SU1082154A1 - Downhole gamma-spectrometer - Google Patents

Abstract

1. BOTTOM GAMMA-SPECTT ROOMTER containing two pajD detectors (Ho active radiation, connected through a device for generating eranal impulses, a communication cable and a coupling capacitor with an ungrounded terminal of the matching resistor and an inverting amplifier input, the output of which is connected to the input of the separation device of different impulses, the outputs of which are connected to the inputs of the first and second adjustable amplifiers, an analog-to-digital converter, the outputs of which are connected to the inputs of the device are given and OKROi amplitude amplitude information processing unit, two reference outputs of which are connected to the control inputs of the first and second adjustable amplifiers, and information outputs are connected to the recorder's inputs, which are different, in order to improve the measurement accuracy and simplify the device, zero level. S E utsh 1., -..., L. 2,; | summing amplifier, first and second, swarm sensitive discriminators, OR element and transmission device, the output of the amplifier being connected to its non-innovative the rotating input through the zero-level binding device, the outputs of the first and second controllers are connected to the first and second inputs of the summing amplifier and to the inputs of the first and second sensitive discriminators, respectively, whose outputs are connected to the control inputs of the transmission device and through the OR element to the control input devices of zero-level binding, the output of the -sampling amplifier is connected to (L input of the analog-digital converter, and the outputs of the device for setting digital signals through the transmission devices are connected to the inputs of the information processing unit .. 2. Device. according to claim 1, which means that the zero level device contains 00 the first and second terminating resistors, the delay line, the first and second diodes , normally closed-loop controlled single-pole switch, operational amplifier and capacitor, with the input, zero-voltage devices with a first matching resistor, a delay line and a second matching resistor connected to the anode of the first and the cathode of the second diode At ztom first cathode and the anode of the second diode is grounded, and to the input of a controllable SPST switch, whose output is connected to the inverting input of the operational amplifier neinverti

Description

whose input is grounded, and you-. the stroke is the output of the zero-level device and, through a capacitor, is connected to the inverting input of the operational amplifier, the control input of the device of the zero, zero level is connected to the control input. Normally I will close my unipolar key.

3. The device according to claim 1, wherein the transmission device comprises single vibrators and a distributor, wherein the inputs of the transmission device through the single vibrators are connected to its outputs, and the inhibit inputs of the single vibrators through the distributor are connected to the first and second control inputs of the transmission device.

The invention relates to instruments for measuring ionizing radiation and can be used to search for and assess minerals in natural occurrence using nuclear geophysics methods.

A wellbore gamma-spectrometer is known, containing a series-connected nuclear radiation detector, a shaping circuit, a communication cable, an adjustable amplifier, the output of which is connected through parallel first and second differential channels and the integral channel is connected to the inputs of the information processing unit and through the control channel to the control input gain adjustable amplifier.

A disadvantage of this device is the impossibility of organizing the transmission and measurement of spectral information from two radiation sensors, which reduces the functionality of the device.

Closest to the invention is a downhole gamma spectrometer comprising two radioactive radiation detectors connected through a device for generating multi-polar pulses, a communication cable and a coupling capacitor with an ungrounded output matching resistor and an inverting amplifier input, the output of which is connected to the input of the separation device of different polarity pulses, the outputs of which are connected to the inputs of the first and second adjustable amplifiers, an analog-to-digital converter, the outputs of which

connected to the inputs of the setup device for setting the digital amplitude windows, and the information processing unit, two repo outputs of which are connected to the control inputs of the first and second adjustable amplifiers, and information outputs connected to the inputs of the recorder.

A disadvantage of this device is the low measurement accuracy associated with the zero-level fluctuation at the input of the separation device of polar-polar pulses, which leads to an additive error in the measurement of the spectral distribution of the radiation under study. In addition, it contains two signal processing devices operating in parallel, including two amplitudes M) 1x discriminator, which complicates the device as a whole and is not justified, since two pulses belonging to different detectors cannot appear at the same time. The presence of two parallel-connected amplitude discriminators introduces additional error due to the non-identity of their characteristics.

The purpose of the invention is to increase the measurement accuracy and simplify the device.

This is achieved by the fact that the proposed downhole gamma-spectrometer additionally contains a zero-level binding device, a summing amplifier, first and second sensitive discriminators, an OR element and a transmission device, the output of the amplifier being connected to its non-inverting input through a zero-binding device 5, outputs The first and second adjustable amplifiers are connected to the first and second junction inputs of the common amplifier and to the inputs of the first and second sensitive discriminators, respectively, The ports of which are connected to the control inputs of the pass-through device and through the OR element are connected to the control input of the zero-level device, the output of the summing amplifier is connected to the input of the analog-digital converter, and the outputs of the digital amplitude setting window through the pass-through device are connected by d inputs of the processing unit information. In addition, the zero level device contains the first and second matched resistors, the first and second diodes control line, the normally closed single-pole switch, the operational amplifier and the capacitor, and the input of the zero level device through the first matching resistor, delay line and the second terminating resistor is connected to the anode of the first and the cathode of the second diode, while the cathode of the first and anode of the second diode is grounded and to the input of a controlled single-pole switch, the output of which is connected to the inverter The operating input of the operational amplifier, the non-inverting input of which is grounded, and the output is the output of the zero-level device and connected through a capacitor to the inverter through the input of the operational amplifier, the control input of the zero-level device is connected to a normally closed single-pole key. In addition, the transmission device contains single vibrators and a distributor, the inputs of the transmission device through the single vibrators are connected to its outputs, and the inhibit inputs of the single vibrators through the distributor are connected to the first and second control inputs of the transmission device. In FIG. 1 is given a functional diagram of a downhole gamma spectrometer; in fig. 2 is a diagram of a zero level device; in fig. 3functional scheme of the device skip; The blackened arrows point 546 to connect the individual terminals of the device, and the blackened ones - groups of terminals. The device contains a downhole device I consisting of detectors 2 and 3 of radioactive radiation and device A of generating different polarity pulses, a communication cable 5, a split capacitor 6, terminating resistor 7, amplifier 8, device; 9 zero level adapters, a device 10 for separating bipolar pulses, a first 11 and a second 12 adjustable amplifiers, a summing amplifier 13, an OR element 14, a first 15 and a second 16 sensitive discriminators, a recorder 17, an information processing unit 18, a transmission device 19, a device 20 digital amplitude window settings, analog-to-digital converter 21 .. V Zero-level device 9 contains control input 22, output 23 and input 24 terminals, first matching resistor 25, delay line 26, 1 second matching register 27, the first 28 and second 29 diodes, controlled by a normally closed single-pole switch 30, a capacitor 31, an operational amplifier 32. The transmission device 9 contains first 33 and second 34 control inputs, a distributor 35, one-shot 36-1 .. .36-S. , inputs 371 ... 37-S and outputs 38-1 .... 38-S. The outputs of the radiation detectors 2 and 3 through the device for forming multi-polar pulses, the communication cable 5 and the separation capacitor 6 are connected to the first input. do the amplifier 8 and the cable terminating resistor 7 - to the bus ground. The output of the amplifier 8 is connected to the input of a device 10 for separating bipolar pulses and through the device 9 of zero-level coupling to the second input of the amplifier 8. The outputs of a device for separating bipolar pulses 10 through the first 11 and second 12 adjustable amplifiers. Are connected to the inputs of the summing an amplifier 13, the output of which is through an analog-digital converter 21, a device for setting digital amplitude windows, a transmission device 19 and an information processing unit 18 are connected to the inputs of the recorder 17. Two separate outputs of the unit 18 The information flows are connected to the control inputs of the first 11 and second 12 adjustable amplifiers, and their inputs are connected to the inputs of the first 15 and second 16 sensitive discriminators, whose inputs are connected to the control inputs of the transmission device 19 and to the inputs of the ITY 14, the output of which is connected to the input The device of the 9 strapping zero. Level.

The terminal 24 of the zero-voltage device 9 is connected via the first terminating resistor 25, the delay line 26 and the second matching resistor 27 are connected to the anode of the diode 28 and the cathode of the diode 29, and the cathode and anode of the diode 28 and 29 are respectively grounded A normally open closed key 30, the output of which is connected to the first input of the operational amplifier 32, the second input of which is grounded, and the output is the output of the zero-clamping device 9, and is connected via a capacitor 31 to the first input of the operating amplifier. 32.

The inputs 37-1 ... 37-S of the transmission device 19 through the single vibrators 36-1 ... 36-S are connected to its outputs 38-1.,. 38-S, respectively, and the outputs of the ban on one of the selectors 361 ... 36-S through the distributor 35 are connected to the first 33 and second 34 control inputs of the transmission device 19. , . The device works as follows. . The pulses from the output of the radiation detectors 2 and 3 are fed to the input of the device for the formation of different polarity pulses, which expands and transmits the pulses of the detectors 2 and 3 to the communication cable 5 in such a way that the pulses belonging to different detectors have different polarity and can occur at the output of a device for forming opposite-polarity pulses simultaneously. From the output of the cable 5, the voltage across the voltage across the coupling capacitor 6 is fed to the terminating resistor 7 and then to the inverting input of the amplifier. The amplifier 8 is caught by the negative feedback through the zero-voltage device 9, which turns on when there is no input pulse of the amplifier 8 and turns off when present. This is accomplished by compensating for the offset of the left and left levels at the output of the amplifier 8,

which arises due to the recharge and separation capacitor 6.

The amplified voltage pulses are fed to the input of the device 10 for the separation of equipolar pulses, made, for example, as described in the prototype. At the same time, voltage impulses of the same polarity appear at the outputs of the device 10, with pulses corresponding to the first detector 2 appearing at the first output, and corresponding signals to the second detector 3 appearing at the first output. Pulses from the first and second outputs of the device 10 for separating different polarity pulses arrive at the inputs of the first 11 and second 12 adjustable amplifiers with adjustable gain, serving for the purpose of automatic stabilization

energy scale. The output pulses of adjustable amplifiers 11 and 12 are supplied to the inputs of summing amplifier 13, at the output of which pulses of the same field occur, regardless of whether the detector has this pulse. In addition, the output pulses of adjustable amplifiers 11 and 12 are fed to the inputs of sensitive discriminators 15 and 16, respectively. When a pulse is applied to the input of any of the sensitive discriminators 15 and 16, an output pulse, normalized by ashlititude, appears at its output, whose duration is equal to the duration of the input pulse. The output pulses of the discriminators 15 and 16 are indicative of the belonging of the output pulse of the summing amplifier 13 to the first 2 or second 3 radiation detector and control the operation of the transmission device. In addition, through the IDN element 14, the control input of the zero-level device 9, these pulses turn off the device 9 for the duration of the next information pulse from LR9 of Detectors 2 and 3. Such organization of the zero-level device operation allows you to restore the Zero the output level of the amplifier when working with voltage impulses of different polarities. The amplitude of each output pulse of the summing amplifier 13 is converted into a digital code with an analog-to-digital converter 21. Next, the digital amplitude code is fed to the input of the digital, amplitude window 20, which allows you to install S windows. A pulse, whose amplitude falls into the 1st window, causes a signal at the 1st output of the digital amplitude setting device of the Windows 20. The first k windows are set on the measured spectrum from the first radiation detector 2, and the remaining S-kOKOH is measured the spectrum from the second detector 3. The number k can be chosen arbitrarily in the range from O to S. With the help of the transmission device 19, information pulses belonging to the first or second detector are distributed along the corresponding information channel lam Thus, if a signal is output at the output of the sensitive discriminator 15 (which indicates that the information pulse has been assigned to the first detector 2), the transmittance device 19 blocks the last S-k OUTPUTS of the device to set the digital amplitude windows 20 and passes signals only from its first k outputs. When a pulse appears at the output of the sensitive discriminator 16, the situation is reversed. Such a blocking is necessary in order to eliminate spurious signals at the outputs of the digital amplitude window setting device 20. Indeed, when arbitrary Ohms are located, the scientific research institute amplifies the first and second windows radiation detectors 2 and 3, the pulse belonging to the first detector 2 may appear in some of the windows belonging to the second detector 3j No signals are received from the output of the skip device 19 on the S inputs of the information processing unit 18, in which the processing of pulse signals is performed according to a given algorithm (measurement of the difference or ratio:, intensities, background subtraction, calculation of the percentage of the useful component, etc.). The result of the processing is recorded by the recorder 17. In addition, information processing unit 18 contains two systems for automatically stabilizing the energy scale on a reference signal for each of detectors 2 and 3. The error signals are fed to the gain control inputs of amplifiers II and 12. In FIG. 2 shows a functional ion (device circuit of zero-level binding. Input signal from terminal 24 through delay line 26 coordinated by resistors 25 and 27 and a limiter consisting of diodes 28 and 29 is fed to the input of a controlled normal; closed single-pole key 30. Last is in a closed state only in the absence of an information voltage pulse. In this case, the voltage level at the terminal 24 is compared to the zero potential at the inverting input of the operational amplifier 32. If there is a potential on the terminal 24, non-zero, the capacitor 31 will be charged or discharged, due to: the potential will change to 23 of the zero-level linker 9, i.e. at the non-inverting input of the amplifier 8 in Fig. 1. This the process will continue until the output potential of the amplifier 8, i.e., zero potential is established at the terminal 24 of the anchor device 9. The time constant (inertia) of the zero-voltage device 9 is determined by the resistance of the resistors 25 and 27 and the capacitance the capacitor 31 and is chosen so that it next data pulse compensation process urovnYa11 zero offset caused by the preceding pulse ,; managed to end,. When an information impulse appears at the control input 22, a signal is generated that opens the normally closed single-pole key 30, resulting in an information impulse that does not affect the accuracy of operation |

binding systems. After the end of the pulse, the process of restoring the zero level begins.

. A limiter on the diodes 28 and 29 increases the reliability of the operation of the normally closed single-pole key 30 (electronic bipolar key), and the delay line 26 compensates for the delay in propagation of the pulse signal along the circuit: device 10 for separating different polarity pulses. the first 11 (or second 12) power amplifier is the first 15 (or second 16) sensitive discriminator - the OR 14 element.

FIG. 3 shows a functional diagram of a transmission device 19. Signals of the detector are received at the inputs 33 and 34 of the control, which by means of the distributor 35 are fed to the corresponding prohibition inputs of the one-shot 36-1 ... 36-S. When a pulse is detected at the input 33, the single vibrators 36-k + l ... 36-S are blocked, and when a pulse appears at the input 34, the single vibrators 36-1 ... are blocked

... 36-k.

Thus, depending on the presence of a pulse at the inputs 33 and 34, groups, 5

38-k + l ... 38-S or 38-1 ... 38-k outputs, transmission devices 19.

The proposed device eliminates the additive measurement error of the spectral distribution.

pulse amplitudes from two radiation detectors and simplify the device as a whole due to the use of only one analog-digital converter and a device for setting digital amplitude windows. At the same time, the error associated with the non-identity of two different analog-to-digital converters independently operating in each measuring channel is eliminated.

The use of the described device in mineral deposits will improve the accuracy and efficiency of determining their quantitative content in the natural occurrence of nuclear geophysical methods.

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Claims (3)

1. A Borehole GAMMA-SPECT ROMETER containing two radiation detectors connected through a device for generating bipolar impulses, communication drops and an isolation capacitor with an ungrounded terminal of the terminating resistor and an inverting input of the amplifier, the output of which is connected to the input of the device for separating bipolar pulses, the outputs of which are connected with the inputs of the first and second adjustable amplifiers, an analog-digital converter, the outputs of which are connected to the inputs of the digital task device amplitude windows ^ information processing unit, two reference outputs of which are connected to the control inputs of the first and second adjustable amplifiers, information outputs are connected to the inputs of the recorder, characterized in that, in order to increase the accuracy of measurements and simplify the device, it additionally contains a zero binding device level summing amplifier, first and second. a swarm of sensitive discriminators, an OR element, and a transmission device, the amplifier output being connected to its non-inverting input through a zero-level binding device, the outputs of the first and second adjustable amplifiers are connected to the first and second inputs of the summing amplifier and to the inputs of the first and second sensitive discriminators, respectively, 'the outputs of which are connected to the control inputs of the transmission device and through the OR element are connected to the control input of zero-level binding devices, the output is the sum The amplifier is connected to the input of an analog-to-digital converter, and the outputs of the device for setting digital amplitude windows through a transmission device are connected to the inputs of the information processing unit. I ’to 2. The device according to p. ^ Characterized in that the zero-level binding device contains the first and second terminating resistors, a delay line, the first and second diodes, a normally-controlled single-pole switch, an operational amplifier and a capacitor, and the input of the zero-level binding device through the first a termination resistor, a delay line and a second termination resistor are connected to the anode of the first and the cathode of the second diodes', while the cathode of the first and the anode of the second diodes are grounded, and with the input of a controlled single-pole switch, the output which is connected to the inverting input of the operational amplifier, the non-inverting input of which is grounded, and you-. the stroke is the output of the zero-level binding device and is connected through a capacitor to the inverting input of the operational amplifier, the control input of the zero-level binding device is connected to the control input of a normally closed unipolar key. 3. The device according to claim 1, characterized in that the transmission device contains one-shots and a distributor, the inputs of the transmission device through one-shots connected to its outputs, and the inputs for prohibiting one-shots through a distributor are connected to the first and second control inputs of the transmission device.