Ultracold neutrons extracted from a superfluid-helium converter coated with fluorinated grease

Zimmer, O.; Schmidt-Wellenburg, P.; Fertl, M.; Wirth, H. F.; Aßmann, Marc; Klenke, J.; Brandt, B. van den

doi:10.1140/epjc/s10052-010-1327-1

Cited by 24 publications

(28 citation statements)

References 41 publications

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“…Note that, in contrast to the definition of "buildup mode" measurements in earlier experiments [66,80], the neutron beam stayed continuously on the converter vessel. The beam was switched off only for longer breaks in the measurement, e.g., for modifying the setup from vertical to horizontal extraction.…”

Section: B Operating Conditions During the Measurementsmentioning

confidence: 76%

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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Section: B Operating Conditions During the Measurementsmentioning

confidence: 76%

Comparison of ultracold neutron sources for fundamental physics measurements

et al. 2017

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“…Following previous papers [48,63], we write Eq. 3 in its integral form since it is ensemble averages we are concerned with.…”

Section: 08 K Accumulation Measurementmentioning

confidence: 99%

Ultracold-neutron production and up-scattering in superfluid helium between 1.1 K and 2.4 K

et al. 2016

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Ultracold neutrons (UCNs) were produced in superfluid helium using the PF1B cold neutron beam facility at the Institut Laue-Langevin. A 4-liter beryllium-coated converter volume with a mechanical valve and window-less stainless steel extraction system were used to accumulate and guide UCNs to a detector at room temperature. At a converter temperature of 1.08 K the total storage time constant in the vessel was (20.3±1.2) s and the number of UCNs counted after accumulated was 91,700±300. From this, we derive a volumetric UCN production rate of (6.9 ± 1.7) cm −3 s −1 , which includes a correction for losses in the converter during UCN extraction caused by the short storage time, but not accounting for UCN transport and detection efficiencies. The up-scattering rate of UCNs due to excitations in the superfluid was studied by scanning the temperature between 1.2 -2.4 K. Using the temperature-dependent UCN production rate calculated from inelastic neutron scattering data, the only UCN up-scattering process found to occur was from two-phonon scattering. Our analysis for T < 1.95 K rules out the contributions from roton-phonon scattering to < 29% (95% C.I.) and from 1-phonon absorption to < 47% (95% C.I.) of their predicted levels.

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“…The application having motivated this theoretical work is a highprecision study of the level scheme of the neutron in the gravitational potential above the liquid mirror, giving access to short-range, gravitation-like interactions between the neutron and the mirror. A motivation from an experimental point of view has been current work on new UCN sources at the ILL [52,53] which involves cooling many liters of ultrapure, superfluid helium below 0.7 K. The development had been started at the TU Munich [54,55] and builds on theoretical work by Golub and Pendlebury on superthermal UCN production via down-scattering of cold neutrons in superfluid helium [56,57].…”

Section: Discussion and Sketches Of Experimental Implementationsmentioning

confidence: 99%

Neutrons on a surface of liquid helium

et al. 2016

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We investigate the possibility of ultracold neutron (UCN) storage in quantum states defined by the combined potentials of the Earth's gravity and the neutron optical repulsion by a horizontal surface of liquid helium. We analyse the stability of the lowest quantum state, which is most susceptible to perturbations due to surface excitations, against scattering by helium atoms in the vapor and by excitations of the liquid, comprised of ripplons, phonons and surfons. This is an unusual scattering problem since the kinetic energy of the neutron parallel to the surface may be much greater than the binding energies perpendicular. The total scattering time constant of these UCNs at 0.7 K is found to exceed one hour, and rapidly increasing with decreasing temperature. Such low scattering rates should enable high-precision measurements of the scheme of discrete energy levels, thus providing improved access to short-range gravity. The system might also be useful for neutron β-decay experiments. We also sketch new experimental concepts for level population and trapping of UCNs above a flat horizontal mirror.

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Ultracold neutrons extracted from a superfluid-helium converter coated with fluorinated grease

Cited by 24 publications

References 41 publications

Comparison of ultracold neutron sources for fundamental physics measurements

Comparison of ultracold neutron sources for fundamental physics measurements

Ultracold-neutron production and up-scattering in superfluid helium between 1.1 K and 2.4 K

Neutrons on a surface of liquid helium

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