Angular momentum selectivity of the beta-Oslo method to measure gamma-ray strength and nuclear level density*

Recently, the beta-Oslo Method was developed, a new application of the Oslo Method to nuclei formed by beta decay, allowing strength function and level density measurements in neutron-rich nuclei. However, in the case of Gamow-Teller beta decay being dominant, the angular-momentum range of states populated in the daughter nucleus is within 1$\hbar$, much more narrow than for charged-particle reactions used in the Oslo method.

To investigate the effect on the Oslo Method of this angular momentum selectivity, artificial nuclear level schemes for a range of neutron-rich strontium isotopes were generated by the Monte Carlo codes DICEBOX and RANIER. Gamma ray cascades were simulated from distributions of states with angular momentum that can be populated by beta decay and analyzed with the Oslo Method.  The strength functions and nuclear level densities extracted were then compared to both the known models used to generate the cascades and those parameters extracted from a broader initial angular momentum distribution.