Experimental determination of the α-shape factor in the 1/E1+α epithermal-isotopic neutron source-spectrum by dual monitor method

The α-shape factor of real, non ideal 1/E1+α epithermal neutron spectrum in an isotropic neutron field of 241Am–Be isotopic neutron sources was determined by dual monitor method using measured cadmium ratios of 197Au(n,γ)198Au and 98Mo(n,γ)99Mo(β−)99mTc reactions. The irradiations of Gold (Au) and Molybdenum (Mo), chosen as suitable monitors, were carried out with and without a 1 mm-Cd shield case. The induced activities in these monitors was measured by high resolution γ-ray spectrometry with an n-type HPGe detector. The thermal neutron self-shielding effects in the monitor foils used in irradiations are negligibly small, however, the resonance neutron self-shielding effects were taken into account in the determinations. Thus, the obtained results for the α-shape factors for a real 1/E1+α epithermal-241Am–Be neutron source-spectrum at the four irradiation sites of the neutron irradiator are given and discussed. It is emphasized that the 197Au–98Mo isotopes can be chosen as suitable monitors in α-shape factor determination in real epithermal neutron spectra.