RU2572063C1 - Device for detecting fission pulse shape - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: device for detecting the shape of a fission pulse relates to measurement equipment and can be used in nuclear physics when investigating physical parameters of pulsed nuclear research installations. The device comprises a signal receiving unit of a radiation detector which is in the form of a current-to-voltage converter, two measurement circuits, each consisting of, connected to each other, an operational amplifier connected to the output of the current-to-voltage converter and an eighteen-bit analogue-to-digital converter (ADC), one of the inputs of which is connected to a control and synchronisation unit, a data processing unit which includes elements which perform functions of selecting codes and measurement ranges, as well as storing data, wherein the data processing unit is provided with a function for automatic switching of measurement ranges of signals from the ADC.

EFFECT: high accuracy of detecting a neutron radiation pulse, faster detection and high reliability of the detecting device owing to the improvement of the circuit of the device for detecting a fission pulse shape.

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Description

The invention relates to measuring equipment and can be used in nuclear physics when measuring the physical parameters of pulsed research nuclear facilities (INR), for example, when registering the pulse shape of neutron radiation from nuclear reactors, in particular, as part of control and protection systems (CPS) of INR when working in pulse mode.

To increase the safety level of the work carried out at the INP, it is necessary to increase the accuracy and reliability of measuring the output characteristics of the facility, which include the shape of the neutron radiation pulse and the parameters of this pulse characterizing the intensity of the fission process.

A device for an automatic waveform recorder (Goryushkin SI., Ovchinnikov MA, Yakovlev Yu.N. An automatic waveform recorder in the KAMAK standard. PTE, No. 3, 1991, p. 227) containing an automatic normalizing amplifier (ANU), the input of which is the first input of the device of the automatic recorder of the waveform, a device for sampling and storage, an analog-to-digital converter, random access memory, a control unit, a controlled clock generator, a CAMAC interface. The output of the ANU through an operational amplifier is connected to the first input of the analog-to-digital converter, the second input of which is connected to the output of the control unit. The group of outputs and the first input of the control unit are connected respectively to the group of inputs and the output of the controlled clock generator, and the second and third inputs are the second and third inputs of the device of the automatic waveform recorder. The interface output is the output of the automatic waveform recorder device.

The disadvantage of this device is the dependence of the measurement error on the switching error when switching the measurement limits (exact amplitude fixation) in the analog part of the recorder (analog multiplexer in ANU), as well as limited functionality when automating the measurement process due to the inability to automatically adjust and correct some parameters ( gain, bias voltage, etc.).

The closest set of essential features to the claimed invention is a device for recording the pulse shape of a single fast-moving processes according to patent RU 2400762 (published. 09.27.2010, Bull. No. 27). The device contains a buffer amplifier, the output of which through the first operational amplifier is connected to the first input of the first analog-to-digital converter, the second input of which is connected to the first output of the control unit, the group of outputs and the first input of which are connected respectively to the group of inputs and output of the crystal oscillator, and the second and the third inputs are the first and second inputs of the device for registering the form of one-time fast processes, random access memory (RAM), communication interface, cat output Horn is the output of a device for registering the form of one-time fast processes, the first, second and third overvoltage protection circuits, the second and third operational amplifiers, the second and third analog-to-digital converters, the selection block of codes and measurement limits, the group of outputs of which is connected to the group of operational inputs a storage device, the group of inputs and outputs of which are connected to the group of inputs and outputs of the control unit, the second output of which is connected to the input of the communication interface, the input of the first circuit overvoltage is the third input of the device for recording the form of one-time fast processes, and the output is connected to the input of the buffer amplifier, the output of which is connected to the second overvoltage protection circuit connected in series, an operational amplifier and an analog-to-digital converter, and to the third overvoltage protection circuit connected in series , an operational amplifier and an analog-to-digital converter, the second inputs of the second and third analog-to-digital converters are connected With the first output of the control unit, the outputs and the group of outputs of the first, second and third analog-to-digital converters are connected to the corresponding inputs and groups of inputs of the block for selecting codes and measurement limits.

The disadvantages of this device include the fact that the dynamic range of signal registration in amplitude with its help is limited by the bit depth of the used ADC (12 bits), in addition, there is insufficient speed, and due to the large number of connecting lines between the elements, the reliability of the registration device is reduced.

The technical task of the invention is to improve metrological characteristics and expand the functionality of the device for recording the shape of the pulse division.

The technical result of the invention is to increase the accuracy of registration of a neutron radiation pulse, increase the speed of registration and increase the reliability of the registration device by improving the design of the device for recording the shape of the fission pulse. An additional technical result is to increase the recording range in time and amplitude.

The specified technical result is achieved due to the fact that in the device for registering the shape of the pulse division, containing the signal receiving unit of the radiation detector, two measuring paths, each of which consists of an operational amplifier (OA) connected to each other and an analog-to-digital converter (ADC) , one of the inputs of which is connected to a control and signal synchronization unit connected to a crystal oscillator, elements providing functions for selecting codes and measurement limits, as well as storing the results of walkie-talkie, the communication interface, the output of which is the output of the device for registering the shape of the fission pulse and which makes it possible to connect the registration device to a computer (PC), a current-voltage converter is used as the signal reception unit of the radiation detector, to the output of which the opamp of the measuring paths are connected , a generator with a clock frequency of at least 1 MHz was used as a crystal oscillator, an eighteen-bit ADC was used as an ADC, and elements providing selection functions The odes and measurement limits, as well as the storage of the registration results, are combined into a single data processing unit, while their operation algorithm is provided by a common control program, including the function of automatically switching the measurement limits of signals from the ADC, the data processing unit being connected to the control and signal synchronization unit and communication interface.

The use of a current-voltage converter as the signal reception unit of the radiation detector, to the output of which the opamp of the measuring paths are connected, has reduced the number of input elements, which has led to an increase in reliability, in addition, increased the speed of the device. The converter installed at the input of the device allows you to expand the passband, increase the noise immunity and clean the recorded signal from distortion, which leads to an increase in the accuracy of registration, and also extends the range of registration in amplitude.

The use of a generator with a clock frequency of at least 1 MHz as a crystal oscillator increases the reliability, accuracy and speed of devices, in addition, extends the time range of registration.

The use of an 18-bit ADC instead of a 12-bit ADC in the measuring paths made it possible to expand the measurement range in amplitude by two orders of magnitude, thereby increasing the accuracy of recording the shape of a neutron radiation pulse. In addition, the number of measuring paths was reduced from three to two, which ensured the reliability of the device, and also by reducing the number of "digital switching" between the measurement limits, it increased its speed.

The combination of elements providing the functions of selection of codes and limits of measurement, as well as data storage in a single data processing unit, allowed to reduce the number of elements, which led to increased reliability and increased speed, and also allowed the use of a more advanced microprogram of the control of the registration device, which provides increased reliability and measurement accuracy. In particular, it is possible to divide the signal recorded in the device memory into N sections (where N is in the range from 1 to 16), which are recorded with different frequencies, which allows registering significant sections of the pulse with greater accuracy and expanding the measurement range in time.

The connection of the data processing unit with the communication interface allows data transfer directly to the PC without additional elements, which ensures the efficiency, reliability and noise immunity of the communication line of the recording device with an external PC.

The presence of the function of automatic switching of the measurement limits of signals from the ADC in the data processing unit also ensures the efficiency and reliability of the registration device, in addition, automatic switching without additional external commands allows for increased measurement accuracy.

The invention is illustrated in the drawing, which shows a block diagram of the inventive utility model, where

1 - neutron detection unit;

2 - current-voltage converter;

3 - the first op-amp with differential output and gain 1;

4 - the second op-amp with differential output and gain 100;

5 - the first ADC;

6 - second ADC;

7 - control and synchronization unit;

8 - data processing unit;

9 - communication interface;

10 - PC;

11 - biological protection;

12 - input (terminal) of the START signal;

13 - input (terminal) of the external clock signal.

An example of a specific implementation of the present invention can be a device for recording the pulse shape of fission pulsed INR, used to study the shape of neutron radiation pulses in a wide range both in amplitude and in duration with the output of the received information to a personal computer (PC) for subsequent processing (calculation of the parameters of the momentum of the fission of the BIN)

The device for recording the pulse shape of the pulsed pulsed INR has the following technical characteristics: maximum voltage at the input of the ADC - 10 V; ADC capacity - 18 bits; dynamic range in amplitude - 10 ⁷ ; internal sampling rate - from 1 to 10 MHz; bandwidth - from 0 to 500 KHz; relative measurement error - ± 0.05%.

The detection unit (1) converts the energy of neutron radiation into a proportional electric charge (current). As a detection unit, an ionization fission chamber, a current ionization chamber, a vacuum emission diode, and others can be used.

The current signal from the detection unit (1) through biological protection (11) is fed to the current-voltage converter (2), and then to two parallel measurement paths: the first op-amp (3) and ADC (5) and the second op-amp (4) and ADC (6). The first ADC (5) and the second ADC (6) are used to convert the instantaneous values of the samples of the amplitudes of the input voltage into a digital code.

The device is launched through the START input (12). The device provides external clocking via VN.TACT input (13) or internal clocking from the built-in quantum generator, which is part of the control and synchronization unit (7).

The control and synchronization unit (7) is designed to organize the start of the process of registering and issuing clock signals for the ADC (5, 6) and the data processing unit (8).

The data processing unit (8) serves for switching codes from the first and second ADCs (5, 6), decrypting the measurement limits, converting the output code, automatically switching the measurement limits (“digital switching”), storing the measurement results in internal RAM, and organizing the exchange of information via the communication interface (9) with a PC (10).

The communication interface (9) is used to connect the registration device to a PC (10), on which control software is installed to set the registration modes and process the received data.

The operation of the device is as follows.

The device for registering the pulse shape of the divisions uses the start-stop method of starting with a fixed recording of the signal history. Before taking the measurement, the part of the RAM memory bank of the data processing unit (8) allocated to the history is determined and set. The number of sites and the frequency with which registration is made at each site are also set. All these operations are performed according to the commands received from the PC (10) through the communication interface (9). Then the device is transferred to the "Measurement" mode, in which the input signal is encoded and the codes are entered into the memory of the data processing unit (8) cyclically without stopping from ADC1 (5) and ADC2 (6) with a given frequency.

The current signal from the detection unit (1) through biological protection (11) is fed to the current-voltage converter (2), and then to two parallel measurement paths: the first op-amp (3) and ADC (5) and the second op-amp (4) and ADC (6). The first ADC (5) and the second ADC (6) converts the instantaneous sample values of the amplitudes of the input voltage into a digital code with a frequency coming from the control and synchronization unit (7) and converted in the data processing unit (8).

The obtained digital values of the amplitude come from the outputs of the first ADC (5) and the second ADC (6) to the inputs of the data processing unit (8), where they are multiplexed depending on the value of the overflow bit of each ADC, which uniquely determines the number of the measurement limit at which registration was performed . The value of the digital code is decrypted and recorded in the RAM cell, which is part of the data processing unit (8), indicating the measurement range. The contents of RAM are filled in cyclically and marked as "history".

On the leading edge of the signal arriving at the START terminal (12), which is transmitted via the control and synchronization unit (7) to the data control unit (8), or by a command from a PC (10), which is transmitted via the communication interface (9) to the unit data control (8) (the beginning of the history recording), the history counter starts working, which, after completing the write cycles to the memory, generates the signal of the end of the conversion. Thus, in the data processing unit (8), information obtained before the start-up signal arrives (history = total memory - the number of history points) and information obtained after the start-up signal (history).

The data processing unit (8) forms a sign of completion of the registration process, the state of which is read through the communication interface (9) on the PC (10).

Further, according to the commands received from the PC (10) via the communication interface (9), the registration results are read from the data processing unit (8) for subsequent processing (calculation of the pulse parameters of the INR fissions).

Thus, the inventive device has an extended measurement range in time and amplitude, as well as increased measurement accuracy, increased speed and reliability of registration compared to the device, which is the closest analogue.

The industrial applicability of the invention is determined by the fact that the device for recording the pulse shape of the divisions of pulsed INR can be manufactured using well-known technology from known components and materials and used in measuring systems and CPS of INR.

A prototype device was manufactured, the tests of which confirmed the feasibility and practical value of the claimed invention.

Claims (1)

A device for registering the shape of the fission pulse, comprising a radiation detector signal receiving unit, two measuring paths, each of which consists of an operational amplifier (OA) connected to each other and an analog-to-digital converter (ADC), one of the inputs of which is connected to a control unit and synchronization of signals connected to a crystal oscillator, elements providing functions of selection of codes and measurement limits, as well as storage of registration results, a communication interface, the output of which is the output of the device TWA for registering the shape of the fission pulse and which provides the ability to connect the registration device to a computer (PC), characterized in that a current-voltage converter is used as the radiation detector signal receiving unit, the opamp of the measuring paths are connected to its output as a crystal oscillator a generator with a clock frequency of at least 1 MHz was used, an eighteen-bit ADC was used as an ADC, and elements providing functions of selection of codes and measurement limits, as well as storage I registration results are combined into a single data processing unit, while their operation algorithm is provided by a common control program, including the function of automatically switching the signal measurement limits from the ADC, the data processing unit being connected to a signal control and synchronization unit and a communication interface.