SU824767A1 - Ionizing radiation detector - Google Patents

Description

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The invention relates to the field of dosimetry, spectrometry and radiometry of ionizing radiation, and more specifically to ionizing radiation detection units having a device for remote performance monitoring.

Detection blocks are known, consisting of a proportional detector (e.g., scintillation), a pulse filter designed to select pulses with a center frequency proportional to the measured value (e.g., amplifier and discriminator), and devices for remote performance testing, an LED located in front of the photomultiplier 1. When a sequence of current pulses of a certain shape and amplitude is applied to the LED, light flashes occur, which are detected by the photumum ozhitelem. The presence at the output of the pulse detection unit with a predetermined frequency is perceived as information about the serviceability of the detection unit.

The disadvantage of the device is incomplete control — the scintillator is not tested.

The closest technical solution to the claimed is an ionizing radiation detection unit consisting of

from a proportional detector connected in series with a pulse filter of signals coming from the detector, and a device for remote performance monitoring, containing a control radiation source 2.

In a known detection unit, a device installed in front of the detector, containing a control source, mounted on the movable core of the electromagnet and made in the form of a cross-shaped substrate, which is covered with a slotted screen (blender), is used for remote monitoring of operability. Although in this case the whole measurement path is monitored, the device has several significant drawbacks. The use of an electromechanical source drive reduces the reliability of the detection unit. An increase in the intrinsic background due to partial passage of radiation through the screen impairs the metrological characteristics. Finally, in the test mode, the loading of the detecting unit increases markedly, which in a number of cases leads to a decrease in the stability of the parameters of the detecting unit (for example, when the scintillation counter of gamma quanta increases from 1 to 10 quantum / s

the photomultiplier gain is changed by 10%).

The object of the present invention is to increase the reliability while increasing the stability of the measurements.

This goal is achieved by the fact that an ionizing radiation detection unit, consisting of a proportional detector connected in series with a pulse filter of signals coming from the detector, and a device for remote performance monitoring, containing a monitoring radiation source, was additionally introduced a node for remotely changing parameters pulse filter, and as the reference radiation source, a source was chosen, the radiation energy of which is less than that recorded from PhD, and remote output node for changing the pulse filter parameters connected with the control inputs of the pulse filter, and controlling the radiation source is mounted in front of the detector.

FIG. 1 shows a block diagram of the detection unit; in fig. Figure 2 shows the spectra of the amplitudes of the pulses from the radiation of the reference source and the recorded radiation, as well as the position of the discrimination thresholds of the selector, the input s composition of the pulse filter.

The detection unit (Fig. 1) includes: a scintillation detector consisting of scintillator 1 and photomultiplier 2; a pulse filter, which includes a pulse amplifier 3 and a differential discriminator (selector) 4, and a node 5 for changing the parameters of a pulse filter having an input terminal 6. An ionizing radiation source 7 is installed in front of the scintillator; whose energy is lower than the energy of the radiation detected by the detection unit.

The operation of the detection unit is as follows.

When gamma rays enter the scintillator (1), light flashes form in it, which are converted by the photomultiplier 2 into current pulses. Etn pulses after amplifier 3 pass through an amplitude selector to the output of the detecting unit. The discrimination levels of the selector (and the “wick in Fig. 2) are set to the transmission of pulses, the amplitude of which corresponds to the energy of the detected radiation. If it is necessary to conduct a performance check, the control signal drops to the input 6 of the node 5. This signal increases the gain, and the degree of increase corresponds to the ratio of the radiation energies of the recorded database and the control source. At the same time, if necessary (if the selector window when registering the main radiation is too wide), device 5 reduces the discrimination level of the selector (translates to the Lfg position in Fig. 2). With

In this case, the selector window will receive pulses from the quanta of the reference emitter, and the amplitude of the pulses due to the detected radiation will be higher than the passband of the selector, and they will

0 does not pass to the output of the detection unit. A change in the gain (and the discrimination threshold) can be made by changing the division factor in the output divider (or divider).

the reference nanometer in the selector), for example, by connecting parallel additional resistors using reed relays. Such changes have absolutely no effect on the operation modes of these nodes.

 The radiation intensity of the reference source is chosen close to the maximum load of the detecting unit. Therefore, an almost unchanged current flows through the photomultiplier, as in the mode

5 measurements (at any load), and in control mode.

Prototypes of the proposed device were tested within 6 months. As a result of the tests, it was established that the stability of measurements during continuous operation for 24 hours is 2.5 times higher than that of the detection unit, which uses a blender to monitor the operability. At the same time, the establishment of the operating mode was reduced by 2 times. The reliability estimates show that the average uptime of the detection unit constructed according to the present invention is 25% higher than that of the detection unit with blenker.

Formula of Invention

An ionizing radiation detection unit, consisting of a proportional detector, connected in series with a pulse filter of signals from the detector, and a device for remote sensing performance, containing a control radiation source, characterized in that, in order to increase reliability while simultaneously increasing the measurement stability, a node was additionally introduced into the detecting unit for remotely changing the parameters of the pulse filter, and as a control radiation source You have selected a source whose radiation energy is less than

the energy of the detected radiation, the output of the node for remotely changing the parameters of the pulse filter is connected to the control inputs of the pulse filter, and the control radiation source

installed in front of the detector.

Sources of information, (Prmnaty in (in the case of dmsierze 1. Manor S. Hauke D. Nuclear Instrument

and Methods 8, 331, 1960.

2. USSR author's certificate No. 265299, cl. GO IT 1/00, 1964 (prototype).

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In FIG. 2

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Claims (2)

Claim The ionizing radiation detection unit, consisting of a proportional detector connected in series with a pulse filter of signals coming from the detector, and a device for remote health monitoring, containing a control radiation source, characterized in that, in order to increase reliability while improving measurement stability, the detection unit additionally introduced a node for remote changing the parameters of the pulse filter, and as a control source In this case, a source is selected whose radiation energy is less than the energy of the detected radiation, and the node output for remote change of the pulse filter parameters is connected to the control inputs of the pulse filter, and a control radiation source is installed in front of the detector. 'Sources of information, (Taken into account in the examination 1. Nemp S Hauke D. Nuclear Instrument and Methods 8, 331, 1960. 2. Copyright certificate of the USSR No. 265299, cl. G01T 1/00, 1964 (prototype). / Fig. 1