V. L. Ryabov

Permanent-magnet trap for ultracold neutron storage

The design of a permanent-magnet trap for ultracold neutron (UCN) storage is described. This trap excludes neutron collisions with the walls and, hence, eliminates anomalous losses. Used in the experiments on the neutron lifetime determination such UCN traps remove the main systematic error related to the anomalous neutron losses on the walls.

A new permanent-magnet trap for ultracold neutron storage

The design of a new permanent-magnet trap for ultracold neutron storage in an experiment on determining the neutron lifetime is presented. Particular attention is paid in this new trap design to the neutron confinement system. Optimization of this system provides an opportunity to raise the strength of the confinement magnetic field and thus increase considerably the number of neutrons stored within the trap and the statistical accuracy of neutron lifetime measurements.

Mass-spectrometric study of UT-18 fomblin and residual gases in a magnetic trap used for the neutron lifetime measurements

The reference mass spectra of UT-18 fomblin have been obtained using quadrupole and monopole mass spectrometers with electron-impact ionization. The composition of residual gaseous species in a magnetic trap with fomblin-coated walls has been studied. At a total residual gas pressure of 1.2 × 10−6 Torr, the partial pressure of fomblin was on a level of 2 × 10−9 Torr.

Spectroscopy of the YbF molecule in low-pressure inductively coupled plasma

AbstractsThe emission spectra of the YbF molecule excited in low-pressure inductively coupled plasma have been recorded for the plasma formed by three different methods. To assign the spectra observed, the quantum-mechanical calculation of the Frank-Condon factors has been performed. The presence of these molecules in the plasma has also been diagnosed experimentally with a monopole mass analyzer.

On the possibility of measuring the anapole moment of potassium atom

We suggest measuring the nuclear-spin-dependent P-odd amplitude in the transitions between hyperfine structure sublevels in the ground state of potassium isotopes. Since the main contribution to this amplitude is due to the anapole moment of the nucleus, such measurements of the P-odd spin-dependent effects may provide new information about weak interactions. It is established that the measurement of such effects with a statistical error within 1% can be performed for approximately 1 h.

Production and spectroscopy of PbF and SiF radical molecules in low-pressure inductively coupled plasma

A method for producing PbF radical molecules with application of a low-pressure inductively coupled plasma is proposed. The emission spectra of PbF radical molecules have been recorded during decomposition of the PbF2 compound in plasma. Simultaneously, during excitation of a discharge in a quartz tube, spectra of SiF molecules, excited upon interaction of free fluorine with the tube walls, were recorded. Quantum-mechanical calculation of the Franck-Condon factors has been perform to identify the observed spectra.

Application of the particle-in-cell method to calculate the parameters of molecular beams from gasdynamic sources

The particle-in-cell method is used to calculate the flow fields of gases formed by supersonic nozzles of different shapes under flow conditions typical of gasdynamic sources of molecular beams. The proposed calculation scheme is tested by comparing the calculated flow fields from an acoustic nozzle with the semiempirical calculations made by Ashkenas and Sherman. For a nozzle with a conical supersonic section the calculations are compared with the results of time-of-flight measurements made using the molecular beam generator at the St. Petersburg Institute of Nuclear Physics of the Russian Academy of Sciences. Prospects for the further use of these calculation methods to develop and optimize gasdynamic sources of molecular beams are discussed.

A Magnetic Shutter for a Trap Made of Permanent Magnets for Ultracold Neutron Storage

A design of a magnetic shutter for a trap made of permanent magnets for the ultracold neutron storage in experiments on measuring the neutron lifetime is proposed. The data of shutter testing and comparison with the calculated magnetic fields are reported.

Low-pressure inductively coupled plasma as a new source of molecular beams

A new method is proposed for the generation of intense molecular beams, which is based on the use of low-pressure inductively coupled plasma. A test beam of YbF radicals obtained using the proposed method was extracted with an output intensity of 1 × 1018 molecule/(sr s). The beam characteristics were measured using an emission spectrometer and a monopole mass analyzer.

Atomic hydrogen cooling under adiabatic expansion in a magnetic trap

A new method for cooling atomic hydrogen down to 100 µK or below is suggested. The method exploits the unique properties of atomic hydrogen, which are the following: atomic hydrogen does not condense at temperatures as low as 20 µK and cannot be heated by IR radiation in the absence of atom-wall collisions. Therefore, the most efficient and well-known gas cooling technique can be employed, namely, the adiabatic expansion of the volume occupied by the gas (this approach is used in a gas-expansion machine). It is suggested to adiabatically expand the volume of a magnetic trap containing atomic hydrogen.