Research On The Data Acquisition Of The Media Energy Detection Of HXMT

The Hard X-ray Modulation Telescope(HXMT) is an X-ray satellite devoted to a sensitive broad band(1-250 keV) survey and pointed observations.In order to cover this broad energy band,HXMT contains three kinds of scientific instruments:the High Energy X-ray Telescope(HE,NaI/CsI),the Medium Energy X-ray Telescope (ME,Si-PIN),and the Low Energy X-ray Telescope(LE,SCD).Apparently,ME acts as a bridge between HE and LE so as to constitute the detection capability of HXMT in the medium energy band.Since HE is only sensitive above 20 keV and the detection efficiency of LE decreases significantly above 8 keV,ME should have a low energy threshold well below 8 keV and a high energy threshold far above 20 keV.We use Si-PIN as the detectors of ME.Since the increase of Si-PIN pixel size brings higher noise,ME is made up of about 1944 small Si-PIN pixels,and so about 1944 channels of readout electronics are needed.However,the power supply,weight, and volume budgets are limited onboard the satellite.It is impossible to construct the front end electronics with separated components.Therefore,we use the Application Specific Integrated Circuit(ASIC) technology to solve this difficulty.RENA-3 chip is used to realize high integrated multi-channel preamplifier, shaper,peak hold and trigger cirtuit.The structures and the funtion of RENA-3 chip is described.The prototype of the ME readout electronics is designed,including the front-end electronics,the data acquisition system and the data management system.The front-end electronics is based on RENA-3 chip,the low noise hardware design of the front-end elecronics is described.The data acquisition system uses FPGA to timing control the front-end RENA-3 chip,acquire the event data and transfer them to the data management system through the LVDS interface.The data management system is designed as a interface between the data acquisition system and the PC,it controls the USB interface chip to transfer the event data from the data acquisition system to PC,and transfers the command data from PC to the data acquisition system.The hardware design,the logic design and the communication of the data acquisition system and the data management system are described.The whole prototype realize multi-channle front-end signal process and data acquisition.The configuration parameter of the front-end RENA-3 chip and the working mode of the whole system can be easily controlled.Tests have been made based on the prototype,the results of the tests show that the desigh goals are achieved,and the prototype can meet the performance requirements of the ME.At last,a summary of this dissertation is provided.