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Cluster decay; alpha decay.

Taking Coulomb and proximity potentials as the interacting barrier we have studied the cold valley in the radioactive decay of ^244-260Fm 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 (⁴⁶Ar, ^48,50Ca) emissions and stable against light cluster emission, except ⁸Be from ^244-248Fm isotopes. The most probable clusters from these parents are predicted to be ⁴⁶Ar, ^48,50Ca which indicate the role of doubly or near doubly magic clusters ($Z = 20$, $N = 28$) and also stress the role of doubly magic ²⁰⁸Pb 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 $(\beta_{2})$ and hexadecapole $(\beta_{4})$ deformations of parent and fragments on half-lives are also studied. It is found that inclusion of $\beta_{2}$ and $\beta_{4}$ reduces the height and shape of the barrier (increases barrier penetrability) and hence the half-life decreases.

K P Santhosh^{1 2} R K Biju¹ Sabina Sahadevan¹

1. P.G. Department of Physics & Research Centre, Payyanur College, Payyanur 670 327, India
2. School of Pure and Applied Physics, Kannur University, Payyanur Campus, Payyanur 670 327, India

Published

December 2009

Manuscript received

30 December 2008

Manuscript revised

30 May 2009

Accepted

22 June 2009