RU2616088C2 - Method for determining direction to nuclear radiation source - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of searching and detecting sources of the nuclear radiation with the scintillation crystals, the cross-section area of which is significantly smaller than the area of the lateral surface, which compares the number of the registered particles with the scintillation crystals, which are in close proximity to each other but at different angles, of processing the obtained measurement data and deciding about the result of the minimum registered one by the event detector with each individual crystal.

EFFECT: reducing the total weight of the detection system structure and the possibility of searching the nuclear radiation source by one detector.

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Description

The invention relates to a method for determining the direction of a nuclear radiation source by scintillation detectors.

The inventive method relates to the field of radiation monitoring using scintillation detectors and is intended to search and detect sources of nuclear radiation by their gamma and / or neutron radiation, lost or intentionally hidden (in cases of illegal disposal of radioactive waste, etc.). The inventive method can be used in portable portable or moving (for example, automobile, helicopter, unmanned) radiation monitoring devices and can be used to create highly efficient position-sensitive scintillation detectors.

Known methods for determining the direction to the source of nuclear radiation using collimators that shield radiation that enters the scintillation crystal from all sides except the direction chosen by the developer [1-4].

A known method of detecting sources of nuclear radiation (NI) by land or sea mobile radiation monitoring complexes and stationary radiation monitoring devices for search, detection and localization of nuclear [1]. The essence of the invention [1] lies in the fact that the method for searching, detecting and localizing (determining the location) of nuclear weapons by determining the intersection point of the detected direction lines on nuclear weapons from two different places using detection devices equipped with radiation-absorbing screens and a rotary platform.

A known method for determining the direction to the source of nuclear weapons using a multi-module system with anisotropic sensitivity of the recording modules [2-4]. The model, designed for an accelerated search for gamma radiation sources, includes four recording modules (scintillation units) each weighing about 3 kg, separated by a radiation-attenuating screen. The system of detectors is located on a plane. A point source is located at some distance from the detector system. From the radiation intensity recorded by each recording module separately, and using computer processing of the results, it is possible to determine the directions to one or more non-extended radiation sources.

The disadvantage of both of the described methods can be considered that, firstly, in each method several detectors spaced on a plane are used, and secondly, in these methods, absorbing screens that attenuate radiation are used, which are used to select the direction of nuclear radiation and made of material with high density (for example, from lead), which dramatically increases the mass of the final device and reduces the possibility of its widespread use in the mobile version, thirdly, systems for detecting directions to nuclear weapons, based on the above benefits, work only on the plane - with complex terrain accurate measurements using these methods may not be possible.

The present invention solves the problem of reducing the total mass of the design of the detecting system and at the same time provides the ability to search for nuclear weapons with one detector.

The proposed method for detecting the direction to the source of nuclear research is based on comparing the number of registered particles with scintillation crystals located in close proximity to each other in the same plane, but at different angles, FIG. one.

When choosing a value L, obviously greater than d, the path traveled by the particle in the recording element will obviously depend on the angle at which it is oriented relative to the particle flow, FIG. 2. In this case, the maximum range x of the particle for an arbitrary element will be approximately equal to:

or:

величина х будет резко расти, приближаясь к значению L.where n is the number of the element, Q is the angle of the detector, N is the number of crystals in one group of the detector lying in the same plane, FIG. 2. It is easy to see that as ϕ approaches

the value of x will increase sharply, approaching the value of L.

At the same time, the area of the lateral projection of the recording element onto the surface with the source located on it will rapidly decrease according to the law:

or:

For the central element (whose axis coincides with the direction to the source), the lateral projection will be equal to the area of the end face, i.e. ~ d ² , which under the condition d << L gives us a significantly smaller recording surface. Thus, although the maximum particle path in the detector will increase, and most of its energy will be converted into photons, this will be offset by a decrease in the particle flux through the detector elements oriented with the end face toward the source.

The performed mathematical calculations using the GEANT4 software are shown in FIG. 3-4.

In FIG. 1 schematically shows the placement of crystals of one group located in a single plane, where 1 is a recording element, 2 is a solid-state electronic photomultiplier, 3 is a segment of a spherical surface as a directing plane of placement of recording elements, 4 are axes of recording elements converging in a single center.

In FIG. Figure 2 shows schematically how the lateral projection area of the recording element onto the surface with the source on it depends on the angle of rotation of the scintillation crystal relative to the vertical axis, where 5 is the recording element and 6 is the radiation source.

In FIG. Figure 3 shows a comparison of the events recorded by a detector consisting of 41 crystals when the source of Co ^{60 was located} on the axis of symmetry of the detector. For the calculation, the following parameters were used: d = 6 mm, L = 80 mm. It is clearly seen that the number of events recorded by the central crystal is much smaller than the number of events recorded by neighboring crystals.

In FIG. Figure 4 shows the dependence of the events recorded by the detector by each individual crystal at a mutual displacement of the detector and the source of nuclear weapons by 10 m relative to the central axis of the detector in such a way that the source appears on the axis of crystal No. 9, counting from the central crystal with number 0.

.FIG. 3 and FIG. 4 clearly confirm the fact of the above statements about a decrease in the number of recorded events when the angle ϕ tends to

.

The principle of searching for the source of nuclear weapons, based on the presented method, is reduced to moving the detector so that the minimum number of events is recorded by the central crystal. Moving the detector, given its low weight, is possible with the use of unmanned aerial vehicles.

Thus, the proposed method has a number of essential features, the main of which are:

- for parameters d, L, and N selected in a certain way, it is possible to obtain a different picture of the distribution of events in the recording elements, for d << L in elements oriented face to the radiation source, a characteristic decrease in the pulse count rate is observed, which allows one to determine the coordinates of the radiation source;

- the ability to use one multi-chip detector to detect the direction of the nuclear weapons;

- a sharp decrease in the mass of the detecting device due to the rejection of the use of collimators that shield radiation.

Information sources

1. Blagoveshchensky MN, Kuliznev AA, Razumova IN, Shutov ON, “A method for searching, detecting and localizing sources of ionizing radiation”. Patent No. RU 2562142 C1, 03/11/2014

2. Lei Wing, VV Kadilin, G.L. Dedenko, Ney Myo Wu, V. Τ. Samosadny. Investigation of the response of the Ministry of Foreign Affairs with various protective screens during registration of γ radiation flux // Scientific session of MEPhI-2008. Sat scientific works. Volume 3, M .: MEPhI, 2008, S. 177-179.

3. Lei Wing, G.L. Dedenko, V.V. Kadilin, S.V. Isakov, Investigation of the angular characteristics of multi-module detection devices // No. 4-08, Nuclear Measurement and Information Technology. S. 25

4. Lei Wing, VV Kadilin, G.L. Dedenko, Tant Zin, Study of the characteristics of a panoramic sensor designed for accelerated search for sources of γ-radiation // XV International scientific conference of students, graduate students and young scientists "Lomonosov-2008". Sat abstracts, Moscow: Faculty of Physics, Moscow State University, 2008, pp. 19-20.

5. Gorokhova E.I., Tyurin G.P., Khristich O.A. "A method for detecting and recording charged particles." Patent No. RU 2173469 C2, 05/14/1999

6. Jobst J.Ε., A history of aerial surveys radiological incidents and accidents: CONF-860932. - 1987, p. 79-84.

7. V.D. Pal'shina, Yu. Ε. Charikova, R.L. Aptekar, S.V. Golenetskii, A.A. Kokomov, D.S. Svinkin, Z. Ya. Sokolova, M.V. Ulanova, D.D. Frederiks and A.E. Tsvetkova, Konus-Wind and Helicon-Coronas-F Observations of Solar Flares, GEOMAGNETISM AND AERONOMY Vol. 54, No. 7, 2014

Claims (1)

A method for searching and detecting nuclear radiation sources using scintillation crystals whose cross-sectional area is significantly smaller than the side surface area, which consists in comparing the number of registered particles with scintillation crystals located in close proximity to each other, but at different angles, processing the obtained measurement information and making a decision the result of the minimum of events recorded by the detector by each individual crystal.

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