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Title: Spin flip loss in magnetic confinement of ultracold neutrons for neutron lifetime experiments

Authors:
; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1347816
Grant/Contract Number:
FG02-97ER41042
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 95; Journal Issue: 3; Related Information: CHORUS Timestamp: 2017-03-22 22:13:41; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Steyerl, A., Leung, K. K. H., Kaufman, C., Müller, G., and Malik, S. S. Spin flip loss in magnetic confinement of ultracold neutrons for neutron lifetime experiments. United States: N. p., 2017. Web. doi:10.1103/PhysRevC.95.035502.
Steyerl, A., Leung, K. K. H., Kaufman, C., Müller, G., & Malik, S. S. Spin flip loss in magnetic confinement of ultracold neutrons for neutron lifetime experiments. United States. doi:10.1103/PhysRevC.95.035502.
Steyerl, A., Leung, K. K. H., Kaufman, C., Müller, G., and Malik, S. S. Wed . "Spin flip loss in magnetic confinement of ultracold neutrons for neutron lifetime experiments". United States. doi:10.1103/PhysRevC.95.035502.
@article{osti_1347816,
title = {Spin flip loss in magnetic confinement of ultracold neutrons for neutron lifetime experiments},
author = {Steyerl, A. and Leung, K. K. H. and Kaufman, C. and Müller, G. and Malik, S. S.},
abstractNote = {},
doi = {10.1103/PhysRevC.95.035502},
journal = {Physical Review C},
number = 3,
volume = 95,
place = {United States},
year = {Wed Mar 22 00:00:00 EDT 2017},
month = {Wed Mar 22 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevC.95.035502

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  • In this paper, we report a measurement of the spin-flip probabilities for ultracold neutrons interacting with surfaces coated with nickel phosphorus. For 50 μm thick nickel phosphorus coated on stainless steel, the spin-flip probability per bounce was found to be β NiP on SS = (3.3 +1.8, -5.6) X 10 -6. For 50 μm thick nickel phosphorus coated on aluminum, the spin-flip probability per bounce was found to be β NiP on Al = (3.6 +2.1, -5.9) X 10 -6. For the copper guide used as reference, the spin flip probability per bounce was found to be β Cu =more » (6.7 + 5.0, -2.5) X 10 -6. The results on the nickel phosphorus-coated surfaces may be interpreted as upper limits, yielding β NiP on SS < 6.2 X 10 -6 (90% C.L.) and β NiP on Al < 7.0 X 10 -6 (90% C.L.) for 50 μm thick nickel phosphorus coated on stainless steel and 50 μm thick nickel phosphorus coated on aluminum, respectively. Finally, nickel phosphorus coated stainless steel or aluminum provides a solution when low-cost, mechanically robust, and non-depolarizing UCN guides with a high Fermi potential are needed.« less
  • An analysis of data on measurements of neutron lifetime is presented. The new most accurate result of the measurement of neutron lifetime [Phys. Lett. B 605, 72 (2005)]878.5{+-}0.8 s, differs from the world average value [Phys. Lett. B 667, 1 (2008)]885.7{+-}0.8 s, by 6.5 standard deviations. In this connection an analysis and Monte Carlo simulation of experiments [Phys. Lett. B 483, 15 (2000)] and [Phys. Rev. Lett. 63, 593 (1989)] is carried out. Systematic errors of about -6 s are found in each of the experiments. A summary table of neutron lifetime measurements after corrections and additions is given. Amore » new world average value for neutron lifetime, 879.9{+-}0.9 s, is presented.« less
  • A method of measuring the neutron lifetime by storing ultracold neutrons (UCN) in an aluminum container is described. A method of measuring the loss of UCN in the container walls is proposed. The losses were measured by varying the number of collisions per unit time. The systematic measurement errors are given and possible ways to reduce them are discussed.
  • The neutron lifetime has been measured by counting the neutrons remaining in a fluid-walled bottle as a function of the duration of storage. Losses of neutrons caused by the wall reflections are eliminated by varying the bottle volume-to-surface ratio. The result obtained is /tau//sub /beta//=887.6/plus minus/3 s.
  • As part of an on-going program utilizing magnetically trapped ultracold neutrons (UCNs), we are developing a technique that offers the possibility of improving the precision of the neutron lifetime by more than an order of magnitude. The experiment works by loading an Ioffe-type superconducting magnetic trap with UCNs through inelastic scattering of 0.89 nm neutrons with phonons in superfluid 4He. Trapped neutrons are detected when they decay; charged decay electrons ionize helium atoms in the superfluid resulting in scintillation light that is recorded in real time using photomultiplier tubes. At present, we are installing a larger and deeper superconducting magneticmore » trap into our apparatus, implementing techniques to reduce background events, and working to increase the neutron decay detection efficiency. We report the status of the construction of the improved apparatus.« less