Storage of very cold neutrons in a trap with nano-structured walls

Лычагин, Е. В.; Muzychka, A. Yu.; Nesvizhevsky, V. V.; Pignol, G.; Протасов, К. В.; Strelkov, A. V.

doi:10.1016/j.physletb.2009.07.030

Cited by 35 publications

(35 citation statements)

References 12 publications

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“…We do not include in our estimate the various methods by which the initial cold neutron brightness might be increased which are the subjects for ongoing research. Examples include neutronics techniques such as a reentrant moderator designs [133], strategic use of neutron reflector/filters [134], supermirror reflectors [123], and non-specular, high-albedo materials such as diamond nanoparticle composites [135][136][137]. Some of these techniques are not suitable for use at multipurpose spallation sources serving a materials science user community, where sharply defined neutron pulses in time may be required.…”

Section: Design Considerations For An Improved N −N Oscillation Searcmentioning

confidence: 99%

Neutron-antineutron oscillations: Theoretical status and experimental prospects

et al. 2016

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The observation of neutrons turning into antineutrons would constitute a discovery of fundamental importance for particle physics and cosmology. Observing the n−n transition would show that baryon number (B) is violated by two units and that matter containing neutrons is unstable. It would provide a clue to how the matter in our universe might have evolved from the B = 0 early universe. If seen at rates observable in foreseeable next-generation experiments, it might well help us understand the observed baryon asymmetry of the universe. A demonstration of the violation of B − L by 2 units would have a profound impact on our understanding of phenomena beyond the Standard Model of particle physics.Slow neutrons have kinetic energies of a few meV. By exploiting new slow neutron sources and optics technology developed for materials research, an optimized search for oscillations using free neutrons from a slow neutron moderator could improve existing limits on the free oscillation probability by at least three orders of magnitude. Such an experiment would deliver a slow neutron beam through a magnetically-shielded vacuum chamber to a thin annihilation target surrounded by a low-background antineutron annihilation detector. Antineutron annihilation in a target downstream of a free neutron beam is such a spectacular experimental signature that an essentially background-free search is possible. An authentic positive signal can be extinguished by a very small change in the ambient magnetic field in such an experiment. It is also possible to improve the sensitivity of neutron oscillation searches in nuclei using large underground detectors built mainly to search for proton decay and detect neutrinos. This paper summarizes the relevant theoretical developments, outlines some ideas to improve experimental searches for free neutron oscillations, and suggests avenues both for theoretical investigation and for future improvement in the experimental sensitivity.

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Section: Design Considerations For An Improved N −N Oscillation Searcmentioning

confidence: 99%

Neutron-antineutron oscillations: Theoretical status and experimental prospects

et al. 2016

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“…A matter with maximum albedo for cold neutrons, which we have found, is solid methane in phase II at the temperature of ∼4 K (we leave aside composite materials based on nanoparticle reflectors [16][17][18], which we are analyzing currently in view of even further increase in the attainable albedo). On the one hand, albedo of methane is slightly higher than albedo of reflectors considered in [9].…”

Section: The Concept Of Ucn Sources At External Beams Of Thermal Neutmentioning

confidence: 95%

UCN Source at an External Beam of Thermal Neutrons

Лычагин

Muzychka

Nekhaev

et al. 2015

Advances in High Energy Physics

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We propose a new method for production of ultracold neutrons (UCNs) in superfluid helium. The principal idea consists in installing a helium UCN source into an external beam of thermal or cold neutrons and in surrounding this source with a solid methane moderator/reflector cooled down to ∼4 K. The moderator plays the role of an external source of cold neutrons needed to produce UCNs. The flux of accumulated neutrons could exceed the flux of incident neutrons due to their numerous reflections from methane; also the source size could be significantly larger than the incident beam diameter. We provide preliminary calculations of cooling of neutrons. These calculations show that such a source being installed at an intense source of thermal or cold neutrons like the ILL or PIK reactor or the ESS spallation source could provide the UCN density 10 5 cm −3 , the production rate 10 7 UCN/s −1 . Main advantages of such an UCN source include its low radiative and thermal load, relatively low cost, and convenient accessibility for any maintenance. We have carried out an experiment on cooling of thermal neutrons in a methane cavity. The data confirm the results of our calculations of the spectrum and flux of neutrons in the methane cavity.

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“…2) [13,44,85]. Moreover, VCN could be stored in traps with nano-structured walls in some analogy to storage of UCN in traps [45]. Diamond, with its exceptionally high optical nuclear potential and low absorption cross-section, is a particularly suitable material for this application.…”

Section: Nanoparticle Reflectors For Slow Neutrons and Studies Of Weamentioning

confidence: 99%

“…Also we will present a new spectrometer GRANIT constructed for precision studies of the gravitationally bound quantum states of neutrons and for other applications in particle physics, quantum optics, and in surface studies [43]. A promising methodical development in the field consists of building neutron reflectors based on nanostructured materials [44][45][46]. Finally, unique properties of UCN allow using them for experimental studies of motions of weakly bound nanoparticles [13,47].…”

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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Storage of very cold neutrons in a trap with nano-structured walls

Cited by 35 publications

References 12 publications

Neutron-antineutron oscillations: Theoretical status and experimental prospects

Neutron-antineutron oscillations: Theoretical status and experimental prospects

UCN Source at an External Beam of Thermal Neutrons

Experiments with ultracold neutrons

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