The investigation of UCN interaction with the surface of beryllium and stainless steel by the new method based on the neutron induced γ-radiation analysis

Bondarenko, L. N.; Chernyavsky, S. M.; Fomin, A. K.; Geltenbort, P.; Морозов, В. И.; Shilkin, S.

doi:10.1016/s0921-4526(97)00227-5

Cited by 7 publications

(3 citation statements)

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“…Using a hydrogen density N H = 10 17 cm −2 and σ ie,H (k) = 5b v th v UCN = 3100 b for upscattering from a proton of a room temperature sample [57,58] one obtains η T (T = 300 K) = 3.1 × 10 −4 and β = rη T = 2.6 × 10 −6 , which are of the right order of magnitude to explain the experimental findings.…”

Section: B Incoherent Scattering On Hydrogenmentioning

confidence: 81%

“…We have also quoted the respective values of the inelastic cross section σ th ie,H at thermal energy; for comparison, the cross section calculated from the results of Ref. [58] is σ th ie,H = (6.8 ± 0.2) b. The minimum hydrogen surface density to reproduce the data with M eff = 2 and the Debye temperature of graphite (400 K) amounts to ∼7 × 10 16 atoms/cm 2 , or 27% of the DLC number density within the penetration depth of about 18 nm.…”

Section: Sub-barrier Modelmentioning

confidence: 99%

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Loss and spinflip probabilities for ultracold neutrons interacting with diamondlike carbon and beryllium surfaces

et al. 2007

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The storage of ultracold neutrons (UCN) in a combined magnetic, gravitational, and material trap is described. Wall materials investigated were diamondlike carbon (DLC) coatings on solid and flexible foil substrates as well as beryllium coatings on solid substrates. The loss coefficient per wall collision, η, and the depolarization probability β were measured simultaneously as a function of temperature (from 70 to 400 K) and energy (from 30 to 80 neV). The results at 70 K are η = (0.7 ± 0.1) × 10 −4 , β = (15.4 ± 1.0) × 10 −6 for DLC on polyethyleneterephtalate (PET) foil and η = (1.7 ± 0.1) × 10 −4 , β = (0.7 ± 0.3) × 10 −6 for DLC on aluminum foil. At room temperature the loss coefficients are larger by a factor of about 2 whereas the depolarization probabilities are found to be independent of temperature. The corresponding values for Be at room temperature are η ∼ 5 × 10 −4 , β ∼ 10 × 10 −6 . The DLC results for β and for the temperature-dependent part of the loss coefficient, η T , are interpreted in terms of incoherent scattering by hydrogen. The hydrogen admixture was measured independently by elastic recoil detection analysis to be about 1 × 10 16 atoms/cm 2 . The data do not support the hypothesis of hydrogen being chemically bound within the top layers of the DLC. Using two different models with a thin waterlike film on top of the substrate we obtain consistency between the temperature-dependent loss contribution and the measured hydrogen contamination.

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Section: B Incoherent Scattering On Hydrogenmentioning

confidence: 81%

Section: Sub-barrier Modelmentioning

confidence: 99%

Loss and spinflip probabilities for ultracold neutrons interacting with diamondlike carbon and beryllium surfaces

et al. 2007

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“…UCN are widely used in precision particle physics experiments [21], such as, for instance, searches for additional fundamental shortrange forces [22][23][24][25][26][27][28], searches for non-zero neutron electric dipole moment [29,30], precision neutron lifetime measurements [31][32][33][34][35][36] and constrains for the neutron electric charge [37,38]. Applications of UCN are emerging in surface and nanoparticle physics [39,40]. We focus on recent advances in the field including observation of the centrifugal quantum states of neutrons.…”

Section: Introductionmentioning

confidence: 99%

Experiments with ultracold neutrons

Nesvizhevsky

2011

Low Temperature Physics

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Ultracold neutrons (UCN) form a tiny low-energy fraction in Maxwelian spectrum of thermal neutrons in moderators of nuclear reactors and spallation sources. Their energy is extremely small (~10-7 eV), their velocity is a few meters per second, and their effective temperature is as low as ~1 mK. Specific feature of UCN consists of their nearly total elastic reflection from nuclear-optical potential of many materials at any incidence angle; therefore they could be stored in closed traps for many minutes, thus they could be used for extremely sensitive measurements. A fraction of UCN in the thermal neutron flux is as low as 10-11-10-12 , and serious efforts are undertaken all over the world to produce UCN in larger amounts. UCN are widely used in precision particle physics experiments. Applications of UCN are emerging in surface and nanoparticle physics. Here we will focus on recent advances in the field.

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