ISSN:
1434-601X
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract High-spin states in204Pb were populated in the204Hg(α,4n) reaction using α-particles in the energy region 42–51 MeV. Prompt and delayedγ-rays as well as conversion electrons were studied in addition to excitation functions, angular distributions andγ-γ coincidences. In this way a stretched cascade ofγ-rays from a level at 8125.9 keV was found to feed the previously known isomeric 9− level at 2185.7 keV. Spins and parities were established for levels up to and including a 19− level at 6098.0 keV. The levels with c= 172212; and 19− at excitation energies of 5664.3 and 6098.0 keV are likely to be due to the simplep 1 2/s-1 i 13 2/−3 andf 5 2/−1 i 13 2/−3 configurations. The agreement between calculated and experimental energies for all observed levels in the regionJ=9–19 is very good in cases where the empirical two-particle interactions used are satisfactorily well known. Above the 19− level there are three weakly populated levels at 7402.1, 7849.2 and 8125.9 keV, which are likely to haveJ≥20. None of these energies agrees with the calculated value 7695±20 keV for the 20+ state of thei 13 2/−4 configuration which has the highest angular momentum produced by the four valence neutron holes. This apparent anomaly can be understood if the yrast levels withJ≥20 have angular momentum contribution from the core. It seems likely that the states at 7402.1, 7849.2 and 8125.9 keV are due to proton core excited states of the typeπh 9/2 h 11 2/−1 ×νp 1 2/−2 i 13 2/−2 withJ π=20+ andJ π=21+ andπh 9/2 h 11 2/−1 ×νp 1 2/−1 f 5 2−1 i 13 2/−2 withJ π=22+ or 23+, respectively. The state at 8126 keV has the highest energy so far directly observed in a stretched cascade ofγ-rays from the decay of a heavy nucleus produced in (α, xn) reactions.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01411332
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