Experimental energy-dependent nuclear spin distributions

A new method is proposed to determine the energy-dependent spin distribution in experimental nuclear-level schemes. This method compares various experimental and calculated moments in the energy-spin plane to obtain the spin-cutoff parameter sigma as a function of mass A and excitation energy using a total of 7202 levels with spin assignment in 227 nuclei between F and Cf. A simple formula, sigma(2)=0.391 A(0.675)(E-0.5Pa('))(0.312), is proposed up to about 10 MeV that is in very good agreement with experimental sigma values and is applied to improve the systematics of level-density parameters.