V.M. Lobashev

New measurement of the electric dipole moment of the neutron

Abstract A new experiment on the search for the electric dipole moment of the neutron was carried out using a magnetic resonance set-up with electric field and stored ultracold neutrons. The EDM of the neutron was measured to be +(2.6±4.2±1.6)×10−26 e cm, the first error being RMS or statistical and the second one systematical. An upper limit at the 95% CL is |dn|

A new upper limit on the electric dipole moment of the neutron

Abstract New measurements have reduced the upper limit for the electric dipole moment of the neutron to | d | −25 e cm (90% confidence level).

Search for an Electric Dipole Moment of the Neutron

The result of measuring the electric dipole moment (EDM) of the neutron by using ultracold neutrons is presented. The results of the measurements give the value of the EDM: d/sub n/4=(plus-or-minus7.5) x 10/sup -25/ excm. Hence, it can be concluded that vertical-bardvertical-bar<1.6 x 10/sup -24/ excm at the 90% confidence level.

An adiabatic resonance spin-flipper for thermal and cold neutrons

Abstract A device to reverse the polarization of a wide velocity spectrum neutron beam is described. The method does not require the switching of static magneti

Observation of parity violating effects in the polarized thermal neutron total and radiative capture cross sections of 117Sn and 139La

Abstract Parity violating effects in the transmission and radiative capture of longitudinally polarized thermal neutrons have been observed for 117 Sn and 139 La targets. Helicity dependent asymmetries a = 10 6 ( σ + -− σ − )/( σ + + σ − ) were found in the total cross section of 117 Sn ( a = 6.2 ± 0.7) and 139 La (a = 9.0 ± 1.4) , and also in the (n, γ) cross section of 117 Sn ( a = 22.6 ± 1.9) and of 139 La ( a = 16.1 ± 2.0).

A liquid hydrogen source of ultra-cold neutrons

Abstract A liquid hydrogen source of ultra-cold neutrons (UCN) developed for an experimental search for the electric dipole moment of the neutron is described. The results of an investigation of the yield of UCN from gaseous, liquid, and solid hydrogen as a function of temperature are presented. The UCN counting rate obtained at the output of the 6 × 7 cm 2 neutron guide tube is 5 × 10 4 n/s. This counting rate corresponds to a flux of neutrons whose velocity along the axis of the neutron guide tube is below 7 m/s. Preliminary measurements of the UCN yield from liquid and solid deuterium have been carried out.

Circular polarization of γ-quanta in np→dγ reactions with polarized neutrons

Abstract The circular polarization of the 2.23 MeV γ -quanta in the reaction np→d γ with polarized cold neutrons has been measured to be P γ =(−1.5±0.3)×10 −3 . A high-purity solid parahydrogen target was used. The circular polarization was measured with two magnetic transmission polarimeters, NaI(Tl) crystals with photomultipliers were used as detectors. The result is examined from the point of view of recent theoretical calculations.

Fast multichannel stabilization of the magnetic resonance in a magneto-resonance spectrometer

Abstract A method of fast stabilization of the magnetic resonance in a magnetic resonance spectrometer has been developed and tested. The source of the oscillatory field is the synthesizer which frequency follows variations of the average magnetic field in spectrometer. To search for the neutron electric dipole moment in the experimental setup under unfavorable conditions in the reactor experimental hall a stability of the magnetic resonance has been achieved that is equivalent to a magnetic field stability at the level of ≈ 2.5 × 10 −12 T per 6 min in a volume of about 501 with an electric field of 1.5 MV/m.