The Development Of ReadOut Module For RPC Electronics Prototype Of Daya Bay Reactor Neutrino Experiment

Cosmic rays are the central background noise of Daya Bay reactor anti-neutrino experiment. The water Cerenkov detector and the RPC detector are used in the experiment to reject cosmic rays background noise effectively. This paper describes the plan, realization and the analysis of the test in field of the RPC detector electronics prototype modle which is made up by RPC detector, FEC, ReadOut Module for prototype and the computer. The design of the ReadOut Module for prototype (ROM-USB) of RPC detector Electronics of Daya Bay reactor anti-neutrino experiment will be introducted, including the system architecture, the hardware structure and the logic design of the FPGA on the ROM-USB.Each module of RPC detector is made up by four layers which has eight channels. The 32 channel analog signals on each RPC detector are read out by one FEC board (Front‐ End‐ Card, FEC) in the form of modularization. The FEC translate these analog signals into digital signals and give out the time stamp, the trigger signals are given out by the trigger logic on board. After treatment of RPC Trigger Module (RPC Trigger Module, RTM) these trigger signals are send back to FEC to decide to receive the data or not. The data are read out by ReadOut Module (ReadOut Module, ROM) on VME bin to DAQ for further treatment. During this process, the long distance transmission of trigger signals and data is realized by ReadOut Transceiver(ReadOut Transceiver, ROT).The ROM-USB is the test and debugging tool of the RPC detectors and the copy and installation project of FEC. ROM-USB is similar to ROM, the difference between them is the interface, the ROM-USB interface to computer is the USB bus while the ROM interface is the VME bus. Another difference between them is the ROM-USB can connect to FEC without ROT which ROM must work with. ROM-USB places extra emphasis on the simple way to test FEC in many fields. In the prototype modle, ROM-USB who instead of ROT, ROM and RTM is in charge of data transmission, trigger selection and data collection. In the same time, ROM-USB can realize only one or full test of FEC for different settings from software. The design of ROM-USB must be very steady, anti-jamming and can realize all the test requestions of FEC according to the requestions of field test.The RPC detector electronics prototype takes the field test at IHEP on December, 2008. During the test, ROM-USB successfully completed the FEC functional testing and stability testing, acceptance of the detector field test of complex environments. The experimental data which collectted and record by ROM-USB provides the analytical basis for the RPC detector efficency and the quality of test results. After the latter analysis these experimental data can also set up the further detector three-dimensional trajectory model of particles hit.