The Research And Design On The Pre-research Readout Electronics System Of The External Experiment In CSR

With the development of Heavy Ion Physics, the branch subject of nuclear physics, the governments over the world put a large number of funds and resources into the construction of heavy ion accelerators. The Heavy Ions Research Facility in Lanzhou(HIRFL) Cooler Storage Ring’s main ring has been set up, the detector systems of which consist of a start time detector、Multi-wire Drift Chamber, Time of Flight Wall and Neutron Wall, etc. The Start time detector is used to measure the arrive time of the ion beam at the target zone, which is the original time point of the reaction; the Multi-wire Drift Chamber to obtain the traces of the ions by measuring the drift times.; the Time of Flight Wall to measure the flight time of charge particles, the Neuron Wall to measure the flight time of neutron; the two Walls is constructed with the structure of Plastic scintillators and PMT to detect the ions. The gamma detector is used to measure the energy of gamma ray generated in the collisions, and distinguish the Isotopes. The paper will introduce the research in the Pre-research of the readout electronics system of the external experiment system, which consists of a clock distribute module, a trigger module, high precision time and charge measurement modules, a MWDC measurement module etc. The charge measurement and the time measurement. are two important parts of readout electronics of detectors. There are three methods of charge measurement that are charge to time conversion, wave sampling and charge to time conversion. Charge to time converter based Time-over-threshold technique has the characteristic of simple circuit, low price and low power. Time measurement includes time discrimination and time to digital convert (TDC). Leading end discriminator circuit is easily realized and integrated. But it has to be corrected to decrease the "time walk" effect.The technologies used in the Pre-research system are the charge measurement based on the TOT (Time over Threshold), the Leading End discriminator and the time stamp TDC etc. The HPTDC chips are used as the kernel of the time measurement module and the SFE16as the kernel of the charge measurement module. The HPTDC chip is developed by the CERN, which is suitable to Nuclear Physics experiments as a data driven TDC. SFE16is an16-channel ASIC chip base on the TOT. The two chips are applied in the system for their high performance and the high Integration、low cost and low power. In the system, the clock module provides high precision synchronous working clocks for the other modules in the chassis; the trigger module combines the sub trigger signals from the measurements modules, generates the global trigger signals and then distributes them to the other modules form the backplane of the chassis. The MWDC measurement module measures the width of pulses from the128channels of the QTC on the FEE. The time and charge measurement module measures16channels signals from detectors. The signals are split to2parts, one put to the time measurement module, and the other to the charge measurement module. The charge results will be used to correct the time walk effect. The Pre-research system is designed based on the PXI6U Specification, and the data results are transferred to the remote PC. The tests of the Pre-research system consist of tests in the electronics lab and tests with the detectors, including time measurement and charge measurement performance.The test results shows that the pre-research system works well and steadily as designed.