A 16-channel gated integrator(GI) module following semi-Gaussian shaping amplifiers was developed for high-resolution energy spectroscopy systems at Institute of Modern Physics,Chinese Academy of Sciences.This GI solved the ballistic deficit problem by integrating the signal until all the charge was collected from the detector at counting rates up to 100 K.In this paper,a fast shaper was used to optimize the gate logic to ensure nonlinearity of the GI less than 0.17%;and a novel compensation approach,to reduce the charge injection from the switches in the GI; and a T-switch configuration,to eliminate leakage current in the reset switch.
A single width NIM module that includes eight channels of the time-to-amplitude converter （TAC） and the charge-to-amplitude converter （QAC） is introduced in the paper, which is designed for the large neutron wall detector to measure charge （energy） and time interval simultaneously. The module adopts a high precision gated integration circuit to realize TAC and QAC. ：The input range of TAC is from 30 ns to 1 μs, and the input range of QAC is from 40 pC to 600 pC. The linearity error of TAC is lower than 1.28%, and the time resolution of TAC is less than 0.871%. The linearity error of QAC is lower than 0.81%, and the resolution of QAC is better than 0.936%.
Front-end readout electronics have been developed for silicon strip detectors at our institute. In this system an Application Specific Integrated Circuit （ASIC） ATHED is used to realize multi-channel energy and time measurements. The slow control of ASIC chips is achieved by parallel port and the timing control signals of ASIC chips are implemented with the CPLD. The data acquisition is carried out with a PXI-DAQ card. The software has a user-friendly GUI developed with LabWindows/CVI in the Windows XP operating system. The test results show that the energy resolution is about 1.14% for alpha at 5.48 MeV and the maximum channel crosstalk of the system is 4.60%. The performance of the system is very reliable and is suitable for nuclear physics experiments.
The Gamma Ray Array Detector （GRAD） is one subsystem of HIRFL-ETF （the External Target Facility （ETF） of the Heavy Ion Research Facility in Lanzhou （HIRFL））. It is capable of measuring the energy of gamma-rays with 1024 CsI scintillators in in-beam nuclear experiments. The GRAD trigger should select the valid events and reject the data from the scintillators which are not hit by the gamma-ray. The GRAD trigger has been developed based on the Field Programmable Gate Array （FPGAs） and PXI interface. It makes prompt trigger decisions to select valid events by processing the hit signals from the 1024 CsI scintillators. According to the physical requirements, the GRAD trigger module supplies 12-bit trigger information for the global trigger system of ETF and supplies a trigger signal for data acquisition （DAQ） system of GRAD. In addition, the GRAD trigger generates trigger data that are packed and transmitted to the host computer via PXI bus to be saved for off-line analysis. The trigger processing is implemented in the front-end electronics of GRAD and one FPGA of the GRAD trigger module. The logic of PXI transmission and reconfiguration is implemented in another FPGA of the GRAD trigger module. During the gamma-ray experiments, the GRAD trigger performs reliably and efficiently. The function of GRAD trigger is capable of satisfying the physical requirements.
