Research Of The Testing Platform For Two Dimensional Position Sensitive Detector

In 2008,the Chinese spallation neutron source is under construction in Dongguan city.The general powder diffraction spectrometer(GPPD)for the internal microstructure research of the sample will be installed and commissioned in 2017.The scintillator neutron detector,which is the main component of GPPD,has good detection performance and low cost,and has become the first choice for large area neutron detection under the current trend of~3He price soaring.In practical applications,the scintillator neutron detector can achieve large area neutron imaging on the order of square meters by array splicing.Before the scintillator neutron detector array is spliced,it is necessary to solve the problem of detector detection efficiency nonuniformity to ensure the neutron imaging quality.In order to solve this problem,it is necessary to detect the quality of the produced scintillator neutron detector unit.First,the optical path consistency is optimized by detecting and matching the main photoelectric device-multi-anode photomultiplier tube.The light response of each pixel unit is detected by the standard light source,and finally the electronic threshold value of each pixel of the detector unit is modified according to the test results of the light response of each pixel unit to realize the detection efficiency uniformity of the detector.A set of photoelectric detection platform system was built up.The laser pulse produced by the modulated laser was used as the standard light source.The laser was divided into two groups after eliminating the mold,and then the optical fiber was led to the manipulator to project to the device under test.The other is connected to the monitor for calibration of the stability of the standard light source.Mobile device based on EPICS controller to achieve the coordinates of the alignment and point by point to move,with the VME bus data acquisition,to complete of all the test points of the scan.Data results are deduced from the analysis program and the light response curve of the test object is deduced after the background and normalization processing,which is used as the optimization parameter index of the detector detection efficiency.After the design of the detection platform is completed,through the test of multi-anode photomultiplier tube gain,and with the factory report compared to debug the entire testing system and optimization to ensure the accuracy of the scan test results.The optical response curve of each pixel channel of the scintillator neutron detector unit is tested and the electronic threshold value of each pixel of the detector unit is modified according to the curve,and the detection efficiency uniformity of the detector is optimized,Sub-source and neutron beam flow to verify optimization effect.of the detection efficiency uniformity.The experimental results show that the multi-anode photomultiplier(MPMT)and wave-shifting fiber(WLSF)arrays can be scanned quickly and the quantization index of the key devices can be obtained.After optimization,the image quality of the detector is improved,and the neutron imaging effect of the whole GPPD spectrometer can be improved.