Fine Structure in Thermal Neutron (n,α) Reactions

Abstract

<p> Fine structure in thermal neutron (n, α) reactions has been studied for 149Sm, 147Sm, and 143Nd by means of an instrument called an electrostatic particle guide. This device, which was designed to eliminate the problems of background and low energy tailing in (n,α) spectroscopy, is described in detail. Alpha decay has been observed from thermal neutron capture states to levels in the daughter nucleus to greater than 2 MeV excitation. Cross sections and alpha energies are presented for each transition and as well, the alpha decay schemes for 146Nd, 144Nd, 140Ce. Experimental reduced widths have been calculated and are discussed in terms of Mang's theory of alpha decay. Evidence is presented for the (n, γα) process in the 143Nd (n,α) 140Ce reaction. </p>