Search for violation of the Pauli principle through spontaneous neutron emission from lead

Abstract
Neutron emission caused by the spontaneous appearance of a hole state in a nucleus, which could take place as a manifestation of violation of the Pauli principle, was searched for. Neutrons from natural lead were found to be less than 1.6*10-3 neutrons/s kg which gives a lifetime of tau >1.0*1020 y (0.99 CL). It is shown that the present measurement limits spontaneous appearance of a hole state better than the measurement of nuclear gamma -transitions by many orders of magnitude.