O. I. Osetrov

DETECTION OF HIDDEN EXPLOSIVES BY NANOSECOND NEUTRON ANALYSIS TECHNIQUE

One of the most promising methods of detection of hidden explosives and other dangerous substances is the so-called, “neutron in, gamma out” technique. The main idea of this method consists in irradiation of suspicious object or volume with neutrons and measurement of secondary γ-radiation caused by interaction of neutrons with the material of the irradiated object. Different chemical elements produce different characteristic γ-radiation as a result of inelastic scattering or capture of neutrons. By decomposing measured γ-spectra into contributions from different chemical elements, one can obtain elemental composition of the explored object and thus determine whether it contains hazardous (e.g. explosive) material or not.

Decision-Taking Procedure for Explosives Detection by Nuclear Technique

One of the most promising techniques of explosives detection is based on detection of secondary γ-rays that are induced in the inspected object or area by a flux of neutrons (the so-called “neutron-in gamma-out” method). Fast neutrons undergo mostly inelastic scattering (n,n’γ) while thermal neutrons undergo mostly radiation capture (n,γ) reactions on nuclei inside the object. Spectra of secondary γ-rays contain information about the isotopic composition of the object. By using narrow (few nanoseconds) time gates one can determine the time of arrival of the given γ-quantum with respect to a particle which accompanies neutron emission from the neutron source, and thus split the total γ-spectrum into fast (inelastic scattering) and slow (radiation capture) components.

Detector of Hazardous Substances Based on Nanosecond Neutron Analysis

Feasibility of Nanosecond Neutron Analysis/Associated Particle Technique for detection of explosive and flammable liquids has been experimentally demonstrated. Experimental results with imitators and real liquids are discussed.

Application of Thin-Film Breakdown Counters for Registration of Fission Fragments in Photofission and Nuclear Reactor Physics Experiments

Specific examples of arrangements based on thin-film breakdown counters are described. The set-ups were used for investigation of γ-induced fission of spontaneously fissioning nuclei and in experiments at the fast-thermal critical assembly.

Modeling of a Low-Background Spectroscopic Position-Sensitive Neutron Detector

A new low‐background spectroscopic direction‐sensitive neutron detector that would allow one to reduce the neutron background component in passive and active neutron detection techniques is proposed. The detector is based on thermal neutron detectors surrounded by a fast neutron scintillation detector, which serves at the same time as a neutron moderator. Direction sensitivity is achieved by coincidence/anticoincidence analysis between different parts of the scintillator. Results of mathematical modeling of several detector configurations are presented.

Device for Detection of Explosives, Nuclear and Other Hazardous Materials in Luggage and Cargo Containers

Device for detection of explosives, radioactive and heavily shielded nuclear materials in luggage and cargo containers based on Nanosecond Neutron Analysis/Associated Particles Technique (NNA/APT) is under construction. Detection module consists of a small neutron generator with built‐in position‐sensitive detector of associated alpha‐particles, and several scintillator‐based gamma‐ray detectors. Explosives and other hazardous chemicals are detected by analyzing secondary high‐energy gamma‐rays from reactions of fast neutrons with materials inside a container. The same gamma‐ray detectors are used to detect unshielded radioactive and nuclear materials. An array of several neutron detectors is used to detect fast neutrons from induced fission of nuclear materials. Coincidence and timing analysis allows one to discriminate between fission neutrons and scattered probing neutrons. Mathematical modeling by MCNP5 and MCNP‐PoliMi codes was used to estimate the sensitivity of the device and its optimal configurat...

Detection of Bulk Explosives with Inelastic Fast Neutrons Scattering

The existing technical means of explosives detection are not efficient and reliable enough; therefore the development of new methods and equipment designed for this purpose is of prime importance.