Spectroscopy of the isotonesRn215andRa

In-beam spectroscopy of215Rn86

“…Figure 2 shows the experimental level structure of 215 Rn obtained from the present study. The ground state is proposed [7] to have spin-parity 9/2 + , an assignment which is consistent with the g 9/2 orbit of the spherical shell model for N = 129. Also, this same spin-parity was reported in the known N = 129 isotones 217 Ra [2] and 219 Th [5] and in the lighter odd-neutron neighbors.…”

“…2) were clearly established on the basis of coincidence intensities, anisotropy values, and the existence of the 376.4, 317.7, and 203.9 keV transitions linking both sequences and to the previously known 316.4 keV M1 transition [7].…”

“…Only a few transitions belonging to both 215 Rn and 216 Rn were contaminated. The isotopic assignment of lines to 215 Rn was done on the basis of the reaction energy, the coincidences with Rn K x rays, and the measured coincidence relations with the 316.4 keV (11/2 + → 9/2 + ) previously observed M1 transition [7] in this nucleus. The gamma rays assigned to 215 Rn are listed in Table I together with their intensities, anisotropy ratios, and adopted multipolarity.…”

“…We give here a more complete in-beam level scheme of 215 Rn and discuss the relation between its structure and that of its neighbors, in particular its heavier isotone 217 Ra. The hitherto known level structure of 215 Rn consists of a few levels obtained from the 219 Ra α decay [6,7]. The ground state of 215 Rn has been assigned as 9/2 + because it favors the α decay (E α = 8.674 MeV) to the 9/2 + 211 Po [8] ground state with a hindrance factor (HF) of 1.5.…”

Characterization of octupole-type structures inTh221

“…1. The 7/2 + state is the ground state accepted in the literature [25,26], with a half-life of 1.73(3) ms [27]. All levels are assigned with respect to this 7/2 + state, implying that the ground state is the band head of the yrast band.…”