Topography of the neutron field in a MnSO4 solution bath from a directed source at 230 keV neutron energy

The application of the manganese bath technique to precise measurements of neutron fluxes from directed sources with 230 keV neutron energy is considered. The 7Li(p,n)7Be reaction is the neutron source. The following equipment is required for the experiment: a lithium fluoride target; tank with a saturated solution of sodium tetraborate and boric acid; a collimator of polyethylene borate; the SNM-13 neutron counter and a vessel with 30% solution of MnSO4. The topography of neutron field was studied using the SNM-13 counter immersed into the vessel and fixed in a special holder. Radial distributions of slow neutrons are obtained relative to the counter rotation axis at fixed values of THETA angle, and the N(THETA) dependences for three fixed radii are also presented. Neutron leakage through the walls of the spherical manganese bath is estimated. For such a bath with 15 cm radius the neutron leakage is equal to 0.4% in the case of a directed source, and to 0.6% for an isotropic source