Three metre long horizontal cryostat producing ultracold neutrons using superfluid liquid helium at 0.5 K (Mark 3000)

Yoshiki, H.; Sakai, Kazumitsu; Kawai, Takeshi; Goto'o, S.

doi:10.1016/0011-2275(94)90107-4

Cited by 9 publications

(6 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Owing to the vanishing absorption cross section of 4 He and a small probability for scattering UCNs back to higher energies, a converter with reflective boundaries can accumulate a high density of UCNs. If this is to be achieved in storage chambers of size comparable with the converter, a superfluid-helium UCN source at the end of a cold-neutron guide [16,23,24,25,26,27,28,29,30,31,32,33,34], can be competitive with "in-pile" implementations close to a cold-neutron source [35,36,37,38]. The latter have however higher UCN production rates and can hence provide higher steady-state UCN fluxes and total UCN numbers in large vessels.…”

Section: Wavelength Selective Neutron Transport Opticsmentioning

confidence: 99%

Multi-mirror imaging optics for low-loss transport of divergent neutron beams and tailored wavelength spectra

Zimmer

2016

Preprint

View full text Add to dashboard Cite

A neutron optical transport system is proposed which comprises nested short elliptical mirrors located halfway between two common focal points M and M'. It images cold neutrons from a diverging beam or a source with finite size at M by single reflections onto a spot of similar size at M'. Direct view onto the neutron source is blocked by a central absorber with little impact on the transported solid angle. Geometric neutron losses due to source size can be kept small using modern supermirrors and distances M-M' of a few tens of metres. Very short flat mirrors can be used in practical implementations. Transport with a minimum of reflections remedies losses due to multiple reflections that are common in long elliptical neutron guides. Moreover, well-defined reflection angles lead to new possibilities for enhancing the spectral quality of primary beams, such as clear-cut discrimination of short neutron wavelengths or beam monochromation using bandpass supermirrors. Multi-mirror imaging systems may thus complement or even replace ordinary neutron guides, in particular at the European Spallation Source.

show abstract

Section: Wavelength Selective Neutron Transport Opticsmentioning

confidence: 99%

Multi-mirror imaging optics for low-loss transport of divergent neutron beams and tailored wavelength spectra

Zimmer

2016

Preprint

View full text Add to dashboard Cite

show abstract

“…so that for T < 0.5 K, τ −1 up contributes with less than 10% of τ −1 β . The rate constant τ −1 abs can be suppressed below any relevant level by purification of the helium from 3 He using a superleak [61,74,75] or the heat flush technique [76]. As a result, we are left with τ −1 wall and τ −1 slit as dominating contributions, and the rate constant due to neutron decay sets an ultimate lower limit for a perfect converter.…”

Section: Ucn Losses From the Convertermentioning

confidence: 99%

Ultracold neutron accumulation in a superfluid-helium converter with magnetic multipole reflector

Zimmer

Golub

2015

Phys. Rev. C

View full text Add to dashboard Cite

We analyze accumulation of ultracold neutrons (UCN) in a superfluid-helium converter vessel surrounded by a magnetic multipole reflector. We solved the spin-dependent rate equation, employing formulas valid for adiabatic spin transport of trapped UCN in mechanical equilibrium. Results for saturation UCN densities are obtained in dependence of order and strength of the multipolar field. The addition of magnetic storage to neutron optical potentials can increase the density and energy of the low field seeking UCN produced and serves to mitigate the effects of wall losses on the source performance. It also can provide a highly polarized sample of UCN without need to polarize the neutron beam incident on the converter. This work was performed in preparation of the UCN source project SuperSUN at the ILL.

show abstract

“…The lowest attainable temperature of the liquid in this cryostat is 0.45 K and it is quite stable and precisely reproducible. 24 In the measurement, once a wavelength is set by the velocity selector, temperatures of the liquid were set by a heater submerged in the liquid. The machine stability is excellent up to 1.5 K for a heater setting.…”

Section: S(q Co) = S(q Co) + Sm(q A~)mentioning

confidence: 99%

Transmission of slow neutrons (8–15 Å) through superfluid liquid helium

et al. 1997

Self Cite

View full text Add to dashboard Cite

Transmission of very slow neutrons through superfluhl liquid helium has been measuredJrom 8 to 15,4 neutrons at temperatures between 0.45 K and 2.4 K. The results are compared with the single phonon emission and absorption theory.For the production of ultracold neutrons (UCN), the dispersion property of superfluid liquid 4He is used. At a liquid temperature of 0.45 K, the energy and momentum ofa phonon of 0.72 ~, ~ (12 K) equal to those of a free neutron. At the cross point of the two kinematical curves in energymomentum plane, the neutron can exchange its energy and momentum entirely with those of a produced phonon, resulting in a neutron with infinitesimal energy, an UCN.Such a mechanism was discussed by Feynman and Cohen, ~2 by Golub and Pendlebury, 3"4 and later the location of the cross point of two kinematical curves was measured by producing UCN with energy-controlled cold neutrons for liquid helium at 0.45 K. 5 This was a clear demonstration that the single phonon process does take place at the right energy. The interaction of superfluid helium with neutron, whose wavelengths are longer than 9 A, at the liquid helium temperatures below 1 K however was a relatively unexplored area. Sommers, Dash and Goldstein (S.D.G.) 6 measured the total cross sections of cold neutron on the liquid 4He in the temperature region between 1.25 and 4.6 K. We carried out this transmission experiment with the liquid temperature down to 0.45 K. To measure the transmission of the cold neutrons through such a low temperature liquid 4He, a horizontal cryostat with which the production of UCN was observed in 19925 was used in this experiment.

show abstract

Three metre long horizontal cryostat producing ultracold neutrons using superfluid liquid helium at 0.5 K (Mark 3000)

Cited by 9 publications

References 17 publications

Multi-mirror imaging optics for low-loss transport of divergent neutron beams and tailored wavelength spectra

Multi-mirror imaging optics for low-loss transport of divergent neutron beams and tailored wavelength spectra

Ultracold neutron accumulation in a superfluid-helium converter with magnetic multipole reflector

Transmission of slow neutrons (8–15 Å) through superfluid liquid helium

Contact Info

Product

Resources

About