CN213846620U - Charge sensitive preamplification circuit of underwater gamma spectrometer - Google Patents
Charge sensitive preamplification circuit of underwater gamma spectrometer Download PDFInfo
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- CN213846620U CN213846620U CN202023220436.1U CN202023220436U CN213846620U CN 213846620 U CN213846620 U CN 213846620U CN 202023220436 U CN202023220436 U CN 202023220436U CN 213846620 U CN213846620 U CN 213846620U
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Abstract
The utility model provides a charge sensitive preamplification circuit of an underwater gamma spectrometer, which is applied to the underwater gamma spectrometer; the circuit comprises two operational amplifiers, a photosensitive diode D4, capacitors C39, C34 and a resistor R21; the two operational amplifiers are a first operational amplifier U5A and a second operational amplifier U5B; the non-inverting input pin of the first operational amplifier U5A is connected with the output pin of the second operational amplifier U5B, and the inverting input pin of the first operational amplifier U5A is connected with the output pin of the first operational amplifier U5A; the output pin of the first operational amplifier U5A is connected as an output terminal to an external circuit. The circuit is matched with a resistor through two operational amplifiers, a photosensitive diode and a plurality of small quantities of capacitors to ensure that signals from the probe have a certain signal-to-noise ratio. The charge sensitive preamplifier circuit has the advantages of simple circuit structure, low cost and good stability.
Description
Technical Field
The utility model relates to a gamma spectrometer technical field especially relates to a sensitive preamplifier circuit of charge of gamma spectrometer under water.
Background
Currently, radioactive wastewater treatment plants are being developed and deployed gradually, but there is a lack of instrumentation for continuous monitoring of the radioactivity level of a body of water in real time. The working principle of the instrument is that a radiation detection unit measures gamma dose rate, collects energy spectrum data, and determines the type of radionuclide by spectrum analysis software spectrum resolving; when the radioactive nuclide species in the water body to be detected are certain, the radioactive nuclide is uniformly distributed in the water, the activity levels of the water body flowing through the detector at different moments are consistent, and the water flow speed is stable, the gamma detector is used for measuring the accumulated gamma energy spectrum of the water body flowing through the detector, the radioactivity in the measured saturation volume is obtained through passive efficiency scale software and the efficiency scale factors of the characteristic energy of the characteristic nuclide, and then the total water body radioactivity can be equivalently obtained, so that the real-time continuous monitoring of the radioactivity in the water is realized.
The underwater gamma spectrometer is a nuclear detection device specially applied to real-time monitoring of radioactive nuclides in water, and compared with a common gamma spectrometer, the underwater gamma spectrometer needs to have the functions of water resistance, pressure resistance, corrosion resistance, easiness in cleaning and the like. Meanwhile, in order to reduce the shielding influence on low-energy gamma photons, the shell of the gamma spectrometer needs to be made of a light material, and the thinner the shell is, the better the shell is on the premise of meeting the waterproof and pressure-resistant requirements. Common gamma spectrometers have a NaI detector and a LaBr3Detector, LaBr3The detector resolution is about 3% @661keV, better than NaI detector 8% @661keV resolution index, in nuclide identification and heavy peak analysis, LaBr3The detector is superior to the NaI detector. However, LaBr3The size of the detector is small, the current domestic probe can only achieve 3 inches, the price is relatively high, and in comparison, the volume of the NaI detector can achieve a monocrystal of tens of liters. For an underwater gamma detector, the detection efficiency is improved, the measurement sensitivity can be improved, and the method is suitable for monitoring the seawater radioactivity level with high fluidity. The underwater gamma spectrometer detector converts an optical signal into an electric signal through a photomultiplier, and the signal needs to be amplified through a pre-amplification circuit so as to ensure that the signal coming out of the probe has a certain signal-to-noise ratio, so that a charge sensitive amplifier is required to have a better signal-to-noise ratioAnd the stability is not changed along with the change of external conditions. At present, the situation of a charge preposing sensitive amplifying circuit of an underwater gamma spectrometer is unstable.
Therefore, in order to solve the problems in the prior art, it is important to provide a charge sensitive preamplifier circuit technology of an underwater gamma spectrometer with a simple circuit structure and good stability.
SUMMERY OF THE UTILITY MODEL
The utility model discloses an overcome the problem that above-mentioned prior art exists, provided a sensitive preamplification circuit of charge of gamma spectrometer under water, this circuit has circuit structure simply, and is with low costs, advantage that stability is good.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a charge sensitive preamplification circuit of an underwater gamma spectrometer is applied to the underwater gamma spectrometer; the circuit comprises two operational amplifiers, a photosensitive diode D4, capacitors C39, C34 and a resistor R21; the two operational amplifiers are a first operational amplifier U5A and a second operational amplifier U5B;
the non-inverting input pin of the first operational amplifier U5A is connected with the output pin of the second operational amplifier U5B, and the inverting input pin of the first operational amplifier U5A is connected with the output pin of the first operational amplifier U5A; the output pin of the first operational amplifier U5A is used as an output end to be connected with an external circuit;
the non-inverting input pin of the second operational amplifier U5B is grounded, the inverting input pin is connected with the capacitor C34, and the other end of the capacitor C34 is connected with the output pin of the second operational amplifier U5B; the resistor R21 is connected in parallel across the capacitor C34; the inverting input pin of the second operational amplifier U5B is also connected with a capacitor C39, the other end of the capacitor C39 is connected with the cathode of a photodiode D4, and the anode of the photodiode D4 is grounded; the cathode of the photosensitive diode D4 is electrically connected with high voltage.
Specifically, in order to ensure that a signal collected to the feedback capacitor has a certain discharge path, a feedback resistor is added to the feedback capacitor, the feedback resistor can enable a pre-amplification baseline to recover to a reference value after a period of time, the recovery time of the pre-amplification baseline is long, dead time is too large, subsequent filtering forming processing is not facilitated, dead time of the signal needs to be reduced in signal processing, a very zero cancellation circuit is added to ensure that the signal has short dead time, and the baseline cannot overshoot due to reduction of the dead time.
Preferably, the positive pole of the first operational amplifier U5A is connected with 2.5V voltage, and the negative pole is connected with-2.5V voltage.
Preferably, the first operational amplifier U5A and the second operational amplifier U5B are OPA 2320.
Preferably, the amplitude of the output signal of the charge sensitive pre-amplification circuit is Vout Vin × 1/C34.
In particular, since the amplitude of the output signal of the charge sensitive preamplifier depends only on the feedback capacitor, the amplitude of the output signal is Vout Vin × 1/C34, and the signal has excellent stability.
Preferably, the type of the photodiode D4 is LXD/GB5-A1 ELA.
Preferably, an output pin of the first operational amplifier U5A is connected as an output terminal to an AD conversion circuit; the AD conversion circuit comprises an AD conversion chip.
The model of the AD conversion chip is D9240.
Preferably, the resistance value of the resistor R21 is 100M.
Preferably, the capacitance value of the capacitor C34 is 0.22 pF.
The utility model has the advantages that:
the utility model provides a charge sensitive preamplification circuit of an underwater gamma spectrometer, which is applied to the underwater gamma spectrometer; the signal from the probe is ensured to have a certain signal-to-noise ratio by the cooperation of the two operational amplifiers, the photosensitive diode and a plurality of small amounts of capacitors and resistors. The charge sensitive preamplifier circuit has the advantages of simple circuit structure, low cost and good stability.
Drawings
Fig. 1 is a schematic circuit diagram of a charge sensitive preamplifier circuit according to the present invention.
Detailed Description
The following describes the present invention with reference to the accompanying drawings.
As shown in fig. 1, the present embodiment provides a charge sensitive pre-amplification circuit of an underwater gamma spectrometer, which is applied to the underwater gamma spectrometer; the circuit comprises two operational amplifiers, a photosensitive diode D4, capacitors C39, C34 and a resistor R21; the two operational amplifiers are a first operational amplifier U5A and a second operational amplifier U5B;
the non-inverting input pin 3 of the first operational amplifier U5A is connected to the output pin 7 of the second operational amplifier U5B, and the inverting input pin 2 of the first operational amplifier U5A is connected to the output pin 1 of the first operational amplifier U5A; the output pin 1 of the first operational amplifier U5A is used as an output end and is connected with an external circuit;
the non-inverting input pin 5 of the second operational amplifier U5B is grounded, the inverting input pin 6 is connected with the capacitor C34, and the other end of the capacitor C34 is connected with the output pin 7 of the second operational amplifier U5B; the resistor R21 is connected in parallel across the capacitor C34; the inverting input pin 6 of the second operational amplifier U5B is further connected with a capacitor C39, the other end of the capacitor C39 is connected with the cathode of a photodiode D4, and the anode of the photodiode D4 is grounded; the cathode of the photosensitive diode D4 is electrically connected with high voltage.
Specifically, in order to ensure that a signal collected to the feedback capacitor has a certain discharge path, a feedback resistor is added to the feedback capacitor, the feedback resistor can enable a pre-amplification baseline to recover to a reference value after a period of time, the recovery time of the pre-amplification baseline is long, dead time is too large, subsequent filtering forming processing is not facilitated, dead time of the signal needs to be reduced in signal processing, a very zero cancellation circuit is added to ensure that the signal has short dead time, and the baseline cannot overshoot due to reduction of the dead time.
In this embodiment, the positive terminal of the first operational amplifier U5A is connected to a voltage of 2.5V, and the negative terminal is connected to a voltage of-2.5V.
In this embodiment, the first operational amplifier U5A and the second operational amplifier U5B are OPA 2320. The output signal amplitude of the charge sensitive pre-amplification circuit is Vout Vin 1/C34.
In particular, since the amplitude of the output signal of the charge sensitive preamplifier depends only on the feedback capacitor, the amplitude of the output signal is Vout Vin × 1/C34, and the signal has excellent stability.
In the embodiment, the model of the photodiode D4 is LXD/GB5-A1 ELA. An output pin of the first operational amplifier U5A is used as an output end and is connected with an AD conversion circuit; the AD conversion circuit comprises an AD conversion chip. The model of the AD conversion chip is D9240.
Variations and modifications to the above-described embodiments may occur to those skilled in the art, in light of the above teachings and teachings. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should fall within the protection scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (7)
1. A charge sensitive preamplification circuit of an underwater gamma spectrometer is applied to the underwater gamma spectrometer; the circuit is characterized by comprising two operational amplifiers, a photosensitive diode D4, capacitors C39, C34 and a resistor R21; the two operational amplifiers are a first operational amplifier U5A and a second operational amplifier U5B;
the non-inverting input pin of the first operational amplifier U5A is connected with the output pin of the second operational amplifier U5B, and the inverting input pin of the first operational amplifier U5A is connected with the output pin of the first operational amplifier U5A; the output pin of the first operational amplifier U5A is used as an output end to be connected with an external circuit;
the non-inverting input pin of the second operational amplifier U5B is grounded, the inverting input pin is connected with the capacitor C34, and the other end of the capacitor C34 is connected with the output pin of the second operational amplifier U5B; the resistor R21 is connected in parallel across the capacitor C34; the inverting input pin of the second operational amplifier U5B is also connected with a capacitor C39, the other end of the capacitor C39 is connected with the cathode of a photodiode D4, and the anode of the photodiode D4 is grounded; the cathode of the photosensitive diode D4 is electrically connected with high voltage.
2. The charge sensitive pre-amplifier circuit of claim 1, wherein the first operational amplifier U5A has a positive terminal connected to a voltage of 2.5V and a negative terminal connected to a voltage of-2.5V.
3. The charge sensitive pre-amplifier circuit of claim 1, wherein the first operational amplifier U5A and the second operational amplifier U5B are of type OPA 2320.
4. The charge sensitive pre-amplifier circuit of claim 1, wherein the output signal amplitude of the charge sensitive pre-amplifier circuit is Vout Vin 1/C34.
5. The charge sensitive pre-amplifier circuit of claim 1, wherein the photodiode D4 is of the type LXD/GB5-A1 ELA.
6. The charge-sensitive pre-amplifier circuit according to claim 1, wherein the output pin of the first operational amplifier U5A is connected as an output terminal to an AD conversion circuit; the AD conversion circuit comprises an AD conversion chip.
7. The charge-sensitive pre-amplifier circuit according to claim 6, wherein the AD conversion chip has a model number of D9240.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202023220436.1U CN213846620U (en) | 2020-12-28 | 2020-12-28 | Charge sensitive preamplification circuit of underwater gamma spectrometer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202023220436.1U CN213846620U (en) | 2020-12-28 | 2020-12-28 | Charge sensitive preamplification circuit of underwater gamma spectrometer |
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| CN213846620U true CN213846620U (en) | 2021-07-30 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114706116A (en) * | 2022-06-07 | 2022-07-05 | 山东大学 | FPGA-based detector reading electronic system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114706116A (en) * | 2022-06-07 | 2022-07-05 | 山东大学 | FPGA-based detector reading electronic system |
| CN114706116B (en) * | 2022-06-07 | 2022-08-26 | 山东大学 | FPGA-based detector reading electronics system |
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