Study Of The High Sensitivity, High Resolution And Wide Dynamic Range Portable Radiation Detector

As nuclear science and technology roll forward rapidly in recent years, nuclear safetyand environmental nuclear radiation level is drawing more and more attention. Portableradiation detector is reliable and effective instrument in radiation monitor because of itslow power comsumption, easy manipulation and real-time capability. A well-knownproblem in the field of portable radiation detector is the wide energy range and wide doserate range of the exist isotopes which requires the portable radiation detector have highcount rate and the ability to process the wide energy range radiation. And it is very hard toachieve high sensitivity at small size when use scintillator and PMT.A combine-detector technology and an all-digital data acquisition system (DAQ) isproposed in this thesis to realize high sensitivity, high resolution and wide dynamic rangeportable radiation detectors. In the detector design, a YSO/SiPM is used for the lowenergy gamma detection and high dose rate range，a BGO/SiPM is used for the highenergy detection and low dose rate range. Since the high light yiled of YSO and relativelylow light yield of BGO, the combined detector can get high resolution as well as widedose rate range and energy range. An all-digital DAQ based on MVT is used to digitize thescintillation from both detectors, the MVT technology can digitize the scintillation pulsedirectly using a few digital samples to get high count rate, then the energy and the decayconstant of scintillation pulse can be calculated using the prior information.The experiment results and the authority calibration results show that the sensitivityof the YSO/SiPM detector is299cps/μSv/h，the dose rate range is from5μSv/h to100μSv/h, can be achieve to1mSv/h. The energy resolution of is35%at59.5keV, and theenergy range can be achieve from59.5keV to middle energy, the sensitivity of BGO/SiPMdetector is662cps/μSv/h, and the dose rate range is from5μSv/h to100μSv/h, can beachieve to0.01μSv/h. The energy resolution is24%at511keV, and the energy range canbe achieve from511keV to high energy.