PMT based on VME Bus Test System Design and Implementation
|Course||Particle Physics and Nuclear Physics|
|Keywords||PMT Performance Testing Labview VME bus Two -dimensional scanning|
Generation of cosmic rays (including gamma rays) experiment - large, high-altitude air shower observatory (Large High Altitude Air Shower Observatory, LHAASO) is one square kilometer level composite array experiments. To achieve LHAASO scientific objectives, planning and construction of the ground particle array 1K plus not less than 40 000 μ detector array (KM2A array). KM2A is LHAASO main program array, the entire array consists of 5000 and 1200 ¨ electron detector detector. Electron detector and μ are uniform scintillator detector tile assembly components. Each tile is covered with eight scintillating fiber to collect the scintillation light. Wherein the electron detector unit comprises of 4 × 4 tile, finally, bringing together the optical fiber coupled to a PMT. μ detector scintillation light of each unit should be read by an PMT. Hence the need for a large number of PMT. Depending on the experiment, the amplification of the PMT, and linear parameters such as response time request, so the experiments using the PMT must be on before the performance parameters are tested to ensure that the PMT to meet the experiment, the experimental design goal to achieve. Such a large number of PMT to be tested must be to develop a high-precision, fast measurement system. Shandong University laboratory established such a fast and accurate PMT test system, which can simultaneously test for 16 PMT, and the high degree of automation, to achieve a one-button operation. This paper mainly discusses the system's construction work, from the hardware components to the data acquisition and data analysis software development. Performance Test PMT includes the test box, the light scanning system, data acquisition and database systems, measure and record counts of each PMT a single photoelectron, uniformity and linearity. In which the cathode is measured uniformity of the system is the most unique innovations. Black box also contains the plurality of PMT, multi-source system, the light from the optical fiber into PMT, simultaneous measurement of a plurality of PMT, saving the measurement time. Scanning system consists of precision stepper motor control, for an interval of approximately 1 mm-by-point scanning. Providing light from the LED and laser through a plurality of fiber provides the spectrometer signal. Data acquisition system based on VME systems, the use of multi-channel QDC (16 channel) simultaneously for 16 PMT signals. Same time as the trigger signal source driving signal for each PMT are numbered, the measurement results recorded in the database system. All test systems are based on Labview software development, Labview is a leading industry standard graphical programming tools, mainly for the development of test, measurement and control systems. It is specifically designed for engineers and scientists an intuitive graphical programming language. It software and various measuring instruments hardware and computer integrated, creating a virtual instrument system, to form a user-defined solutions. Laboratory use Labview VISA configure serial port provides tools to achieve the right BNC575 control signal generator, and BNC575 multiple output adjustable features coordinating the work of the various subsystems. Use Labview provides Datasocket functions to achieve the SY1527 high voltage power system control. Use Labview VISA Find tool to find available resources and the use oscilloscope VISA read and write functions to achieve their communication, to achieve the temporal characteristics of the test. In addition, Labview comes with a lot of mathematical tools and functions to facilitate the realization of data extraction, conversion, fitting and analysis. After completion of the test system in order to build on XP2012B, XP2262 and R11102 three PMT test, for example, introduced its zoom capabilities, non-linearity and uniformity parameters such as test methods and test results. System can accurately and quickly measure the parameters of PMT and long time stability.