Low energy magnetic radiation enhancement within the Nuclear Shell Model

Abstract:  The $\gamma$-ray strength function ($\gamma$SF), the average $\gamma$-decay reduced probability, is an indispensable quantity for reaction rate calculations. The resonances which dominate the strength function were believed to have been known, however, recent experiments have revealed an intriguing behavior of the strength function. It is found that the $\gamma$SF has a characteristic upbend in the low $\gamma$-energy region, never observed before. This low-energy enhancement cannot be explained by the semiclassical models developed to describe the known resonances and its physical origin is not yet fully understood. We will be presenting the characteristics of the $\gamma$SF, as well as the steps done towards the better undestanding of the mechanism which generates the characteristic upbend.