CN105068112A - Digital neutron spectrometer electronic system - Google Patents
Digital neutron spectrometer electronic system Download PDFInfo
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- CN105068112A CN105068112A CN201510514923.3A CN201510514923A CN105068112A CN 105068112 A CN105068112 A CN 105068112A CN 201510514923 A CN201510514923 A CN 201510514923A CN 105068112 A CN105068112 A CN 105068112A
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Abstract
The invention relates to a digital neutron spectrometer electronic system, which comprises two transmission paths. The first transmission path comprises a first preamplifier, the input end of the first preamplifier is connected with a scintillator detector arranged inside the neutron spectrometer, and the scintillator detector provides negative high voltage via a negative high voltage power supply. the second transmission path comprises a second preamplifier and a main amplifier, the input end of the second preamplifier is connected with an inflatable detector arranged inside the neutron spectrometer, the output end of the second preamplifier is connected with the input end of the main amplifier, the inflatable detector provides positive high voltage via a positive high voltage power supply, and a low voltage power supply provides stable voltage for the positive high voltage power supply and the main amplifier. According to the electronic system, AC interference on weak current by strong current during a neutron spectrometer motor operation process can be solved, the signal-to-noise ratio of the neutron spectrometer circuit system can be improved, interference between the high voltage power supply and the preamplifiers and baseline drift caused in a high counting condition can be reduced, the size is small, and the shielding performance is good.
Description
Technical field
The invention belongs to the fields of measurement of neutron spectrum, be specifically related to a kind of digitizing neutron spectrometer electronic system.
Background technology
Due to the calibration etc. of the research to neutron nuclear data and nuclear excitation energy level, the design and running of reactor, the design of nuclear device and test, radiation shield and protection, radiation treatment and neutron dose instrument, all need to understand neutron spectrum well.So the measurement of neutron spectrum has important theory significance and practical value.
What the application of neutron spectrum measurement technology was maximum is neutron time-of-flight spectrometer, the time of the one section of fixed range that flown by measurement neutron, determines the energy of neutron, quantity and space distribution.Its electronic system is very complicated, and mainly based on NIM plug-in type electronic system, Fig. 1 illustrates a concise and to the point speed and meets type Swift heavy ions electronic system circuit block-diagram.Its circuit theory is that pickup cylinder provides neutron start signal, and obtain neutron flight initial time by constant fraction discriminator device, liquid dodges anode signal and obtains neutron due in through constant fraction discriminator device, usually adopts door-opening mode to reduce random signals event background.By time width change-over circuit neutron time of flight is converted to voltage signal, as the time signal meeting system.Liquid dodges detector dynode signal and is divided into two-way: a road signal is put before too fast, linear delay main amplifier, timing single track, time width converter in order to screen neutron, γ signal; Another road signal is put before too fast, linear delay main amplifier is measured for neutron pulse amplitude spectrum.
The subject matter that flight time electronics circuit exists is: 1. based on traditional NIM plug-in type electronics, NIM plug-in unit electronics integration degree is low, bulky; 2. electronic system circuit is very complicated the flight time, and whole Circuits System quality, volume take very large; 3. flight time electronic system needs tuning parameter repeatedly, does not have the human eye of nuclear electronics commissioning experience be difficult to operation and understand; Therefore time-of-flight method neutron spectrum measurement is confined to laboratory at present, and is not suitable for nuclear industry place neutron spectrum measurement.
This partial content reference book: " neutron time of flight method and application thereof " Shen Guanren writes, Atomic Energy Press
The ROSPEC spectrometer that the ROSPEC spectrometer of the military of NATO tissue research and development in 2000 is traditional has three small size counters (2cm radius), fills 1atm respectively, 4atm, 10atm hydrogen.Large volume counter (diameter 6 inches) fills the argon methane gas of 0.5Mpa.This combinations of detectors can make ROSPEC spectrometer system cover energy range from 50keV ~ 4.5MeV.According to the miniaturization that the military of NATO proposes, easy-operating requirement, has redesigned spectrometer system.Traditional spectrometer by integrated electronics and computer digit treatment technology replace, weight and the size of spectrometer can be reduced like this, simultaneously can complete the operation of spectrometer by visualization interface.These combinations of detectors are arranged on one can on the plate of slow continuous rotation.The electric rotating machine that is rotated through of plate completes.Rotating below plate is a large amount of surface-mounted integrated circuits, comprises main putting, 4 pieces of independently ADCs, low-tension supply and a microcomputer.Data are first stored among buffer memory by the process of conputer controlled signal and collection, are then connected to computer from buffer memory by the RS422 interface that rotates.Data acquisition computer can near spectrometer end of probe, also can beyond 1km.
The subject matter that ROSPEC spectrometer electronics exists is: 1. electronics is suitable for neutron energy narrow range, can only be suitable for 50keV ~ 4.5MeV; 2. electronic system does not consider that neutron, gamma-rays screen design, only has energy information circuit, not free information circuit.3. during electric system work, forceful electric power has AC influence to weak electric signal.This part list of references:
NeutronSpectrometryinMixedFields:ProportionalCounterSpectrometers,RadiationProtectionDosimetryVol.107,Nos1-3,pp.73-93(2003)；
Rospec–ASimpleReliableHighResolutionNeutronSpectrometer,RadiationProtectionDosimetryVol.70,No.1-4pp.273-278.
Summary of the invention
For the defect existed in prior art, the invention provides a kind of electronic system of digitizing neutron spectrometer, solve that forceful electric power in motor operation course is excessive for the AC influence of light current, signal shaping overlong time dead time, baseline wander and the narrow defect of Circuits System energy coverage, improve neutron spectrometer Circuits System signal noise ratio; Volume is little, advantages of good shielding performance.
For reaching above object, the technical solution used in the present invention is: provide a kind of digitizing neutron spectrometer electronic system, this system comprises two-way transmission path, first via transmission path comprises the first prime amplifier, the input end of described first prime amplifier is connected with the scintillator detector arranged in neutron spectrometer, and scintillator detector provides negative high voltage by negative high voltage power source; Second road transmission path comprises the second prime amplifier and main amplifier, the input end of described second prime amplifier is connected with the gas-filled detector arranged in neutron spectrometer, second prime amplifier output terminal is connected with the input end of main amplifier, gas-filled detector provides positive high voltage by positive high voltage power supply, and described positive high voltage power supply and main amplifier provide stable voltage by low-tension supply.
Further, the output terminal of described first prime amplifier is all connected with the input end of routing control module with the output terminal of main amplifier, and the output terminal of this routing control module is connected with data collecting card input end.
Further, described first prime amplifier and negative high voltage power source are integrated in one piece of circuit board; Described second prime amplifier, main amplifier and positive high voltage power supply are integrated on one piece of circuit board.
Further, described first prime amplifier, the second prime amplifier and main amplifier select gain band roomy, the transistor that junction capacity is little and noise figure is little; Select leakage current and the little teflon electric capacity of temperature coefficient; Select the resistance that temperature coefficient is little.
Further, described first prime amplifier, the second prime amplifier and main amplifier use independent control system.
Further, digitizing low-pass filter is equipped with before described first prime amplifier and the second prime amplifier.
Further, described scintillator detector comprises photomultiplier; Described gas-filled detector adopts proportional counter.
Advantageous Effects of the present invention is:
(1) solve forceful electric power in motor operation course and, for the AC influence of light current, improve neutron spectrometer Circuits System signal noise ratio;
(2) circuit design is suitable for neutron energy scope: heat energy-20MeV, solves the defect that ROSPEC Circuits System energy coverage is narrow;
(3) circuit design considers neutron, gamma-ray burst shape discrimination, keeps feature pulse fall time when particle pulse integration is shaped;
(4) adopt differentiator circuit designs, under the prerequisite not changing charge integration amplitude and signal maximum amplitude linear relationship, pulse signal characteristic die-away time, chopped pulse curring time, to 1-2 μ s, reduces the whole electronic system dead time.
Accompanying drawing explanation
Fig. 1 is the structural representation of digitizing neutron spectrometer electronic system of the present invention;
Fig. 2 is without low-pass filter circuit pulse signal and has low-pass filter circuit pulse signal;
Fig. 3 is digitizing neutron spectrometer neutron, gamma-rays particle discrimination spectrum;
Fig. 4 is low voltage electric power system circuit diagram;
Fig. 5 is proportional counter positive high voltage circuit diagram;
Fig. 6 is that organic liquor dodges detector negative high voltage circuit diagram;
Fig. 7 is that organic sudden strain of a muscle liquid detector amplifies and shaping circuit.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.
As shown in Figure 1, digitizing neutron spectrometer electronic system comprises low-tension supply, positive and negative high-voltage power supply, the first prime amplifier, the second prime amplifier and main amplifier.Because digitizing neutron spectrometer has No. 6 detectors, every road probe functionality is different, so every road detector needs to design high pressure, enlarge leadingly, main amplifying circuit respectively.Low voltage electric power system is used for providing stable ± 6V, ± 12V voltage to whole Circuits System, and ripple <1mV, introduces each part system below respectively.
Instinct spectral measurement system has No. 6 detectors.First via detector is organic scintillator detector, inside establishes photomultiplier, and this scintillator detector is by negative high voltage power source for it provides negative high voltage, and signal is exported by dynode, through the first prime amplifier, routing control module to capture card.No. 2nd detector is BF
3detector, No. 3rd detector are bag cadmium BF
3detector, No. 4th detector are the hydrogeneous proportional counter of 1atm, No. 5th detector is the hydrogeneous proportional counter of 3atm, No. 6th detector is the hydrogeneous proportional counter of 10atm, 2-5 road detector is gas proportional counter, electronic system provides positive high voltage by positive high voltage power supply for it, signal through the second prime amplifier, main amplifier, routing control module to capture card.First via high pressure 0----2000V is adjustable, second and third, four road high pressure 0---2000V is adjustable, the 5th road high pressure 0---3000V is adjustable, and the 6th road high pressure 0---5300V is adjustable.
Wherein, each road prime amplifier, main amplifier, high-voltage power supply are all be integrated on one piece of circuit board, like this, insert wide, two slotting wide main amplifier and compare with high-voltage power supply, reduce volume with the list that NIM is separated.Near detector, prime amplifier, main amplifier, together with detector, has good shielding, and can suppress extraneous interference, signal is after prime amplifier and main amplifier, and signal is exaggerated, then through long cable, affects relatively little.
Device selection aspect, bandwidth gain be selected large, and junction capacity is little, the transistor that noise figure is little, selects leakage current and the little teflon electric capacity of temperature coefficient, selects the resistance that temperature coefficient is little.Circuit technology aspect, will reduce interference as far as possible, as pcb board large area ground connection, and reasonable arrangement device layout and cabling etc.System aspect, due to the Switching Power Supply that the motor lift control system controlling detector lifting uses, although can provide larger drive current for motor, efficiency is higher, and Ripple Noise is also comparatively large simultaneously, have impact on the measurement of this signal amplifying system.So, this signal amplifying system, and the separately design of motor lift control system, not altogether.The radiation interference of motor elevating control PLC system Switching Power Supply to be avoided, internal system simultaneously, also will reduce the mutual interference between high-voltage power supply and prime amplifier, add digitized filtered function, be i.e. digital low-pass filtering circuit.In high count rate situation, signal pile-up and capacitance discharge and recharge, the baseline wander caused, although can solve at prime amplifier and main amplifier system, increases the complexity of circuit undoubtedly.Base line restorer solves the effective measures causing resolution to degenerate because a variety of causes causes baseline fluctuation.Nearly ten years, constantly someone proposes to solve high count rate, the baseline fluctuation problem that AC coupling causes, and takes into account the scheme of the noise of filtering performance and other type simultaneously.Derive very good filtering and the comprehensive weight function that is shaped, but be difficult to realize with mimic channel.Along with the development of high-speed digitization and digital processing technology, in various constraint condition with under considering non-self noise situations, realize optimum filtering and shaping becomes possibility.The software section of native system judges impulse magnitude, and to each pulse, carries out baseline restorer optimization respectively, to reduce the change of pulse pile-up and baseline.
In motor operation course, forceful electric power obtains effective suppression for the AC influence of light current by digital low-pass filtering circuit design, during motor runs, and signal to noise ratio (S/N ratio) >10:1; First-order low-pass ripple has good inhibiting effect for PERIODIC INTERFERENCE, and be applicable to fluctuate parametric filtering frequently, and its weak point brings delayed phase, and sensitivity is low.Meanwhile, it can not rejection frequency higher than the undesired signal of sample frequency 1/2.Low-pass filter circuit can attenuates high frequency signals and AC signal, allow direct current signal and low frequency signal pass through, more than 20MHz high frequency ac signal can be eliminated, as shown in Figure 2, it is without low-pass filter circuit pulse signal that figure divides middle and upper part, and lower part has low-pass filter circuit pulse signal.
After 1 road liquid sudden strain of a muscle detector measurement mixing field neutron, gamma-rays after the first prime amplifier, again after Data Acquisition Card and power spectrum processing module carry out particle discrimination process, form neutron, gamma-rays particle discrimination spectrum, as shown in Figure 3, digitizing neutron spectrometer neutron, gamma-rays particle discrimination spectrum, peak, left side is gamma-rays peak, and peak, right side is neutron peak.For 800keV neutron, discrimination factor >1.8.Mainly because consider neutron, gamma-ray burst shape discrimination in circuit design, keep feature pulse fall time when particle pulse integration is shaped.
Adopt differentiating circuit and integrating circuit design, between integration and differentiation values of circuit resistances 5M Ω-6M Ω, capacitance, between 0.01 μ F-0.1 μ F, keeps pulse signal negative edge time response, simultaneously ought pulse width control at 1 μ s, effectively reduce the system dead time.
As shown in Figure 4, be low voltage electric power system of the present invention, this system comprises transformer, linear power supply and select switch.After transformer, 17.5V and 11.5V alternating voltage is become by 220V alternating voltage, DC voltage is changed into respectively through rectification silicon stack, then through three-terminal voltage-stabilizing module with expand current circuit and DC voltage to be converted to required for other Circuits System ± 6V, ± 12V voltage.Again through waver routing, thus select to be communicated with different detector circuit system.Which routing control module waver Non-follow control selects measure, and regulates high pressure with coarse adjustment and fine tuning knob, and shows on digital panel meter.
As shown in Figure 5,2-6 road detector is proportional counter, and proportional counter signal is less, in order to obtain enough magnitude output signal, obtain higher signal to noise ratio (S/N ratio), need amplify through prime amplifier and main amplifier two-stage.Owing to being spectral measurement, higher to the requirement of signal to noise ratio (S/N ratio), what prime amplifier adopted is charge-sensitive preamplifier, and its output gain is stablized, and noise is low, and performance is good, is the maximum prime amplifier in high-resolution spectral measurement.And main amplifier is also the main amplifier that the infinitesimal analysis selecting noise lower is shaped.Pulse shaping time 2 μ s, the pulse shaping time is short can reduce the system dead time.
As shown in Figure 6, first prime amplifier on the 1st tunnel comprises two-stage and amplifies, the 1st grade of resistance through 0.1 μ F electric capacity and 10k ohm carries out signal differentiation, then the input end of first order amplifier is entered, the first order exports the input entering second level amplifying circuit, simultaneously through the resistive degeneration of a 560k ohm, to improve the stability of amplifier.Second level amplifier principle and the first order similar.This circuit design is in guarantee broadband response, and short rise time and fall time, the high count rate meeting photomultiplier is measured.Both be exaggerated signal, remained again the temporal information on edge before and after pulse signal, and be convenient to capture card below and software supporting with it, differentiate different particles.
As shown in Figure 7, be amplification and the wave-shaping circuit figure of organic scintillator detector of the present invention.This circuit diagram adopts amplification of the prior art and wave-shaping circuit figure, but the invention is not restricted to the wiring diagram of this kind of structure, all amplification and wave-shaping circuit figure that can solve the technology of the present invention problem.
Digitizing neutron spectrometer electronic system of the present invention is not limited to above-mentioned embodiment, and those skilled in the art's technical scheme according to the present invention draws and other embodiment belongs to technological innovation scope of the present invention equally.
Claims (7)
1. a digitizing neutron spectrometer electronic system, this system comprises two-way transmission path, it is characterized in that: first via transmission path comprises the first prime amplifier, the input end of described first prime amplifier is connected with the scintillator detector arranged in neutron spectrometer, and scintillator detector provides negative high voltage by negative high voltage power source; Second road transmission path comprises the second prime amplifier and main amplifier, the input end of described second prime amplifier is connected with the gas-filled detector arranged in neutron spectrometer, second prime amplifier output terminal is connected with the input end of main amplifier, gas-filled detector provides positive high voltage by positive high voltage power supply, and described positive high voltage power supply and main amplifier provide stable voltage by low-tension supply.
2. a kind of digitizing neutron spectrometer electronic system as claimed in claim 1, it is characterized in that: the output terminal of described first prime amplifier is all connected with the input end of routing control module with the output terminal of main amplifier, the output terminal of this routing control module is connected with data collecting card input end.
3. a kind of digitizing neutron spectrometer electronic system as claimed in claim 2, is characterized in that: described first prime amplifier and negative high voltage power source are integrated in one piece of circuit board; Described second prime amplifier, main amplifier and positive high voltage power supply are integrated on one piece of circuit board.
4. a kind of digitizing neutron spectrometer electronic system as claimed in claim 3, is characterized in that: described first prime amplifier, the second prime amplifier and main amplifier select gain band roomy, the transistor that junction capacity is little and noise figure is little; Select leakage current and the little teflon electric capacity of temperature coefficient; Select the resistance that temperature coefficient is little.
5. a kind of digitizing neutron spectrometer electronic system as claimed in claim 4, is characterized in that: described first prime amplifier, the second prime amplifier and main amplifier use independent control system.
6. a kind of digitizing neutron spectrometer electronic system as claimed in claim 5, is characterized in that: be provided with digitizing low-pass filter before described first prime amplifier and the second prime amplifier.
7. a kind of digitizing neutron spectrometer electronic system as described in any one of claim 1-6, is characterized in that: described scintillator detector comprises photomultiplier; Described gas-filled detector adopts proportional counter.
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| CN201510514923.3A CN105068112A (en) | 2015-08-20 | 2015-08-20 | Digital neutron spectrometer electronic system |
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| CN201510514923.3A CN105068112A (en) | 2015-08-20 | 2015-08-20 | Digital neutron spectrometer electronic system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CZ307166B6 (en) * | 2017-02-24 | 2018-02-14 | Vf, A.S. | A digital spectrometer |
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| US9029784B1 (en) * | 2011-09-28 | 2015-05-12 | The United States Of America As Represented By The Secretary Of The Navy | Spectrally resolved pulse height analysis for neutron-gamma discrimination |
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| CN102455431A (en) * | 2010-11-25 | 2012-05-16 | 上海新漫传感技术研究发展有限公司 | Channel type radioactive detector with low detection limit |
| CN102445706A (en) * | 2011-09-26 | 2012-05-09 | 华瑞科学仪器(上海)有限公司 | Neutron detector |
| US9029784B1 (en) * | 2011-09-28 | 2015-05-12 | The United States Of America As Represented By The Secretary Of The Navy | Spectrally resolved pulse height analysis for neutron-gamma discrimination |
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| CZ307166B6 (en) * | 2017-02-24 | 2018-02-14 | Vf, A.S. | A digital spectrometer |
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Application publication date: 20151118 |