Next Generation Experiments to Measure the Neutron Lifetime

There is a great interest in improving the limits on neutron lifetime to the level of a precision of 0.1 s. The neutron lifetime is both an important fundamental quantity as well as a parameter influencing important processes such as nucleosynthesis (Helium production in the early universe) and the rate of energy production in the Sun.

Aiming to create a roadmap of R&D for a next generation neutron lifetime experiment that can be endorsed by the North American neutron community, the focus of the workshop was on experiments using traps that utilize ultracold neutrons and confinement by a combination of magnetic and/or gravitational interaction in order to avoid systematic uncertainties introduced by neutron interactions with material walls. The papers in this volume summarize the limitations of present experiments, the discussion of new experiments in planning stage, and the discussion of systematic effects that must be addressed to achieve a lifetime measurement at an accuracy of 0.1 second.

Sample Chapter(s)
Neutron Lifetime Theory (126 KB)

Contents:Welcome & Charge (Seestrom)Theoretical Introduction (Marciano)Overview of Beam Experiments (Wietfeldt)Overview of Material Bottle Experiments (Geltenbort)Overview of Magnetic Trap Experiments (Huffman)Phase Space Evolution (Liu)Marginal Trapping (Coakley)Chaos (Bowman)Spin-Flip Losses (Steyerl)UCN heating in Traps (Walstrom)UCN Detection (Golub)Absolute Flux Monitoring (Yue)Relative Monitoring + Uniformity of Detectors (Morris)Overview of UCN Sources & Statistics Needed for 0.1 s Experiments (Young)Ezhov Experiment (Naviliat-Cuncic)NIST UCN Experiment (Mumm)Hope (Leung)LANL Experiment (Saunders)Penelope (Picker)J-PARC Lifetime (Yamada)
Readership: Graduate students and researchers in nuclear and particle physics.