Storage of Ultracold Neutrons in the Magneto-Gravitational Trap of the UCN Experiment

Journal Article · Wed Jan 01 00:00:00 EST 2014 · Physical Review C

OSTI ID:1133590

Salvat, D. J. ^[1]; Adamek, E. R. ^[1]; Barlow, D. ^[2]; Bowman, James D ^[3]; Broussard, L. J. ^[2]; Callahan, N. B. ^[1]; Clayton, S. M. ^[2]; Cude-Woods, C. ^[1]; Currie, S. ^[2]; Dees, E. B. ^[4]; Fox, W. ^[1]; Geltenbort, P. ^[5]; Hickerson, K. P. ^[6]; Holley, A. T. ^[1]; Liu, C. -Y. ^[1]; Makela, M. ^[2]; Medina, J. ^[2]; Morley, D. J. ^[2]; Morris, C. L. ^[2]; Penttila, Seppo I ^[3] ; Ramsey, J. ^[2]; Saunders, A. ^[2]; Seestrom, S. J. ^[2]; Sharapov, E. I. ^[7]; Sjue, S. K. L. ^[2]; Slaughter, B. A. ^[1]; Vanderwerp, J. ^[1]; VornDick, B. ^[4]; Walstrom, P. L. ^[2]; Wang, Z. ^[2]; Womack, T. L. ^[2]; Young, A. R. ^[4]

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1. Indiana University
2. Los Alamos National Laboratory (LANL)
3. ORNL
4. North Carolina State University, Raleigh
5. Inst Max Von Laue Paul Langevin, Grenoble, France
6. University of California, Los Angeles
7. Joint Institute for Nuclear Research, Dubna, Russia

The UCN experiment is designed to measure the lifetime 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 provides a background holding field to eliminate depolarization-induced UCN loss caused by magnetic field nodes. We present a measurement of the storage time 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 store = 860 19 s, within 1 of current global averages for n. The storage time with the holding field deactivated is found to be store = 470 160 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.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1133590
• Journal Information: Physical Review C, Vol. 89, Issue 5
• Country of Publication: United States
• Language: English