[en] Results are presented on the conservation of UCN with energies between 10 and 30x10^-9 eV. A dependence of the conservation time of the UCN in l an aluminium vessel on the wall temperature is observed. The energy spectra for UCN in a copper vessel are measured for various periods of conservation. It is demonstrated that the time-averaged increase of the UCN energy in a single encounter with the wall does not exceed approximately 0.7x10^-10 eV

[en] The design and operating criteria of an integral magnetic spectrometer intended for measuring ultracold (E approximately 10^-7 eV) neutron (UCN) spectra are described. The performance of the spectrometer in different regimes has been studied. In the storage regime neutrons passed over the energy barrier are accumulated in the area between the detector and magnetic poles. In the once-through regime neutrons passed over the barrier are registered by the detector at once. In the collimation regime there is a collimator in front of the magnetic poles to reduce the probability of neutron bakage out of the neutron guid. The dependence of the UCN counting rate on the energy barrier height has been investigated. The experimental results of applying the magnetic spectrometers to analize widths of neutron lines extracted by a gravitational differential spectrometer are also presented

[en] A set-up for formation of monoenergetic beams of neutrons with energies of 2x10^-8-7x10^-7 eV is described. The set-up consists of the neutron transportation system for extracting the ultracold neutrons (UCN) from the reactor SM-2 and from the gravitational accelerator channel, in which the UCN are accelerated up to the energy required by the gravity field. The 5.5 m neutronguide is maid of electropolished stainless steel tubes of 90 mm diameter and has three 45 deg bends in the horizontal plane. The neutronguide is devided into two parts by the 100 μm aluminium membrane: the high-vacuum part located in the reactor biological shielding and the low-vacuum part in the experimental hall. The gravitational channel is a vertical 7 m neutronguide maid of the electropolished stainless steel tube of 90 mm diameter. Presented are parameters of the set-up: the flux of extracted neutrons with the neutronguide operating in the storage mode is 56 n/cm²xs; intensity of monoenergetic beams - 0.1, 0.5 and 1 n/s at absolute energy spread of beams 10^-8, 3x10^-8 and 4x10^-8 eV, respectively

No abstract available

[en] The ultracold neutron transmission has been studied using the cylindrical neutron guides made of copper and stainless steel of various geometries. A method has been developed and experimentally tested for calculation in the diffusion approach of the complex geometry neutron guide transmission. The performance of the horizontal transport neutron guides and the feasibility of their transmitting ability increase were analyzed. The unit is described intended for producing the ultra cold neutrons at the SM-2 reactor with the horizontal neutron guide of the high transmitting capability

[en] The process of the ultracold neutrons (UCN) interaction with beryllium surface is investigated. It has been found that the main reason for UCN anomalous leakage of neutrons out of the beryllium vessels is neutron heating at wall impacts. The heated UCN energy Constitutes 25 MeV at the 300 K temperature. The dependence of the UCN heating probability and heated neutrons energy on the vessel walls temperature is studied. It is shown that the process of UCN anomalous leakage out of the beryllium vessels can be effectively suppressed by vessels cooling. Possible physical reasons for the observed UCN heating are discussed

No abstract available

[en] The results of measuring neutron lifetime τ by the method of ultracold neutron storage (UCN) in a vessel cooled to 80 K are presented. Special clean-up of the vessel surface in combination with its cooling made it possible to reduce UCN losses at impacts upon the walls to ∼ 20% of total losses. It permits to measure τ with relative error of 1.4%, that is not limiting for this method. Neutron gas was accumulated and stored in a 75 cm high aluminium cylindrical vessel 105 cm in diameter. The obtained result made up 903±13 s. Preliminary data on measuring neutron lifetime at UCN storage in a vessel with walls of heavy water ice are presented

[en] Technique for measuring the neutron life time using the storage of ultra-cold neutrons (UCN) in an aluminium vessel is described. The dependence of the total probability of UCN losses on the number of collisions per time unit was investigated to take account of the UCN losses during impacts against the vessel walls. Then the dependence found was extrapolated to the frequency of impact equal to zero. The number of collisions was varied with the change of the surface area of the storage vessel. An experimental device for realizing the technique is described; methodical errors have been analyzed. It is shown that the methodical errors are mainly related to the UCN absorption by the vessel walls and to their heating with residual gas; possibilities for decreasing the errors are shown. The neutron life time obtained during previous measurements constituted (875+-95) c

[en] Some systems of electromagnetic mirrors, electric power supply, electromagnetic coil cooling, vacuum system and trap admission system are described. Magnetic intensity in the trap is approximately 0.25 T. The experiments show that 1+-0.15 neutrons are stored in the trap during one admission cycle. The average confinement time equals 35+-10 s