Measurements of the 48 Ca ( γ , n ) reaction

The 48Ca(γ ,n) cross section was measured by using γ -ray beams of energies between 9.5 and 15.3 MeV generated at the Triangle Universities Nuclear Laboratory high-intensity γ -ray source. Prior to this experiment, no direct measurements had been made with γ -ray beams of sufficiently low energy spread to observe a structure in this energy range. The cross sections were measured at 34 different γ -ray energies with an enriched 48Ca target. Neutron emission is the dominant decay mechanism in the measured energy range that spans from the threshold, across the previously identified M1 strength, and up the low-energy edge of the E1 giant dipole resonance. This paper found B(M1) = 6.8 ± 0.5μN for the 10.23-MeV resonance, a value greater than previously measured. Structures in the cross section have been observed whose magnitudes are in agreement with existing data and that are commensurate with extended random-phase approximation calculations.