Measurement of alpha to fission branching ratios of heavy actinides by sequential etching of alpha and fission tracks in CR-39

Abstract

A sequential etching method for revelation of alpha and fission tracks m CR-39 was developed and optimized. Using this technique alpha and fission tracks can be differentiated unambiguously because of significant differences in their sizes and appearance times. This registration and revelation procedure for alpha and fission tracks may be used for studies of half lives, alpha to fission branching ratios and identification of radionuclides based on their decay schemes. It has the added advantage that both alpha emissions and fission events can be studied using one detector and hence uncertainties related to efficiency registration geometry, registration times, amount of radionuclides etc. can be eliminated or minimised. The sequential etching procedure was used to measure the α /S.F. branching ratio of252Cf and244Cm and compared with published data in which other techniques were used. These two radionuclides were chosen because in252Cf both alpha and spontaneous fission rates are comparable and in244Cm alpha events are much more than spontaneous fission events and hence form two extremes. The results indicate that the present method gives very precise and accurate values for α /S.F. branching ratio for252Cf and244Cm and can be considered as reference nuclides for this technique of measurement.