CN106324655A - Plastic scintillator doped with neutron-sensitive material uranium and method thereof for measuring thermal neutrons - Google Patents

Abstract

The invention belongs to the field of radiation measurement, and particularly relates to a plastic scintillator doped with the neutron-sensitive material uranium and a method thereof for measuring thermal neutrons. According to the invention, uranium-contained raw materials are added into the plastic scintillator. The uranium-doped plastic scintillator and a photomultiplier tube are connected and are sealed inside an opaque housing so as to form a probe. The probe is placed in a measurement environment and the nuclear reaction occurs between incident neutrons and the uranium-contained raw materials in the plastic scintillator, so that the materials are in an excited state. During de-excitation, photons are sent out. The number of photons is proportional to the number of incident neutrons. Meanwhile, through recording the electrical impulses semaphore of the photomultiplier tube per unit time, the neutron fluence can be calculated, so that the measurement of the neutron fluence is realized. The neutron fluence is multipled by a fluenc-dose conversion coefficient to obtain the neutron dose equivalent. The plastic scintillator and the method are low in cost, wide in application range and high in detection efficiency.

Description

The plastic scintillant of doping neutron-sensitive material uranium and the method for measurement thermal neutron thereof

Technical field

The invention belongs to actinometry field, the plastics being specifically related to a kind of neutron-sensitive material uranium that adulterates dodgeBright body and the method measuring thermal neutron thereof.

Background technology

Plastic scintillant is typically done substrate by polystyrene, is blended into other organic additive and makees scitillating material, thenMaking plus Wavelength shifter, it has, and detection efficient is high, photoyield is high, and signal pulse width is narrow, machinabilityCan good, adaptive capacity to environment is strong, stable mechanical performance, the advantage such as with low cost and be widely used in radiation and surveyIn amount work, but owing to the main component of plastic scintillant is C, H, O, they cut with neutron interactionFace is relatively low, typically cannot be directly used to the monitoring field of neutron, to this end, the period of the day from 11 p.m. to 1 a.m also needs doping or embedding in Tan CeEnter other materials and export to increase optical signal, just can be used for soon as embedded one layer of ZnS:Ag film at plastic scintillantNeutron measurement.

Owing to ZnS:Ag film is light tight, the method therefore embedding ZnS:Ag film in plastic scintillant can be lostA lot of photons, causes detection efficient and sensitivity to decline.

Summary of the invention

Present invention aims to problems of the prior art, it is provided that one can be used for thermal neutronThe plastic scintillant of doping neutron-sensitive material uranium measured, and use and this mix uranium Plastic scintillation bulk measurementThe method of thermal neutron.

Technical scheme is as follows: the plastic scintillant of a kind of neutron-sensitive material uranium that adulterates, by polyphenylSubstrate made by ethylene, is blended into scitillating material and Wavelength shifter, wherein, mixes and contain in described polystyrene substrateThe raw material of uranium, the incorporation of the raw material containing uranium accounts for the 5%-10% of plastic scintillant gross mass.

Further, the plastic scintillant of the neutron-sensitive material uranium that adulterates as above, wherein, described containsThe raw material having uranium includes triuranium octoxide, uanate, during preparing plastic scintillant, and will be containing uraniumRaw material mix in polystyrene substrate by corresponding proportion and be sufficiently mixed.

The method of the Plastic scintillation bulk measurement thermal neutron of above-mentioned doping neutron-sensitive material uranium, will mix uranium plastics and dodgeBright body is connected with photomultiplier tube, and is sealed in opaque shell, forms probe；Probe is placed inMeasure in environment, incident neutron and the raw material generation nuclear reaction containing uranium in plastic scintillant, nuclear reactionWhole energy losses in mixing uranium plastic scintillant, are made material be in excited state, de excitation by the alpha-particle releasedTime release photon, photon numbers be proportional to alpha-particle loss energy, i.e. the quantity of nuclear reaction, also with regard to direct ratioIn incident neutron number, the record photomultiplier tube electric impulse signal amount in the unit interval can calculate neutronFluence, thus realize the measurement of neutron fluence, it is multiplied by fluence-dose conversion coefficient and can get neutron DE.

Beneficial effects of the present invention is as follows: neutron sensitive material uranium is mixed in plastic scintillant by the present invention,Neutron can effectively be measured by the material of uranium-bearing.The side of uranium Plastic scintillation bulk measurement thermal neutron is mixed in this employingMethod is cheap, applied range, and its detection efficient is far above embedding ZnS:Ag film in plastic scintillantMethod.

Accompanying drawing explanation

Fig. 1 is for mixing uranium plastic scintillant structure and nuclear reaction schematic diagram；

Fig. 2 is the schematic diagram of plastic scintillator detector.

Detailed description of the invention

With embodiment, the present invention is described in detail below in conjunction with the accompanying drawings.

The key component of scintillator detector has scintillator, collection optical system, the phototube of detection lightPart (such as photomultiplier tube), and give the potentiometer of each electrode power supply of photomultiplier tube, they are closed in oneIn individual opaque shell, being referred to as probe, this belongs to the known features of this area.Wherein plastic scintillantPrimary structure is typically done substrate by polystyrene, is blended into other organic additive and makees scitillating material, adds shiftingRipple agent is made, and these materials are not had an effect with thermal neutron containing C, H, O, and the most general plastics dodgeBright body cannot be directly used to measure thermal neutron.

Neutron can will embed a certain proportion of neutron-sensitive with a lot of material generation nuclear reactions in plastic scintillantAfter material, incident neutron reacts, and reaction can pass to plastic scintillant material makes it excite, during de excitationReleasing photon, photon is transferred to photomultiplier tube through Wavelength shifter, by follow-up electricity after being converted into the signal of telecommunication and amplifyingRoad record.Photon numbers is directly proportional to the energy of absorbed, and the reaction of nuclear reaction can be certain, number of photonsAmount is the most just proportional to number of neutrons.

As it is shown in figure 1,²³⁵U fissions under the bombardment of neutron, releases the energy of about 170Mev, mainDistribute to two fission fragments¹³¹I and¹³⁷Cs, therefore contains²³⁵The material of U can effectively measure neutron, sideMethod is while preparing former plastic scintillant, adds the microgranule of uranium-bearing.The present invention gathering at plastic scintillantMixing the raw material containing uranium in styrene substrate, the incorporation of the raw material containing uranium accounts for plastic scintillant gross mass5%-10%.The described raw material containing uranium can choose triuranium octoxide, uanate etc., former by containing uraniumExpect to mix in polystyrene substrate by corresponding proportion to be sufficiently mixed.

It is connected as in figure 2 it is shown, uranium plastic scintillant 1 will be mixed with photoconduction 2, the most again with photomultiplier tubeConnecting, and be sealed in opaque shell, form probe, in figure, K is photocathode, and F is for focusing onPole, D₁～D₁₀For dynode, A is anode.Probe is placed in measurement environment, incident neutron and plasticsThe raw material generation nuclear reaction containing uranium in scintillator, energy can be damaged by the fission fragment that uranium fission generatesLosing in plastic scintillant, make material be in excited state, will necessarily release photon during de excitation, photon numbers is justRatio, in the quantity of the quantity of fission reaction, i.e. nuclear reaction, is the most just proportional to incident neutron number, thus in realizingThe measurement of sub-fluence, is multiplied by fluence-dose conversion coefficient and can get the Radiation Protection Quantities such as neutron DE.

Embodiment

Mix uranium plastic scintillant and made substrate by the polystyrene mixing the raw material containing uranium, be blended into scitillating material andWavelength shifter forms, and concrete preparation method is to make substrate with the polystyrene of the triuranium octoxide containing corresponding proportionAdd the first solute three ditolyls and the second solute PoPo post polymerization are made to mix uranium plastic scintillant block, thenCleaved molding obtains mixes uranium plastic scintillant.

The reaction occurred in uranium plastic scintillant is mixed as it is shown in figure 1, incide by neutron；Uranium plastics will be mixedScintillator and collection optical system, the photoelectric device (such as photomultiplier tube) of detection light, and give photomultiplier transitThe potentiometer managing each electrode power supply is enclosed in an opaque shell, forms probe, internal structure of popping one's head inAs shown in Figure 2.Being placed in by probe in measurement environment, incident neutron occurs with the uranium mixed in uranium plastic scintillantReaction, reaction can pass to the first solute makes it excite three ditolyls, launches wavelength during its de excitationThe fluorescence of 350-400nm, the second solute PoPo absorbs the light that this fluorescence emission wavelengths is longer, main peak position wavelengthAt 423nm, photon is transferred to photomultiplier tube through photoconduction, is amplified electricity by signal after being converted into electric impulse signalRoad is amplified and record, and the quantity of this electric pulse is proportional to the neutron number of times with uranium generation nuclear reaction,The most just being proportional to incident neutron quantity, the electric impulse signal amount of record unit time can calculate the note of neutronAmount, it is achieved the measurement of neutron fluence.The number of pulses that one neutron ultimately forms with mix the ratio of uranium, photoelectricityMultiplier tube model is relevant with photomultiplier tube duty, and mixing, uranium ratio-dependent, photomultiplier tube model are trueIn the case of fixed and photomultiplier tube circuit design completes, the method simulation of available Monte Carlo calculates and passes throughThe method of experimental verification obtains.

Obviously, those skilled in the art can carry out various change and modification without deviating from this to the present inventionBright spirit and scope.So, if the present invention these amendment and modification belong to the claims in the present invention andWithin the scope of its equivalent technology, then the present invention is also intended to comprise these change and modification.

Claims (3)

1. a plastic scintillant for neutron-sensitive of adulterating material uranium, is made substrate by polystyrene, is blended into flickerMaterial and Wavelength shifter, it is characterised in that: in described polystyrene substrate, mix the raw material containing uranium, containThe incorporation of the raw material of uranium accounts for the 5%-10% of plastic scintillant gross mass.

2. the plastic scintillant of the neutron-sensitive material uranium that adulterates as claimed in claim 1, it is characterised in that:The described raw material containing uranium includes triuranium octoxide, uanate, during preparing plastic scintillant,Raw material containing uranium is mixed in polystyrene substrate by corresponding proportion and is sufficiently mixed.

3. the Plastic scintillation bulk measurement using the neutron-sensitive material uranium that adulterates described in claim 1 or 2 is hankeredThe method of son, it is characterised in that: uranium plastic scintillant will be mixed and be connected with photomultiplier tube, and be sealed in notIn transparent shell, form probe；Probe is placed in measurement environment, incident neutron and plastic scintillantIn the raw material generation nuclear reaction containing uranium, whole energy losses are moulded mixing uranium by the alpha-particle that nuclear reaction is releasedIn material scintillator, making material be in excited state, release photon during de excitation, photon numbers is proportional to alpha-particle and damagesThe energy lost, i.e. the quantity of nuclear reaction, the most just it is proportional to incident neutron number, record photomultiplier tube is in unitThe electric impulse signal amount of time can calculate the fluence of neutron, thus realizes the measurement of neutron fluence, is multiplied byFluence-dose conversion coefficient can get neutron DE.