The determination of the half-life of 32Si and time varying nuclear decay

Jordan M Heim, Purdue University


The aim of this work is to make an accurate determination of the half-life of 32Si as well as to investigate reported variations in nuclear decay rates. Primarily, we focus on a previous experiment at Brookhaven National Lab (BNL), which measured the ratio of interwoven 32Si and 36Cl decays over a 4 yr period and reported unexplained annual periodicities. Utilizing the very same sources and shuffling apparatus, we have observed the decay of 32Si and 36Cl for more than 6,000 hours each, over the last ∼ 2 yr, while recording ∼ 5 × 10 6 individual environmental readings. The half-life of 32Si, which has been quoted between 101(18) yr and 330(40) yr, is redetermined by this data to be 159.4 yr ± 1.9 yr (statistical) ± 3.7 yr (systematic) with χ2DOF = 1.01. We have also observed a periodic signal in the 32Si/ 36Cl ratio decay data, similar to that in the original experiment at BNL, which we analyze at length. Finally, a related topic concerning self-induced decay and its relationship to systematic dead-time corrections is presented.




Fischbach, Purdue University.

Subject Area

Nuclear physics

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