SU1131333A1 - Device for measuring small variations of intensity of nuclear particle flux - Google Patents

Abstract

A DEVICE FOR MEASURING SMALL VARIATIONS OF THE INTENSITY OF A NUCLEAR PARTICLE FLOW, containing two nuclear particle detectors, a two-channel amplifier-shaper, integrator, key, power supply, bus, and measuring unit, different in that, in order to increase reliability and accuracy, it has to be used. pulses, a switch and an external sensor in the form of a switch, and the measuring unit is made in the form of two pulse counters, the counting inputs of which are connected to the output of the pulse generator and to the control at the input of the key, connected by its output to the common bus, and by the information input to the integrator's output, the nuclear particle detectors connected to the terminals of opposite power supply voltages are connected to the integrator's input, the output of which is connected to the input of a two-channel driver, connected by its outputs to the corresponding inputs of the switch, the outputs of which are connected to the control inputs of the corresponding pulse counters, and the control input of the switch is connected through the external sensor to the common bus.

Description

WITH

00 00 00 The invention relates to the field of nuclear electronics, and humanely to the measurement of small variations in the intensity of nuclear radiation arising from external influences. Such measurements are usually carried out by determining the variation of asymetry that occurs with etcee in the number of events detected by the nuclear radiation detector in the presence and absence of H; detector count with exposure; Nj is the detector count with no effect. A device 11 is known that contains two nuclear particle detectors, an amplifier and a switch device, where the differential current of the detectors is measured to determine small variations in the nuclear particle flux of nuclear particles. Both detectors are in the same source field: The intensity of the particle flux varies under external influence, the other outside this area, the only thing that is known about the device is the low accuracy and accuracy of the measurements, due to the fact that) the stability of the measuring device The temperature exceeds the measured intensity variations of the nuclear radiation. The closest technical solution is the difference intensity meter J2, which contains two nuclear particle detectors, a two-channel amplifier-shaper, an integrator, a power supply source, a common bus, and a measuring unit. The disadvantage of this device is the low accuracy and accuracy of the measured, due to the fact that the error of the measuring unit exceeds the values of the measured nuclear radiation intensity. The aim of the invention is to increase the reliability and accuracy of measuring small variations in the intensity of nuclear radiation caused by external factors. impacts. The goal is achieved by the fact that the device containing two nuclear particle detectors, a two-channel amplifier-shaper, an integrator, a capacitor, a power source, a common bus and a measuring unit, a pulse generator, a switch, an external sensor in the form of a switch, and the block is made in the form of two pulse counters, the counting inputs of which are connected to the output of the pulse generator and to the control input of a key connected by its output to the common bus and information input to the integrato output Pa, with nuclear particle detectors connected to the opposite polarity of the power supply, are connected by their outputs to the input of an integrator, the output of which is connected to the input of a two-channel amplifier –former connected by its outputs to the corresponding 01Ц1 {m inputs of the switch, the outputs of which are connected to the control inputs of the corresponding pulse counters, and the control input of the switch is connected via an external sensor to the common bus. FIG. 1 is a block diagram of a device for measuring small variations in the intensity of nuclear particle flux; in fig. 2 is the probability integral function of the instantaneous value of the fluctuating voltage on the integrator capacitor; in fig. 3 shows the dependence of the gain on the integrator time constant. A device for measuring small variations in the flux density of nuclear particles (Fig. 1) contains two detectors 1 and 2 nuclear particles, integrator 3, dual-channel amplifier-4, switch 5, two counters 6 and 7 pulses, pulse generator 8, switch 9 and sensor 10 external influence. The outputs of the detectors 1 and 2 nuclear particles, located respectively in the variable zone and outside it, are connected by their outputs to the input of the integrator 3, the output of which is connected to the information input of the key 9 and to the input of the two-channel amplifier of the driver 4 connected to the corresponding inputs of the switch 5 , the control input of which is connected via an external sensor 10 to a common bus and outputs to the control inputs of counters 6 and 7 pulses connected by their counting inputs to

31

the output of the pulse generator 8 and to the control input of the key 9, the output of which is connected to the common bus.

The device works as follows.

The detectors 1 and 2 of the nuclear particles are under the influence of the same source of nuclear radiation, so that the instability of the source itself over time is practically excluded. The differential current from the output of the detectors 1 and 2 nuclear particles is fed to the input of the integrator 3, the voltage at the output of which at each time instant will be determined by the difference in charges from the outputs of both detectors. 1 and 2 nuclear particles, and the time constant 1 of the integrator 3. The voltage at the output of the integrator 3, fluctuating with respect to zero, is fed to the input of a two-channel amplifier, Former A, whose operating point stability is maintained by introducing deep negative feedback to it. the input to the input with a time constant, much longer than the time constant of the integrator 3 and the period of external influence. At the outputs of the dual-channel amplifier 4, at the moments when the input fluctuating voltage passes through zero, the potentials of +0.2 V and -10 V are set for a positive value of the input voltage and -10 V and +0.2 V for a negative value . The outputs of the two-channel amplifier 4 through the switch 5, controlled by the signal from the output of the external sensor 10, are connected to the control inputs of the counters 6 and 7 pulses

The counting inputs of counters 6 and 7 pulses continuously receive pulses from the generator output 8 pulses. The period of the pulses coming from the generator of 8 pulses is less than the time constant of the integrator 3. At least once a pulse from the generator of 8 pulses will occur for each change of polarity of the voltage at the output of the integrator 3. Depending on the polarity of the voltage at the output of the integrator 3, these pulses will be considered a counter of 6 or 7 pulses. Using switch 5 synchronously with the appearance and disappearance of the signal from the sensor output

334

10 external actuation control inputs of the sensors 6 and 7 of the pulses are interchanged. This makes it possible to eliminate possible asymmetry in the counting of counters 6 and 7 of pulses that are not related to the measured variation. With this, the change of the Nfe-N / p ema asymmetry of x is on

MB-K,

impulses counters 6 and 7 impulses

.,, I Srtit is enhanced in k-y -;:;: - by

compared with the asymmetry of the initial variation of the flux of nuclear particles in the region recorded by the detector 1 of nuclear particles. .

In the above expressions: Nj, N7 is the number of pulses counted respectively by counters 6 and 7 pulses;

 - number of nuclear particles in

second recorded in each of the detectors 1 and 2 nuclear particles;

о - constant integration of integrator 3.

The basis of gain is based on the following. If there are two nuclear particle detectors, one of which is located in a variable flow and registers m, ± ± particulates per second, and the other is in a constant flow and registers m particles per second, then the difference current from two nuclear detectors that are turned on towards each other particles will create a high intensity integral

Rattor ct) RC voltage (t,

where O is the capacity of the integrator;

Q is the charge arising in the detection of nuclear particles upon registration of a single particle. If n, mj, then the average

° i, voltage value of ± -umt j

however, there is a fluctuation of this april relative to the mean, since the values of hi, and t have a statistical scatter. The magnitude of this fluctuation is defined as m, -m2 and may be large compared to the effect of urn, however, the manifestation of the effect against its background turns out to be strong compared with its manifestation on). Let us estimate this effort. Assume contribution to fluctuating

51

voltage dU at time1 0, created by the statistical scatter of particles that arrived in the time interval j-t-b time ago. This contribution is caused by the fluctuation (rn + lrr ui / Y2rnJ- (: events. The rms value of the potential associated with

I

this fluctuation - mlT to the moment

 .one

 decreases S / S times. Thus, the root mean square contribution di to the value of the LU will be from the time interval that is i from the moment t 0. Over time to i 0, these contributions add up quadratically

tufl

- it

di

Hence the absolute rms

will be equal

 - Nrni

v

ABOUT

((

oh (

 24Tv

The instantaneous values of the fluctuating voltage on the capacitor of the integrator measured at regular intervals should follow the normal distribution law:

- (E € -)

2Z

about - relative value

Where

2V

instantaneous voltage fluctuations;

.And - initial asymmetry 2

Particle Flow Variations 2 shows the integral function of this distribution from-oo.

 (g-aef ig

- (. ". O-2-kl

- with

which yields the asymmetry X of the sum of the number of events with e. and iV. ABOUT

X 2A-1.

From here you can determine the gain factor:

.

K 3 "Zee

- just

 , R

1 gi (

° and

31333

If you have m-v units / s nuclear particle detector loads, you can get gain factors K 160-1600. The experimental values — the ratios of the obtained asymmetry X to the initial asymmetry of the EG, 0.910, and the dependence of the gain factor K f (C) on the constant time of the integrator are shown in FIG.

The introduction of the key 9, which periodically discharges the capacitance of the integrator 3, makes it possible to quickly determine the accuracy of the result obtained, since the measurement accuracy is determined by the total number of counted pulses from the generator 8 pulses.

If after each pulse from the generator 8 pulses through the key 9 (Fig. 1) to discharge the capacity of the integrator 3, then the gain will be:

TO

where T is the pulse following period

from the generator 9 pulses. In this case, when a pulse arrives from the generator, 8 pulses are bu-. The sign of the voltage at the output of the integrator 3 accumulated during the period between pulses will be determined. For this, the integrator time constant should be much longer than the period T. In this case, the static measurement error is directly related to the number of pulses O counted during the measurement time, and

looks like

and the value is attributed to

a statistical statistical problem in measuring the desired effect

.

t

Imtn

The use of the invention makes it possible to measure the asymmetry in the counting of two nuclear radiation detectors in the order of 10 -10 parts of the total count of each detector using simple counting technology. At the same time, there is no need to use expensive and precision equipment, such as analog-digital converters, electronic computing

large-capacity memory devices, input / output information devices in digital codes, which are commonly used to measure small asymmetries in the count of nuclear particle detectors. Requirements for stability and accuracy of instrumentation

reduced by (times comparing with existing devices of similar purpose.

f% M 0--

+ 0.26

J l

Ypres

Bi.

-0

+ W

Figure 1 (/ J, t, f; rfj

Claims (1)

DEVICE FOR MEASURING SMALL VARIATIONS OF NUCLEAR PARTICLE FLOW INTENSITY, containing two nuclear particle detectors, a two-channel amplifier-former, an integrator, a key, a power supply, a common bus and a measuring unit, characterized in that, in order to increase the reliability and accuracy of measurement, they are introduced into it a pulse generator, a switch and an external impact sensor in the form of a switch, and the measuring unit is made in the form of two pulse counters, the counting inputs of which are connected to the output of the pulse generator and to the control the key’s input, connected by its output to the common bus, and the information input - with the integrator’s output, and the nuclear particle detectors connected to the terminals of the opposite polarity of the power supply are connected by their outputs to the integrator’s input, the output of which is connected to the input of the two-channel amplifier a shaper connected by its outputs to the corresponding inputs of the switch, the outputs of which are connected to the control inputs of the respective pulse counters, and the control input of the switch is connected to Res external impact sensor to a common bus. With 1 1131333