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Yu. N. Pokotilovski

Publications and source records attributed to Yu. N. Pokotilovski.

At least 19 recordsLinked to original sources
arXiv2018

Experimental investigation of the low molecular weight fluoropolymer for the ultracold neutrons storage

The experimental setup for examining the low-molecular-weight fluoropolymer CF$_{3}$(CF$_{2})_{3}$-O-CF$_{2}$-O-(CF$_{2})_{3}$CF$_{3}$, which is a promising coating material for the walls of storage chambers for ultracold neutrons, is described. The results are detailed. The measurement data are interpreted in the model of a multilayer complex quantum-mechanical potential of the chamber walls.

physics.ins-det↗
arXiv2018

Experimental search for the bound state singlet deuteron in the radiative n-p capture

We performed an experimental search for the bound state singlet deuteron predicted in some microscopic calculations. The predicted energy of this metastable level is in vicinity of the deuteron disintegration threshold. This state should manifest itself in two-photon transition following thermal neutron capture by protons. The experiment consists in the search for the second gamma-ray in the cascade through a high statistics measurement of $γ$-ray spectra after cold neutron capture by hydrogen nuclei. The upper limit $2μ$b (2$σ$ level) is obtained for the cross section of the singlet deuteron production with the bound energy in the range 10-125 keV.

nucl-ex↗
arXiv2018

Experiments with ultracold neutrons - first 50 years

This year is 50 anniversary of the first experimental observation of ultracold neutrons (UCN). I present my reminiscences of the first experiment in Dubna, first encounter with F.L. Shapiro -- pioneer of the UCN investigations, and the early stage of the UCN experiments. Present status of investigations with UCN is shortly reviewed.

physics.hist-ph↗
arXiv2013

Constraints on strongly coupled chameleon fields from the experimental test of the weak equivalence principle for the neutron

The chameleon scalar field is considered as a possible cause of accelerated expansion of the Universe. The chameleon field induces an interaction potential between a particle and a massive body. Previous experiments with falling cold neutrons intended to measure the neutron coherent scattering lengths and verification of the weak equivalence principle for the neutron are used to constrain the parameters characterizing the strength of the scalar chameleon fields.

nucl-ex↗
arXiv2013

Potential of the neutron Lloyd's mirror interferometer for the search for new interactions

We discuss the potential of the neutron Lloyd's mirror interferometer in a search for new interactions at small scales. We consider three hypothetical interactions that may be tested using the interferometer. The chameleon scalar field proposed to solve the enigma of accelerating expansion of the Universe produces interaction between particles and matter. The axion-like spin-dependent coupling between neutron and nuclei or/and electrons may cause P- and T-non-invariant interaction with matter. Hypothetical non-Newtonian gravitational interactions mediates additional short-range potential between neutrons and bulk matter. These interactions between the neutron and the mirror of the Lloyd's type neutron interferometer cause phase shift of neutron waves. We estimate the sensitivity and systematic effects of possible experiments.

nucl-ex↗
arXiv2013

Experimental Search for the Singlet Metastable Deuteron in the Radiative n-p Capture

We performed an experimental search for the bound state singlet deuteron predicted in some microscopic calculations. The experiment consists in a high statistics measurement of gamma ray spectra after thermal neutron capture by hydrogen nuclei. The upper limit is obtained for the probability of the 3S1 - 1S0 -transition population of the deuteron singlet bound state with the bound energy in the interval 25-125 keV.

nucl-ex↗
arXiv2013

Strongly coupled chameleon fields: possible test with a neutron Lloyd's mirror interferometer

The consideration is presented of possible neutron Lloyd's mirror interferometer experiment to search for strongly coupled chameleon fields. The chameleon scalar fields were proposed to explain the early and late time acceleration of expansion of the Universe. They may produce short-range interaction between particles and matter. This interaction causes phase shift of neutron waves in the interferometer. Estimates of sensitivity are performed.

nucl-ex↗
arXiv2012

UCN transport simulation in solid deuterium crystals

The extraction efficiency of ultracold neutrons from cryogenic moderators depends critically on the neutron transparency of the moderator material. The Monte Carlo simulation of the probability of the UCN going out from non-ideal (disordered) solid deuterium crystals has been performed. It was based on the use of the correlation function describing the density fluctuations in a disordered material, the latter being inferred from the measured very low neutron energy total cross sections for this material.

nucl-ex↗
arXiv2011

Neutron experiments to search for new spin-dependent interactions

The consideration is presented of possible neutron experiments to search for new short-range spin-dependent forces. The spin-dependent nucleon-nucleon interaction between neutron and nuclei may cause different effects: phase shift of a neutron wave in neutron interferometers of different kind, in particular of the Lloyd mirror configuration, neutron spin rotation in the pseudo-magnetic field, and transverse deflection of polarized neutron beam by a slab of substance. Estimates of sensitivity of these experiments are performed.

nucl-ex↗
arXiv2011

A Differential Time-of-flight Spectrometer of Very Slow Neutrons

A time-of-flight spectrometer of neutrons in the energy range (0.05 -- 2.5)$μ$eV is described. This spectrometer has been tested my measuring the total and differential neutron cross sections for a number of materials: Al, Cu, $^{6}$LiF, Si, Zr, teflon, polyethylene and liquid fluoropolymers, that are essential for experiments in the physics of ultracold neutrons.

nucl-ex↗
arXiv2010

Correlation Time-of-flight Spectrometry of Ultracold Neutrons

The fearures of the correlation method used in time-of-flight spectrometry of ultracold neutrons are analyzed. The time-of-flight spectrometer for the energy range of ultracold neutrons is described, and results of its testing by measuring spectra of neutrons passing through interference filters are presented.

nucl-ex↗
arXiv2010

Options for the Neutron Lifetime Measurements in Traps

Different geometries for the neutron lifetime measurements by the method of ultracold neutron storage in material traps and additional possibilities for the neutron storage in the magnetic storage ring are considered.

nucl-ex↗
arXiv2010

Reply to 'Comment for "Limits on a nucleon-nucleon monopole-dipole (axionlike) P,T-noninvariant interaction from spin relaxation of polarized He-3" [arXiv:0912.4963], by A.P. Serebrov'

It is shown, that criticism, presented in [arXiv:0912.4963], is based on an elementary error in the calculation of the collision frequency of an atom in a gas with walls of a container and misunderstanding of the method used in [arXiv:0902.1682v2] for obtaining constraints on new short-range spin-dependent interactions.

nucl-ex↗
arXiv2009

Neutron lifetime measurements using gravitationally trapped ultracold neutrons

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before:the probability of UCN losses from the trap was only 1% of that for neutron beta decay. The neutron lifetime obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental measurement to date.

nucl-ex↗