Maximum-likelihood analysis and goodness-of-fit estimation in low count-rate experiments: ~(85)Kr β activity in the test facility of the Borexino detector and double-beta decay of ~(76)Ge in the Heidelberg-Moscow experiment

摘要

Statistical methods for low count-rate experiments are reviewed and applied to two samples of experimental data. In one case the β activity of ~(85)Kr in the test facility of the Borexino detector is determined. In another case a data sample from the Heidelberg-Moscow experiment used to claim the discovery of the neutrinoless double-beta decay of ~(76)Ge is analyzed. Exploiting a Bayesian technique a conservative upper limit on the half-life of the 0v2β decay of ~(76)Ge is found at T)(1/2)~(0_v) ≥ 1.2 x 10~(25) yr (90% CL) in the window (2000-2080) keV.