Search for $P$-odd asymmetry of prompt neutrons emission in $^{235}$U fission induced by cold polarized neutrons

The preliminary result of the $P$-odd asymmetry of prompt neutron emission in $^{235}$U fission induced by polarized cold neutrons is $a = (2.7 \pm 0.8)\cdot10^{-5}$. Only the scission neutrons can show such asymmetry, whereas neutrons emitted by excited fragments are the unavoidable background, which suppress the sought asymmetry. The $P$-odd asymmetry of light fragment emission for $^{235}$U is equal to $(8.4 \pm 0.6)\cdot10^{-4}$. Assuming that last figure defines the parity mixture of fissile nucleus then the suppression factor is equal approximately to 3.