A new semi-empirical model is proposed for determining the half lives of radioactive nuclei exhibiting cluster radioactivity. The parameters of the formula are obtained by making a least-square fit to the available experimental cluster decay data. The calculated half-life time for cluster decay is compared with the corresponding experimental values and with the values proposed by earlier scaling laws and with those predicted by the Coulomb and proximity potential model. The semi-empirical formula is applied to alpha decay of parents with Z = 85–102 and is compared with experimental data and with other semi-empirical formula predictions. The predicted alpha and cluster decay half-life time values are found to be in good agreement with the experimental data. The calculated alpha decay half-life time is also compared with the values predicted by Viola–Seaborg–Sobiczewski and Horoi systematics.

Half life for the emission of exotic clusters like 8 Be, 12 C, 16 O, 20 Ne, 24 Mg and 28 Si are computed taking Coulomb and proximity potentials as interacting barrier and many of these are found well within the present upper limit of measurement. These results lie very close to those values reported by Shanmugam et al using their cubic plus Yukawa plus exponential model (CYEM). It is found that 12 C and 16 O emissions from 116 Ce and 16 O from 118 Ce are most favorable for measurement´T 1 2 10 10 s). Lowest half life time for 16 O emission from 116 Ce stress the role of doubly magic 100 Sn daughter in exotic decay. Geiger-Nuttall plots were studied for different clusters and are found to be linear. Inclusion of proximity potential will not produce much deviation to linear nature of Geiger-Nuttall plots. It is observed that neutron excess in the parent nuclei slow down the exotic decay process. These findings support the earlier observations of Gupta and collaborators using their preformed cluster model (PCM).

Considering Coulomb and proximity potentials as barriers, we have calculated the half lives for ½¾ C emission from various Ba isotopes using different mass tables. The half life for ½½¾ Ba isotope calculated by us is 6.020 ¢ 10 ¿ s which is comparable with the experimental value 5.620 ¢ 10 ¿ s. From our study it is found that ½½ Ba is the good parent for ½¾ C emission whose emission rate is favorable for measurement. The half lives predicted by us lie very close to those reported by Shanmugam et al using their cubic plus Yukawa plus exponential model. It is observed that inclusion of proximity potential does not produce significant deviation from the linear nature of the GeigerNuttall plots. Also it is found that the neutron excess in the parent nuclei slows down the exotic decay process.

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