Stability of 244–260Fm isotopes against alpha and cluster radioactivity

Abstract

Taking Coulomb and proximity potentials as the interacting barrier we have studied the cold valley in the radioactive decay of 244−260 Fm isotopes. It is found that in addition to alpha particle minima, other minima occur at S, Ar and Ca clusters. We have computed the half-lives and other characteristics of different clusters emitted from these parents treating parent, daughter and emitted cluster as spheres. Our study reveals that most of these parents are unstable against alpha and heavy cluster ( 46 Ar, 48,50 Ca) emissions and stable against light cluster emission, except 8 Be from 244−248 Fm isotopes. The most probable clusters from these parents are predicted to be 46 Ar, 48,50 Ca which indicate the role of doubly or near doubly magic clusters (Z = 20, N = 28) and also stress the role of doubly magic 208 Pb daughter. The computed half-lives for alpha decay are in good agreement with the experimental data. It is found that the presence of neutron excess in the parent nuclei slows down the cluster decay process. The effect of quadrupole (β 2) and hexadecapole (β4) deformations of parent and fragments on half-lives are also studied. It is found that inclusion of β2 and β4 reduces the height and shape of the barrier (increases barrier penetrability) and hence the half-life decreases.