GENERAL RESEARCH LINES

1. Development and creation of semiconductor detectors of charged particles for working in static (non-pumped) vacuum conditions.

The method of nanosecond neutron analysis (NNA) on the basis of portable neutron generator, elaborated at Applied Physics Laboratory, required to create the new type of detectors for charged particles, which main advantage consists in possibility of working in conditions of static (non-pumped) vacuum and high electronic and X-ray radiation background. The designed detectors are characterized with high radiation stability against neutron and alpha-radiation, and keep their basic characteristics unchangeable both in a period of realization of process procedures on neutron generator fabricating and during the whole period of neutron generator operating. The figure below presents patterns of semiconductor detectors fabricated and operated with success inside of neutron generators.

Semiconductor detectors of accompanying alpha particles for working in static vacuum conditions inside of neutron generator (single-pin, nine-pins).

At present they carry out the works at Applied Physics Laboratory to create more complicated semiconductor detectors (25-100-pins).

2. Improvement of production technologies and fabricating of silicon surface-barrier detectors; regeneration of Ge(Li) detectors, and also - detectors of especially pure germanium.

At the Laboratory there is refined detector fabricating technology for spectrometry of short-range (alpha-particles, fission fragments, etc.) and long-range (protons, electrons, etc.) charged particles with sensitive surface area from 10 to 4000 mm² (for low-intensity particle flux) and energy resolution from 12 to 80 KeV (depending on detector's area) for 5.5-MeV alpha- particles. Sensitive area thickness is from 0.3 to 2 mm. The thickness of detector window (on the basis of golden equivalent) is about 100 Å.

We produce channel detectors with cylindrical sensitive surface, destined to measure gas targets under accelerator fluxes, and also to fabricate detective assemblies and to realize 4π-geometry measurements. Energy resolution for 5-MeV alpha-particles from 25 to 50 KeV (depending on detector's area).

3. Receipt of experimental and calculation data on ionizing radiation transfer through a substance

Applied Physics Laboratory has accumulated sizeable experience in designs of neutron and gamma-radiation transfer in various mediums, calculated by Monte Carlo method. The main problem to be solved is a search for possibility to detect explosives, drugs, other dangerous substances, and also special nuclear materials by methods using neutron, X-ray, and gamma emanations.

The calculations are based on Monte Carlo N-Particle Transport Code System (MCNP4C2, license MCNP4C2/MCNPDATA C00701ALLCP00 & D00200ALLCP02) together with the codes created by own efforts.

In this way in 2001 the availability of nanosecond neutron analysis (NNA) method, using portable neutrons generator, was demonstrated by means of calculations, and the limits of it's availability for solving a problem of infantry mines revealing. Later on with the help of calculations there was elaborated physical basis for NNA method, and possibilities of this method application with the purpose to solve various tasks on dangerous substances detection were assessed.

In 2002-2003 they proved possibility of NNA method application with the purpose to detect explosives, drugs and toxic substances, special nuclear materials in hand luggage, air cargo containers, high-tonnage overseas transport containers, and also indicated the advantages of NNA method in comparison with other available methods, such as X-ray, neutron, etc.

The calculations, which have been carried out, as well as the experience of working with active prototypes of devices for detection and identification of explosives, made in Applied Physics Laboratory serve as a basis to design a series of perfectly new devices for dangerous substances detection.

4. Development of methods and devices to detect and identify dangerous substances, including drugs and explosives

4.1 Detection of explosives with the help of MW-range electromagnetic radiation (MW radar)
4.2 Detection of explosives and other dangerous substances, using neutron-and-gamma methods
4.2.1. The method of nanosecond neutron analysis (NNA)
4.2.2.Portable installation for dangerous substance detection on the basis of NNA method, provided with neutron source
4.2.3.Portable installation destined to detect dangerous substances on the basis of portable neutron generator provided with built-in detector of concomitant particles
4.2.4.Outlooks for developing of NNA technology with the purpose to detect dangerous substances in luggage and freights

4.1. Detection of explosives with the help of MW-range electromagnetic radiation (MW radar)

A prototype of MW radar, developed at Radium Institute to detect explosives in homogeneous mediums and in luggage represents a subsurface probing radio-locator with stepped radiation frequency variation (Stepped Frequency Continuous Wave Radar) and gives opportunity to scan a medium and to make provisional identification of objects detected on the basis of their form and dielectric characteristics.

A depth of homogeneous medium scanning with MW radar is as follows: for sandy soil at humidity below 0.1% - 50 cm, for sandy soil at humidity about 16% - 5 cm, for concrete- 20 cm. MW radiation power does not exceed 1 mW; mass of radar - 5 Kg.

MW radar aimed to detect explosives hidden in homogeneous mediums and in luggage

4.2. Detection of explosives and other dangerous substances, using neutron-and-gamma methods

General idea of the known "neutron-and-gamma" analysis methods consists in radiation treatment of suspect object with neutrons and in measuring of secondary gamma emission induced by neutrons within the given object material. When resolving the measured gamma-emission spectrum into the contributions from various chemical elements, it is possible to define an element composition of the studied object, and to determine at that way, whether this object contains any explosives and other dangerous materials, or not.

Modified version of "neutron-and-gamma" method (Nanosecond Neutron Analysis - NNA) developed at Applied Physics Laboratory is based on gamma-quantum registration in short (nanosecond) time intervals. The development of this method has allowed to sizeable decrease (about two orders of magnitude) in photon component of gamma-spectra and thereby - to essential shortening of time required to identify an object.

4.2.2. Portable installation for dangerous substance detection on the basis of NNA method, provided with neutron source

This is a working prototype of mobile device destined to detect explosives hidden in soil, walls, and hand luggage. The device includes a compact ionization chamber with isotopic source of neutrons (²⁵²Cf, 4ћ10⁶neutrons/sec), and specially made electronic block provided with feeding from rechargeable batteries. Working prototype of the device identifies 400 grams of hidden explosive in 5 minutes. The weight of this installation does not exceed 30 Kg. The device is entirely volatile and is fed from rechargeable batteries.

A prototype of mobile device designed to detect explosives

4.2.3. Portable installation destined to detect dangerous substances on the basis of portable neutron generator provided with built-in detector of concomitant particles

There is created working prototype of portable device aimed to detect and identify explosives, designed on the basis of neutron generator (1.10⁸ neutrons/sec) provided with built-in position-sensitive detector of alpha-particles, accompanying neutrons in reaction t(d,n)α taking place within neutron generator.

Working prototype of portable device destined to detect and identify explosives, based on neutron generator equipped with built-in detector of accompanying particles

Application of segmented detector of accompanying particles in NNA method gives opportunity to determination of neutron and substance interaction area, as well as to increase in signal-to-noise merit. In a period of measuring ("on-line") information from gamma-detector, as well as from alpha-detector's segments is automatically analyzed, and operator of the device obtains information about a composition of dangerous substance available in the volume under examination, its quantity, and location.

The created working prototype of this device detects and identifies 100 grams of explosive in a period about 1 minute, indicating its location accurate to 10 cm. An area to be simultaneously examined is 30И30И30 cm³. Mass and dimensions of the device do not exceed, as respects, 40 Kg and 50И40И30 cm3. Power consumption at self-contained power supply - 50 W.

4.2.4. Outlooks for developing of NNA technology with the purpose to detect dangerous substances in luggage and freights

At present at the Laboratory of Applied Physics they carry out the works to design the following prototypes of devices for explosives detection, based on application of neutron generators provided with built-in detectors of accompanying particles: an installation to examine passengers' luggage ("NNA Luggage Inspector"), an installation to examine air freight containers ("NNA AirCargo Inspector"), a system to detect hazardous substances (matters) in 40- feet freight containers ("HM NNA Inspector").

A scheme of the system to detect hazardous substances in 40-feet freight containers ("HM NNA Inspector"). Measuring module. Detector of neutrons. Interior space of container to be examined by means of single measuring module. Under-frame to fix basic modules. Remote electronic block and control board