| dc.description | In order to overcome the shortage of 3He detectors
for subcritical experiments in the IPEN/MB-01 reactor, some
experiments were performed employing less sensitive detectors,
such as BF3, and a logic input module, which sums the counts
from different detectors. Through microscopic and macroscopic
neutron noise technique, it was possible to obtain, respectively,
Rossi-?? distribution and Auto Power Spectral Densities (APSD)
for each detector configuration and various subcritical levels, and
the prompt neutron decay constant (??) was extracted through
a least squares procedure. In addition, Cross Power Spectral
Densities (CPSD) were acquired for different types of detectors
and the correlation among those detectors was confirmed. It was
also observed that there was no loss of correlation among the
neutron pulses, and therefore, the CPSD curves demonstrated the
presence of correlated events. The ?? parameter was used as an
indicator for the comparison of the results and for the quality of
the experimental data. The obtained values demonstrate that the
sum of counts technique does not present loss of information
(correlated neutrons) even for different models and types of
detectors, suggesting that the technique may be employed in
neutron noise measurements for subcritical reactivity. | |
