SU1100546A1 - Method of x-ray radiometric determination of element content in substance - Google Patents

Abstract

METHOD OF X-RAY RADIOMETRIC DETERMINATION OF THE ELEMENT CONTENT IN MATTER, consisting in. that a sample of an analyte is irradiated with x-rays or gamma rays, the characteristic x-rays are recorded, the emission of a detectable element in two adjacent energy intervals of the instrument spectrum and the scattered YY, the sample of primary radiation and the content of the characteristic X-ray radiation of a detectable element and scattered radiation, about tons of l and h and with the fact that, in order to expand the range of measured contents, the The element, the intensity of the scattered radiation is also measured in two adjacent energy intervals in the region of the peak of the scattered radiation and is controlled by the mismatch of the transmission spectrometry path by the signal {and proportional to the value of the CP N, + N3 with N, + N N +. where N (, the intensity of the characteristic X-ray radiation of the determined element in two adjacent energy layers, Nj.N, 4 the intensity of the scattered breakdown of the primary radiation in two adjacent energy and tervals, and the increase in the number of the interval corresponds to the increase in the energy of the detected radiation.

Description

The invention relates to X-ray fluorescence analysis and can be used to determine the content of any element in a substance. A known method for determining the concentration of elements involves irradiating a sample with x-ray or soft gamma radiation, measuring the ratio of the characteristic radiation fluxes of the sample and the radiation scattered by the medium, and determining the concentration of the element to be determined by this ratio. The disadvantage of this method is the low accuracy of the measurement of the concentration of the element being detected with significant changes in temperature, supply voltage and other external factors. The known method of x-ray radiometric analysis of the composition of a substance in which the stabilization of the transmission coefficient of the spectrometric tract is carried out using the characteristic x-ray radiation of the material of the additional target irradiated by the primary radiation pj. However, this radiation damages the spectrum of the secondary radiation and, in the case of low energy resolution of the secondary radiation detector, increases the detection threshold of the element being detected .. The closest to the proposed method is an x-ray radiometric determination of the element content in a substance, which means that an analyte sample is irradiated with X-ray or gamma radiation, record the characteristic X-rays of the element being detected in two adjacent energy intervals of the instrument. primary radiation scattered by the sample and judged on the content of the element to be determined by the intensity ratio of the characteristic x-ray radiation of the element being detected and the scattered radiation. The counting rates of characteristic radiation in adjacent intervals serve to stabilize the transmission coefficient of the spectrometric tract to which the detector, preamplifier, main amplifier and discriminator belong. Stabilization is most often carried out by the difference in count rates in the adjacent energy intervals of the L3J spectrum. The disadvantage of the known method is the limited range of contents of the element being determined, at which stabilization is carried out effectively. The purpose of the invention is to expand the range of the measured contents of the element being determined. The goal is achieved by the method of X-ray radiometric determination of the content of an element in a substance, which consists in the fact that a sample of an analyte is irradiated with X-ray or gamma radiation, the characteristic X-ray emission of the element being detected is recorded in two adjacent energy intervals, the instrument spectrum and the primary sample scattering radiation and judge the content of a detectable element in relation to the intensities of the characteristic x-ray radiation and p the measured radiation, the intensity of the scattered radiation is also measured in two adjacent energy intervals in the peak area of the scattered radiation and control the transmission coefficient of the spectrometric path by an error signal proportional to the magnitude value. N, 4 N3 N-, 4-N5 N2 N4 where N ,, N ,, are the intensities of the characteristic X-ray radiation of a determined element in two adjacent energy intervals j N «4 of the intensity of the scattered breakdown of the primary radiation in two adjacent energy intervals, and the increase Interval numbers correspond to an increase in the energy of his radiation. FIG. 1 to 3 show the spectra of thorium radiation obtained by irradiating a solution containing chromium by the radiation of the IRIPL source on the base of the plutonium-238 nuclide. 4 is a block diagram of a device for implementing the method. The secondary radiation spectra contain the characteristic radiation peaks of chromium and the primary radiation scattered by the solution for low g / l in FIG. 1, medium (100 g / l) in FIG. 2 and high (300 g / l) in FIG. 3 concentrations of chromium oxide. As can be seen from FIG. 1-3, the use of the peak of the characteristic radiation of chromium for stabilization of the spectrometric path is difficult at its low concentrations, and the use of the peak of incoherently scattered radiation Рц-238 is difficult at high concentrations of chromium due to the smallness of the peaks. The proposed method allows to stabilize the spectrometric tract regardless of the concentration of the element being determined. Radioactive radiation from source 1 Rc-238 is directed to sample 2. 2. The characteristic radiation of chromium and scattered primary radiation is detected by detector 3 (NaJ crystal (Tl) and PMT-85) whose pulses are amplified by amplifier 4. The output of amplifier 4 is connected to inputs of differential discriminators 5-8, the outputs of which are connected to the inputs of the OR circuitals 9-12, respectively. The outputs of the OR 9 and 10 circuits are connected to the recording device 13, and the outputs of the OR 11 and 12 circuits are connected to the RS flip-flop inputs 14. The direct RS flip-flop output 14 is connected to the inverting input and the RS flip-flop inverse output 14 the input of the differential integrator 15, the output of which is connected to the regulating element 16. The output signal of the regulating element 16 controls the supply voltage of the detector 3 through the high voltage power supply unit 17. It is also possible to control the gain of the amplifier 4 or the differential voltage thresholds discriminators 5-8. The method is carried out as follows. Determination of the concentration of metal dubiters (chromium) in the technological processes, the folds of the leather industry using the device, the representation of go in FIG. 4, The sample of the solution of chrome tanning agent 2 analyzed is irradiated with a source of X-ray radiation, Ru, -238. The characteristic radiation of chromium and the scattered primary radiation of the Rc-238 are recorded with a NaJ (Tl) scintillation detector in combination with an FEU-85 PMT. From the output of the photomultiplier, electric pulses, whose amplitude is proportional to the energy of the detected quanta, arrive at the input of amplifier 4, the output of which is connected to the inputs of four different differential discriminators 5–8. The thresholds of the differential discriminators 7 and 8 are set so that they register the intensities N, and Nj of the characteristic radiation of chromium in two adjacent energy intervals 1 and 2 (Fig. 1), and the thresholds of the discriminators 5 and 6 are set so that they register the intensities of the scattered primary radiation in two adjacent energy intervals 3 and 4 (Fig. 1). The outputs of the discriminators 7 and 8 are connected to the OR 10 circuit, the output of which receives the total intensity N, + 2 characteristic chromium radiation, and the outputs of the discriminator 5 and 6 are connected to the circuit OR 9, the output of which receives the total intensity N + N scattered primary radiation. The outputs of the OR circuit 9 and 10 are connected to the recording device 13, with which the ratio of the intensities of the characteristic and scattered primary radiation is determined, the value of which is proportional to N. - according to the concentration of metal - du-, betel (chromium oxide) in the analyzed sample. The outputs of the differential discriminators 5 and 7 are also connected to the OR 12 circuit, the output of which receives the total intensity 2, + N4 in the energy intervals 2 and 4, and the discriminators 6 and 8 are connected to the circuit OR 11, the output of which half the total intensity NI + N3 in the energy intervals 1 and 3. The output of the circuit or 11 is connected to the 5th input of the 5th trigger 14, and the output of the OR circuit 12 is connected to the R. input of the R5 trigger 14. At the same time, the Q-code of the trigger 14 receives pulses with a duty cycle proportional to the ratio; Na —N4 a at the Q output of iH, + N, sb. duty ratio, proportional Outputs of the R5-Trigger Connected Na N4. yens with corresponding inputs of an int 15, whose output is with a mismatch signal equal to NZ + N Ng, -JLfu / li: Bb x-RcJ N, tN3 Mg + L4 where tr is the amplitude of the real 5-trigger pulse, RC. - constant integration. pacce f HOzOi

v.1

Lick HeKoief) SHfnHO

66 The error signal through the regulation element 16 controls the output voltage of the high-voltage power supply unit 17 of the PMT. The use of the proposed method expands the range of the measured contents of the element being determined, as the transmission coefficient of the spectrometric tract is stabilized regardless of the content of the element being determined.

Cr / GoS

P1 / -2E6

20, ka &

Claims (1)

, METHOD FOR X-RAY RADIOMETRIC DETERMINATION OF THE ELEMENT CONTENT IN MATTER, which consists in the fact that the sample of the analyte is irradiated with x-ray or gamma radiation, the characteristic x-ray radiation of the element being determined is recorded in two adjacent energy intervals of the instrument spectrum and the scattered element is measured for the primary radiation the ratio of the intensities of the characteristic x-ray radiation of the element being determined and the scattered radiation, about characterized in that, in order to expand the range of measured contents of the element being determined, the scattered radiation intensity is also measured in two adjacent energy intervals in the region of the scattered radiation peak and the transmission coefficient of the spectrometric path of the mismatch signal 4 is proportional to the value N ₂ + N ₄ + Ν _ή + 14¾ N ₂ + Ν ₄ where N ₂ are the intensities of the characteristic x-ray radiation of the determined element in two adjacent energy intervals, '' N $ .N <1 - the intensities of the primary radiation scattered by the breakdown in two adjacent energy ranges, and an increase in the interval number corresponds to an increase in the energy of the detected radiation.