A precise method to determine the activity of a weak neutron source using a germanium detector

A standard high purity germanium (HPGe) detector was used to determine the previously unknown neutron activity of a weak americium-beryllium (AmBe) neutron source. γ rays were created through 27Al(n,n′), 27Al(n,γ) and 1H(n,γ) reactions induced by the neutrons on aluminum and acrylic disks, respectively. These γ rays were measured using the HPGe detector. Given the unorthodox experimental arrangement, a Monte Carlo simulation was developed to model the efficiency of the detector system to determine the neutron activity from the measured γ rays. The activity of our neutron source was determined to be 307.4±5.0n/s and is consistent for the different neutron-induced γ rays. •Neutron activation analysis is used to measure a weak neutron source's strength.•Gamma rays are produced from three neutron reactions on different targets.•Gamma measurements are performed only with a standard germanium detector.•Monte Carlo simulation is used to find neutron activities from produced gamma rays.•Consistent activities are found across measurements with varying reactions/targets.