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Title: Colloquium: The neutron lifetime

Abstract

The decay of the free neutron into a proton, electron, and antineutrino is the prototype semileptonic weak decay and is the simplest example of nuclear beta decay. It played a key role in the early Universe as it determined the ratio of neutrons to protons during the era of primordial light element nucleosynthesis. Neutron decay is physically related to important processes in solar physics and neutrino detection. The mean neutron lifetime has been the subject of more than 20 major experiments done, using a variety of methods, between 1950 and the present. The most precise recent measurements have stated accuracies approaching 0.1%, but are not in good agreement as they differ by as much as 5{sigma} using quoted uncertainties. The history of neutron lifetime measurements is reviewed and the different methods used are described, giving important examples of each. The discrepancies and some systematic issues in the experiments that may be responsible are discussed, and it is shown by means of global averages that the neutron lifetime is likely to lie in the range of 880-884 s. Plans and prospects for future experiments are considered that will address these systematic issues and improve our knowledge of the neutron lifetime.

Authors:
;  [1];  [2]
  1. Department of Physics, Tulane University, New Orleans, Louisiana 70118 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22038828
Resource Type:
Journal Article
Journal Name:
Reviews of Modern Physics
Additional Journal Information:
Journal Volume: 83; Journal Issue: 4; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6861
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; ANTINEUTRINOS; BETA DECAY; ELECTRONS; LIFETIME; NEUTRINO DETECTION; NEUTRONS; NUCLEOSYNTHESIS; PROTONS; SEMILEPTONIC DECAY; UNIVERSE; VISIBLE RADIATION

Citation Formats

Wietfeldt, Fred E., Greene, Geoffrey L., and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996 and Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831. Colloquium: The neutron lifetime. United States: N. p., 2011. Web. doi:10.1103/REVMODPHYS.83.1173.
Wietfeldt, Fred E., Greene, Geoffrey L., & Department of Physics, University of Tennessee, Knoxville, Tennessee 37996 and Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831. Colloquium: The neutron lifetime. United States. doi:10.1103/REVMODPHYS.83.1173.
Wietfeldt, Fred E., Greene, Geoffrey L., and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996 and Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831. Sat . "Colloquium: The neutron lifetime". United States. doi:10.1103/REVMODPHYS.83.1173.
@article{osti_22038828,
title = {Colloquium: The neutron lifetime},
author = {Wietfeldt, Fred E. and Greene, Geoffrey L. and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996 and Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831},
abstractNote = {The decay of the free neutron into a proton, electron, and antineutrino is the prototype semileptonic weak decay and is the simplest example of nuclear beta decay. It played a key role in the early Universe as it determined the ratio of neutrons to protons during the era of primordial light element nucleosynthesis. Neutron decay is physically related to important processes in solar physics and neutrino detection. The mean neutron lifetime has been the subject of more than 20 major experiments done, using a variety of methods, between 1950 and the present. The most precise recent measurements have stated accuracies approaching 0.1%, but are not in good agreement as they differ by as much as 5{sigma} using quoted uncertainties. The history of neutron lifetime measurements is reviewed and the different methods used are described, giving important examples of each. The discrepancies and some systematic issues in the experiments that may be responsible are discussed, and it is shown by means of global averages that the neutron lifetime is likely to lie in the range of 880-884 s. Plans and prospects for future experiments are considered that will address these systematic issues and improve our knowledge of the neutron lifetime.},
doi = {10.1103/REVMODPHYS.83.1173},
journal = {Reviews of Modern Physics},
issn = {0034-6861},
number = 4,
volume = 83,
place = {United States},
year = {2011},
month = {10}
}