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

Abstract

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.