| The low-background alpha and beta measuring instrument is a laboratory instrument used to detect the total alpha and total beta in environmental samples,gas samples,water samples and other media.At present,the R&D and manufacturing technology of low background α andβ measuring instruments have been developed to a certain level at home and abroad.The PIPS(Passivated Ion-implanted Planar Silicon)semiconductor detector,a newly developed nuclear detector,is the current application direction of low background α and β measurement technology.A low-background α and β measurement system based on two PIPS detectors is designed to serve this purpose.The system consists of PIPS detectors,anti-coincidence detectors,preamplifiers,multi-channel analyzers,detector high-voltage plates,vacuum system,measuring chamber and computer,etc.In the PIPS low-background α and β measurement system,scintillator detectors are generally used as anti-coincidence detectors.But the scintillator is relatively large in volume,so PIPS detector is used as anticoincidence detector to miniaturize the instrument.The PIPS detector is not sensitive to gamma rays.Experiments were conducted to verify whether the PIPS detector responds to gamma rays so as to verify the feasibility of this method.In addition,the distance between the detector surface and the radioactive source,and the vacuum degree of the measuring chamber are the main factors affecting the detection efficiency of the PIPS detector.In order to study the influence of these two environmental factors on the performance of the PIPS low background αand β measuring instrument,experiments were conducted to explore and compare the background counting rate,detection efficiency and cross-channel ratio under different conditions and the changes in the performance indicators of the low background α and β measuring instruments.The degree of each influence factor on the low background αand β measuring instrument was analyzed.The results show that the PIPS detector can detect gamma rays,and the PIPS detector can be used as an anti-coincidence detector;the source distance and vacuum degree will affect the performance of the instrument,and that the source distance has a great influence,especially on detection efficiency,while the influence of vacuum degree is relatively slight.When the source distance is extremely small,the influence of vacuum degree on performance indicators is relatively slight.To sum up,the test results can provide a reference for further optimization of PIPS-low background α and β measuring instrument design. |
