Further studies on positron lifetimes in γ-irradiated teflon in low dose range

Positron lifetime spectra in teflon are measured as a function of γ-dose from 3000 Ci cobalt-60 assembly. The irradiations and positron lifetime measurements are carried out, both in air and vacuum. The values of lifetimes τ1, τ2, τ3 and their respective intensities I1, I2, and I3 are determined with the help of three component fit. Electron spin resonance, density, dielectric constant, and nuclear magnetic resonance measurements are also carried out on teflon samples irradiated in a similar way. Initial γ-dose results in increased free volume of voids, where orthopositronium rests. Hence the lifetime t3 increases. As the dose is increased further quenching effect of free radicals becomes dominant and lifetime of positronium decreases. Similar trend is observed in dielectric constant and NMR data

Further experimental test of nucleon charge conservation through the reaction <SUP>113</SUP>Cd &#8594;<SUP>113m</SUP>In+neutrals

A new experiment to search for the charge-nonconserving decay of a nucleon through the decay <SUP>113</SUP>Cd --> <SUP>113m</SUP>In+neutrals has been performed employing the coincidence-detection technique between the K-conversion electrons and the K x rays in <SUP>113m</SUP>In separated chemically from a bulk sample of CdCl<SUB>2</SUB>. The measurement yields a lower limit on the mean life <SUB>t</SUB><SUP>CNC</SUP>N&gt;=1.4&#215;10<SUP>18</SUP> yr

The spin of <SUP>228</SUP>Ac from beta-decay experiments

The spin of the odd nucleus <SUP>228</SUP>Ac(T<SUB>&#189;</SUB> = 6.13h) has been determined to be I = 3 from the beta circularly-polarized gamma correlation studies on two prominent beta-gamma cascades: (i) the 1.19 MeV beta group (966 and 908) keV gamma rays and (ii) the 1.76 MeV beta group- 3.38 keV gamma ray. The matrix element ratio X for the 1.76 MeV beta transition has been determined to be X = 0.40&#177;0.10