Multi-layer fast neutron detectors based on composite heavy-oxide scintillators for detection of illegal nuclear materials

The article of record as published may be found at https://doi.org/10.1016/j.nima.2018.06.074We developed and characterized a new type (designated ZEBRA) of multi-layer composite heavy-oxide scintillator detectors for fast neutron detection for homeland security and nuclear safeguards applications. In this heterogeneous detector medium, composite layers comprised of micro-granules of heavy-oxide scintillators (ZWO, CWO, PWO, BGO, GSO(Ce), GOS(Ce) and others) dispersed in transparent plastic are alternated with layers of clear plastic that serve as scintillation light guides and as a neutron moderator material. The physical peculiarities of the neutron interactions and the principal mechanisms of fast neutron registration in these detectors are discussed in detail. The fast neutron intrinsic detection efficiencies and sensitivities of ZEBRA-detectors based on BGO, ZWO and GSO(Ce) composite scintillators in response to neutrons from 239Pu–Be and 252Cf sources were measured. These detectors had cross-sectional areas ranging from 16 to 100 cm2. The sensitivities of such detectors of size 100 × 100 × 41 mm3 were found to be 40–51 cps/(nps × cm−2), a level that is comparable to the sensitivity of a typical 3He counter of 1600 cm2 area. The intrinsic efficiencies and sensitivities of the ZEBRA-detectors also compare favorably with those of fast neutron detectors based on large-size heavy-oxide single crystals, but the multi-layer composite ZEBRA structures are much less expensive and can be easily manufactured in much larger dimensions. This work represents a significant advance from earlier single-crystal detector types as part of our effort to explore alternatives and improvements to conventional 3He counters

The highly efficient gamma-neutron detector for control of fissionable radioactive materials

Comparative measurements and analysis of detection efficiency of fast and thermal neutrons from ²³⁹Pu-Be source by heavy oxide scintillators (Z≥50) confirmed high detection efficiency (∼ 40-50 %). The most probable mechanism determining the fast neutron detection efficiency is the reaction of inelastic scattering (n, n ′ γ ) as the main mechanism of interaction of neutrons with nuclei of oxide scintillators. The fast neutron detection efficiency was determined by the method of internal counting of gamma-quanta emerging in the scintillator under (n, n ′ γ ) reaction. It has been shown that the use of heavy oxide scintillators (which are also efficient gamma-detectors) in inspection systems can allow detection of fissionable radioactive materials

Advanced scintillation single crystals based on complex oxides with large atomic number

An improved production technology has been developed for scintillation single crystals based on complex oxides with large atomic number – bismuth germanate (BGO), gadolinium silicate (GSO), cadmium tungstate (CWO) and lead tungstate (PWO). Scintillators based on these crystals have good energy resolution and light output, high detection efficiency, they are not hygroscopic, have high radiation stability and mechanical strength. This makes it possible to use them as radiation detectors for high energy physics (PWO), in instruments for radiation and radioecological monitoring (BGO,CWO,GSO)

Portable radiation monitoring system on the base of CdWO₄ scintillator

A portable high-sensitivity monitor for the detection of radioactive materials is developed and manufactured on the base of CdW0₄ scintillation crystal. The monitor has an independent power supply which provides continuous operation at least during 120 hours.Розроблено і виготовлено портативний високочутливий портал для виявлення радіоактивних матеріалів на базі сцинтиляційного кристала CdW0₄. Портал має власний блок живлення, який забезпечує його безперервну роботу протягом 120 годин.Разработан и изготовлен портативный высокочувствительный портал для обнаружения радиоактивных материалов на базе сцинтилляционного кристалла CdWO₄. Портал оснащен собственным источником питания, который обеспечивает его непрерывную работу в течение 120 часов