Design of a MAPS readout electronics prototype for BESIII inner tracker

Background The spatial resolution and the reconstruction efficiency of the main drift chamber of the Beijing Spectrometer III has degraded aftermore than nine years of operation.An improved new inner drift chamber has been constructed to replace the old chamber in case of the radiation damage.Amonolithic active pixel sensor(MAPS)based detector prototype is selected as one of the prototype schemes for the inner chamber upgrade.Purpose Design a set of MAPS readout electronics system for the inner drift chamber upgrade.This system can verify the function and performance of the selected MAPS chip and discover the matters needing attention when designing large-scale detectors.Methods The electronics system design is composed of three parts.The first part is flexible printed circuit boards(PCBs)assembled with the MAPS chips.The second part is digital readout boards,which are connected to the flexible PCBs via FPGA mezzanine card cables.The digital readout board realizes the configuration of the MAPS chip register,receives and processes the data output by the MAPS chip,and transfers the processed data to the DAQ device.The third part includes a readout control board and two fan-out boards that used to separately fan out the trigger signal and the start signal to all the digital readout boards.Results and conclusion AMAPS readout electronics system consisting of five MAPS based detector prototypes is designed.The system can work stably under the electron beam experimental conditions with a frequency up to 2 kHz and energy ranging from 1 to 5 GeV.The system detection efficiency of the electron beam is∼95%,and the spatial resolution is∼5.3μm at electron energies of 1 GeV.The design of the electronics system meets the requirements for verifying the performance of the MAPS chips and the technical feasibility of the detector structure.

LHAASO KM2A distributed long-distance data transmission

Background The large high-altitude air shower observatory(LHAASO)is being built near Daocheng(4410 m a.s.l.)in the Sichuan province of China.Its main instrument is the one-kilometer square extensive air shower array(KM2A)which will comprise nearly 7000 detectors.The system adopts a distributed architecture where each detector has local front-end electronics for signal digitization and transmission.White Rabbit(WR)is the communication protocol used within KM2A to reach the required 1-ns synchronization accuracy between detectors.Purpose To provide data transport and synchronization over the same network.Methods We have developed a firmware implementation of the TCP/IP protocol in Verilog hardware description language that can be coupled with a WR intellectual property core.Results LHAASO KM2A distributed data and clock synchronization network meets the high requirement of the array for reliable data transmission and clock synchronization.Conclusion The data transmission method based on the TCP/IP protocol suite and WR can be run in Xilinx Spartan6 FPGA with low resource needs,which greatly expand its application field.