Survival analysis approach to account for non-exponential decay rate effects in lifetime experiments

Published

January 13, 2016

Author(s)

Kevin J. Coakley, Maynard S. Dewey, Michael G. Huber, Hans P. Mumm, Alan Keith Thompson, Andrew T. Yue, C. R. Huffer, P. R. Huffman, C. M. O'Shaughnessy, K. W. Schelhammer, D. E. Marley

Abstract

In experiments that measure the lifetime of trapped particles, in addition to loss mechanisms with exponential survival probability functions, particles can be lost by mechanisms with non-exponential survival probability functions. Failure to account for such loss mechanisms produces systematic mea- surement error and associated systematic uncertainties in these measurements. In this work, we develop a general competing risks survival analysis method to account for the joint effect of loss mechanisms with either exponential or non-exponential survival probability functions, and a method to quantify the size of systematic effects and associated uncertainties for lifetime estimates. As a case study, we apply our survival analysis formalism and method to the Ultra Cold Neutron lifetime experiment at NIST. In this experiment, neutrons can escape a magnetic trap before they decay due to a wall loss mechanism with an associated non-exponential survival probability function.

Citation

Nuclear Instruments & Methods in Physics Research A

Volume

813

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.nima.2015.12.064

Keywords

competing risks, magnetic trapping, marginally trapped neutrons, neutron lifetime, survival analysis, symplectic integration

Citation

Coakley, K. , Dewey, M. , Huber, M. , Mumm, H. , , A. , Yue, A. , Huffer, C. , Huffman, P. , O'Shaughnessy, C. , Schelhammer, K. and Marley, D. (2016), Survival analysis approach to account for non-exponential decay rate effects in lifetime experiments, Nuclear Instruments & Methods in Physics Research A, [online], https://doi.org/10.1016/j.nima.2015.12.064 (Accessed October 10, 2025)