Scintillation detectors yog ib yam ntawm cov cuab yeej ntsuas tsim los xyuas cov khoom me me. Lawv qhov tshwj xeeb yog qhov kev nyeem ntawv tshwm sim los ntawm kev siv lub teeb-sensitive systems. Thawj thawj zaug cov cuab yeej no tau siv hauv xyoo 1944 los ntsuas qhov hluav taws xob ntawm uranium. Muaj ntau hom kev ntes nyob ntawm seb tus neeg ua haujlwm li cas.
Destination
Cov ntsuas ntsuas hluav taws xob tau dav siv rau cov laj thawj hauv qab no:
- sau npe ntawm hluav taws xob muaj kuab paug ntawm ib puag ncig;
- tshuaj xyuas cov khoom siv hluav taws xob thiab lwm yam kev tshawb fawb lub cev thiab tshuaj;
- siv los ua lub hauv paus los tsim cov tshuab ntes ntau dua;
- kev tshawb fawb txog cov tshuaj;
- kos npe rau hauv cov kab hluav taws xob tiv thaiv hluav taws xob (piv txwv li, cov khoom siv dosimetric tsim los ceeb toom txog kev nkag ntawm lub nkoj mus rau thaj tsam ntawm cov kab mob sib kis).
Cov txee tuaj yeem tsim tau ob qho kev sau npe zoohluav taws xob thiab ntsuas nws lub zog.
Nthuav qhia kev npaj
Cov qauv ntawm lub tshuab hluav taws xob hluav taws xob hluav taws xob tau pom hauv daim duab hauv qab no.
Lub ntsiab ntawm cov cuab yeej muaj raws li hauv qab no:
- photomultiplier;
- scintillator tsim los hloov lub excitation ntawm cov siv lead ua lattice rau hauv pom lub teeb thiab xa mus rau qhov kho qhov muag converter;
- kho qhov muag ntawm thawj ob lub cuab yeej;
- voltage stabilizer;
- electronic system rau sau cov hluav taws xob impulses.
Type
Muaj kev faib tawm hauv qab no ntawm cov hom tseem ceeb ntawm cov tshuaj tua kab mob raws li hom tshuaj uas muaj fluoresces thaum raug hluav taws xob:
- Inorganic alkali halide meters. Lawv siv los sau npe alpha, beta, gamma thiab neutron hluav taws xob. Muaj ntau hom crystals ib leeg yog tsim nyob rau hauv kev lag luam: sodium iodide, cesium, potassium thiab lithium, zinc sulfide, alkaline ntiaj teb hlau tungstates. Lawv tau qhib nrog cov impurities tshwj xeeb.
- Organic ib leeg siv lead ua thiab pob tshab daws teeb meem. Cov thawj pab pawg muaj xws li: anthracene, tolane, trans-stilbene, naphthalene thiab lwm yam compounds, pawg thib ob muaj xws li terphenyl, sib tov ntawm anthracene nrog naphthalene, cov ntsiab lus hauv plastics. Lawv yog siv rau kev ntsuas lub sijhawm thiab txhawm rau kuaj cov neutrons ceev. Activating additives nyob rau hauv cov organic scintillators tsis yogpab.
- Gas nruab nrab (He, Ar, Kr, Xe). Xws li cov detectors feem ntau yog siv los xyuas cov fission fragments ntawm hnyav nuclei. Lub wavelength ntawm cov hluav taws xob yog nyob rau hauv lub ultraviolet spectrum, yog li lawv xav tau cov photodiodes tsim nyog.
Rau cov khoom siv hluav taws xob hluav taws xob nrog lub zog hluav taws xob txog li 100 keV, zinc sulfide crystals qhib nrog boron isotope nrog cov lej ntawm 10 thiab 6 Li yog siv. Thaum sau npe alpha hais, zinc sulfide yog siv rau hauv ib txheej nyias ntawm lub pob tshab substrate.
Ntawm cov organic tebchaw, cov khoom siv hluav taws xob yog cov siv dav tshaj plaws. Lawv yog cov kev daws teeb meem ntawm luminescent tshuaj nyob rau hauv high-molecular plastics. Feem ntau, scintillation plastics yog tsim los ntawm polystyrene. Cov phaj nyias yog siv los sau npe alpha thiab beta hluav taws xob, thiab cov phaj tuab yog siv rau gamma thiab X-rays. Lawv yog tsim nyob rau hauv daim ntawv ntawm pob tshab polished cylinders. Piv rau lwm hom scintillators, yas scintillators muaj ntau yam zoo:
- short flash time;
- resistance rau mechanical puas, ya raws;
- tsis tu ncua ntawm cov yam ntxwv ntawm kev siv hluav taws xob ntau;
- nqi qis;
- easy to make;
- kev sau npe ua haujlwm siab.
Photomultipliers
Lub luag haujlwm tseem ceeb ntawm cov khoom siv no yog photomultiplier. Nws yog ib qho system ntawm electrodes mountedhauv ib lub khob iav. Txhawm rau tiv thaiv kev sib nqus sab nraud, nws tau muab tso rau hauv cov hlau casing ua los ntawm cov khoom siv nrog siab sib nqus permeability. Qhov no tiv thaiv electromagnetic cuam tshuam.
Nyob rau hauv lub photomultiplier, lub teeb nyem hloov mus rau hauv hluav taws xob impulse, thiab cov hluav taws xob tam sim no kuj yog amplified vim qhov thib ob emission ntawm electrons. Tus nqi ntawm tam sim no nyob ntawm tus naj npawb ntawm dynodes. Kev tsom xam ntawm electrons tshwm sim vim qhov chaw electrostatic, uas nyob ntawm cov duab ntawm cov electrodes thiab cov peev txheej ntawm lawv. Lub khob tawm ntawm cov khoom siv hluav taws xob tau nrawm nrawm rau hauv qhov chaw interelectrode thiab, poob rau ntawm lub dynode tom ntej, ua rau lwm qhov emission. Vim li no, tus naj npawb ntawm electrons nce ntau zaus.
Scintillation detector: nws ua haujlwm li cas
Cov neeg ua haujlwm zoo li no:
- Cov khoom siv hluav taws xob nkag mus rau cov khoom ua haujlwm ntawm lub tshuab hluav taws xob.
- Ionization thiab excitation ntawm siv lead ua, kua los yog roj molecules tshwm sim.
- Molecules emit photons thiab tom qab labths ntawm ib thib ob lawv rov qab mus rau qhov sib npaug.
- Nyob rau hauv lub photomultiplier, lub teeb ntawm lub teeb yog "amplified" thiab hits lub anode.
- Lub anode Circuit Court amplifies thiab ntsuas cov hluav taws xob tam sim no.
Lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm lub ntsuas hluav taws xob yog ua raws li qhov tshwm sim ntawm luminescence. Cov yam ntxwv tseem ceeb ntawm cov cuab yeej no yog kev hloov dua siab tshiab - qhov piv ntawm lub zog ntawm lub teeb ntawm lub teeb mus rau lub zog poob los ntawm cov khoom siv hauv cov khoom siv hluav taws xob ntawm scintillator.
pros and cons
Cov txiaj ntsig ntawm cov khoom siv hluav taws xob hluav taws xob muaj xws li:
- nrhiav kom pom kev ua haujlwm siab, tshwj xeeb tshaj yog rau lub zog luv luv gamma rays;
- kev daws teeb meem ntawm lub cev zoo, uas yog, muaj peev xwm muab cov duab cais ntawm ob yam khoom (nws ncav cuag 10 -10 s);
- ntsuas ib txhij ntawm lub zog ntawm cov khoom kuaj pom;
- muaj peev xwm tsim cov txee ntawm ntau cov duab, yooj yim ntawm kev daws teeb meem.
Qhov tsis zoo ntawm cov txee no yog qhov rhiab heev rau cov khoom uas tsis muaj zog. Thaum lawv tau siv los ua ib feem ntawm cov spectrometers, kev ua cov ntaub ntawv tau los ua nyuaj dua, vim tias cov spectrum muaj ib daim ntawv nyuaj.
