Fine structure in theαdecay ofPo188,192

Abstract

The ␣ decay of 188,192 Po has been reexamined in order to probe the 0 + states in the daughter nuclei 184,188 Pb that can be associated with coexisting spherical, oblate, and/or prolate configurations. Improved values were measured for the excitation energy and the feeding ␣-decay intensity of the 0 2 + state in 184,188 Pb and conflicting results on the 0 3 + state in 188 Pb were clarified. All known cases of fine structure in the ␣ decay of the even-even Po nuclei are reviewed. The reduced ␣-decay width systematics combined with potential-energy-surface calculations confirm the onset of deformation in the ground state of the polonium nuclei around the neutron midshell. An isomeric state with a half-life of 580͑100͒ns has been identified in 192 Po.

Nuclear shape coexistence in Po isotopes: An interacting boson model study

“…α-decay studies, moving from the Po nuclei into the Pb nuclei, have been a major fingerprint, in particular, in view of the shape coexisting structure in the daughter Pb nuclei. There exists an extensive set of results that has been accumulated during a period of about 2 decades [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109].…”

“…Use is made of the fact that for the Pb nuclei, it was shown, through study of the Pb nuclear charge radii [6] and very weak E0 decay strength from the 0 In those studies, and using a two-state mixing model [97], an intruder character for the ground state 0 + 1 state in 192 Po turns out to be ≈63% [100], or, even larger, >65% [101]. More recently, α decay from 188,192 Po has been observed into the final 0 + excited states in 184,188 Pb [104]. Their analyses results in hindrance factors into the first excited 0 + 2 state of 0.08 ± 0.03 and 0.57 ± 0.12, respectively, which may well turn out to be an indication of a very large overlap of the wave functions in the initial and excited states in the final nucleus.…”

Cross section systematics for the lightest Bi and Po nuclei produced in complete fusion reactions with heavy ions

“…By using the high sensitivity of the velocity filter SHIP, combined with high-intensity heavy-ion beams and specially designed large-area rotating targets, we were able to extend the cross section systematics to the new isotopes 184 Bi [23] and 186−189 Po [24][25][26][27]. Furthermore, in contrast to most of the previous works, both the xn and pxn evaporation channels of the studied reactions could be simultaneously investigated, which is important for the subsequent analysis within the statistical model.…”

The Pt isotopes: Comparing the Interacting Boson Model with configuration mixing and the extended consistent-Q formalism

“…The review paper of Julin et al [3] gives an extensive overview of the rich variety in nuclear excitation modes for both the Pb, Hg, Pt and, Po, Rn nuclei. Since the publication of that paper, however, many experiments have been performed highlighting properties of excited band structures and lifetimes for the Pb nuclei [5,6,7,8,9,10,11,12,13] and nearby nuclei, also illuminating the underlying mechanisms that are at the origin of the formation of collective excitations in the neutron-deficient nuclei near to the Z = 82 proton closed shell.…”