Experimental verification of the flatness of response of a multi-BF3- counter neutron detection system

Abstract The constancy of the detection efficiency η of a multi-BF 3 - counter neutron detection system built after a proposal by Thies 1 ) was tested experimentally. In experiment (1) the neutron yield from 2 D(γ,n) for bremsstrahlung peak energies 6 MeV E 0 2 D(γ,n)-cross-section. In experiment (2) - for the range 18.5 MeV E 0 3 -counter neutron detection system and concurrently by counting the 20.3 min positron activity induced in 11 C. Finally the neutron yield from a carbon target enriched in 13 C to 90% was measured, and the 12 C(γ,n)-yield obtained from the natural carbon one by subtraction. By intercomparison of yields in experiments (1) and (2) the constancy of η was verified independently for the respective ranges of mean neutron energies 0.75 MeV E n 1.3 MeV E n MeV . Combining these results with those from an earlier experiment 2 ) it was verified that η is constant for 30 keV E n MeV , deviating by less than 1% from its average value in the range 1 MeV E n MeV .