Studies on the level structure of154Gd via the ?-decay of154Eu nucleus

Abstract

The excited states of aS4Gd populated by the fi-decay of lS4Eu (T1/2=8.5 y) have been studied. With a HPGe-NaI(T1) Compton suppression spectrometer and a HPGe-NaI (T1) coincidence circuit 7-ray singles spectra, coincidence spectra and the 7-7 directional correlational functions have been obtained. The deduced mixing ratios of multipolarities are presented. The energy levels and the relative B(E2) values of the various ?-transitions in XS4Gd nucleus have been calculated both in the IBA model and it's extended version with boson surface delta interaction (BSDI).

On the Level Structure of154Gd

“…The analysis of singles, suppressed and gammaĝ amma cioncidence spectra results in observation of 92 gamma transitions belonging to the decay of 154 Eu to 154 I. The 346.7 and 598.4 keV gamma transitions were reported only by Meyer [1] and Sharma et al [3] while the 1136.2 keV line observed by Meyer [1] and Kiang et al [4] are con¢rmed in the present work. One should note that the 346.7 keV is a member of the ground state rotational band.…”

N=90region: The decay ofEu154toKulp1, Wood2, Krane3 et al. 2004Phys. Rev. C

“…The 506.5, 642.4, and 1400.0 keV ␥ rays out of this level have been observed in other methods, and reported [14,15,17,19] in the decay of 154 Eu. We do not observe any of these transitions in this study (cf.…”

“…However, Table 1 in Ref. [17] and the statement, "no ␥ ray associated with [levels adopted [2] at 1277, 1510, 1699, 1839, and 1895 keV] was observed in our measurements," indicates that this listing is in error. Based upon coincidence data, we have placed transitions associated with these levels elsewhere in the decay scheme (cf.…”

“…Only studies of 154 Eu decay have reported ␥ rays associated with proposed levels in 154 Gd at 1136 [14,16,17], 1233 [14], 1510 [14,15,18], 1879 [14,15], and 1895 keV [14,15]. The 1387 keV ␥ ray is the strongest of the transitions associated with these levels, and (with the 1510.0 keV ␥ ray, the other transition which defines the 1510 keV level) should be visible in our singles spectrum.…”

“…Other confirmations have come from reports of transitions associated with the levels at 1277 [15,19], 1839 [15], and 1861 keV [15]. The work by [15] includes a detailed comparison of ␥ rays emitted in 154 Eu decay which lists also that 1717 and 1838 keV transitions were observed [17] associated with the 1839 keV level. However, Table 1 in Ref.…”