Neutron Detection in Mixed Neutron-Gamma Fields with Common NaI(Tl) Detectors

Abstract

<p>Searching digitized detector signals for piled-up delayed components with distinct energy and delay time signatures is a smart method to provide common NaI(Tl) detectors with additional neutron detection capabilities at no extra cost. This technique nicely complements the idea of neutron detection by analyzing events with high energy depositions above the range of common gamma-ray energies. In combination, both approaches can provide half of the neutron sensitivity offered by a commercial <sup>6</sup>Li co-doped NaI(Tl) (NaIL™) scintillator of the same size, at the price of higher and load-dependent background contributions. Delayed-coincidence techniques are most suitable for neutron monitoring or long-term measurements, where the statistics of the acquired delay-time distributions allows separate fitting of the effect and background contributions. In this case, the thermal neutron flux can be quantified in parallel to gamma-ray spectroscopy at overall detector loads exceeding 10 kcps.</p>

Cosmic Muon Rates and Neutron Background in a Backpack Radiation Detection System

“…deployed for neutron detection with so-called Neutron-Capture Detectors [7]- [10], meaning optimized combinations of gamma-ray detectors with efficient external neutron absorbers [7]- [8], or gamma-ray detectors comprising neutron-absorbing constituents [9]. The NaI(Tl) scintillators used in many instruments, for instance, generate an enhanced rate of neutroncapture signals as they comprise 127 I, distinguished by a quite large neutron-capture cross-section.…”