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arXiv · 1310.5759

Storage of ultracold neutrons in the UCN$τ$ magneto-gravitational trap

D. J. Salvat·E. R. Adamek·D. Barlow·L. J. Broussard·J. D. Bowman·N. B. Callahan·S. M. Clayton·C. Cude-Woods·S. Currie·E. B. Dees·W. Fox·P. Geltenbort·K. P. Hickerson·A. T. Holley·C. -Y. Liu·M. Makela·J. Medina·D. J. Morley·C. L. Morris·S. I. Penttila·J. Ramsey·A. Saunders·S. J. Seestrom·S. K. L. Sjue·B. A. Slaughter·E. I. Sharapov·J. Vanderwerp·B. VornDick·P. L. Walstrom·Z. Wang·T. L. Womack·A. R. Young
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Abstract

The UCN$τ$ experiment is designed to measure the lifetime $τ_{n}$ of the free neutron by trapping ultracold neutrons (UCN) in a magneto-gravitational trap. An asymmetric bowl-shaped NdFeB magnet Halbach array confines low-field-seeking UCN within the apparatus, and a set of electromagnetic coils in a toroidal geometry provide a background "holding" field to eliminate depolarization-induced UCN loss caused by magnetic field nodes. We present a measurement of the storage time $τ_{store}$ of the trap by storing UCN for various times, and counting the survivors. The data are consistent with a single exponential decay, and we find $τ_{store}=860\pm19$ s: within $1 σ$ of current global averages for $τ_{n}$. The storage time with the holding field deactiveated is found to be $τ_{store}=470 \pm 160$ s; this decreased storage time is due to the loss of UCN which undergo Majorana spin-flips while being stored. We discuss plans to increase the statistical sensitivity of the measurement and investigate potential systematic effects.

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D. J. Salvat, E. R. Adamek, D. Barlow, L. J. Broussard, J. D. Bowman, N. B. Callahan, S. M. Clayton, C. Cude-Woods, S. Currie, E. B. Dees, W. Fox, P. Geltenbort, K. P. Hickerson, A. T. Holley, C. -Y. Liu, M. Makela, J. Medina, D. J. Morley, C. L. Morris, S. I. Penttila, J. Ramsey, A. Saunders, S. J. Seestrom, S. K. L. Sjue, B. A. Slaughter, E. I. Sharapov, J. Vanderwerp, B. VornDick, P. L. Walstrom, Z. Wang, T. L. Womack, A. R. Young. 2013-10-31. Storage of ultracold neutrons in the UCN$τ$ magneto-gravitational trap. https://doi.org/10.1103/physrevc.89.052501

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