Prototype Mn-solution bath for low activity primary standard neutron dosimetry

In this work, a prototype Mn-bath was designed and constructed in our laboratory. It is composed of a spherical 304 stainless steel vessel with a diameter of 34 cm. A hydraulic system for circulating the ⁵⁵Mn solution between the bath and the detection system. The detection system is composed of a Marinelli beaker attached to a 3× 3' NaI(TI) crystal detector connected to the Nomad analyzer. A ²⁵²Cf source with a flux of order 10³ (n cm^-2 S^-1) was used. The output dose was measured by a standard NM2 neutron monitor. The output flux was calculated from the flux-dose relationship. It was found that the flux delivered by the used ²⁵²Cf was 170.56 ± 6.41 n cm^-2 S^-1as calculated from the dose measured by NM2. Different concentrations of ⁵⁵Mn solution with the molarity of 0.89,1.18 and 1.48 (mol/l) extracted a flux of 194.48, 186.46, and 169.79 n cm^-2 S^-1, respectively. Data of neutron flux obtained from concentrations of 1.18 and 1.48 mol/l was in a good agreement with the flux measured by the standard neutron monitor and the guaranteed value of the used source. Uncertainty of flux measured by Mn bath was enhanced with increased concentration. (author)