  Stability of 248-254^Cf nuclei against alpha and cluster emission is studied
within our Coulomb and proximity potential model (CPPM). It is found that these
nuclei are stable against light clusters (except alpha particle) and instable
against heavy cluster emissions. For heavy cluster emissions the daughter
nuclei lead to doubly magic 208^Pb or neighbouring one. The effect of
quadrapole and hexadecapole deformations of parent nuclei, daughter nuclei and
emitted cluster on half lives are also studied. The computed alpha decay half
life values (with including quadrupole deformation {\beta}2) are in close
agreement with experimental data. Inclusion of quadrupole deformation reduces
the height and width of the barrier (increases the barrier penetrability) and
hence half life decreases.
