Fast neutron induced gamma rays from (n,n’), (n,p) and (n,α) reactions on CaCO 3

Emission of prompt gamma rays following (n,n’), (n,p) and (n,α) reactions induced by irradiation of a calcium carbonate (CaCO 3 ) sample with a beam of fission neutrons was investigated with a modified version of the FaNGaS (Fast Neutron-induced Gamma-ray Spectrometry) instrument operated at the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching. The neutron spectrum has an average energy of 2.30 MeV and at sample position the fast neutron flux was (1.13 ± 0.04) × 10 8 cm −2 s −1 . The measurement was performed at an angle of 90° between neutron beam and detector. In total, we claim the identification of 38 prompt gamma lines, from which we have assigned 12 to the (n,n’) reaction in calcium (7 for 40 Ca, 1 for 42 Ca and 4 for 44 Ca), 1 to the 12 C(n,n’) 12 C reaction, and 2 to the (n,n’) reaction in oxygen (1 for 16 O and 1 for 18 O). The other observed gamma lines are attributed to the 40 Ca(n,p) 40 K reaction (20 lines) and to the 40 Ca(n,α) 37 Ar reaction (3 lines). Relative intensities and fast neutron spectrum averaged partial cross sections of the gamma lines are presented and compared with available literature data. Our results were found to be in good agreement with available literature data but also improved and complemented it, as we have pointed out possible errors and identified new lines. Additionally, for a counting time of 12 h the detection limits of calcium, carbon and oxygen were determined as 5, 13 and 64 mg, respectively.