Decay of mass-separatedI136to levels in theN=82nucleus

Abstract

A total of 142 y rays were observed in the decay of the 45and 85-sec isomers of " I using an on-line isotope separator system. Of these, 116 were placed in a level scheme for " Xe consisting of 50 excited levels up to 6624 keV using results from Ge(Li) y singles and yy-coincidence measurements. Our results are compared with results from earlier decay and reaction experiments, and the levels below 2.8 MeV are compared with predictions of recent shell-model calculations. Strong P population was observed to states above 3.5 MeV which are interpreted as neutron particle-hole states. RADIOACTIUITY 36I [from 3 U(n, f)]; measured Ey Iy p~coin, Ge(Li) detectors; 3 Xe deduced levels, J, n, lpgf t. Mass-separated 3 I activity.

Seniority structure of Xe82136

“…2849.6 keV (0 + ) level: In previous β − -decay measurements, a ground-state transition from this level was observed [17]; however, we find no evidence of such a γ ray, even when summing the spectra for all of the angles in the angular distribution data set to increase the statistics. We only observe the 1536.5 keV γ ray with an isotropic angular distribution and thus conclude a tentative spin assignment of 0 + .…”

Investigating the Pygmy Dipole Resonance UsingβDecay

“…For this purpose the case 136 I ½J 0 ¼ ð1 − Þ → 136 Xe has been chosen as an example. For this decay Q β ¼ 6.93 MeV is sufficient to populate higher-lying 1 − levels in a stable nucleus and published data from β-decay studies [41] as well as NRF [42] exist. In the 136 Xeðγ; γ 0 Þ reaction, large numbers of spin-1 levels were observed below Q β (see Fig.…”

“…Candidates for 1 − levels in 136 Xe. Part (a) shows the BðE1Þ-strength distribution as extracted from the ðγ; γ 0 Þ reaction[42], part (b) shows the relative level population intensity in the 136 I J π ¼ ð1 − Þ β decay[41], and part (c) the ground-state branching ratios extracted from β decay. Levels marked with red bars were populated in both reactions.…”