Neutron leakage form a manganese bath from isotropic and unidirectional sources

Investigations have been conducted on optimization of dimensions of a manganese bath for calibrating intermediate neutron fluxes from isotropic and unidirectional sources. A lithium target bombarded with protons served as a neutron source. Experimental spatial distributions of neutrons in water and 30% MnSO4 aqueous solution are presented for initial neutron energies of 25 and 230 keV. Thus obtained relaxation lengths of neutrons were used to calculate neutron leakage from the spherical bath. In the neutron energy range up to 230 keV the spherical manganese bath of 15 cm in radius has been shown to yield neutron leakage less than 1% and 0.3% for isotropic and unidirectional neutron sources respectively. The neutron distributions in water and the MnSO4 solution are pointed out to differ substantially in the energy range