Decay properties of139mSm and139Eu

Abstract

The structure of 1398m is investigated through the decay properties of 139roam and ~39Eu. The decay of 139mSm is measured to have a half-life of (10.7_+0.6) s. Gamma-ray and internal conversion electron measurements lead to the construction of a decay pattern comprising seven transitions among five states. The decay of a39Eu with a measured half-life of (17.9_+0.6)s is studied with beta decay spectroscopy techniques. A decay scheme consisting fourteen states in 1398m is proposed. Using deduced ft values and transition multipolarities, J~ assignments are made. Nuclear systematics of the odd-A, N= 77 and 76 are discussed.

In-beam study of the doubly-odd nucleus 61 140 Pm79 above the 8− β +-decaying isomer

“…The low-lying level structure in the transitional nuclei with N__< 82 near Z = 64 can be interpreted in terms of the spherical shell model with the active neutrons and protons filling the lg7/2, 2d5/2, lhtl/2, 3s~/2 and 2d3/2 orbitals [- [1][2][3]. The effects of the Z = 64 sub-shell closure have been verified to disappear for nuclei with neutron number N < 78 [4], but can still influence the properties of nuclei in the vicinity of the N = 82 main shell closure.…”

States inN=79142Eu populated in the decay of142Gd

“…A single 7-ray spectrum was accumulated simultaneously and the two spectra were normalized by counting a 2~ standard source in the same geometry as the samples obtained by irradiation. The results were further checked by using the intense conversion electron peaks from the decay of 139mSm and 142mEu which have been studied by Deslauriers et al [12] and Kennedy et al [3], respectively. Our results were found to be in very good agreement with those already reported for these two nuclides.…”

“…The data acquisition was started 20 s after the bombardment in order to allow shorter-lived activities to decay substantially. Several well known contaminating activities were also inevitably produced, either directly or as daughter activities, at this bombardment energy: 145 g, mGd [22,23], 144Gd [24], a43 g, mGd [25,26], 143Eu [2], a42g'mEu [3], 14lg'mEu [8], 141g'mSm [7,27], 14~ [13,28], 139g'mSm [11,12] la9 Pm [9] and 138Pm [10]. Several lines from the decay of ~42Gd that were clearly observed in the X-y coincidences were thus strongly contaminated in the y-ray singles spectrum.…”

Structure of N=81144Eu from the decay of144Gd

“…This is part of our continuing effort to investigate the structure of neutron deficient nuclides in the 50 < (N, Z) < 82 mass region, using beta decay spectroscopy techniques (see for examples [1][2][3][4][5] and references therein]. The systematic study of doubly-odd nuclei should provide valuable information on the neutron-proton residual interaction.…”