4π-detectors for neutron cross section measurements

The application of 4π-multidetector systems to gamma-multiplicity measurements for the neutron spectroscopy purposes is discussed. Two multisectional detectors used for multiplicity measurements of the γ-ray cascades following neutron radiative capture are described. These 4π-NaI(Tl) multidetector systems have geometric efficiency over 80% and have been used for gamma-multiplicity measurements at IBR-30 booster in JINR Dubna (16 sections) and stationary research reactor IRT2000 in INRNE BAS Sofia (12 sections NaI(Tl)). Both are created and studied in cooperation with G.V. Muradyan from Kurchatov Institute (Moscow, Russia). The measurements of neutron gamma-capture, neutron transmission and self-indication in the resonance region, as well as the capture to fission cross sections ratio in the thermal point have been performed. The neutron data for reactor technology were obtained and structural characteristics of the investigated nuclei were determined. The response function of the detectors was determined using an algorithm based on Monte Carlo simulation of the neutron and gamma transport in the detector material. (authors)