The Development Of A CsI Detector Based On Pocket Dosemeter

Along with the national economic and social development, the rapid GDP growth,the deterioration of the environment and energy into the exhaustion of the for thesociety has the focus of attention, nuclear power as a new clean energy, can alleviateenergy and environmental pressure. China plans to2020nuclear power installedcapacity of70million kw or more, nuclear power in the country’s electricity generatingcapacity of the percentage will more than4%. At the same time, radiation monitoring isan important part, in case the nuclear damage to huma n body and pollution to theenvironment. As the homemade nuclear instruments can’t fully satisfy people’s needs.Many nuclear instruments still rely on imports, so developed high-performance nuclearinstruments, and the localization of nuclear instruments, has the very vital significance.γ rays detectionas a kind of radiation monitoring technology, and in the scientificresearch, the nuclear medicine, industry, agriculture and geological exploration areas tobe used. γ radiation detector is one of the most effective and use the most convenientprofessional testing instrument, and scintillation detector tend to be used for thedetection of gamma rays faint the highest efficiency detection devices. By those bigdensity, high effective atomic number, can absorb the γ rays of energy will convert thevisible "scintillating crystal" and high efficiency "photoelectric devices" are a kind ofdetector, is the most classic and most direct way to test the gamma rays. The past fewdecades, NaI(Tl) and traditional photomultiplier tubes coupling detecting way a widerange of development and utilization. Along with the development of the nuclearradiation detection technology, CsI(Tl) crystals as many unique advantages to get thefavour. In recent years, the area of the silicon p hotoelectric diode manufacturer hasbeen launched, these new silicon photoelectric diode have higher quantum efficiency (~70%), sensitive area achieve square centimeters of category. So silicon photoelectric diode and CsI (Tl) couple a kind of detector has wide application prospects.Based on the above factors, this article do more research about γ radiationscintillating detector based on silicon PIN photoelectric diode and CsI(Tl) crystal. Theγ radiationdetector bythe detector, preamplifier, pulse linear amplifier, discriminator,the central control processing unit and power supply module part.The detector by the photosensitive face size10x10mm2silicon PIN photoelectricdiode S3590and10x10mm3CsI (Tl) crystal, when scintillation stimulate issuedemit fluorescent inthe γradiation,photoelectricdiodewill transform these photons intoelectrical impulses signal. Need to pay special attention to the signal is very weak,low-energy rays of the output signal amplitude slightly greater than only statisticalnoise, so as to reduce the electronic noise. In this regard, in the back of the detector inthe circuit design primary is especially important. A specially designed sensitive chargeamplifier (CSP) is used as the photoelectric diode and the interface circuit, this circuit isthe function of a probe of charge of the output will be collected, and will convert tovoltage signal output. Sensitive charge amplifier circuit choose the low noise integratedCMOS operational amplifier chip AD8606, a tiny capacity capacitance and a preciseresistor which has a very big resistance as the main form of the device to therequirements of the noise.At this time of the output pulse signal of the probe amplitude and waveform is notapplicable to further analysis of the circuit requirements, in order to obtain the bestsignal-to-noise ratio and provide pulse amplitude circuit analysis required pulse shape,we must have a pulse signal processing. In order to make the pulse signal gain betterSNR, and make signal waveform closer to Gaussian wave, we design a zerodestructively circuit and the RC filter plastic circuit. The voltage comparator MAX987constitute the discernment into digital signals. Then, digital signal to AVRmicro-controller ATmega-8for counting processing, realize the counting of time toadjust, keyboard input control, alarm buzzer alarm, LCD monitor device etc.Instrument use two7battery power supply, the power management module willpower transformation to the desired voltage. In addition, in order to make silicon PINphotoelectric diode good operation, performance, it needs a24V bias voltage.TPS61040booster type DC-DC converter, can make+5V to rise to+24V level. Andan electronic filter is used to reduce power supply ripple.Through the test, this instrument can be in more wide radiation intensity andenergy range, in strong electromagnetic field environment stable operation for a longtime.