Isomers in 203Tl and core excitations built on a five-nucleon-hole structure

Abstract

Isomers with three-and five-nucleon-hole configurations have been established in 203 Tl. These include newly identified levels with a three-nucleon structure: I π = (15/2 − ) with T 1/2 = 7.9(5) ns, and I π = (35/2 − ) with T 1/2 = 4.0(5) ns. In addition, five-quasiparticle states: I π = (39/2 − ) with T 1/2 = 1.9(2) ns, and I π = (49/2 + ) with T 1/2 = 3.4(4) ns have also been established. The previously determined long-lived decay [T 1/2 = 6.6(3) µs from this work] is associated with isomerism of the I π = (29/2 + ) state. Levels above this long-lived isomer have been identified through a delayed-prompt coincidence measurement. Five-nucleon-hole states with excitation energies Ex ≈ 7 MeV have been established as well as possible octupole excitations of the 208 Pb core built on these levels. The level scheme of 203 Tl is extended up to Ex ≈ 11 MeV with the inclusion of 25 new transitions. Empirical and shell-model calculations have been performed to aid in the description of the observed states which are found to be predominantly of intrinsic character.

Systematic shell-model study of Rn isotopes with A = 207 to 216 and isomeric states

“…A solvable model for octupole phonons for 208 Pb is reported in reference [18]. Also, several isomeric states are observed in this region [19][20][21][22]. The level scheme of 212 Rn with up to spins of ∼39h and excitation energies of about 13 MeV has recently been reported using 204 Hg( 13 C, 5n) 212 Rn reaction [23].…”