| Neutron nuclear data is fundamental in defense military,nuclear energy development,nuclear medicine,nuclear physics,and nuclear astrophysics.Based on China spallation neutron source,back-streaming neutrons facility(Back-n)with a wide and continuous neutron spectrum has been built for nuclear data measurement.GAmma spectrometer with GErmanium Array(GAEA)is in planning at Back-n,consisting of LaBr3(Ce)detectors and three kinds of HPGe detectors.There are 180 signal channels in GAEA,among which 60 are from BGO escape suppression shields around HPGe detectors.HPGe detectors have superior energy resolution(0.15%@1274.5 keV(FWHM)),while LaBr3(Ce)detectors have excellent performance concerning the time resolution(100 ps～300 ps(FWHM)).GAEA will be the first 4π HPGe spectrometer in China and facilitate frontier scientific research works such as neutron-induced crosssections,nuclear structure,and in-beam nuclear spectroscopy.The existing HPGe detector readout system in China is constructed with commercial modules.With the complex structure and the limited function,the readout system can not support enough readout channels and the flexible trigger method for GAEA.GAEA needs advanced readout electronics technology to measure in-beam y spectrum and nuclear structure precisely at Back-n.There are several challenges for the readout system,such as the adaptation of different detectors,180 acquisition channels,the high acquisition accuracy for HPGe detectors,the high time resolution for LaBr3(Ce)detectors,the global timing synchronization,and the reconfigurable digital hardware L1 trigger system.In this paper,the readout electronics of GAEA is researched.This paper includes the readout electronics scheme,waveform digitization,data readout system,global clock,trigger processing,test,and verification.This paper aims to provide an advanced signal readout electronics technology for nuclear data measurement spectrometers in China.The investigation in readout methods of international HPGe spectrometers provides a reference for this paper.The high-speed trigger exchange network between digitizers and the switching node is constructed based on the Fabric[A]channel in the MicroTCA chassis backplane and the high-speed serial GTH transceiver of FPGA.The synchronization system is based on the TCLKC star network.With the trigger network and the synchronization system,a digital L1 trigger system is achieved.A clock and trigger module and several high-performance digitizers are designed in this paper,which provide high-speed and high-precision signal acquisition and data readout for five detector types and 180 signal channels.The prototype of the readout electronics is developed in this paper.Several test platforms are built to evaluate and verify the key performances of the readout electronics.The trigger packet switching rate is 10 Gbps,and the trigger latency is 5.6824 μs(Mean)with a jitter of 2.3 ns(RMS),which achieves a high-performance real-time trigger system for GAEA.The time resolution of the acquisition channel of the high-speed digitizer is 34.7 ps(FWHM),which can support the time resolution of the LaBr3(Ce)detector.The energy resolution of the high-precision digitizer and the HPGe detector is 0.145%@1274.5 keV(FWHM).Therefore,the readout electronics studied in this paper can meet the readout requirements of GAEA.In addition,it provides technical support for in-beam y spectrum and nuclear structure measurement at Back-n. |
