurements on 134 Te [6].…”

“…Anomalous magnetism, the M1 operator, and single-proton g factors Figure 1 shows the experimental [1,2,6,12,13] and theoretical [14,16,15,17] g(2 + 1 ) systematics for the Te isotopes near N = 82. There is quite good agreement between theory and experiment for 130 Te and 132 Te, however the theories do not agree for 134 Te where the experimental g factor falls between the predictions of the QRPA calculation [16] and the two shell model calculations [14,15].…”

“…The g factor and B(E2; 0 + 1 → 2 + 1 ) for the first-excited state of the neutron-rich N = 82 isotone 134 Te have been measured at HRIBF [6]. The precision achieved for these radioactive beam measurements is remarkable: a comparison of the precision of the B(E2) and g-factor ratios in Table 4 shows that the radioactive beam case of 134 Te matches the precision of the three stable-beam cases.…”

“…This paper will focus on the N = 82 nuclide 134 Te, which has two valence protons added to 132 Sn. With the recent measurements of the g factor and a precise value for B(E2; 0 + 1 → 2 + 1 ) [6], 134 Te becomes the only nuclide to date with two protons added to a double-magic core for which the g factors of all states formed (predominantly) by the lowest j 2 configuration, and the transition rates between them, have been measured. After discussing the electromagnetic properties of 134 Te itself, comparisons will be made between 134 Te and other nuclides which have two valence protons added to a double magic (or near double magic) core.…”