Superconducting UCN Polarizer for a New EDM Spectrometer.

A test experiment has shown that the number of ultracold neutrons (UCN) of one polarization state, transmitted through a 100 µm Al foil when placed in a 5 T magnetic field, is greater by 3.8 times. The increased transmission is due to the higher velocity of the UCN passing through the foil.

A Silicon UCN Detector With Large Area and With Analysis of UCN Polarization.

A silicon ultracold neutron (UCN) detector with an area of 45 cm(2) and with a (6)LiF converter is developed at St. Petersburg Nuclear Physics Institute (PNPI). The spectral efficiency of the silicon UCN detector was measured by means of a gravitational spectrometer at Institut Max von Laue - Paul Langevin (ILL). The sandwich-type detector from two silicon plates with a (6)LiF converter placed between them was also studied. Using this type of technology the UCN detector with analysis of polarization was developed and tested. The analyzing power of this detector assembly reaches up 75 % for the main part of UCN spectrum. This UCN detector with analysis of UCN polarization can be used in the new electric dipole moment (EDM) spectrometer.

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 ß-asymmetry in neutron decay, A 0, of -0.1189(7) is in a good agreement with the Standard Model.