A simple way to overcome the shortage of 3He detectors in the IPEN/MB-01 nuclear reactor

To overcome the shortage of 3He detectors for subcritical experiments in the IPEN/MB-01 reactor, some experiments were performed using less sensitive detectors, such as BF3, and a logic input module, which sum the counts from different detectors. Through macroscopic neutron noise technique, the Auto Power Spectral Densities (APSD) were obtained for each detector configuration and various subcritical levels, and the prompt neutron decay constant (α) was extracted through a least squares procedure. The α parameter was used as an indicator for the comparison of the results and the quality of the experimental data. The values obtained show that the sum of counts technique presents no loss of information (correlated neutrons) even for different models and types of detectors, suggesting that the technique can be employed in neutron noise measurements.