On the measurement of the neutron lifetime using ultracold neutrons in a vacuum quadrupole trap

Journal Article · Fri Jul 01 00:00:00 EDT 2005 · Journal of Research of the National Institute of Standards and Technology

DOI:https://doi.org/10.6028/jres.110.054· OSTI ID:1628761

Bowman, J. D. ^[1]; Penttila, S. I. ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

We present a conceptual design for an experiment to measure the neutron lifetime (~886 s) with an accuracy of 10^-4. The lifetime will be measured by observing the decay rate of a sample of ultracold neutrons (UCN) confined in vacuum in a magnetic trap. The UCN collaboration at Los Alamos National Laboratory has developed a prototype UCN source that is expected to produce a bottled UCN density of more than 100/cm³. The availability of such an intense source makes it possible to approach the measurement of the neutron lifetime in a new way. We argue below that it is possible to measure the neutron lifetime to 10^-4 in a vacuum magnetic trap. The measurement involves no new technology beyond the expected UCN density. If even higher densities are available, the experiment can be made better and/or less expensive. We present the design and methodology for the measurement. The slow loss of neutrons that have stable orbits, but are not energetically trapped would produce a systematic uncertainty in the measurement. We discuss a new approach, chaotic cleaning, to the elimination of quasi-neutrons from the trap by breaking the rotational symmetry of the quadrupole trap. The neutron orbits take on a chaotic character and mode mixing causes the neutrons on the quasi-bound orbits to leave the trap.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1628761
• Journal Information: Journal of Research of the National Institute of Standards and Technology, Vol. 110, Issue 4; ISSN 1044-677X
• Publisher: National Institute of Standards (NIST)
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Instruments & Instrumentation
Physics
chaos
neutron lifetime
neutron trap
quadrupole trap
ultra cold neutrons