Joint Research Conference

June 24-26, 2014

Bayesian Model Comparison for a Set of Lithium-6 Foils

Abstract:

Lithium-6, one of the two stable isotopes of lithium, is often used for neutron detection in physics experiments. For example, a team of physicists from NIST and several other organizations used lithium-6 in an experiment to determine the lifetime of the neutron, originally reported as 886.3 s ± 1.2 s with a potential systematic error of up to 3.2 s in 2005. Further measurements made since that time have recently allowed this result to be refined to 887.7 s ± 1.2 s with a potential systematic error of up to 1.9 s. This talk outlines comparisons of three models for the performance over time of a set of lithium-6 foils used in this work. Comparisons are made using Bayes factors computed using the product-space method of Carlin and Chib. A Bayesian method was chosen for use in this in this situation to allow the incorporation of a constraint on the model based on prior knowledge.