Alpha Decay ofAm243

Abstract

The decay of M Am has been studied by observing a-y coincidences using Si (Au) surface-barrier and Ge (Li) detectors in conjunction with a 4096-channel two-parameter analyzer, y rays of 31.2, 43.6, 50.6, 55.4, 74.8, 86.7, 117.8, 142.0, 169, 195, and 220 keV were observed. Only the 43.6-, 74.8-, and 117.8-keV y rays have been previously reported. These results confirm many features of the previously accepted level scheme of the 239 Np daughter. Furthermore, new levels at 72 and 123 keV have been found which are apparently the f-f and ^+ members, respectively, of the ground-state rotational band. These energies agree well with predictions based on the collective model. The intensity ratio of a groups to the ground and first excited states has been measured to be 1.17, in poor agreement with a theoretical estimate of 2.03.

A ?? coincidence study of transitions in239Np and239Pu from decay of243Am

“…However, from the chemically separated 243Am source, the intensity of the l l7.60keV 7-ray was obtained relative to the 74.67 keV 7-ray from a spectrum taken 15 min after separation. The intensity obtained by this method for the 117.60 keV transition is 0.84 _+ 0.12, which differs somewhat from the reported value of 1.2 obtained by e-?, coincidence measurements [8], but agrees well with 0.88_+0.39 as reported by Aleksandrov et al [15]. A high energy singles spertrum taken with the large volume Ge(Li) detector confirmed the presence of previously reported transitions with the possible addition of three very weak 7-rays at 361.6, 418.6, and 552.8 keV.…”

“…Only the 142.18 and 117.60 7-rays were observed in the singles data. The 50.5, 55.4, 98.5, 169.0, and 195.0 keV transitions were observed [8,9] by ~-7 coincidence or conversion electron studies from the decay of 243Am.…”

“…However, only a few of the gamma transitions have been confirmed by coincidence data. The level structure of 239Np from 243Am decay was studied by Engelkemeir [8,9] by c~-7 coincidences and conversion electron spectrometry. However, since 243Am decays preferentially to the low lying energy states, no 77 coincidence measurements had been attempted.…”