An ultracold neutron source at the NC State University PULSTAR reactor

Korobkina, E.; Wehring, B.W.; Hawari, Ayman I.; Young, A. R.; Huffman, P. R.; Golub, R.; Xu, Yanping; Palmquist, Grant

doi:10.1016/j.nima.2007.04.116

Cited by 28 publications

(18 citation statements)

References 10 publications

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“…Superthermal UCN sources are now in operation or being under construction at different places worldwide, such as PSI (Villigen) [17], Los Alamos [18], ILL (Grenoble) [12], RCNP, Osaka University [13], PULSTAR reactor (NC State University) [19], FRM-II (Garching) [20] , and TRIUMF [6] .…”

Section: Introductionmentioning

confidence: 99%

Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz

et al. 2014

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Abstract. The performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz with a maximum peak energy of 10 MJ is described. The solid deuterium converter with a volume of V=160 cm 3 (8 mol), which is exposed to a thermal neutron fluence of 4.510 13 n/cm 2 , delivers up to 550 000 UCN per pulse outside of the biological shield at the experimental area. UCN densities of ~ 10/cm 3 are obtained in stainless steel bottles of V ~ 10 L resulting in a storage efficiency of ~20%. The measured UCN yields compare well with the predictions from a Monte Carlo simulation developed to model the source and to optimize its performance for the upcoming upgrade of the TRIGA Mainz into a user facility for UCN physics.

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Section: Introductionmentioning

confidence: 99%

Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz

et al. 2014

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“…[21][22][23] New UCN sources, using superthermal production 1 with either superfluid helium or solid deuterium as a converter material, are being built at several facilities. [24][25][26][27][28] Recently, a very encouraging result has been published by Masuda for a prototype source based on production in superfluid helium. 29 The lifetimes of UCN in solid ortho-deuterium are limited by the neutron's decay time, nuclear absorption of UCNs on the deuterium, nuclear absorption on contaminating hydrogen, thermal upscattering from the deuterium, 013304-2 Saunders et al Rev.…”

Section: Introductionmentioning

confidence: 99%

Performance of the Los Alamos National Laboratory spallation-driven solid-deuterium ultra-cold neutron source

Saunders

Makela

Bagdasarova

et al. 2013

Review of Scientific Instruments

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A.; Makela, M.; Bagdasarova, Y.; et al., "Performance of the Los Alamos National Laboratory spallation-driven solid-deuterium ultra-cold neutron source," Rev. Sci. Instrum. 84, 013304 (2013); http://dx.doi.org/10.1063/1.4770063 REVIEW OF SCIENTIFIC INSTRUMENTS 84, 013304 (2013) Performance of the Los Alamos National Laboratory spallation-driven solid-deuterium ultra-cold neutron source In this paper, we describe the performance of the Los Alamos spallation-driven solid-deuterium ultracold neutron (UCN) source. Measurements of the cold neutron flux, the very low energy neutron production rate, and the UCN rates and density at the exit from the biological shield are presented and compared to Monte Carlo predictions. The cold neutron rates compare well with predictions from the Monte Carlo code MCNPX and the UCN rates agree with our custom UCN Monte Carlo code. The source is shown to perform as modeled. The maximum delivered UCN density at the exit from the biological shield is 52(9) UCN/cc with a solid deuterium volume of ∼1500 cm 3 .

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“…All indications point to the growth of frost layers on the top surface which subsequently impede the transmission of UCN. These findings are supported by the visual offline inspection of sD 2 surfaces under a heat pulse operation at the North Caroline State University (NSCU) UCN facility [34]. The UCN transport simulation in Sec.…”

Section: Introductionmentioning

confidence: 54%

Solid deuterium surface degradation at ultracold neutron sources

et al. 2018

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Solid deuterium (sD2) is used as an efficient converter to produce ultracold neutrons (UCN). It is known that the sD2 must be sufficiently cold, of high purity and mostly in its ortho-state in order to guarantee long lifetimes of UCN in the solid from which they are extracted into vacuum. Also the UCN transparency of the bulk sD2 material must be high because crystal inhomogeneities limit the mean free path for elastic scattering and reduce the extraction efficiency. Observations at the UCN sources at Paul Scherrer Institute and at Los Alamos National Laboratory consistently show a decrease of the UCN yield with time of operation after initial preparation or later treatment ("conditioning") of the sD2. We show that, in addition to the quality of the bulk sD2, the quality of its surface is essential. Our observations and simulations support the view that the surface is deteriorating due to a build-up of D2 frost-layers under pulsed operation which leads to strong albedo reflections of UCN and subsequent loss. We report results of UCN yield measurements, temperature and pressure behavior of deuterium during source operation and conditioning, and UCN transport simulations. This, together with optical observations of sD2 frost formation on initially transparent sD2 in offline studies with pulsed heat input at the North Carolina State University UCN source results in a consistent description of the UCN yield decrease.

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An ultracold neutron source at the NC State University PULSTAR reactor

Cited by 28 publications

References 10 publications

Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz

Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz

Performance of the Los Alamos National Laboratory spallation-driven solid-deuterium ultra-cold neutron source

Solid deuterium surface degradation at ultracold neutron sources

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