Photonuclear Physics : ⁴⁸Ca(γ,n)⁴⁷Ca

The absorption of a γ ray may cause a transition to a 1⁺ or 1^- state in ⁴⁸Ca. For 10 to 15 MeV γ rays these states may be a single particle excitation but more often are collective vibrations of the entire nuclear system. The transition strengths, or loosely relative probabilities, of exciting these different collective modes are dependent upon the nuclear level structure of the ⁴⁸Ca nucleus. ⁴⁸Ca is a nucleus whose magnetic dipole transition strength distribution is fragmented, the transition does not occur at a single γ ray energy. Understanding the cause for the fragmentation has driven theorists to implement various extensions of the random phase approximation and to consider new effective interactions in calculations.

The Photonuclear Group has been involved in measuring both the magnetic and electric dipole transitions of ⁴⁸Ca to aid in the understanding of the above phenomena and provide more insight into characteristics of the fp shell nuclei.