Scintillator Neutron Detectors Arrays (SNDA) were successfully installed at General Purpose Powder Diffractometer (GPPD) at the China Spallation Neutron Source (CSNS). The inhomogeneity of the detection efficiency in each detector module, which caused by the gain nonuniformity of the multi-anode photo-multiplier tubes (MA-PMTs) and the inconsistency of the wave-length shifting fibers in collecting scintillation photons, need to be mitigated before the installation.
An automated rapid measurement system based on the blue laser and the two-dimensional mobile platform was developed to calibrate the light response of each channel in detector modules. According to the test results of this system, the electronics threshold of each channel of the SNDA is adjusted. Before the installation of the all 40 SNDA modules in GPPD, the electronics thresholds of each channel are adjusted according to the measurement results of this rapid measurement system.
Results and Conclusion
Compared with the unadjusted detector module, the adjusted one obtained a better uniformity of the neutron detection efficiency. The inhomogeneity of the detection efficiency is improved from 27.4% to 10.9%. The test result of the diffraction peak of the standard sample Si showed that the adjusted SNDA works well in GPPD.