RU2685047C1 - Apparatus and method for determination of element composition of materials by layered neutrons - Google Patents

Abstract

FIELD: physics.SUBSTANCE: use: to determine elemental composition of samples of solid or liquid materials. Summary of invention consists in the fact that device for determining elemental composition of samples of solid or liquid materials has a neutron block made with a receiving vessel for placing the analyzed sample of material and equipped with: (a) neutron generator for generating a stream of labeled neutrons and alpha particles, wherein the neutron generator has an alpha detector; (b) gamma-ray detectors for detecting spectra of characteristic gamma-radiation occurring when a sample of material is irradiated with a stream of labeled neutrons; (c) data analysis system for collecting and analyzing data obtained from alpha detector of neutron generator and gamma-ray detectors; and (d) biological protection of neutron block, providing safe operation of the working personnel, wherein data analysis system is configured to determine elemental composition of sample of material using only gamma-quanta falling in selected time interval of time spectrum of alpha-gamma match and corresponding to sample of material, and using the other portion of the alpha-gamma match time spectrum for energy calibration of the obtained gamma-ray spectra at each measurement of each sample. Also disclosed is a corresponding method implemented in the disclosed device.EFFECT: technical result is enabling determination of concentration of elements in samples of large mass and large size without any sample preparation.11 cl, 8 tbl, 43 dwg

Description

The technical field to which the invention relates.

[0001] The invention relates to the field of research or analysis of materials by radiation methods with the measurement of the secondary emission of characteristic nuclear gamma radiation arising under the action of fast labeled neutrons, to determine the elemental composition of materials.

Background of the invention

[0002] Detectors based on the tagged neutron method (MCM) have been used to detect explosives hidden in various inspection sites. However, in terms of their physical nature, only such relative concentrations of carbon, oxygen and nitrogen are determined using such detectors of explosives.

[0003] There is also known a method and device for the detection of diamonds in kimberlite using the method of labeled neutrons (see patent number RU 2521723 C1, published 07/10/2014). However, the method and device described in this patent allow only determining the presence in the irradiated sample of the excess of the local carbon concentration above its average level and do not allow determining the carbon concentration in the sample.

Disclosure of the invention

[0004] The technical task to be solved by the invention is to determine the concentrations of various chemical elements in samples of different materials and to determine the concentrations of various chemical compounds (for example, oxides, minerals) based on the results of such determination.

[0005] Another technical problem to be solved by the present invention is to ensure the determination of the concentration of elements in samples of large mass and large size (up to 50 cm in diameter), for example, in rock samples taken directly from the quarry or from transport containers, or from the conveyor belt, and without any sample preparation.

[0006] the task is solved by the following means set forth in the claims.

[0007] Item 1: A device for determining the elemental composition of samples of solid or liquid materials, containing a neutron unit, made with a receiving vessel to accommodate the sample of material under investigation and equipped with:

(a) a neutron generator designed to generate a flux of labeled neutrons and alpha particles, with an alpha detector embedded in the neutron generator;

(b) gamma-ray detectors designed to record the spectra of the characteristic gamma-rays that occur when a sample of a material is irradiated with a tagged neutron flux; and

(c) a data analysis system designed to collect and analyze data obtained from an alpha detector of a neutron generator and gamma-radiation detectors;

(d) biological protection of the neutron unit, ensuring the safe operation of the personnel discussing,

the data analysis system is designed to determine the elemental composition of a sample of a material using only gamma quanta that fall within a selected time interval of the alpha gamma coincidence time spectrum and corresponding to the material sample, and using another part of the alpha gamma coincidence time spectrum for energy calibration gamma-ray spectra obtained with each measurement of each sample.

[0008] Clause 2. The device of clause 1, wherein the neutron generator in the neutron unit is located under the sample of material under investigation, and the gamma-ray detectors are located in the neutron unit above the sample of material under investigation.

[0009] Clause 3. The device according to claim 1, wherein the neutron generator in the neutron unit is located above the sample of material under investigation, and the gamma-radiation detectors are located in the neutron unit under the sample of material under investigation.

[0010] Clause 4. The device of clause 1, in which the neutron generator is located on the first side of the sample of material being investigated, and the gamma-ray detectors are located on the second, opposite to the first side of the sample of material being examined.

[0011] Clause 5. The device of clause 1, in which the flux of labeled neutrons in the neutron block has the shape of a truncated pyramid, and, accordingly, the receiving vessel for accommodating the sample of material under study also has the shape of a truncated pyramid.

[0012] Clause 6. The device of clause 1, which further comprises a system for feeding a sample of material into a receiving vessel, for example, a conveyor for alternately feeding the test samples of material.

[0013] Item 7. The device according to claim 1, wherein the neutron unit is designed to generate a flux of labeled neutrons and alpha particles during acceleration of deuterons and their interaction with a tritium target due to the implementation of the following binary reaction:

d + t → α + n,

where d is a deuteron, t is a triton, α is an alpha particle, n is a neutron.

[0014] Clause 8. The device according to clause 1, which is intended to determine the elemental composition of samples of good rocks, ores or ore materials.

[0015] Clause 9. The device of clause 1, wherein the selected time interval is of the order of 1-100 nanoseconds.

[0016] Clause 10. A method for determining the elemental composition of samples of solid or liquid materials, carried out using the device according to any one of claims 1-9, comprising the following steps:

(a) placing the sample material in the receiving vessel;

(b) irradiating a sample of a material with a flux of fast tagged neutrons;

(c) registration of the spectra of the characteristic gamma radiation arising from the irradiation of the above-mentioned sample with a stream of fast tagged neutrons in step (b);

(d) analyzing the spectra of the characteristic gamma radiation registered from the sample in step (c), with the determination of the elemental composition of the sample,

at the same time, to determine the elemental composition of the sample, only gamma rays are used that fall within the selected time interval of the alpha-gamma coincidence spectrum and correspond to the material sample, and the other part of the alpha-gamma coincidence spectrum is used for energy calibration of the obtained gamma-radiation spectra during each measurement each sample.

[0017] Clause 11. The method of clause 10, further comprising the step of pre-setting and calibrating the device before step (a).

Brief Description of the Drawings

 [0018] The present invention is explained further in more detail by the example of non-limiting drawings, which show the following.

[0019] FIG. 1 is a schematic representation of the general principle of operation of the device according to the invention.

[0020] FIG. 2 is a general perspective view of one specific embodiment of the device according to the invention, located in a transport container.

[0021] FIG. 3 is a general perspective view with a local section of the neutron unit of the device according to the invention.

[0022] FIG. 4 is a general view of one specific embodiment of the device according to the invention with a conveyor for feeding ore samples.

[0023] FIG. 5 - the energy spectrum of the characteristic gamma radiation of carbon.

[0024] FIG. 6 - the energy spectrum of the characteristic gamma radiation of liquid water.

[0025] FIG. 7 - the energy spectrum of the characteristic gamma radiation of silicon.

[0026] FIG. 8 - the energy spectrum of the characteristic gamma radiation of magnesium.

[0027] FIG. 9 - the energy spectrum of the characteristic gamma radiation of iron oxide.

[0028] FIG. 10 - the energy spectrum of the characteristic gamma radiation of titanium.

[0029] FIG. 11 - the energy spectrum of the characteristic gamma radiation of aluminum.

[0030] FIG. 12 - the energy spectrum of the characteristic gamma radiation of calcium oxide.

[0031] FIG. 13 - the energy spectrum of the characteristic gamma radiation of nickel.

[0032] FIG. 14 - the energy spectrum of the characteristic gamma radiation of manganese.

[0033] FIG. 15 - the energy spectrum of the characteristic gamma radiation of copper.

[0034] FIG. 16 - the energy spectrum of the characteristic gamma radiation of zirconium oxide.

[0035] FIG. 17 - the energy spectrum of the characteristic gamma radiation of chromium oxide.

[0036] FIG. 18 - the energy spectrum of the characteristic gamma radiation of sulfur.

[0037] FIG. 19 - the energy spectrum of the characteristic gamma radiation of bismuth.

[0038] FIG. 20 - the energy spectrum of the characteristic gamma radiation of tin.

[0039] FIG. 21 - the energy spectrum of the characteristic gamma radiation of zinc.

[0040] FIG. 22 - the energy spectrum of the characteristic gamma radiation of tetrafluoromethane.

[0041] FIG. 23 - the energy spectrum of the characteristic gamma radiation of phosphorus oxide.

[0042] FIG. 24 - the energy spectrum of the characteristic gamma radiation of lead.

[0043] FIG. 25 - the energy spectrum of the characteristic gamma radiation of carbon tetrachloride.

[0044] FIG. 26 - the energy spectrum of the characteristic gamma radiation of potassium carbonate.

[0045] FIG. 27 is the energy spectrum of characteristic gamma radiation of sodium carbonate.

[0046] FIG. 28 - the energy spectrum of the characteristic gamma radiation of melamine.

[0047] FIG. 29 is the result of fitting the energy spectrum of the characteristic gamma radiation of aluminum with aluminum lines and the background function.

[0048] FIG. 30 is the result of fitting the energy spectrum of the characteristic gamma radiation of aluminum with aluminum lines plus a continuum.

[0049] FIG. 31 is the energy spectrum of the characteristic gamma radiation of a sample of calcite marble.

[0050] FIG. 32 - the energy spectrum of the characteristic gamma radiation sample of dolomite marble.

[0051] FIG. 33 is the energy spectrum of the characteristic gamma radiation of a calcipir sample.

[0052] FIG. 34 - the energy spectrum of the characteristic gamma radiation of the sample gneiss.

[0053] FIG. 35 - the energy spectrum of the characteristic gamma radiation of an amphibolite sample.

[0054] FIG. 36 - the energy spectrum of the characteristic gamma radiation sample apatite-nepheline ore.

[0055] FIG. 37 are specific examples of alpha-gamma coincidence time spectra.

[0056] FIG. 38 is a graph of the correlation relationship in the determination of phosphorus pentoxide in apatite-nepheline ore.

[0057] FIG. 39 is an example of a calibration dependence in the determination of phosphorus pentoxide in apatite-nepheline ore.

[0058] FIG. 40 - the energy spectrum of gamma rays from the irradiation of the sample of aluminum oxide.

[0059] FIG. 41 - the energy spectrum of gamma rays from irradiation of a sample of calcium carbonate.

[0060] FIG. 42 is a calibration dependence showing the correlation between the measured atomic concentration of silicon and the mass fraction of SiO ₂ determined by chemical analysis, i.e. connection of the analytical signal values of the device according to the invention for samples of -100 mm and -3 mm size, with the results of the analytical signal for -100 mm samples on the X-axis, and for the same samples crushed to -3 mm along the Y axis.

[0061] FIG. 43 is a calibration dependence showing the correlation between the measured atomic concentration of magnesium and the mass fraction of MgO determined by chemical analysis, where the red line is an approximating straight line of the form Y = a + b · X, and the black line is a diagonal.

Detailed description of embodiments of the invention.

[0062] the Proposed invention is directed, in particular, to achieve at least one of the following technical results:

- determination of the elemental composition of the sample material without any sample preparation allows you to significantly speed up and simplify the analysis of chemical elements, as well as significantly reduce the cost of carrying out this analysis;

- determination of the elemental composition of the sample material using only gamma rays that fall within the selected time interval of the alpha-gamma coincidence time spectrum and corresponding to the material sample itself, when using another part of the alpha-gamma coincidence time spectrum for energy calibration of the obtained gamma-radiation spectra each measurement of each sample can significantly improve the accuracy and reproducibility of measurement results;

- determination of the elemental composition of the sample material without any sample preparation allows you to avoid contamination of the sample by impurities, for example, during grinding, crushing, dissolving, dispersing, etc., used in other known methods;

- the high penetrating power of fast neutrons makes it possible to analyze the elemental composition of the total volume of the material in the sample, and either the averaged total elemental composition or the distribution of the elemental composition over the sample;

- determination of the concentrations of various chemical elements in samples of large mass and size, for example, rock samples, ore or ore material, provides the possibility of input control over the quality of the material entering the processing plants, which is necessary for the correct choice of enrichment mode;

- determination of the concentrations of various chemical elements in samples of large mass and fineness, which can be carried out in field conditions, for example, on rock, ore or ore material samples, provides the possibility of operational control over the quality of ore, for example, from quarries or mine workings or from geological batches.

 [0063] In this case, depending on the circumstances, any of these technical results can be considered as the main one, and the rest - as auxiliary ones. However, in more preferred embodiments of the invention, all these results are achieved together with each other.

 [0064] In order to achieve at least one of these technical results in a device or method according to the invention, designed to determine the elemental composition of a wide variety of solid and / or liquid materials, and in particular, concentrations of various chemical elements in rocks, ores or ores materials, a sample of a material is irradiated with a flux of fast tagged neutrons; as a result of such irradiation, a gamma-ray spectrum is obtained from inelastic neutron scattering reactions on the nuclei of the irradiated sample, and, based on the field scientific spectrum, determine the concentration of various chemical elements.

[0065] As shown in the general scheme of the device of the invention shown in FIG. 1, the following binary nuclear reaction is used as a source of fast tagged neutrons:

d + t → α + n (1),

Where

d is the deuteron (i.e., the nucleus of the hydrogen isotope deuterium, ² H),

t is triton (i.e., tritium hydrogen isotope core, ³ H),

α is the alpha particle (i.e., the nucleus of the helium atom, ⁴ He), and

n is a neutron,

moreover, the energy of deuterons incident on a tritium target is about 60–100 keV, and the values of the energies of the generated alpha particles and the fast neutron are about 3.5 MeV and about 14.1 MeV, respectively.

[0066] Thus, as a source of fast tagged neutrons in the device according to the invention, a neutron generator is used in which the above binary nuclear reaction (1) proceeds.

[0067] The neutron generator serves as a source of fast tagged neutrons in the neutron unit, which necessarily contains: (a) a neutron generator and (b) gamma-radiation detectors. The neutron generator is equipped with an alpha particle detector, which is hereinafter simply referred to as an “alpha detector” and which can be of any type, provided that it is capable of detecting alpha particles. An alpha detector can be subdivided into a plurality of elements (pixels) and therefore is sometimes referred to as “multi-element”, with such a plurality of elements (pixels) meaning “two or more”, and their number can be any integer greater than 2. Alpha detector placed and configured to work inside the neutron generator and therefore also referred to as "built-in". For example, the alpha detector can be silicon or made on the basis of another semiconductor material. For example, a neutron generator can be equipped with a built-in alpha detector with 9-64 pixels. The neutron generator can be made portable. In particular, in one particular embodiment, the neutron generator may be a ING-27 model neutron generator manufactured by FSUE VNIIA. N.L. Duhova (Moscow).

[0068] Thus, using a neutron generator, a sample of the material is irradiated with a stream of fast neutrons with an energy of about 14.1 MeV and with an intensity of, for example, from 1 × 10 ⁷ to 4 × 10 ⁸ neutrons per second (n / s), preferably from 1 × 10 ⁸ to 2 × 10 ⁸ n / s. As a result of the inelastic scattering of fast neutrons by atomic nuclei that make up the irradiated sample, a characteristic (i.e., characteristic for each specific type of chemical element) gamma radiation with energies in the range of about 0.5-10 MeV arises. This characteristic gamma radiation is recorded using gamma radiation detectors, which are also part of the neutron unit. Preferably, gamma-ray detectors can be made on the basis of bismuth germanate crystals (BGO) or yttrium-lutetium orthosilicate (LYSO) crystals, however the present invention is not limited to a specific type and / or scintillation material of gamma-radiation detectors provided they are capable of detecting gamma -radiation in the specified energy range. In this case, using a multi-element alpha detector embedded in a neutron generator, the direction of emission of fast neutrons from a tritium target of a neutron generator is also recorded, approximately corresponding to the direction opposite to the direction of emission of alpha particles from a tritium target (the actual angle of spread between the generated alpha particle and the fast neutron is 171-175 degrees, for a deuteron energy range of 50-150 keV), i.e. The alpha detector produces the so-called “tagging” of fast neutrons (from the English “tagging”) in the direction of their departure in space and according to the moment of their departure in time, therefore, the term “labeled neutrons” is used hereafter in relation to such fast neutrons. It should be noted here that fast neutrons are emitted by a neutron generator at a full solid angle of 4π, but due to this “tagging” of fast neutrons with an alpha detector, the tagged neutron flux taken into account in the subsequent analysis of the characteristic gamma radiation has a shape diverging from the target smaller solid angle determined by the size of the alpha detector and the distance between the tritium target and the alpha detector. The number and position in space of individual beams of labeled neutrons in their common flow is determined by the number and position of the elements (pixels) of the alpha detector relative to the tritium target of the neutron generator. The characteristic gamma radiation emanating from the sample under study in the form of spectra is recorded using gamma radiation detectors (hereinafter referred to as gamma detectors for short). The recorded spectra of the characteristic gamma radiation coming from gamma detectors are analyzed by the data analysis system in coincidence with the signals from the alpha detector corresponding to each voxel of the irradiated sample. Here, the “voxel” is an element of the volume of the irradiated sample, with the size of the voxel in the direction of the flow of labeled neutrons is determined by the time resolution of the system of alpha-gamma coincidences (α-γ matches), and in a plane perpendicular to the flow of labeled neutrons, the dimensions of the voxel are determined by the linear dimensions of the pixel detector and the ratio of the distance from the tritium target to the alpha detector in the neutron generator and the distance from the tritium target to the irradiated material in the volume of each voxel of the sample (c It is schematically labeled as "s" in Fig. 1).

[0069] In addition, it should be understood that the term "tagged neutron flux" as used herein means at least one beam of labeled neutrons necessary to ensure the fundamental possibility of realizing the invention. However, in preferred embodiments, the flux of labeled neutrons as a whole may consist of a set of neutron beams, the number of which may be equal to the number of neutron generators or the number of pixels in a multi-element alpha detector, for example, 2, 3, 4, 5, 10, 16 , 25, 36, 49, 64, 100, 192, 256, 500 and more bundles. Thus, the terms “flux” and “beam” used with reference to labeled neutrons may or may not be equivalent to each other.

[0070] The labeled neutrons n emerging from the neutron generator, entering the sample under study, induce inelastic scattering reactions in the atomic nuclei A of the sample:

n + A → n '+ A, A * → γ + A (2),

as a result of which the excitation of the nucleus is removed by the emission of gamma-ray quanta with an energy spectrum characteristic of each specific chemical element. Characteristic γ-radiation is detected by gamma detectors in coincidence with the signal from the alpha detector. This makes it possible to determine all three coordinates of the sample area from which gamma-ray quanta were emitted. Two coordinates are determined by the pixel into which the α-particle hit, and the third coordinate characterizing the distance s from the tritium target to the point of emission of the gamma quantum, is calculated using the time-of-flight technique. Indeed, knowing the distance from the tritium target to the alpha detector, the distance s from the tritium target to the sample and the distance from the sample to the gamma detector, as well as knowing that the speed of a fast neutron with an energy of 14.1 MeV is constant and is 5 cm / ns, and the speed of the γ-quantum (ie, the speed of light c) is approximately 3 · 10 ⁸ m / s, and measuring the time difference between the time of registration of the α-particle in the alpha detector (T ₁ ) and the time of registration of γ- quantum in the gamma detector (T ₂ ), it is easy to determine the point of emission of the γ-quantum in the sample.

[0071] Further, by measuring the total γ-spectrum of a sample consisting of several chemical elements with a gamma detector, you can decompose the total γ-spectrum into components and determine the fractions of each chemical element in the sample.

[0072] Thus, the difference between the tagged neutron method (MCM) and the well-known methods of neutron activation analysis (NAA) is that the chemical (their) element (s) are identified according to the spectrum of direct γ-quanta emitted in inelastic scattering (n, n 'γ), and in the analysis of the sample, only γ-quanta are taken into account, which came during a short time interval from the moment of arrival of the signal from the α-particle, in particular, the time interval of the order of 1-100 ns (in a specific embodiment the invention uses a time inte tore 6 ns). This makes it possible to select γ-quanta emitted directly from the sample, and not from its environment, which significantly improves the background conditions during the measurement. It is shown that the use of MCM allows you to increase the signal-to-background ratio by 200 times or more.

[0073] Another important difference between the MCM is the use of fast neutrons with an energy of 14.1 MeV, which allow you to well determine the concentration of light elements such as Li, Be, B, C, N, O, F, which is difficult as for the method NAA, as well as for X-ray fluorescence analysis (XRF), since it is difficult to determine elements with Z <11 by X-ray fluorescence analysis.

[0074] In addition, compared with other methods of rapid analysis of the elemental composition of materials, such as, for example, XRD, the following advantages of MCM can be noted:

(1) a large test zone, since X-ray fluorescence sensors have a test zone of several millimeters, and the test zone in the case of MCM detectors can be, for example, 30 × 30 cm with a distance of 60 cm;

(2) it is possible to determine the distribution of the concentration of elements inside the sample;

(3) the use of MCM detectors does not require any sample preparation;

(4) The use of MCM detectors does not require the use of expensive reference samples.

[0075] Finally, the possibility of using MCM in field conditions is important. Unlike the NAA method, the MSM does not need to irradiate samples in a nuclear reactor, and the role of a neutron source is performed by a portable neutron generator, the overall dimensions of which can be only a few tens of centimeters (in particular, about 30 cm) and whose mass can be only a few kilograms (in particular, about 8 kg).

[0076] In the present invention, solid and / or liquid materials of various compositions (for example, inorganic, organic, metallic, oxide, halide or mixed, etc. can be used as materials in which the concentrations of chemical elements are determined. , etc.) and of different origin (natural, artificial or mixed), as a preferred option - samples of rocks, ores or ore material, and this can be any rocks, any ores or any ore materials. In particular, the possibility of applying the invention to the analysis of 24 chemical elements: Na, Mg, C, N, O, F, Al, Si, P, S, Cl, K, Ca, Ti, Cr, is now well studied and experimentally confirmed. Mn, Fe, Ni, Cu, Zn, Zr, Pb, Sn and Bi, and based on this analysis - determination of the relative atomic or mass content of chemical compounds and / or minerals (such as, for example, SiO ₂ , CaO, MgO, Fe ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , etc.), for example, in rocks. However, in principle, the invention can be used to determine the concentration of almost any chemical element in almost any sample.

[0077] However, there are certain physical limitations. For efficient operation of the tagged neutron method, it is required that one or several narrow gamma lines with a large excitation cross section with fast neutrons be present in the spectrum of the element. Of importance is also the desirable absence of gamma lines close in energy from other elements that may interfere with the correct recognition of the lines of the desired element. And although the further description is mainly applied to ores (in particular, minerals), the invention is not limited to any one particular type of material, or to a specific type of ore or ore material.

[0078] Turning now to the specific and preferred embodiments of the invention, the device according to the invention can be made as shown in any of figures 2-4.

[0079] The device of the invention shown in FIG. 2, contains the neutron unit 1, the gamma detector unit 2, the cabinet 3 for the electronics of the data analysis system and for the power supply of the gamma detectors. There is also a workplace 4 operators. The device according to the invention can be enclosed inside the container, while the workplace 4 of the operator can be located both in the same container in which the device according to the invention is placed, and outside this container. Thus, the device according to the invention can be installed directly at the site of ore mining.

[0080] As shown in FIG. 3, the neutron unit 1 contains a neutron generator 8 surrounded by biological shielding 6. The gamma detector unit consists of separate gamma detectors 5 surrounded by a casing and located completely or partially around the receiving vessel (for example, a tray) 7 in which the sample is placed (for example , sample of ore or sample with ore placed in the package).

[0081] In one particular embodiment of the invention shown in FIG. 4, ore samples can be submitted for analysis to the neutron unit 1 on the conveyor 9, passing between the neutron unit 1 located below it and the gamma detector unit 2 located above it with the gamma detector 5 surrounded by the casing.

 [0082] One of the features of the invention may be that the receiving vessel (for example, a tray) 7 has in its cross section a shape corresponding to the shape of the flux of labeled neutrons.

[0083] The method of operation of the device in preferred embodiments of the invention may comprise one or more of the following specific operations (steps).

[0084] Immediately before turning on the device, it is necessary to energize it, turn on the interior lighting in the container, turn on the personal computer (PC) at the workplace 4 of the operator and wait until it is fully loaded. This will automatically open the remote desktop with the neutron generator control program 8.

 [0085] Then, the sample is loaded into the receiving vessel 7. The sample can be, for example, one sample or two or more ore samples, for example with a particle size (particle size) up to -100 mm, while the entire sample can have a mass of 3-7 kg They can be placed in the receiving vessel 7 in canvas bags, directly into which they were selected from the quarry. No preliminary sample preparation is required.

[0086] After that, the operator through a special interface via the communication line with the control unit of the neutron generator 8 sends the command to turn on the neutron generator 8 into the neutron emission mode. The sample measurement process begins, in which the neutron generator 8 emits fast neutrons, an alpha detector embedded in the neutron generator 8, marks these fast neutrons, recording the alpha particles emitted simultaneously with them, and the gamma detectors 5 register the characteristic gamma radiation of the material sample.

[0087] In the on-line mode, all information obtained from the alpha detector of the neutron generator 8 and from the gamma detectors 5 is fed to block 3 of the recording electronics, which is part of the data analysis system, with the aim of receiving, collecting and processing these data and preliminary selection of events recorded by the mentioned alpha and gamma detectors. With very high accuracy (such as less than 1 nanosecond (ns), for example, less than 0.1 ns or less than 0.01 ns) determine the time elapsed since the registration of alpha particles with an alpha detector of the neutron generator 8 until the registration of gamma -radiation in each of the gamma-detectors 5. After collecting the required statistics of events recorded by the alpha detector and gamma-detectors 5, and a preliminary analysis of these events, information about the previously analyzed events (for example, pre-selected, in particular, filters These events) are sent via a communication line (for example, via an Ethernet line) from block 3 of recording electronics through an interface to console 4 of an operator. According to the program installed in the console 4 operators, produce amplitude and temporal analysis of events previously analyzed (selected) by block 3 of recording electronics, in order to obtain data on the concentration of chemical elements in the sample.

 [0088] The method of operation of the device according to another preferred embodiment of the invention, shown in FIG. 4, is as follows. The ore is loaded into / on the conveyor 9 (which is in this case the receiving vessel, for example, in the form of a gutter), then, at the command of the operator’s console 4, the conveyor 9, which comes in translational motion, is actuated. The first portion of the ore, located on the conveyor 9, is moved to the neutron unit 1 in the area of irradiation of the ore by the flow of labeled neutrons. The contents of the first ore portion are irradiated with a tagged neutron flux. In the on-line mode, information from the alpha detector and gamma detectors 5 of the neutron unit 1 enters unit 3 of the recording electronics in order to receive and pre-select events recorded by alpha and gamma detectors. After dialing the required statistics recorded by the alpha detector and gamma detectors 5 events and their preliminary analysis and selection, information on the Ethernet line is fed from block 3 of the recording electronics via the interface to the operator panel 4. According to the program installed in the console 4 operators, produce amplitude and temporal analysis of pre-selected events by block 3 of the recording electronics in order to obtain data on the concentration of chemical elements in the first ore portion. Then a signal is received to continue the movement of the conveyor 7 and feed the next portion of ore to the irradiation area.

[0089] Furthermore, in various embodiments of the present invention, the following features can be used and the following advantages achieved:

[0090] The device according to the invention for determining the elemental composition of the sample uses the tagged neutron method, which involves analyzing gamma radiation only in the time window corresponding to the signal from the sample under study. The use of α-γ coincidences leads to a significant suppression of the background. So, for example, for a sample of apatite ore with a mass of 500 g, it was shown that the signal / background ratio increases 176 times as compared to conventional neutron activation analysis (NAA).

[0091] Since labeled neutrons with an energy of about 14 MeV belong to the category of fast neutrons, they have a small cross section of interaction with matter, which leads to the fact that they practically do not induce radioactivity in the irradiated ore, which makes the proposed device and method safe for personnel, serving device or working subsequently with the analyzed ore.

[0092] The implementation of the receiving vessel with a shape corresponding to the shape of the flow of labeled neutrons, for example, a tray with a cross section in the form of an inverted truncated pyramid, allows you to irradiate the contents of the vessel with neutrons. In the case of using a vessel in the form of a rectangular parallelepiped with dimensions equal to the linear dimensions of the flux of labeled neutrons in the plane of the bottom of the vessel, an incorrect determination of the elemental concentration of the entire sample volume will be observed, since part of the flux of labeled neutrons will interact with the material of the surrounding structures. In the case of using a vessel in the form of a rectangular parallelepiped with dimensions equal to the linear dimensions of the flux of labeled neutrons in the uppermost plane of the vessel, only a fraction of the ore in the vessel in the volume bounded by the outer contour of the flux of neutrons will be irradiated. The rest of the ore in the vessel will be outside the zone of irradiation by the flow of labeled neutrons, which will lead to an incorrect determination of the concentration of chemical elements.

[0093] The above embodiments of the device according to the invention can be used both in a stationary version, for example, aboard a mining pit or at a concentration plant, and in a mobile version when the neutron unit moves on a self-propelled chassis, or in a trailer version, when the neutron unit moves in a car trailer.

[0094] The method of determining the concentrations of chemical elements by the method of labeled neutrons is based on the idea that, knowing the cross section σ _{ij of a} certain characteristic gamma line i of element j, it is possible to determine the number of atoms of this element in the sample. To do this, it is necessary to know the mass of the irradiated sample, the magnitude of the neutron flux passing through the sample, and to evaluate the efficiency and acceptance of the device (i.e., the solid angle covered by gamma detectors) taking into account the various effects of rescattering and absorption of neutrons and gamma radiation quanta sample

[0095] For a thin sample from a single chemical element, the number of gamma quanta N _f entering the gamma detector as a result of the interaction of neutrons with atoms of this element can be calculated by the following formula:

(3),

(3)

where N _in is the number of neutrons incident on the sample, σ is the total cross section of the reaction (n, n 'γ), N _Av is the Avogadro number, ρ is the sample density, l is the sample thickness, A is the atomic weight of the element in the sample, W is the probability registration of gamma quantum gamma detector.

[0096] In the case of a sample consisting of j different elements, formula (2) is converted to sum over all elements j, taking the following form:

(4),

(four),

where N _in is the number of neutrons incident on the sample, ρ is the sample density, l is the sample thickness, N _Av is the Avogadro number, σ _j is the interaction cross section for element j in the sample, n _j is the number of nuclei of element j in the sample, w _j is probability of gamma-spectrum detection from element j in a sample with a gamma detector, A _j is the atomic number of element j in a sample.

[0097] The energy spectrum of gamma rays from irradiating a sample with fast neutrons with an energy of about 14 MeV is represented as the sum of the spectra of individual gamma lines, the continuum spectrum and the background spectrum:

(5),

(five),

where N _j is the parameter that determines the content of the element j in the sample, and this parameter is proportional to the number of atoms of the element in the sample and is the same for all gamma lines i of the element j;

n _j - the number of gamma lines i at the element j;

σ _ij (E) is the cross section for the production of gamma quanta with energy E, corresponding to gamma line i, in the interaction of a neutron with an element j;

P _ij is the response function of the gamma detector corresponding to the gamma line i of the element j;

F ^Cont _j (E) is the amplitude of the continuum spectrum, which is observed at high excitation energies for practically all nuclei except the lightest;

R ^Cont _j is the normalization coefficient for the continuum spectrum;

BG (E) = A · exp ^-BE - background function,

A and B - fitting parameters (phi).

[0098] The function P _{ij of the} response of the gamma detector for one gamma line i of element j is represented as the sum of three Gaussians G (x, σ) corresponding to the peak of the total absorption and peaks of single and double leakage of gamma quanta with energy of 0.511 MeV from the crystal gamma detector scintillator for detecting gamma-quanta with energy E _i , as well as the function C (E _i , E), which describes the Compton scattering process taking into account possible multiple interactions of the gamma-quantum with the scintillator crystal of the gamma detector:

(6),

(6),

– энергетическое разрешение гамма-детектора, соответствующее пику полного поглощения при энергии гамма-кванта E_i; Where

- energy resolution of the gamma detector, corresponding to the peak of the total absorption at the gamma quantum energy E _i ;

A _e - fit parameter;

ε is the detection efficiency of gamma-quanta with the energy corresponding to the peak of the total absorption, and the dependence of this parameter on the energy of the gamma-quantum is established by simulating the response of the gamma detector by the Monte-Carlo method;

σ^es _i, σ^es2 _i - energy resolution of a gamma detector corresponding to peaks of single and double leakage of gamma rays with an energy of 0.511 MeV from a scintillator crystal of a gamma detector;

N ^es _i and N ^es2 _i are the parameters that determine the amplitudes of the leak peaks;

R is the trimming factor for the amplitude of the function C (E _i , E).

[0099] The dependence of the relations N ^es _i / N _j and N ^es2 _i / N ^es _i on the energy of gamma rays is also determined from the simulation results, however, the parameter R _{es is} used for adjustment.

[0100] The contribution from Compton scattering and multiple gamma-ray interactions with a scintillator crystal of a gamma detector is determined by approximating it with the function C (E _i , E):

C (E _i , E) = F ₁ (E) + F ₂ (E) (7),

where F ₁ (E) is a function describing a single Compton scattering:

F ₁ (E) = F _1v (E) x F _1t (E) (8),

Where

(9),

(9),

(10),

(ten),

(11),

(eleven),

F ₂ (E) - the function describing the Compton scattering of the annihilation photon:

(12),

(12),

Where

(13),

(13),

(14),

(14),

(15),

(15),

here

(16),

(sixteen),

(17),

(17),

where m ₀ is the electron mass,

E _i - the energy of the incident photon,

E - the observed energy of the photon,

E _p = E _i - E.

[0101] The parameters P ₀ -P ₆ depend on the photon energy and are determined from the simulation results.

[0102] Evaluating the relative shares of elements in a sample using the formula:

(18),

(18),

and assuming compliance with the ratio:

(19),

(nineteen),

You can calculate the mass fractions of elements in the sample as:

(20),

(20),

where m _j is the atomic weight of the element j.

[0103] To calculate the mass fractions of oxides of the elements W _j, we define the mass fraction r _{j of the} element j in the oxide, the formula of which in general form can be represented as J _x O _y :

(21).

(21).

[0104] Then W _j is:

(22).

(22).

[0105] Practically for the nuclei of all elements except the lightest, the existence of a continuous spectrum of gamma rays, the so-called continuum, with excitation energies above the typical neutron separation energy (≈8 MeV) is known. To determine the continuum spectrum for each pure chemical element, the experimental spectrum is fitted with a set of discrete line spectra and an exponential substrate BG (E). Then the response from the discrete lines for each pure chemical element is fixed and the spectrum of the continuum is determined as the difference between the experimentally measured spectrum and the sum of the contributions from the discrete lines.

[0106] As a result, the fit function for an individual chemical element is the sum consisting of responses for all given discrete gamma lines, Compton contribution, and histogram of the continuum F ^Cont _j (E), with normalization determined from the reference spectrum.

[0107] Thus, to determine the elemental composition of the sample under study, 6 common spectral parameters A, B, A _e , R _es , R, R ^Cont and several N _j parameters directly related to the concentrations of individual chemical elements are fitted.

[0108] The correct description of the so-called "substrate" under the peaks of total absorption and peaks of leaks is crucially important for the correct determination of the relative concentrations of various chemical elements in the sample. The usual parametrization of a background in the form of a polynomial or an exponential function can give a good general description of the spectrum, but a fundamentally wrong decomposition of the spectrum in elemental composition. For example, the use of an exponential background to describe the spectrum of water can simulate the appearance of a nitrogen signal, which occurs due to the 5108 keV oxygen line.

[0109] Thus, the parameters of the approximating function are determined for all elements and all possible values of the energy of gamma quanta involved in the fitting procedure of the experimentally measured spectra of the characteristic radiation of a sample of a material.

[0110] Next will be given some experimental results confirming the practical applicability of the invention with the achievement of these technical results.

Experimental Part A

1. Spectra of pure elements

[0111] To determine the reference energy spectra of pure elements by the method of labeled neutrons, we measured the spectra of some pure chemical elements and relatively simple inorganic and organic compounds. The number of characteristic gamma lines, their energy and the birth cross section for a particular element are subject to customization based on the available tables and cross section libraries, as well as the experimental spectra obtained by the authors.

1.1. Carbon

[0112] The measured energy spectrum of carbon (according to GOST 7885-86, sample weight 1.8 kg) is shown in FIG. 5, where the experimental data are shown with crosses, and the solid line shows the fit results. It is the simplest compared to the spectra of other elements. A clear signal is visible from the 4439 keV line (i.e., 4.439 MeV). Its cross section was determined by us at 209.7 mb.

1.2. Oxygen

[0113] The energy spectrum of oxygen was extracted from the measured water spectrum (TU 0131-005-51909887-12, sample volume 0.5 l), which is shown in FIG. 6, where the experimental data are shown with crosses, and the solid line shows the fit results. The dominant lines in the spectrum are the lines at 6130 keV and 3684 keV.

1.3. Silicon

[0114] To measure the spectrum of silicon, a sample of chemically pure silicon was used (according to TU 48-0513 / 91-8-7, sample weight 0.5 kg). The resulting silicon energy spectrum is shown in FIG. 7, where the experimental data are shown with crosses, and the solid line shows the fit results. It highlights the peak from the 1779 keV line, the cross section of which is 400 mb. That is, the signal from this silicon line is almost twice as strong as the signal from the 4439 keV carbon line.

1.4. Magnesium

[0115] The measured energy spectrum of magnesium (TU 3-303-10, sample weight 0.5 kg) is shown in FIG. 8, where the experimental data are shown with crosses, and the solid line shows the fit results. The characteristic line Mg at 1369 keV also has a large cross section - 425 mb. This circumstance facilitates the release of magnesium.

1.5. Iron

[0116] The measured energy spectrum of iron oxide Fe ₂ O ₃ (according to specification 1526-12; sample weight 0.5 kg) is shown in FIG. 9, where the experimental data are shown with crosses, and the solid line shows the fit results. The dominant Fe line is at 1238 keV and also has a large cross section - 393 mb.

1.6. Titanium

[0117] The measured energy spectrum of titanium Ti (sample weight 0.4 kg) is shown in FIG. 10, where the experimental data are shown with crosses, and the solid line shows the fit results. It is dominated by the line 984 keV with a cross section of 470 mb.

1.7. Aluminum

[0118] The measured energy spectrum of aluminum (TU 6-09-02-529-92, sample weight 0.5 kg) is shown in FIG. 11, where the experimental data are shown with crosses, and the solid line shows the fit results. It is characterized by three lines at 1809, 2211 and 3004 keV.

1.8. Calcium

[0119] For the determination of calcium, calcium oxide CaO was measured (according to GOST 4530-76, sample weight 0.5 kg). Its energy spectrum is shown in FIG. 12, where the experimental data are shown by crosses, and the solid line shows the results of the fit, and is characterized by three lines at 1809, 2211 and 3004 keV.

1.9. Nickel

[0120] The measured energy spectrum of nickel Ni (according to GOST 4341-78, the mass of the sample TU 3-272-10) is shown in FIG. 13, where the experimental data are shown with crosses, and the solid line shows the fit results. It is characterized by two lines at 1334 and 1454 keV.

1.10. Manganese

[0121] The measured energy spectrum of manganese Mn (TU 2-26810, sample weight 0.5 kg) is shown in FIG. 14, where the experimental data are shown by crosses, and the solid line shows the fit results. It is characterized by two lines at 858 and 1164 keV.

1.11. Copper

[0122] The measured energy spectrum of copper Cu (TU 3-270-10, sample weight 0.5 kg) is shown in FIG. 15, where the experimental data are shown with crosses, and the solid line shows the fit results. It is characterized by two lines at 962 and 1179 keV.

1.12. Zirconium

[0123] To determine zirconium, zirconium oxide ZrO _{2 was} measured (according to TU 6-09-2486-77, sample weight 0.5 kg), the energy spectrum of which is shown in FIG. 16, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.13. Chromium

[0124] For the determination of chromium, chromium oxide Cr ₂ O _{3 was} measured (according to TU 6-09-4272-84, sample weight 0.5 kg), the energy spectrum of which is shown in FIG. 17, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.14. Sulfur

[0125] The measured energy spectrum of sulfur S (according to TU 6-09-2546-77, sample weight 0.5 kg) is shown in FIG. 18, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.15. Bismuth

[0126] The measured energy spectrum of Bi bismuth (TU 6-09-3616-82, sample weight 0.5 kg) is shown in FIG. 19, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.16. Tin

[0127] The measured energy spectrum of Sn tin (according to TU 3-291-10, sample weight 0.5 kg) is shown in FIG. 20, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.17. Zinc

[0128] The measured energy spectrum of zinc Zn (according to TU 6-09-5294-86, sample weight 0.5 kg) is shown in FIG. 21, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.18. Fluorine

[0129] To determine the fluorine spectrum, carbon tetrafluoride CF ₄ (4.4 kg) was measured, the energy spectrum of which is shown in FIG. 22, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.19. Phosphorus

[0130] To determine the phosphorus spectrum, phosphorus oxide was measured as P ₂ O ₅ (according to specification 1-250-10, sample weight 0.5 kg), the energy spectrum of which is shown in FIG. 23, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.20. Lead

[0131] The measured energy spectrum of lead Pb (according to TU 6-09-02-987-95, sample weight 0.5 kg) is shown in FIG. 24, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.21. Chlorine

[0132] For the determination of chlorine, carbon tetrachloride CCl ₄ (according to GOST 20288-74, sample weight 1.6 kg) was measured, the energy spectrum of which is shown in FIG. 25, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.22. Potassium

[0133] For potassium determination, potassium carbonate was measured as K ₂ CO ₃ (GOST 422-76, sample weight 0.5 kg), the energy spectrum is shown in FIG. 26, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.23. Sodium

[0134] For the determination of sodium, sodium carbonate Na ₂ CO ₃ (GOST 83-79, sample weight 1 kg) was measured, the energy spectrum of which is shown in FIG. 27, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.24. Nitrogen

[0135] For the determination of nitrogen, melamine C ₃ H ₆ N _{6 was} measured (GOST 7579-76, sample weight 0.7 kg). The energy spectrum of C ₃ H ₆ N _{6 is} shown in FIG. 28, where the experimental data are shown with crosses, and the solid line shows the fit results.

1.25. Accounting for the continuum spectrum

[0136] Practically for the nuclei of all atoms, except the lightest, the existence of a continuous gamma-ray spectrum, the so-called continuum, is known at excitation energies above the typical neutron separation energy (~ 8 MeV). This is explained by the fact that the density of nuclear levels is usually low at low excitation energies E _ex (the distance between ΔE levels is about 1 MeV) and increases sharply with increasing E _ex (ΔE decreases to tens of keV). For example, in the ²⁸ Si core, the number of levels with E _ex <8 MeV is about 10, and the number of levels with 8 <E _ex <14 MeV is already about 70. Considering the fact that the excitation removal usually occurs through cascades, the multiplicity of gamma quanta at high E _{ex is} significant, and together with the proximity of various levels, these factors lead to the observation of almost continuous continuum spectra.

[0137] FIG. 29 shows the result of fitting the energy spectrum of aluminum. The experimental spectrum is shown with black dots, the result of the fit with aluminum lines and the BG (E) background function is shown with a solid line, the sum of the response of all discrete aluminum lines is shown with a three-dot dash line, and the difference between the experimental points and the sum of discrete aluminum lines is shown with triangles, and in The box on the top right shows the fitting parameters. This histogram, normalized to the sum of the cross sections of discrete lines, was used as the spectrum of the aluminum continuum. As a result, the fitting function for an individual aluminum element is the sum of the above functions (6) for all given discrete lines and a continuum histogram, with normalization determined from the reference spectrum of the element. Accounting for the continuum significantly improves the accuracy of the experimental data description by fitting curves. FIG. Figure 30 shows an example of the result of fitting the energy spectrum of aluminum, taking into account the spectrum of the continuum, where the black dots are the experimental spectrum, and the solid line is the result of the fit with the aluminum lines plus the continuum. it is seen that in the fit in FIG. 30 compared with the fit in FIG. 29 χ ² decreased from 1.118 · 10 ⁴ to 7.267 · 10 ^-6 , and the normalization of the background function A decreased by two orders of magnitude, which indicates a significant decrease in poorly controlled factors.

Experimental part B

1. Samples and experiments

[0138] As another example, the results of applying the MCM to determine the elemental composition of rocks in the field are given below. For the research, samples from the silicate rocks of the basic composition and carbonate rocks selected at the Olkhonsky geodynamic polygon were used. The measurements were carried out on the geological base Chernorud (ISTU). The main objective of these measurements was to test the ability of the MCM to carry out the correct rapid analysis of the elemental composition of rocks from relatively homogeneous groups of indicator elements. So, for carbonate rocks, it is important to divide into calcite marbles (without magnesium), dolomite and dolomite-calcite marbles (with a significant proportion of magnesium) and calciphyres (rocks with a significant admixture of silicates and varying ratios of calcium and magnesium). It was interesting to check how correctly the results of the MCM correlate with the results of the petrographic analysis performed in the field, and how well they correlate with the control results of the chemical analysis carried out in the laboratory.

[0139] Measurements were performed using a DVIN-1 portable detector. The DVIN-1 detector consists of a measuring module, which is connected by cable to the operator’s computer. The measuring module has dimensions of 740 × 510 × 410 mm and a weight of 40 kg. A neutron source, a gamma detector and electronics of the data analysis system are located inside the measuring module. The power of the measuring module is carried out from a network of 220 V or from an autonomous battery. Power consumption is about 300 watts. The source of neutrons is the ING-27 portable neutron generator manufactured by the FSUE “VNIIA im. NL Dukhova ”with integrated 9-pixel silicon α-detector. The intensity of the neutron flux generated by the neutron generator (NG) was I = 5 · 10 ⁷ n / s. The silicon α-detector built into the NG is a 3 × 3 matrix of pixels with a pixel size of 10 × 10 mm. The silicon α-detector is located at a distance of 62 mm from the tritium target. The α-detector signal preamplifiers are mounted on a flange coupled to an NG package.

[0140] The detection of γ-quanta was carried out by a single gamma detector based on a BGO crystal with a diameter of 76 mm and a thickness of 65 mm. GGO-based detectors based on BGO crystals have a fairly good energy resolution of the order of (8–2.5%) in the characteristic radiation energy range of 1–12 MeV. On the carbon γ-line (Eγ = 4.439 MeV), the energy resolution of the BGO-based gamma detector averaged 4.4%. BGO-based gamma detectors are also distinguished by high efficiency of γ-quanta detection in the specified energy range and low sensitivity with respect to background neutron detection. The time resolution of α-γ coincidences is 3.3 ns.

[0141] The recording electronics of the system for collecting and analyzing data from alpha and gamma detectors are made in the form of a 16-channel card, which has the size of a standard PCI card with the ability to install a personal computer (PC) slot in the PCI-E. Information is exchanged with a PC via a PCI-E bus. The system of recording signals from alpha and gamma detectors is based on the principle of their digitization with the subsequent restoration of the time and amplitude characteristics of pulses. To ensure the required data transfer rate over the PCI bus, the interface operates in the direct memory access mode of the PC.

[0142] In measurements at the Olkhonsky geodynamic test site based at the Chernorud hospital (ISTU), the DVIN-1 detector was installed in the geological base, where rapid analysis of rock samples from nearby areas was carried out. The radiation safety rules for operating the DVIN-1 detector require the operator to observe a safety radius of 8.5 m, and for the public, the safety radius is 10 m.

[0143] Sample size ranged from 20 to 50 cm, and their weight ranged from 2 to 6 kg. No sample preparation was carried out. For the analysis, irregularly shaped samples from three groups of rocks were presented: carbonate rocks (dolomite, calcite marbles and calciphyres, 17 samples in total), gneisses (23 samples in total) and amphibolites (7 samples in total).

2. Control measurements by chemical methods

[0144] In order to compare with the proposed method, the chemical composition of the samples was also determined by the chemical control method of silicate analysis at the Analytical Center of the Institute of the Earth's Crust of the SB RAS using standard methods. For the decomposition of the samples, fusion with a mixture of soda and borax in a muffle furnace at t = 940 ° C and acid opening with a mixture of perchloric and hydrofluoric acids was used. The chemical method for the determination of silicon, aluminum and total iron is based on the ability of these elements to form colored complexes. The determination of elements from solutions of their colored complexes was carried out on the spectrophotometric complex GENESYS 10S, Thermo Fisher Scientific, USA. For the control determination of calcium and magnesium, we used the method of atomic absorption spectrometry with spraying the test solution in a flame (acetylene-air) in the form of an aerosol and measuring the degree of attenuation of radiation of a standard light source (a hollow cathode lamp) due to absorption of this radiation by atoms of the element being analyzed. The determination was carried out on a spectrophotometer SOLAAR M6, Thermo Elemental, INTERTECH Corporation, USA. To eliminate the interfering influence of extraneous elements in the determination of CaO and MgO as a spectrophotometric buffer, lanthanum (III) chloride was introduced into the studied solutions. For the control determination of carbon dioxide (CO ₂ ), the method of volumetric titration with the decomposition of the sample with hydrochloric acid and the release of carbon dioxide was used. Hygroscopic water was determined by drying the sample of the rock in a crucible to constant weight at 10 ° C. Loss on ignition was determined by calcining the sample at a temperature of 1000 ° C to a constant weight. The silicate analysis was completed by counting the sum of all detectable components, which should be close to 100%. In most cases, this is a good benchmark for quality control benchmarking. The accuracy of component determination in samples was monitored by repeated measurement of standard samples with known certified element concentrations.

3. Results of measurements and spectra processing

3.1 Calcite Marbles

[0145] FIG. 31 shows the energy spectrum from the irradiation of a calcite marble sample with an elemental composition of CaCO ₃ (sample SE2869), where the experimental data are shown with crosses, the contributions of the elements Ca, C, O are shown by the corresponding lines, and the solid line shows the result of fitting all the parameters. The characteristic oxygen lines shown in FIG. 31 dashed lines. Three oxygen peaks are visible at E = 2742, 3089 and 3854 keV. In the characteristic spectrum of calcium, a peak is released at an energy of E = 3737 keV. The imposition of this line on the peak corresponding to the cascade transition during the de-excitation of the oxygen nucleus (the transition energy is E = 3854 keV) creates a diffuse structure of a non-Gaussian shape. The characteristic carbon spectrum is the simplest: it only clearly distinguishes one line at E = 4439 keV and a peak of leakage of one gamma quantum shifted 500 keV from the main line. These qualitative features of calcites are confirmed by the quantitative results of the determination of the elemental composition using the parameter fitting procedure. Table 1 shows the mass fractions of various elements for some samples of calcite marbles obtained in the central labeled beam, which covered a 3 × 3 cm area on the sample.

Table 1 . Mass fractions of elements in samples of calcite marbles obtained as a result of measurements with the DVIN-1 detector. The errors of the measurement results are given at the 1σ level.

Sample Si,% Mg,% Fe,% Al,% Ca,% C,% O% SE2869 - - - 2.6 ± 1.0 34.9 ± 1.8 13.3 ± 0.6 48.8 ± 1.4 SE2801 - - - - 42.3 ± 1.3 16.1 ± 0.7 41.6 ± 1.2 SE2766 1.0 ± 0.4 - - - 43.6 ± 1.7 13.2 ± 0.6 42.1 ± 1.1

3.2 Dolomite Marbles

[0146] FIG. 32 shows the spectrum of a sample of dolomite marble with the elemental composition CaCO ₃ × MgCO ₃ (sample SE2789), where the experimental data are shown with crosses, the contributions of the elements Mg, Ca, C, O are shown by the corresponding lines, and the solid line shows the result of fitting all the parameters. In the spectrum in FIG. 32, in addition to the characteristic lines Ca, C and O present in FIG. 31, the signal from the magnesium line at 1369 keV is clearly visible. This is also reflected in the results of the determination of the concentrations of the elements in Table 2. They correctly show the four main elements present in the dolomite marbles. Mass fraction of magnesium reaches 7-10%.

Table 2 . Mass fractions of elements in samples of dolomite marbles, obtained as a result of measurements with a DVIN-1 detector. The errors of the measurement results are given at the 1σ level.

Sample Si,% Mg,% Fe,% Al,% Ca,% C,% O% SE2789 0.2 ± 0.8 9.6 ± 0.6 - 2.5 ± 1.0 27.5 ± 2.2 14.4 ± 0.7 45.3 ± 1.9 SE2871 0.5 ± 0.8 7.7 ± 0.6 2.1 ± 1.1 - 25.3 ± 2.0 15.0 ± 0.7 48.8 ± 1.7 SE2842 - 8.9 ± 0.6 - 2.0 ± 0.8 28.3 ± 2.1 15.9 ± 0.8 44.6 ± 1.7

3.3 Calcifires

[0147] FIG. 33 shows the energy spectrum of gamma rays from the irradiation of a calciphir sample (sample SE2803). The experimental data are shown with crosses, the contributions of the elements Si, Ca, C, O are shown by the corresponding lines, and the solid line shows the result of fitting all the parameters. Calcifires consist of calcite or dolomite mixed with silicate materials. Indeed, in the manner shown in FIG. In the spectrum of the calcifira sample, a characteristic silicon peak appears at E = 1779 keV. The magnitude of this peak is small, since the silicon impurity is 3-4% (see Table 3).

Table 3 . Mass fractions of elements in calcipir samples taken as a result of measurements with the DVIN-1 detector. The errors of the measurement results are given at the 1σ level.

Sample Si,% Mg,% Fe,% Al,% Ca,% C,% O% SE2841 3.9 ± 0.9 - - - 40.2 ± 2.7 14.0 ± 0.8 39.9 ± 2.0 SE2803 2.9 ± 1.0 - - 2.2 ± 1.4 39.6 ± 2.5 13.9 ± 0.8 41.4 ± 2.0 SE2794 3.0 ± 0.7 - - - 43.7 ± 1.2 14.2 ± 0.6 38.5 ± 0.9

3.4 Gneisses

[0148] FIG. 34 shows the spectrum from a typical gneiss sample (sample SE2840), where the experimental data are shown with crosses, the contributions of the elements Si, Fe, Al, O are shown by the corresponding lines, and the solid line shows the result of fitting all the parameters. The spectrum does not contain a carbon peak at 4.439 MeV. There is also no contribution from calcium. This corresponds to the elemental composition of gneisses, in which the main contribution is made by silica SiO ₂ and alumina Al ₂ O ₃ . The results of determining the mass fractions of these elements, shown in Table 4, fully correspond to this pattern.

Table 4 . Mass fractions of elements in samples of samples of gneisses, obtained as a result of measurements with a DVIN-1 detector. The errors of the measurement results are given at the 1σ level.

Sample Si,% Mg,% Fe,% Al,% Ca,% C,% O% SE2840 26.9 ± 1.5 6.7 ± 0.7 0.9 ± 1.3 16.4 ± 1.7 6.8 ± 2.4 - 42.4 ± 1.9 SE2870 33.1 ± 2.3 2.8 ± 0.8 - 13.4 ± 2.2 0.8 ± 3.3 1.2 ± 0.8 47.1 ± 3.0 SE2786 32.1 ± 1.8 1.5 ± 0.6 4.7 ± 1.4 11.5 ± 1.6 6.5 ± 2.2 - 43.3 ± 1.9

3.5 Amphibolites

[0149] FIG. 35 shows the energy spectrum of gamma rays from the irradiation of an amphibolite sample (sample SE2843), where the experimental data are shown with crosses, the contributions of the elements Si, Fe, Al, O are shown by the corresponding lines, and the solid line shows the result of fitting all the parameters. There is no carbon line in this spectrum, a bright signal from silicon and peaks from aluminum and magnesium are visible. This is consistent with the elemental composition of amphibolites, mainly consisting of silicates and aluminosilicates of magnesium, iron and calcium. The data on the elemental composition of some amphibolite samples obtained as a result of measurements with the DVIN-1 detector are shown in Table 5.

Table 5 . Mass fractions of elements in samples of amphibolite samples, obtained as a result of measurements with the DVIN-1 detector. The errors of the measurement results are given at the 1σ level.

Sample Si,% Mg,% Fe,% Al,% Ca,% C,% O% SE2843 22.9 ± 1.9 6.0 ± 0.9 10.3 ± 2.1 7.8 ± 2.0 9.8 ± 4.7 - 42.6 ± 3.0 SE2850 17.6 ± 1.6 4.1 ± 0.7 9.9 ± 1.6 11.5 ± 1.7 15.3 ± 2.8 - 41.6 ± 2.7 SE2816 21.4 ± 1.6 4.7 ± 0.7 11, 1 ± 1.7 10.7 ± 1.7 12.3 ± 2.7 0.8 ± 0.6 39.0 ± 2.3

4. Discussion of the results of the analysis of rocks

[0150] The spectra shown in FIG. 31-35, clearly show the ability of the MCM to identify key rock-forming elements - C, O, Si, Mg, Al, Fe, Ca. Earlier, the use of MCM was limited to determining concentrations of carbon, nitrogen, and oxygen.

[0151] For these elements, the largest excitation cross section under the action of neutrons of 14.1 MeV has a carbon line of 4439 keV, the excitation cross section of which is 210 mb. For comparison, the cross section of the 1779 keV silicon line is 400 mb, and the magnesium line of 1369 keV has a cross section of 425 mb. Separate lines of iron, calcium, and aluminum also have significant excitation cross sections, which makes the determination of their concentrations promising.

[0152] The data in Tables 1-5 show that the MCM in general correctly reproduces the ratio of the mass fractions of the various elements in the samples under study.

[0153] Knowing the values of the mass fractions of elements, it is possible by formulas (20) - (22) to calculate the concentration of the corresponding oxides. Table 6 shows the concentrations of oxides Si, Al, Fe, Mg, Ca and C, obtained for various samples using DVIN-1, as well as the control results of silicate analysis.

Table 6 . Concentrations of oxides in various samples, obtained as a result of measurements with a DVIN-1 detector (designated by the MCM) and as a result of performing silicate analysis (CA). The errors of the measurement results are given at the 1σ level. FeO _total is the sum of the contributions of iron oxides FeO and 0.9 Fe ₂ O ₃ .

Sample SiO ₂ ,% Al ₂ O ₃ ,% FeO _total ,% MgO,% CaO,% CO ₂ % SE2843, SA 47.16 ± 0.1 15.67 ± 0.14 11.69 ± 0.06 6.66 ± 0.08 10.97 ± 0.11 0,44 ± 0,07 SE2843, MMD 47.8 ± 5.0 14.3 ± 3.8 12.9 ± 2.8 9.7 ± 1.5 13.3 ± 6.4 - SE2850, CA 44.28 ± 0.1 14.96 ± 0.14 13.62 ± 0.06 6.84 ± 0.08 17.18 ± 0.11 - SE2850, MMD 39.9 ± 3.7 18.7 ± 3.2 13.9 ± 2.1 5.2 ± 1.1 21.8 ± 3.9 0.5 ± 2.5 SE2869, CA 2.29 ± 0.1 - - 0.68 ± 0.08 53.35 ± 0.11 42.3 ± 0.07 SE2869, MMD - 4.8 ± 1.8 - - 47.4 ± 2.8 47.2 ± 2.5 SE2801, CA 1.1 ± 0.1 - 0.12 ± 0.06 0.65 ± 0.08 54.4 ± 0.11 42.98 ± 0.07 SE2801, MMD - - - - 50.1 ± 1.8 50.0 ± 2.3 SE2841, CA 4.95 ± 0.1 0.5 ± 0.14 0.51 ± 0.06 0.31 ± 0.08 51.8 ± 0.11 40.18 ± 0.07 SE2841, MMD 7.0 ± 1.7 - - - 47.3 ± 3.5 43.2 ± 2.9 SE2840, CA 66.2 ± 0.1 16.25 ± 0.14 4.65 ± 0.06 1.87 ± 0.08 3.02 ± 0.11 - SE2840, MMN 52.2 ± 3.4 28.1 ± 3.0 - 2.8 ± 1.3 8.6 ± 3.0 - SE2870, CA 73.16 ± 0.1 13.34 ± 0.14 2.79 ± 0.06 0.81 ± 0.08 2.38 ± 0.11 - SE2870, MMD 65.4 ± 5.8 23.4 ± 4.0 - 4.2 ± 1.3 - 4.0 ± 2.8 SE2786 SA 73.13 ± 0.1 14.06 ± 0.14 2.36 ± 0.06 0.53 ± 0.08 3.58 ± 0.11 0.51 ± 0.07 SE2786, MMD 62.7 ± 4.3 19.8 ± 2.9 5.5 ± 1.7 2.3 ± 0.9 8.3 ± 2.9 - SE2800, CA 62.31 ± 0.1 17.05 ± 0.14 6.54 ± 0.06 2.34 ± 0.08 3.72 ± 0.11 - SE2800, MMD 54.5 ± 3.9 21.0 ± 2.8 5.7 ± 1.9 5.4 ± 0.4 12.6 ± 3.2 -

[0154] Comparison of sample measurement data using DVIN-1 with the control results of silicate analysis showed a generally good comparability of the results. For some samples, the concentrations of oxides obtained by the two methods of the MCM and SA coincided within 3σ. In a number of samples, the differences in the concentrations of oxides obtained by the two methods of the MCM and SA were more significant. This is not surprising, since no sample preparation for measurements with DVIN-1 was carried out, in contrast to the preparation of samples for silicate analysis. Nevertheless, the question of the magnitude of the systematic errors of the method of the MCM required a separate study. It was necessary to perform multiple measurements of certified samples.

[0155] The results in Tables 2-6 give an indication of the accuracy of the measurements. It should be noted that for the present analysis only data for the central tagged beam were used. If we take the results for all 9 beams, then the error in determining the concentration decreases, on average, twice.

[0156] The main result of the tests is that measurements using the tagged neutron method correctly reproduced all the main characteristics of the studied rocks. For example, measurements by the MCM correctly reproduced the elemental composition of calcite, dolomite marbles and calciphyres (marbles with admixture of silicate minerals): in calcite marbles insignificant contents of Mg and Si are recorded, in dolomite marbles the amount of Ca is significantly reduced and significant concentrations of Mg appear, in calcipher there is an increased Si content (see Tables 1-3). In amphibolites, the Si content is 18–20%, and elevated concentrations of Fe, Mg, Ca are recorded, which is typical of basic composition rocks (Table 5). Silicon content in gneisses is higher than in amphibolites (25-30% Si) with very low concentrations of Ca and Mg (Table 4). The results of the MCM correctly showed the absence of carbon in both groups of silicate rocks.

[0157] Thus, the results of measurements in the field have shown that detectors based on MCM can be successfully used to determine Si, Al, Fe, Mg, Ca, C and their oxides in rocks. However, it should be emphasized that the method of MCM does not necessarily serve as an alternative to traditional methods of analysis, but can be effectively used when it is necessary to determine the elemental composition of rocks promptly. The use of detectors MCM allows in the field to get a relatively accurate result after 15-20 minutes of irradiation. To improve the accuracy of measurements using the MCM method, one should increase the duration of the collection of event statistics, for example, to 30-60 minutes (1 hour) or more.

[0158] The demand for express analysis of the composition of rocks is most likely when determining the position of mine workings (quarries, mines, tunnels) in existing and explored deposits and ore occurrences.

[0159] The results obtained by the MCM method for the elemental composition of various groups of rocks are fully consistent with the identified mineralogical and petrographic features.

[0160] Since the determination of the elemental composition of rocks with the help of the MCM in field conditions was carried out for the first time in world practice, further research will undoubtedly be carried out on the development of methods on reference samples with a known content of components. It is advisable to pay special attention to the determination of the contents of ore components (S, Ni, Pb, Cu, Zn, Zr) for use of the device in geological exploration.

[0161] The tagged neutron method has good prospects for use in geological practice in analyzing rock samples. The advantage of the method is its rapidity, the absence of requirements for sample preparation, the possibility of determining the elemental composition within the rock at a considerable thickness, the ability to determine the variations of components in the volume of the rock directly at the sites of exploration or mining.

Experimental Part B

[0162] FIG. 36 shows another experimental example of the energy spectrum of an apatite-nepheline ore sample and the result of its approximation, which also shows the contributions from the spectra of various chemical elements.

[0163] An important difference of the device and method for determining the elemental composition of the sample, i.e. specific concentrations of the constituent chemical elements, is a special selection of events, using information about the temporal distribution of events alpha-gamma coincidences.

[0164] FIG. 37 shows examples of temporal spectra of alpha-gamma coincidences, obtained by irradiating a sample of apatite-nepheline ore. They consist of a plateau of random coincidences and a peak from gamma-quanta arising when the sample is irradiated with labeled neutrons. In the usual method of neutron activation analysis (NAA) there is no possibility to separate events from the sample and from the external background, since there is no information on the temporal distribution of events. In the method of tagged neutrons (MCM), gamma radiation can only be isolated from the nuclei of the elements of the sample itself. Therefore, to determine the concentration of elements in a sample, only events within the time interval (time window) shown in FIG. 37 two solid vertical lines. In this case, this interval is 6 ns. This method of special selection of events makes it possible to sharply reduce the background level and to better isolate the useful signal from the sample under study. The use of this technique for apatite-nepheline ore made it possible to increase the signal-to-background ratio by a factor of 176.

[0165] In addition to the background of random coincidences, there is a so-called correlation background, which is directly related to the object being measured and is due to neutron scattering on the sample material. Since the neutron flight speed is lower than the gamma quantum speed, then in the time distribution the peak from such events appears at later times than the peak from the gamma quanta of characteristic radiation. The two-humped time spectrum structure is clearly visible in FIG. 37. Therefore, an important feature of the present invention is the algorithm for determining the time window within which the energy spectrum of the sample is analyzed.

[0166] Another important difference of the method, as mentioned above, is the use of fast neutrons with an energy of about 14 MeV. This makes it possible to correctly determine the mass concentration of chemical elements in samples of large size (for example, 100-300 mm) and large mass (for example, several kg) without any sample preparation. From a physical point of view, this result is logical: a 14 MeV neutron energy is quite sufficient to excite the nuclei of a substance 100-300 mm thick. The energy of the gamma-quanta of characteristic radiation is also high and amounts to 0.5–7 MeV. This allows gamma-quanta to leave the sample substance freely enough to enter the gamma-ray detector.

[0167] Moreover, in the device according to the invention and in the method for determining the elemental composition of samples, the calibration of spectra by energy is important. It allows you to automatically make a correction to the measured spectra of the registered characteristic gamma radiation with each measurement of each sample. That is, for each measurement, the amplitude distributions are reduced to distributions obtained under certain fixed conditions. This significantly reduces the systematic error and increases the stability of measurements over time.

[0168] Energy calibration is performed for each measurement. It uses data on the position of 6 lines of elements, which are extracted from the one shown in FIG. 37 time window spectrum alpha-gamma coincidence. For energy calibration, events are selected that are outside of the shown and highlighted vertical lines in FIG. 37 peaks from gamma rays from the sample. By their physical nature, these events most often occur during neutron irradiation of the material of biological protection 6 of the neutron unit 1 (see Fig. 3). Since biological protection 6 is always present in the measurement process, the presence of 6 reference lines is always guaranteed.

[0169] To obtain the value of the mass concentration of a chemical element in a sample of large mass and large size (up to a size of 300 mm), a double conversion of the obtained value of the analytical signal of the device according to the invention is carried out. Consider this on the example of the determination of phosphorus pentoxide in apatite-nepheline ore. The corresponding correlation plot is shown in FIG. 38

[0170] A sample weighing 5 kg and a particle size of -100 mm, taken directly from the quarry, without any sample preparation, was measured on the device according to the invention. Then the sample was crushed to a particle size of -3 mm and their signals were compared. Based on these data, the dependence №1 was obtained:

Y _-3mm = a ₁ + b ₁ · X _-100mm (23).

[0171] The analytical signal from samples of small size (-3 mm), measured on the device according to the invention, was compared with the control results of chemical analysis of these samples. Based on these data, the calibration dependence No. 2 was constructed:

Y _HA = a ₂ + b ₂ · X _-3mm (24).

[0172] An example of such a calibration dependence is shown in FIG. 39

[0173] Knowing the coefficients in equations of type (23) and (24), it is possible to determine the concentration of chemical elements in any sample of ore of the required mass and fineness.

[0174] In this particular embodiment of the invention, the relative accuracy of determining the concentration of phosphorus pentoxide in apatite-nepheline ore was less than 5% at a confidence level of P = 0.95. It should be noted that, if necessary, the accuracy of the determination can be improved by increasing the measurement time (the duration of the collection of event statistics), the number of gamma detectors and increasing the intensity of the neutron generator.

Experimental part G

1. The decomposition of the spectra of oxides into elements

[0175] FIG. 40 shows the spectrum of gamma rays from the irradiation of an Al ₂ O ₃ sample with fast labeled neutrons, where the experimental data are shown with crosses, and the solid line shows the result of the fit. The dashed line reflects the contribution of the spectrum of oxygen, the dash-dotted line with two points represents the contribution of the spectrum of aluminum. Fit determined the fraction of aluminum atoms n _Al = 0.4 ± 0.002 and the fraction of oxygen atoms n _O = 0.6 ± 0.003. This agrees well with the chemical formula of alumina.

[0176] It is worth noting that the adjustment of the cross sections of aluminum was performed on a sample of chemically pure aluminum, so correct decomposition of the spectrum of aluminum oxide into elements is a test of the method as a whole.

[0177] FIG. 41 shows the spectrum of gamma rays from the irradiation of CaCO _{3 with} fast neutrons, where experimental data are shown with crosses, the full line shows the fit result, the dashed line shows the oxygen contribution, the dotted line shows carbon, the dash-dotted line with two points shows calcium. Fit determined the proportion of calcium atoms n _Ca = 0.206 ± 0.001, the proportion of carbon atoms n _C = 0.196 ± 0.002 and the proportion of oxygen atoms n _O = 0.597 ± 0.003. It can be seen that the ratios between the atoms of Ca and C are reproduced very well, whereas the contribution of oxygen atoms is somewhat underestimated, by an amount less than two statistical errors.

[0178] A similar decomposition of the spectrum of acetone C ₃ H ₆ O resulted in the following ratio between C and O atoms: the proportion of carbon atoms n _C = 0.732 ± 0.005 and the proportion of oxygen atoms n _O = 0.237 ± 0.002.

2. Determination of the elemental composition of rocks

[0179] To determine the elemental composition of substances consisting of several elements, 8 geological samples with a known elemental composition, taken during work at the Olkhonsky geodynamic test site, were studied. Samples consisted of powder in cardboard envelopes. The mass of a single sample ranged from 300 to 600 g. The sample measurement time was 30 minutes. The specificity of the control chemical analysis in this case was that the relative concentrations of oxides, and not the primary elements, were determined. Therefore, we used two methods of presenting the results: comparing the concentrations of elements and comparing the concentrations of oxides.

2.1. Comparison of oxide concentrations

[0180] For comparison with the data of the control chemical analysis of samples that were presented as the percentage of various oxides, the method of constructing calibration curves was applied. An example of such curves is shown in FIG. 42 and FIG. 43.

[0181] Each of the 8 measurements on these graphs is represented as a point, the abscissa of which corresponds to the value of the fit parameter (atomic concentration of the element), and the ordinate to the value of the mass concentration of oxides, determined using the control chemical analysis. It is seen that the results of all measurements with good accuracy fall on straight lines. Deviations of individual measurements from a straight line do not exceed 1-2%. This indicates that the fitting procedure correctly defines the hierarchy of the content of a given element in the sample under study.

[0182] The magnitudes of the relative concentrations of the various oxides, calculated using the calibration curves, are shown in Table 7.

[0183] Here, two values are given for each sample. The first value, which is considered without experimental errors, corresponds to the control result of chemical analysis. The second value, labeled with MCM, corresponds to the measurement result by the method of the invention. It can be seen that there is good agreement on all elements, the results of measurements by the method of MCM differ from the control results of chemical analysis by no more than 1-2%.

2.2. Comparison of concentrations of various elements

[0184] The initial values determined by fitting are the relative atomic concentrations of the individual elements. Their values are given in Table 8. The first line of this table shows the control results of chemical analysis, recalculated in the concentration of elements, in the second line - the results obtained by the method according to the invention using the MCM without calibration, and in the third line - the results obtained by the method invention using MCM with regard to calibration.

[0185] It can be seen that the results obtained by the method of the invention using the MCM calibration method are closer to the control results of chemical analysis. However, the data obtained by direct fitting quite satisfactorily describe the overall ratio between the elements in the samples.

[0186] The accuracy of the elemental composition determination is 1–1.5% for element concentrations of 0.2–0.5.

Table 7 : Mass fraction of oxides according to chemical analysis and determined according to the invention as a result of fitting. For each sample, the first line shows the results of chemical analysis, the second line shows the results obtained by the method according to the invention using the MCM. As calciphyr was forsterite-spinel calcipher with tazheranit. Calcite marble-1 - a sample of calcite marble with forsterite and graphite. Calcite marble-2 - a sample of calcite marble with graphite.

SiO ₂ MgO Feo Al ₂ O ₃ Cao CO ₂ 13А142 gabbro phlogopite 0.5431 0.0536 0.07851 0.167 0.0984 0.0006 MMN 0.527 ± 0.007 0.046 ± 0.004 0.071 ± 0.006 0.186 ± 0.006 0.065 ± 0.008 0,005 ± 0,005 13A243 gabbro metasomatized 0.4698 0.0657 0.06847 0.1852 0.1734 0.0007 MMN 0.471 ± 0.007 0.077 ± 0.004 0.058 ± 0.006 0.171 ± 0.007 0.169 ± 0.009 0.013 ± 0.006 13A254 gabbro metasomatized 0.4678 0.0548 0.04218 0.2142 0.1882 0,0068 MMN 0.466 ± 0.005 0.068 ± 0.003 0.039 ± 0.004 0.191 ± 0.005 0,200 ± 0,007 0,000 ± 0,004 AS229C trachydolerite 0.4778 0.0537 0.13352 0.1444 0.0965 0,0011 MMN 0.483 ± 0.006 0.037 ± 0.003 0.139 ± 0.005 0.155 ± 0.005 0.103 ± 0.007 0.017 ± 0.004 SE2536A metaphoritis 0.5046 0.0383 0.12586 0.1435 0.0793 0,0013 MMN 0.530 ± 0.005 0.051 ± 0.003 0.128 ± 0.004 0.163 ± 0.005 0.075 ± 0.007 0,000 ± 0,004 SE2699C Calcifer 0.138 0.2147 0,00885 0.0464 0.3111 0,2291 MMN 0.127 ± 0.003 0,214 ± 0,002 0.022 ± 0.003 0.037 ± 0.003 0.326 ± 0.005 0,214 ± 0,003 SE2357-6 calcite marble-1 0.0467 0.0265 0.00362 0,0015 0.5138 0.3379 MMN 0.050 ± 0.003 0.022 ± 0.003 0.011 ± 0.004 0,001 ± 0,023 0.514 ± 0.008 0.338 ± 0.006 SE2365A calcite marble-2 0,009 0,0016 0,0038 0,0025 0.5502 0.3379 MMN 0.010 ± 0.002 0,000 ± 0,003 0,000 ± 0,005 0,006 ± 0,004 0.530 ± 0.008 0.361 ± 0.005

Table 8 : Relative atomic concentrations according to chemical analysis and obtained by the method of the invention using the MCM method as a result of fitting. For each sample, the first line shows the control results of chemical analysis, the second line shows the results obtained by the method according to the invention using the MCM without calibration (marked “raw”), the third line shows the results obtained by the method according to the invention using the MCM taking into account calibration (labeled "calib").

Si Mg Fe Al Ca Ti WITH O 13A142 0.266 0.034 0.064 0.093 0.074 0,006 0,000 0.459 raw 0,236 ± 0,003 0.020 ± 0.001 0.059 ± 0.003 0.093 ± 0.003 0.042 ± 0.006 0.034 ± 0.005 0.011 ± 0.002 0,505 ± 0,005 calib 0,258 ± 0,004 0.028 ± 0.002 0.058 ± 0.005 0.103 ± 0.004 0.045 ± 0.007 0.026 ± 0.009 0,001 ± 0,002 0.476 ± 0.005 13A243 0,226 0.0407 0.055 0.101 0.127 0,004 0,000 0.443 raw 0,208 ± 0,003 0.031 ± 0.001 0.050 ± 0.003 0.085 ± 0.004 0.112 ± 0.006 0.011 ± 0.007 0.013 ± 0.002 0.489 ± 0.005 calib 0,230 ± 0,003 0.048 ± 0.003 0,047 ± 0,005 0.095 ± 0.005 0.126 ± 0.008 0,002 ± 0,008 0,003 ± 0,002 0.466 ± 0.005 13A254 0,223 0.034 0.033 0.116 0.137 0,002 0,002 0.449 raw 0.206 ± 0.003 0.028 ± 0.001 0.040 ± 0.003 0.093 ± 0.003 0.133 ± 0.004 0,002 ± 0,005 0,009 ± 0,001 0.489 ± 0.004 calib 0,229 ± 0,003 0.042 ± 0.002 0.032 ± 0.005 0.104 ± 0.004 0.150 ± 0.006 0,000 ± 0,006 0.000 ± 0.001 0.466 ± 0.004 AS229C 0.236 0.034 0.110 0.081 0.073 0.026 0,000 0.435 raw 0,209 ± 0,003 0.016 ± 0.001 0.096 ± 0.003 0.075 ± 0.003 0.067 ± 0.006 0.040 ± 0.004 0.014 ± 0.001 0.483 ± 0.004 calib 0,236 ± 0,003 0.022 ± 0.002 0.115 ± 0.006 0.086 ± 0.003 0.076 ± 0.007 0.034 ± 0.009 0,005 ± 0,001 0.469 ± 0.004 SE2536A 0.255 0.025 0.106 0.082 0.061 0.021 0,000 0.445 raw 0.233 ± 0.003 0.022 ± 0.001 0.092 ± 0.003 0.080 ± 0.003 0.049 ± 0.004 0.016 ± 0.005 0,007 ± 0,001 0.501 ± 0.004 calib 0,259 ± 0,004 0.032 ± 0.002 0.107 ± 0.006 0.090 ± 0.004 0.054 ± 0.006 0,007 ± 0,007 0.000 ± 0.001 0.479 ± 0.004 SE2699C 0.067 0.136 0,007 0.026 0.233 0,000 0.066 0.460 raw 0.056 ± 0.001 0.085 ± 0.001 0.031 ± 0.003 0.019 ± 0.001 0,231 ± 0,004 0.012 ± 0.002 0.079 ± 0.001 0.487 ± 0.005 calib 0.063 ± 0.002 0.135 ± 0.003 0.017 ± 0.005 0.021 ± 0.002 0,250 ± 0,007 0,002 ± 0,004 0.063 ± 0.001 0.443 ± 0.005 SE23576 0.023 0,017 0,003 0.001 0.393 0,000 0.099 0.459 raw 0.019 ± 0.001 0.012 ± 0.001 0.025 ± 0.003 0,001 ± 0,012 0.361 ± 0.006 0,002 ± 0,005 0.118 ± 0.002 0.460 ± 0.006 calib 0.025 ± 0.002 0.014 ± 0.002 0,009 ± 0,005 0,002 ± 0,013 0.396 ± 0.010 0,000 ± 0,006 0.099 ± 0.002 0.422 ± 0.005 SE2365A 0,005 0.001 0,003 0.001 0.432 0,000 0.101 0,451 raw 0,001 ± 0,001 0,002 ± 0,001 0.014 ± 0.003 0,003 ± 0,001 0.377 ± 0.006 0.010 ± 0.005 0.127 ± 0.002 0.466 ± 0.005 calib 0,006 ± 0,002 0,000 ± 0,002 0,000 ± 0,005 0,004 ± 0,002 0.409 ± 0.010 0,000 ± 0,006 0.105 ± 0.002 0.423 ± 0.005

[0187] Therefore, the proposed in the invention, the device and method for determining the elemental composition of samples of various materials by the method of labeled neutrons were successfully tested in practice. In particular, a comparison of the results of the determination of the elemental composition of rocks with the control values obtained by the MCMN method according to chemical analysis data shows that these values are in good agreement, taking into account statistical errors.

[0188] Thus, the presetting and calibration step of the device according to the invention in the method according to the invention may preferably include the following steps:

(0-1) measure the energy spectra of individual chemical elements that are presumably present in the sample and whose mass concentrations are supposed to be estimated in order to experimentally determine the partial cross sections for the formation of gamma quanta with a set of specific energies for each individual chemical element;

(0-2) describe the energy spectrum of gamma quanta obtained by irradiating a sample with fast neutrons, in the form of a functional that is the sum of three components: functions describing the set of chemical elements that make up the sample and the corresponding gamma lines for their spectra; functions describing the gamma spectrum continuum; and functions describing the background spectrum of events detected by gamma detectors;

(0-3) parameterize the energy dependence of the response of the gamma detector in accordance with the results of Monte-Carlo simulation;

(0-4) determine the continuum in the continuous spectrum of gamma rays from each individual chemical element as the difference between the measured experimental spectrum and the sum of the contributions from the spectra of discrete lines;

(0-5) conduct a double conversion of the obtained value of the analytical signal of the device for a given chemical element (or its oxide) with obtaining the value of the mass concentration of the chemical element in the sample of large mass and large size (up to the size of 300 mm);

(0-6) compare the analytical signal of the device from the sample of large mass and large size with the analytical signal of the device from the same sample, crushed to small size, resulting in the dependence of the correlation connection of these signals No. 1;

(0-7) compare the analytical signal from the sample of small size with the control results of chemical analysis, as a result of which get the calibration dependence No. 2 for the sample of small size; and

(0-8) receive as a result of transformation of dependences No. 1 and No. 2 calibration dependence for a sample of large size.

[0189] The preceding description has been given in the form of various embodiments or implementations of the present invention. It should be understood that in such options specialist can be made numerous and various modifications and changes without deviating from the essence of the present invention, which is determined solely by the attached claims.

[0190] Thus, for example, a structural element of a device or a method step, mentioned here in the singular, should be understood as not excluding the possibility of the presence of multiple elements or steps, if such an exception is not explicitly indicated or follows from the context. In addition, references to an “embodiment of” or “an embodiment of” should not be interpreted as excluding the existence of other variants that also include the indicated features. In addition, unless explicitly stated otherwise, options “including”, “containing” or “having” some element or a plurality of elements with some specific property or attribute may include additional elements regardless of whether they have property or attribute.

[0191] It should also be noted that the specific arrangement of the structural elements of the device according to the invention (for example, their number, types, placement, etc.) or the specific sequence of steps of the method in the illustrated embodiments may be changed to others in various alternative embodiments. In various embodiments, different amounts of a given module or block may be used, another type or types of a given module or block may be used, a given module or block may be added, or a certain module or block may be excluded.

[0192] It should be clearly understood that the above description is intended to illustrate the present invention, and not to limit the scope of its protection. For example, the above described embodiments (and / or their features) can be used in any combination with each other. In addition to this, numerous modifications can be made to adapt one particular embodiment to information from various other embodiments without departing from the scope of protection of the invention. The sizes, types, orientations, number and positions of the various structural elements described here are intended to characterize the parameters that are currently considered to be preferred embodiments and are by no means limiting, but merely exemplary. After considering the above description, numerous other variations and modifications of the invention will become apparent to those skilled in the art within the spirit and scope of the invention. Therefore, the scope of protection should be determined taking into account only the claims, along with the full scope of equivalents to which this claim gives the right.

[0193] In the present description and the claims, the terms "including", "including", "containing", "having", "equipped" and their other grammatical forms are not intended to be interpreted in an exceptional sense, but, on the contrary, are used in non-exclusive sense (i.e. in the sense of "having in its composition"). As an exhaustive list should be considered only expressions such as "consisting of". In addition, the terms "first", "second" and "third", etc. they are used simply as conditional markers, without imposing any numerical or other restrictions on the enumerated objects.

[0194] List of reference symbols in the drawings:

1 - neutron unit

2 - gamma detector unit

3 - data analysis system

4 - operator's workplace

5 - gamma detectors

6 - biological protection

7 - receiving vessel

8 - neutron generator with built-in alpha detector

9 - sample conveyor.

Claims (23)

1. A device for determining the elemental composition of samples of solid or liquid materials containing a neutron unit, made with a receiving vessel to accommodate the sample of material under investigation and equipped with: (a) a neutron generator designed to generate a flux of labeled neutrons and alpha particles, with an alpha detector embedded in the neutron generator; (b) gamma-ray detectors designed to record the spectra of the characteristic gamma-rays that occur when a sample of a material is irradiated with a tagged neutron flux; and (c) a data analysis system designed to collect and analyze data obtained from an alpha detector of a neutron generator and gamma-radiation detectors; (d) biological protection of the neutron unit, ensuring the safe operation of the personnel discussing, the data analysis system is designed to determine the elemental composition of a sample of a material using only gamma quanta that fall within a selected time interval of the alpha gamma coincidence time spectrum and corresponding to the material sample, and using another part of the alpha gamma coincidence time spectrum for energy calibration gamma-ray spectra obtained with each measurement of each sample. 2. The device according to claim 1, in which the neutron generator in the neutron unit is located under the sample of the material under study, and the detectors of gamma radiation are located in the neutron unit above the sample of material under study. 3. The device according to claim 1, wherein the neutron generator in the neutron unit is located above the sample of material under study, and the gamma-ray detectors are located in the neutron unit under the sample of material under study. 4. The device according to claim 1, wherein the neutron generator is located on the first side of the material sample under investigation, and the gamma-radiation detectors are located on the second, opposite to the first side side of the material sample under study. 5. The device according to claim 1, in which the flow of labeled neutrons in the neutron unit has the shape of a truncated pyramid, and, accordingly, the receiving vessel to accommodate the sample of material under study also has the shape of a truncated pyramid. 6. The device according to claim 1, which further comprises a system for feeding a sample of the material into a receiving vessel, for example, a conveyor for alternately feeding the test material samples. 7. The device according to claim 1, wherein the neutron unit is designed to generate a flux of labeled neutrons and alpha particles when accelerating deuterons and interacting with a tritium target due to the implementation of the following binary reaction: d + t → α + n, d is a deuteron, t is a triton, α is an alpha particle, n is a neutron. 8. The device according to claim 1, which is intended to determine the elemental composition of samples of suitable rocks, ores or ore materials. 9. The device according to claim 1, in which the selected time interval is about 1-100 nanoseconds. 10. The method of determining the elemental composition of samples of solid or liquid materials, carried out using the device according to any one of paragraphs. 1-9, comprising the following steps: (a) placing the sample material in the receiving vessel; (b) irradiating a sample of a material with a flux of fast tagged neutrons; (c) registration of the spectra of the characteristic gamma radiation arising from the irradiation of the above-mentioned sample with a stream of fast tagged neutrons in step (b); (d) analyzing the spectra of the characteristic gamma radiation registered from the sample in step (c), with the determination of the elemental composition of the sample, at the same time, to determine the elemental composition of the sample, only gamma rays are used that fall within the selected time interval of the alpha-gamma coincidence spectrum and correspond to the material sample, and the other part of the alpha-gamma coincidence spectrum is used for energy calibration of the obtained gamma-radiation spectra during each measurement each sample. 11. A method according to claim 10, further comprising the step of pre-setting and calibrating the device before step (a).

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