Startup of the high-intensity ultracold neutron source at the Paul Scherrer Institute

Lauss, B.

doi:10.1007/s10751-012-0578-7

Cited by 32 publications

(39 citation statements)

References 11 publications

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“…The experiment was performed at the beam line PF2/EDM [79,80] of the Institut Laue-Langevin (ILL) in Grenoble, France, and at the UCN source at the Paul Scherrer Institute in Villigen, Switzerland [15][16][17][18]. The vacuum in the sample tubes was typically 1 × 10 −6 mbar.…”

Section: Data Collectionmentioning

confidence: 99%

“…(1) The total number of neutrons, which is permanently increased by improving the intensity of the present source of ultracold neutrons (UCN) 1 at PSI [15][16][17][18][19]. This source is based on a very cold moderator-converter using solid deuterium (sD 2 ) [20][21][22][23][24][25][26][27][28][29][30][31][32][33] at a temperature around 5 K. (4) The initial polarization of the neutrons, which is increased to ∼100% by means of a superconductive solenoid with a field of 5 T [34].…”

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confidence: 99%

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Losses and depolarization of ultracold neutrons on neutron guide and storage materials

et al. 2017

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At Institut Laue-Langevin (ILL) and Paul Scherrer Institute (PSI), we have measured the losses and depolarization probabilities of ultracold neutrons on various materials: (i) nickel-molybdenum alloys with weight percentages of 82/18, 85/15, 88/12, 91/9, and 94/6 and natural nickel Ni100, (ii) nickel-vanadium NiV93/7, (iii) copper, and (iv) deuterated polystyrene (dPS). For the different samples, storage-time constants up to ∼460 s were obtained at room temperature. The corresponding loss parameters for ultracold neutrons, η, varied between 1.0 × 10 −4 and 2.2 × 10 −4 . All η values are in agreement with theory except for dPS, where anomalous losses at room temperature were established with four standard deviations. The depolarization probabilities per wall collision β measured with unprecedented sensitivity varied between 0.7 × 10 −6 and 9.0 × 10 −6 . Our depolarization result for copper differs from other experiments by 4.4 and 15.8 standard deviations. The β values of the paramagnetic NiMo alloys over molybdenum content show an increase of β with increasing Mo content. This is in disagreement with expectations from literature. Finally, ferromagnetic behavior of NiMo alloys at room temperature was found for molybdenum contents of 6.5 at.% or less and paramagnetic behavior for more than 8.7 at.%. This may contribute to solving an ambiguity in literature.

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Section: Data Collectionmentioning

confidence: 99%

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confidence: 99%

Losses and depolarization of ultracold neutrons on neutron guide and storage materials

et al. 2017

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“…Also the most recent and best nEDM limit [13] is limited in statistics, and for efforts to improve this limit more UCNs are imperative. Therefore, worldwide efforts to increase UCN intensities started in the 1990'ies [48,49] and new, so-called 'superthermal' UCN sources [50] based on superfluid helium or solid deuterium have become operating in recent years [51][52][53][54][55].…”

Section: Introductionmentioning

confidence: 99%

“…The operating UCN sources under investigation were one out of four beamlines (the so-called EDM beamline) at PF2 (ILL) [4], Grenoble, France, at the TRIGA reactor of the Johannes Gutenberg University Mainz, Germany [53,60,61], at the Paul Scherrer Institute, Villigen, Switzerland [55,[62][63][64], and the new superfluid helium SUN-2 UCN source at ILL. 2 In January 2015 comparison measurements at the solid deuterium based UCN source of the Los Alamos National Laboratory (LANL), Los Alamos, USA, were performed [70], but due to the atypical performance of the UCN source at that time in comparison to the one given in Refs. [52,71,72] the LANL UCN collaboration did not wish to include the results in this paper.…”

Section: Introductionmentioning

confidence: 99%

Comparison of ultracold neutron sources for fundamental physics measurements

et al. 2017

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Ultracold neutrons (UCNs) are key for precision studies of fundamental parameters of the neutron and in searches for new CP violating processes or exotic interactions beyond the Standard Model of particle physics. The most prominent example is the search for a permanent electric dipole moment of the neutron (nEDM). We have performed an experimental comparison of the leading UCN sources currently operating. We have used a 'standard' UCN storage bottle with a volume of 32 liters, comparable in size to nEDM experiments, which allows us to compare the UCN density available at a given beam port.

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“…Measurements of the UCN intensity over time were performed at beamports West-1 and West-2 at the PSI UCN facility detailed in Fig.1 of Ref. [28], where a Cascade UCN detector 2 was installed directly at the beamport. The West-1 beamport is located about 1.13 m and the West-2 beamport 3.23 m above the sD 2 surface.…”

Section: Measurements At the Psi Facilitymentioning

confidence: 99%

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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Startup of the high-intensity ultracold neutron source at the Paul Scherrer Institute

Cited by 32 publications

References 11 publications

Losses and depolarization of ultracold neutrons on neutron guide and storage materials

Losses and depolarization of ultracold neutrons on neutron guide and storage materials

Comparison of ultracold neutron sources for fundamental physics measurements

Solid deuterium surface degradation at ultracold neutron sources

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