Energy levels of {sup 249}Bk populated in the {alpha} decay of {sup 253} {sub 99}Es and {beta}{sup -} decay of {sup 249} {sub 96}Cm.
The level structure of {sup 249}Bk has been investigated by measuring the {gamma}-ray spectra of an extremely pure {sup 253}Es sample obtained by milking this nuclide from {sup 253}Cf source material produced in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Additional information on the {sup 249}Bk levels was obtained from the {beta}{sup -}-decay study of {sup 249}Cm, produced by neutron irradiation of {sup 248}Cm. Using the results of the present study together with the data from previous {sup 248}Cm({alpha},t) and {sup 248}Cm({sup 3}He,d) reactions, the following single-particle states have been identified in {sup 249}Bk: 7/2{sup +}[633], 0.0 keV; 3/2{sup -}[521], 8.78 keV; 1/2{sup +}[400], 377.55 keV; 5/2{sup +}[642], 389.17 keV; 1/2{sup -}[530], 569.20 keV; 1/2{sup -}[521], 643.0 keV; 5/2{sup -}[523], 672.9 keV; and 9/2{sup +}[624], 1075.1 keV. Four vibrational bands were identified at 767.9, 932.2, 1150.7, and 1223.0 keV with tentative assignments of {l_brace}7/2{sup +} [633] {circle_times}1{sup -}{r_brace}9/2{sup -}, {l_brace}7/2{sup +} [633] {circle_times}0{sup -}{r_brace}7/2{sup -}, {l_brace}7/2{sup +} [633] {circle_times}1{sup -}{r_brace}5/2{sup -}, and {l_brace}7/2{sup +} [633] {circle_times}0+{r_brace}7/2{sup +}, respectively. A band at 899.9 keV was observed in {gamma}-{gamma} coincidence measurements and given a tentative spin assignment of 3/2. It is possibly associated with a 2{sup -} phonon coupled to the ground state, with configuration {l_brace}7/2{sup +} [633] {circle_times}2{sup -}{r_brace}3/2{sup -}. Three levels at 624.3, 703.5, and 769.1 keV were assigned spins of 5/2, 7/2, and 9/2, respectively. These could be the members of the 3/2{sup +} [651] band, expected in this energy region.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 953429
- Report Number(s):
- ANL/PHY/JA-51852; PRVCAN; TRN: US0902760
- Journal Information:
- Phys. Rev. C, Vol. 71, Issue 5 ; May 2005; ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- ENGLISH
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