Measurement of the neutron lifetime by counting trapped protons in a cold neutron beam

A measurement of the neutron lifetime {tau}{sub n} performed by the absolute counting of in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto a silicon detector held at a high potential and counted with nearly unit efficiency. Th...

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Bibliographic Details
Published in:Physical review. C, Nuclear physics Nuclear physics, 2005-05, Vol.71 (5), Article 055502
Main Authors: Nico, J. S., Dewey, M. S., Gilliam, D. M., Wietfeldt, F. E., Fei, X., Snow, W. M., Greene, G. L., Pauwels, J., Eykens, R., Lamberty, A., Gestel, J. Van, Scott, R. D.
Format: Article
Language:English
Subjects:
ABSOLUTE COUNTING
BETA DECAY
COLD NEUTRONS
CROSS SECTIONS
DATA ANALYSIS
EFFICIENCY
ENERGY LEVELS
LIFETIME
LITHIUM 6 TARGET
NEUTRON BEAMS
NEUTRON REACTIONS
NUCLEAR PHYSICS AND RADIATION PHYSICS
SI SEMICONDUCTOR DETECTORS
TRAPPED PROTONS
TRAPS
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Summary:A measurement of the neutron lifetime {tau}{sub n} performed by the absolute counting of in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto a silicon detector held at a high potential and counted with nearly unit efficiency. The neutrons were counted by a device with an efficiency inversely proportional to neutron velocity, which cancels the dwell time of the neutron beam in the trap. The result is {tau}{sub n}=(886.3{+-}1.2[stat]{+-}3.2[sys]) s, which is the most precise measurement of the lifetime using an in-beam method. The systematic uncertainty is dominated by neutron counting, in particular, the mass of the deposit and the {sup 6}Li(n,t) cross section. The measurement technique and apparatus, data analysis, and investigation of systematic uncertainties are discussed in detail.
ISSN:0556-2813
1089-490X
DOI:10.1103/PhysRevC.71.055502