CN208547723U - A kind of sensitive neutron detector of high efficiency three-dimensional position - Google Patents

Abstract

The utility model relates to nuclear radiation detection technical fields, and espespecially one kind can replace³The sensitive neutron detector of high efficiency three-dimensional position of He pipe detector；Multilayer square pipe structure is constituted to plate the aluminium flake item of boron using surface；Each unit square pipe center is provided with resistive anodic wire, it is obtained by Charge Division Method along the position in silk direction, position where unit pipes determines lateral position, layer position where unit pipes provides lengthwise position, it is specifically detected in which unit so as to precise measurement neutron, realize the three-dimensional detection of neutron；It is alternative³The neutron detection technology of He pipe, detection efficient are greater than 30%；The thickness of effective boron neutron conversion layer can be increased by the number of plies of adding unit square pipe, to realize increase detection efficient, reduce production cost.

Description

A kind of sensitive neutron detector of high efficiency three-dimensional position

Technical field

The utility model relates to nuclear radiation detection technical fields, and espespecially one kind can replace³The high efficiency of He pipe detector The sensitive neutron detector of three-dimensional position.

Background technique

Neutron scattering technology is the ideal probe for studying the structure of matter and kinetic property, has been widely used in condensed state Physics (solid and liquid), chemical (especially polymer chemistry), life science, medicine, material science (especially nano material Science), in the research of numerous areas [1] such as aviation and national defense construction.Compared with X-ray scattering technology, Neutron scattering technology It is extremely strong with penetration capacity, light element is sensitive, isotope is differentiated and the irreplaceable advantage such as magnetic structure micro-analysis.China Heavy water research reactor is just utilized to carry out neutron scattering research early in last century the fifties, late nineteen nineties China's atomic energy science is ground Study carefully institute to start to build China Advanced Research Reactor (CARR), be mainly used to carry out neutron scattering work, be condensed the research of state substance, The heap is in beginning trial operation in 2010.As high current neutron source of new generation, MW class pulsed spallation neutron target has more advantage, High-throughput pulsed neutron beam can not only be provided, have the characteristics that high efficiency, energy spectrum width and Low background, and safer reliable. 2011, China, which formally goes into operation, built developing country's First spallation neutron target (CSNS), and government investment is up to 1,400,000,000, plan Time-consuming six and half will enter the big spallation neutron target ranks in the world four, provide for domestic and international scientist world-class after building up Neutron science integration experimental provision, wherein most spectrometer are used for the application of neutron scattering the relevant technologies.

Neutron scattering technology is mainly used for studying condensed state matter in atom, the microcosmos structure characteristic of molecular scale range, Therefore it is often used the hot and cold neutron beam after slowing down, wave-length coverage is generally in 0.1-10, through detector measurement after sample scatters Neutron energy and momentum variation, study microstructure and the characteristics of motion of the substance on atom, molecular scale.Neutron detection Device is one of the critical component of neutron scattering spectrometer device, largely decides the resolution capability of spectrometer, High Resolution Spectrum Instrument requires detector to have following excellent properties:

Detection efficient: greater than 40%

Positioning accuracy: 0.1-1cm

TOF temporal resolution :~10 μ s

N/ γ inhibits ratio: being better than 10-7

Counting rate: greater than 100kHz

Large area :-m2 magnitude

Under present international situation, the development and application of neutron detector face huge challenge.For thermal neutron (wavelength 1.8 ), generally detected using nuclear reaction method, there are commonly³He(n, p)T、¹⁰B(n, α)⁷Li and⁶Tri- cores of Li (n, α) T are anti- It answers, they are all bigger with the reaction cross-section of neutron, wherein³He aerochemistry is stable, section is big, still has at high pressure very Good positive ratio characteristic, is considered ideal thermal neutron detection material.The neutron scattering spectrometer in the world more than 70% or more is adopted at present With³He gas detector, there are mainly two types of, one kind is using more location-sensitive hyperbars³He pipe forms a surface detector Array cooperates read-out electronics appropriate to can get the position resolution of -5mm；Another kind of is hyperbar³He multiwire proportional chamber, Position resolution about 2mm；These two types of detectors can realize that large area detects, and detection efficient is up to 50% or more, γ rejection ability Height, and have commercially produced product, it is the technology of a technical maturity.However³He gas is by the raw material for the device hydrogen bomb that makes nuclear arms Tritium is generated through β decay (12.3 half-life period), then obtains high-purity by purification³He gas, all the time only U.S. Can the mass production gas, yield be decided by tritium production and³The demand of He gas, the U.S. closed tritium in 1988 Production, with increasingly sharp increase in recent years³The demand of He gas caused since 2008, occurred³He gas resource supplies The international situation of wretched insufficiency is answered, price also goes up in nearly 5 years more than 20 times, and³He gas by as strategic material by The outlet of U.S. Department of Energy strict control, the appearance of this case is so that neutron scattering spectrometer continues to use hyperbar³He gas is visited It surveys device and builds extensive detection system almost no longer possibility, research and development new neutron detector is extremely urgent.

After decades of development, China have now been formed three large-scale neutron scientific application platform: Chinese spallation Neutron source, two, China Physics Institute research reactor and Chinese Atomic Energy Research Institute Advanced Research Reactor, however the country still cannot be certainly The neutron detector of main production large area, it is nearly all to have run and all relied on external import in the detector for building spectrometer, exist The disadvantages of period is long, risk in transit is high, maintenance is big with upgrade cost is customized, construction and operation to neutron spectrometer are brought greatly Inconvenience, or even will cause neutron spectrometer and be not normally functioning for a long time, it has also become it is long-term to restrict the development of China's Neutron scattering technology One of important technology bottleneck.

In recent years, whole world scientist, which has been working hard, seeks to substitute³The new neutron Detection Techniques of He gas, so that should Direction has become the new hot spot in particle detection field at present.Substantially there are five research directions in the world at present: one, being based on 6LiF/ ZnS (Ag) scintillator: although technology can make thermal neutron detection efficiency be greater than 30%, position resolution about 1mm, γ inhibit energy Power is low, and cost is high；Two, based on painting boron GEM detector: although technology can make thermal neutron detection efficiency be greater than 30%, position resolution About 3mm, area 100mm × 100mm, but detection area is small；Three, it is based on interior painting boron pipe detector: although technology can make to hanker Sub- detection efficient about 30%, but detection efficient is low；Four, it is based on BF₃Pipe: technology uses 2atm BF₃Pipe, the long 2m of every single tube, by 32 are arranged together composition array, although making detection efficient about 30%, detection efficient is low；Five, grid detection of gas Device: technology can make effective area reach 192cm × 8cm, pixel 2cm, and detection efficient is greater than 40%, be easy large area extension, position Setting resolution can be improved, overall performance with³He detector is suitable.

Summary of the invention

For the technical bottleneck problem of current neutron detection, the utility model is intended to provide a kind of production install convenient detection Neutron detector with high accuracy, espespecially one kind can replace³The sensitive neutron detection of high efficiency three-dimensional position of He pipe detector Device.

The technical solution adopted in the utility model is: a kind of neutron detector, and the neutron detector is using surface The aluminium flake item for plating boron constitutes multilayer square pipe structure.

The plating boron is plated using the method for magnetron sputtering on aluminium substrate surface with a thickness of 1-3 μm¹⁰B thin layer conduct Neutron conversion layer.

Card slot is offered every a certain distance on the aluminium flake item.

Card slot on the aluminium flake item for plating boron is injected in pre-designed aluminium frame, forms network.

Distance between the square pipe is the spacing between card slot,.

The number of insertion plating boron aluminium flake item is the square pipe number of plies in the aluminium frame, each unit pipe center is equal It is provided with resistive anodic wire, is obtained by Charge Division Method and determines lateral position along the position where the position in silk direction, unit pipes It sets, the layer position where unit pipes provides lengthwise position, and it is specifically detected in which unit so as to precise measurement neutron, Realize the three-dimensional detection of neutron.

The square pipe both ends design has end face, is used to stationary positioned, and resistive anodic wire passes through wired and welding Method be fixed on the copper pipe of locator.

The utility model has the beneficial effects that first, the utility model is intended to research and develop substitution³The neutron detection technology of He is right The further investigation and innovation of New Grid Detection Techniques, by the design of development, gridding detector to small-sized principle prototype with Production, multichannel high pressure are drawn and the innovation of signal playback mode, by testing and verification, so that the neutron detection of the utility model The detection efficient of device is greater than 30%；Second, the detector of the utility model can be increased by the number of plies of adding unit square pipe Added with the thickness of effect boron neutron conversion layer, to realize increase detection efficient；Third, the Machine Design of the utility model detector Multilayer square pipe is constituted using a series of aluminium flake item of plating boron, each unit square pipe center is resistive anodic wire, is led to It crosses Charge Division Method acquisition and determines lateral position along the position where the position in silk direction, unit pipes, the layer position where unit pipes It sets and provides lengthwise position, it is specifically detected in which unit so as to precise measurement neutron, realize the three-dimensional detection of neutron, Each channel signal is drawn independent with read-out electronics, and signal and high-pressure channel number are more, by the experimental study of principle prototype, The research for carrying out multiple signals and high pressure lead-out process reduces signal and high pressure in the case where not reducing read-out channel density The space occupied is drawn, convenient for the realization of large area detector, reduces production cost.

Detailed description of the invention

Fig. 1 is the agent structure schematic diagram of the utility model neutron detector.

Fig. 2 is the structural schematic diagram of aluminium flake item in the utility model.

Fig. 3 is the utility model neutron transfer efficiency and boron layer thickness relationship.

Fig. 4 is the junior unit structure and measuring principle schematic diagram of the utility model neutron detector.

Attached drawing mark explanation: 1- square pipe, the resistive anodic wire of 2-, 3- aluminium frame, 11- aluminium flake item, 110- card slot.

Specific embodiment

Specific embodiment of the present utility model is described in detail below by way of specific experiment combination Figure of description 1-4:

As shown in Figs. 1-2, a kind of sensitive neutron detector of high efficiency three-dimensional position, the main body knot of the neutron detector Structure constitutes multilayer square pipe 1 using the aluminium flake item 11 of plating boron, plates boron raw material using the isotope of boron¹⁰B, the same position of boron Element¹⁰B is common thermal neutron sensitivity transition material, and chemical activity is low convenient for application, rich content, and easily obtains concentration boron (¹⁰B abundance 99%), it is ideal solid neutron transition material to improve neutron transfer efficiency；Since the fusing point of boron is high and not It is conductive, it is difficult to be realized with conventional film plating process, magnetron sputtering is suitble to fusing point high as a kind of advanced industrial coating technique The plated film of non-conductive medium, the utility model are plated using the method for magnetron sputtering in aluminium substrate with a thickness of 1-3 μm¹⁰B thin layer As neutron conversion layer, has many advantages, such as quality of forming film height, film adhesive force is strong, the thickness uniformity is good, impurity introducing is small.

As shown in Figs 1-4, card slot 110 is offered every a certain distance on the aluminium flake item 11, so that square pipe 1 Between distance be spacing between card slot 110, the card slot 110 on the aluminium flake item 11 for plating boron is injected into pre-designed chamber body In (aluminium frame 3), network is formed, since detector uses normal atmospheric pressure flow gas operating mode, machinery is may be selected in chamber body material The good aluminium alloy of performance, neutron action section is small, light-weight, is the common chamber body material of neutron detector, is inserted into aluminium frame 3 The number for plating boron aluminium flake item 11 is 1 number of plies of square pipe, each 1 center of unit square pipe is provided with resistive anodic wire 2, it is 25 μm of nichrome wire that resistive anodic wire 2, which selects diameter, using the fixed resistive anodic wire 2 of locator, 1 liang of square pipe End design has end face, is used to stationary positioned, and locator is that III drift chamber special designing of BES is used to fixed field silk and signal silk Important component, positioning accuracy is high, and silk guarantees that silk has certain tension across locator wire drawing first, then passes through wired and welding Method be fixed on the copper pipe of locator, high pressure resistant material is used outside the copper pipe of locator, is realized simultaneously by locator The fixation of anodic wire and the extraction of high pressure.

The detector of the utility model constitutes multilayer square pipe 1, each list using a series of aluminium flake item 11 of plating boron First pipeline center is provided with resistive anodic wire 2, is obtained by Charge Division Method along the position where the position in silk direction, unit pipes Determining lateral position is set, the layer position where unit pipes provides lengthwise position, so as to precise measurement neutron specifically at which A unit is detected, realizes the three-dimensional detection of neutron, and each channel signal is drawn and read-out electronics are independent, and signal and high pressure are logical Road number is more, can carry out the research of multiple signals and high pressure lead-out process by the experimental study of principle prototype, not reduce reading Out in the case where channel density, reduce signal and high pressure and draw the space occupied, convenient for the realization of large area detector, it is lower at This.In conjunction with maturation³The scheme of He pipe positioning electronic technical research gridding detector read-out system is improved along the position in silk direction Set measurement accuracy and reading speed.

The neutron detector is provided with special high pressure distributor disk behind, and positive high voltage is defeated all the way in high pressure distributor disk Enter, it is straight by a cadmium per signal all the way after two stage filter circuit and protective resistance, while to provide high pressure per anodic wire all the way Capacitor is directly drawn from anodic wire both ends, finally puts before menstruation and subsequent conditioning circuit measures the position that neutron is hit by Charge Division Method It sets.

Hereinafter, to detector principle carry out simulated experiment, prove the neutron detector of the utility model detection efficient and The precision and reliability of position resolution.

Simulated experiment principle: firstly, carry out detector simulation calculating, is calculated in detail using GEANT4 neutron and¹⁰B conversion layer Transfer efficiency, α with⁷The angle and energy of the outgoing of Li particle and their ionization energy loss in working gas, optimization detection Device uses the structural parameters such as number, each layer of thickness and each layer of the spacing of boron layer；Utilize ANSYS calculating detector electricity Field distribution, and GARFIELD is combined to calculate the drift, horizontal proliferation and multiplicative process of originally ionization electron, research obtains optimal Detector running parameter；The base of the detectors such as position resolution and the time resolution of detector is obtained using ROOT analysis data This performance parameter provides the reference frame of science for the detailed construction design of detector；Then, in place in conjunction with high energy institute MWPC institute It sets and sensitive³The experience of He pipe in detail studies the design and Precision Machining, anodic wire of detector chamber body by prototype design Accurate fixation, multichannel high pressure are drawn and the key technical problems such as the mode of signal-obtaining；Finally, detailed by being carried out to model machine Performance test provides experimental data reference for next step research work.

A kind of experimental principle: neutron detector is detected, the detector detection operations include three and are mutually independent The course of work, neutron conversion, gas multiplication and signal are read.

Neutron conversion: to neutron detector using an atmospheric pressure flow gas gas supply, to guarantee detector the operation is stable, prolong Long life, working gas use Ar and CO₂Mixed gas, makes detector work in proportional region, and incident neutron injects chamber body Boron layer is plated with the conversion layer on aluminium flake item 11¹⁰Nuclear reaction occurs for B, as shown in figure 3, there are two reaction channels for the nuclear reaction, wherein 93% The generation of branching ratio is reacted as follows: → α+⁷Li+ γ+2.31MeV, E_α=1.47MeV, E_Li=0.84MeV, it is clear that the reaction is raw At excitation state⁷Li, moment de excitation generate 1.47 MeV α and 0.84 MeV⁷Two kinds of particles of Li, another 7% branching ratio occur following anti- It answers: n+¹⁰B→α+⁷Li+2.79MeV, E_α=1.79MeV,E_Li=1.0MeV, reaction directly arrive ground state generation 1.79MeV α with 1.0MeV ⁷Li,⁷The direction of motion of two particles of Li, α is on the contrary, occur Coulomb interactions with boron atom, and gradually lose energy Amount, the two is respectively less than 3 μm in range wherein, therefore it is nothing to neutron transfer efficiency is improved that the thickness for plating boron film layer, which is more than 3 μm, Meaning, if Fig. 3 neutron transfer efficiency and boron layer thickness relationship are it is found that the maximum conversion efficiency of monolayer of boron is about 5%, so most Good method is to apply one layer of 1-3 μ m-thick in inner surface ¹⁰B thin layer, and multilayered structure is used, it both can guarantee in this way⁷Li, α ion It can go out shoot out from conversion body, and incident neutron can be allowed to pass through sufficiently thick conversion body and realize high transfer efficiency, to improve The detection efficient of detector.

Gas multiplication: when incident neutron quilt¹⁰After B capture, generation⁷Two kinds of contrary particles of Li, α, wherein α particle Direct losses are applying in boron aluminium base,⁷Li particle enters working gas, generates a large amount of primary electron-ionization to (about 10⁴It is right), Under the driving of unit pipes internal electric field, electronics drifts about to anodic wire, and gas amplifies near resistive anodic wire 2, and gain is about 100bel。

Signal is read: inductive signal is generated on resistive anodic wire 2, per signal all the way by a straight capacitor of cadmium directly from resistance Property 2 both ends of anodic wire draw, put before menstruation and subsequent conditioning circuit by Charge Division Method acquisition neutron hit 1 position of square pipe Divide as shown in figure 4, the signal-obtaining of a unit is completed in the position that measurement neutron is hit wherein passing through charge with temporal information It is obtained with method and determines lateral position along the position where the position in silk direction, unit pipe 1, the layer position where unit pipes provides Lengthwise position, it is specifically detected in which unit so as to precise measurement neutron, realize the three-dimensional detection of neutron, in Fig. 4, L is effective length of the detector along silk direction, and X is the distance for the positional distance detector right end that neutron is hit, Q_LFor neutron The quantity of electric charge measured when hitting from detector left end, Q_RThe quantity of electric charge measured when being hit for neutron from detector right end.

To sum up, the utility model is carried out New Grid Detection Techniques and is furtherd investigate, and passes through the design to detector chamber body The mode with signal-obtaining is drawn with Precision Machining, the selection of chamber body material, the accurate fixation of anodic wire, multichannel high pressure, is solved The critical issue of the important indicators such as detector reality detection efficient and position resolution, so that detection efficient > 30% of detector；It should Grid gas detector uses the structure of multilayer square pipe 1, and for interior plating boron circular pipe, square tube has smaller Dead zone between wall effect and Guan Yuguan is easy splicing and realizes large-area manufacturing, and multilayered structure can realize higher detection efficient, More particularly, the direction of neutron incidence is determined, the measurement accuracy of detector depends entirely on the measurement accuracy of single pipeline, with Incident direction is unrelated, related with boron thickness, as shown in figure 3, single layer transfer efficiency is about 5%, institute at about 2 microns of boron thickness The thickness of effective boron neutron conversion layer can be increased by the number of plies of adding unit with detector, to realize increase detection effect Rate.

Compared to round tube, square tube gas thickness is uniform, and wall effect is small, and manufacture craft is simple, can the big face of period expansion realization Product detection, splicing dead zone is small, is substitution³One of the important solutions of He technology.

The detector system of the utility model has carried out the measurement of plateau curve and power spectrum, knot in high energy institute CF-252 neutron source It closes the read-out electronics system that we there is now and carries out position resolution measurement and scale, realize the first pacing to detector performance Examination.The accurate test needs of detection efficient and position resolution are just able to achieve on neutron bunch using monochromatic neutron beam, therefore Later period, project team will strive for that a bunch completes test on CARR heap.The detector has been used as in spallation in the world at present Component and reactor spectrometer detector substitution³One of the important solutions of He technology.

Claims (3)

1. a kind of neutron detector, it is characterised in that: the neutron detector is more using the aluminium flake item composition of surface plating boron Layer square pipe structure, offers card slot every a certain distance on the aluminium flake item, by the card slot on the aluminium flake item for plating boron It injects in pre-designed aluminium frame, forms network；The number of insertion plating boron aluminium flake item is as rectangular in the aluminium frame The pipeline number of plies, the distance between square pipe are the spacing between card slot, each unit pipe center is provided with resistive anode Silk is obtained by Charge Division Method and determines lateral position along the position where the position in silk direction, unit pipes, where unit pipes Layer position provides lengthwise position, specifically detected in which unit so as to precise measurement neutron, realizes the three-dimensional of neutron Detection.

2. a kind of neutron detector according to claim 1, it is characterised in that: the plating boron is using magnetron sputtering Method plates the 10B thin layer with a thickness of 1-3 μm as neutron conversion layer on aluminium substrate surface.

3. a kind of neutron detector according to claim 1, it is characterised in that: the square pipe both ends design has end Face, is used to stationary positioned, and resistive anodic wire is fixed on the copper pipe of locator by the wired method with welding.