Signatures for “phase” transitions in finite systems

The existence of “phase” transitions in finite nuclear systems has been predicted in several models. However fluctuations in the relevant order parameters are generally large enough to prevent their use as signatures for the transitions. In present work both the specific heat and the square of the fluctuations in the internal energy over temperature squared have been calculated in a realistic calculation in²⁴Mg. These are equivalent in an exact canonical ensemble calculation for fixed particle number but differ in the thermal mean field approach. Both clearly indicate the presence of “phase” transitions, the first being more useful for the higher lying second order shape transitions, the second more appropriate for the lower lying first order transitions.