Structure of even-even138Nd from the decay of138Pm

Abstract

The structure of 13SNd is investigated through the fi+-decay of 138pm, whose decay half-life is measured to be 3.24_+0.05 min. A level structure comprising 27 excited states and 52 transitions is constructed. With the help of deduced ft values and internal conversion coefficients, spin-parity assignments are made to many states in 138Nd and to the ground states of 138pm. From the positron end-point energy measurement, the total decay energy is determined to be 5.4 +_0.2 MeV, which is compared with the predictions of several mass formulae and with the decay energy systematics of the N = 77 isotones. The structure of 138Nd is discussed in the light of nuclear systematics of the N = 78 isotones.

Tilted axis rotation, candidates for chiral bands, and wobbling motion in138Nd

“…Most of the observed transitions were grouped in 4 bands of negative parity at low spins (N1 -N4), 8 bands at medium spins (L1 -L8) and 8 bands of dipole transitions (D1 -D8). We also draw the levels which were assigned to the γ-band from β-decay studies [18], even though they were not observed in the present experiment. The energies, relative intensities, DCO ratios and spin-parity assignments of the observed transitions are reported in Table I.…”

“…The energies, relative intensities, DCO ratios and spin-parity assignments of the observed transitions are reported in Table I. The spectroscopic data on 138 Nd are very much enriched with respect to the previous studies [11,[17][18][19][20][21]. The newly constructed level scheme will be discussed separately for the bands of quadrupole and dipole transitions.…”

“…The level structure of 138 Nd was first studied using a (p, 4n) reaction by Yoshikawa [17] and through the β + decay of 138 Pm by Deslauriers et al [18]. High-spin states in 138 Nd have been previously studied by Müller-Veggian et al [19,20] and de Angelis et al [21] up to spin 19 and 21 , respectively.…”

Structure of140Pm from beta decay of140Sm

“…In order to measure the internal conversion coefficients of the intense electromagnetic transitions in the spectrum of the conversion electrons was studied using a Si(Li) detector coupled with a miniorange spectrometer as described earlier [3]. The spectrum obtained is shown in Fig.…”

“…Calibration of gamma-ray and electron spectrometers was performed by counting a 15ZEu standard source in the same geometry as the irradiated targets. The normalization was further checked by using the conversion electron peak of the intense 196.8 keV M1 transition from 141 mSm decay [3] which was always present in the irradiated targets. The conversion coefficients ~k of many low energy lines were thus measured.…”