Project of neutron β-decay A-asymmetry measurement with relative accuracy of (1-2)×10−3

We are going to use a polarized cold neutron beam and an axial magnetic field in the shape of a bottle formed by the superconducting magnetic system. Such configuration of magnetic field allows to extract the decay electrons inside a well-defined solid angle with a high accuracy. The electrostatic cylinder with a potential of 25 kV defines the detected region of neutron decays. The protons, which come from this region will be accelerated and registered by a proton detector. The use of coincidences between the electron and proton signals allows in considerably suppressing the background. The final accuracy of A-asymmetry will be determined by the accuracy of the neutron beam polarization measurement, which is at the level of (1-2)×10−3 as it was shown in previous studies.