Ultracold-neutron production in a pulsed-neutron beam line

Journal Article · Thu Jul 15 04:00:00 EDT 2010 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.82.015502· OSTI ID:21389228

Lavelle, C M; Liu, C -Y; Fox, W; Manus, G; McChesney, P M; Salvat, D J; Shin, Y; Makela, M; Morris, C; Saunders, A; Couture, A; Young, A R ^[1]

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1. Physics Department, Indiana University, Bloomington, Indiana 47408 (United States)

We present the results of an ultracold neutron (UCN) production experiment in a pulsed-neutron beam line at the Los Alamos Neutron Scattering Center. The experimental apparatus allows for a comprehensive set of measurements of UCN production as a function of target temperature, incident neutron energy, target volume, and applied magnetic field. However, the low counting statistics of the UCN signal can be overwhelmed by the large background associated with the scattering of the primary cold-neutron flux that is required for UCN production. We have developed a background subtraction technique that takes advantage of the very different time-of-flight profiles between the UCN and the cold neutrons, in the pulsed beam. Using the unique timing structure, we can reliably extract the UCN signal. Solid ortho-{sup 2}H{sub 2} is used to calibrate UCN transmission through the apparatus, which is designed primarily for studies of UCN production in solid O{sub 2}. In addition to setting the overall detection efficiency in the apparatus, UCN production data using solid {sup 2}H{sub 2} suggest that the UCN upscattering cross section is smaller than previous estimates, indicating the deficiency of the incoherent approximation widely used to estimate inelastic cross sections in the thermal and cold regimes.

• OSTI ID: 21389228
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 1 Vol. 82; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
APPROXIMATIONS
BARYONS
BEAMS
CALCULATION METHODS
COHERENT SCATTERING
COLD NEUTRONS
CROSS SECTIONS
DIFFRACTION
EFFICIENCY
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MAGNETIC FIELDS
NEUTRON BEAMS
NEUTRON DIFFRACTION
NEUTRONS
NUCLEON BEAMS
NUCLEONS
PARTICLE BEAMS
PARTICLE PRODUCTION
SCATTERING
TIME-OF-FLIGHT METHOD
TRANSMISSION
ULTRACOLD NEUTRONS