Yu. N. Pokotilovski

Measurement of the Neutron Lifetime Using a Gravitational Trap and a Low-Temperature Fomblin Coating

We present a new value for the neutron lifetime of 878.5 ± 0.7stat. ± 0.3syst. This result differs from the world average value by 6.5 standard deviations and by 5.6 standard deviations from the previous most precise result. However, this new value for the neutron lifetime together with a β-asymmetry in neutron decay, A 0, of -0.1189(7) is in a good agreement with the Standard Model.

Production and storage of ultracold neutrons at pulse neutron sources with low repetition rates

Abstract High densities of ultracold neutrons can be stored in experimental volumes if one uses a pulse thermal neutron source with a low repetition rate, a very low temperature converter, a high quality curved neutronguide and a shutter at the entrance window of the storage volume.

On the experimental search for neutron → mirror neutron oscillations

Abstract Fast neutron → mirror neutron ( n → n ′ ) oscillations were proposed recently as the explanation of the GZK puzzle. We discuss possible laboratory experiments to search for such oscillations and to improve the present very weak constraints on the value of the n → n ′ oscillation probability.

Constraints on new interactions from neutron scattering experiments

Constraints for the constants of hypothetical Yukawa-type corrections to the Newtonian gravitational potential are obtained from analysis of neutron scattering experiments. Restrictions are obtained for the interaction range between 10−12 and 10−7 cm, where Casimir force experiments and atomic-force microscopy are not sensitive. Experimental limits are obtained also for nonelectromagnetic inverse-power-law neutron-nucleus potentials. Some possibilities are discussed to strengthen these constraints.

INTERACTION OF ULTRACOLD NEUTRONS WITH LIQUID SURFACE MODES AS A POSSIBLE REASON FOR NEUTRON ENERGY SPREAD DURING LONG STORAGE IN FLUID WALL TRAPS

Abstract Interaction of ultracold neutrons with surface liquid modes is considered in connection with recent possible observation of small ultracold neutron cooling and heating during long storage in closed traps covered with Fomblin grease.

Investigation of liquid fluoropolymers as possible materials for low-temperature liquid-wall chambers for ultracold neutron storage

Several hydrogen-free liquid low-temperature fluoropolymers are investigated from the point of view of their possible use as the material for walls of ultracold neutron traps with low losses. Viscosity was measured in the temperature range 150–300 K, and neutron scattering cross sections were measured in the temperature range 10–300 K and in the neutron wavelength range 1–20 Å. Some conclusions are made for their possible ultracold neutron bottle properties. Quasi-elastic neutron reflection from the surface of a viscous liquid is considered in the framework of the Maxwell dynamic model.

Limits on short-range spin-dependent forces from spin relaxation of polarized 3He

Abstract A new limit is presented on the axion-like monopole–dipole P , T -non-invariant coupling in a range ( 10 − 4 − 1 ) cm . The gradient of spin-dependent nucleon–nucleon potential between 3 He nucleus and nucleons and electrons of the walls of a cell containing polarized 3 He gas should affect its spin relaxation rate. The limit is obtained from the existing data on the relaxation rate of spin-polarized 3 He.

Possibility for low temperature fluid-wall neutron bottle with very low neutron upscattering losses

Abstract The new recently synthesized polymers – perfluorinated polyformaldehydes have long liquid range and low melting point. Due to the expected low upscattering losses of ultracold neutrons, at low temperatures, these fluids may be good candidates for precision measurement of neutron lifetime by the method of storage of ultracold neutrons in traps.

Cubic boron nitride: A New prospective material for ultracold neutron application

Abstract At the ultracold neutron (UCN) source of the TRIGA research reactor in Mainz, we have measured for the first time the material optical wall-potential of cubic boron nitride. The measurements were performed with a time-of-flight (TOF) spectrometer. The samples investigated had a wall-potential of ( 305 ± 15 ) neV . This value is in good agreement with the result extracted from neutron reflectometry data and theoretical expectations. Because of its high critical velocity for UCN and its good dielectric characteristics, cubic boron nitride coatings (isotopically enriched) will be useful for a number of applications in UCN experiments.

Correlation time-of-flight spectrometry of ultracold neutrons

The features 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.