The Research On FELIX-based Scalable Readout System For Micro-Pattern Gas Detectors

Gas Detector is an indispensable measuring device in modern particle physics experiment.In recent years,with the rapid development of technology and increasing demand of the physical experiment,Micro Pattern Gas Detectors(MPGDs)have been fully developed,typically presented by Micromegas(MICRO Mesh-GASeous-structure)and GEM(Gas Electron Multiplier).For the advantages of high position and time resolution,robustness,high counting rate,high radiation resistance and large area,MPGDs have been widely used in many fields,such as high-energy physics experiments,nuclear medical imaging and so on.Various and different applications have different requirements on MPGDs and corresponding readout electronics,such as channel number,measurement accuracy,area,radiation resistance,price,power consumption,counting rate,etc.Based on these diversified needs,many ASIC chips for MPGDs have been developed and applied at home and abroad,such as AGET,MICROROC,GASTONE,etc.While great progress has been made in the fields of MPGDs and ASICs,the related readout electronics system for MPGDs in China is backward and lags behind,which has become a bottleneck to the further development and application of MPGDs.Modern and planned large-scale particle physics experiments are characterized by different scale of experimental apparatus,complex detectors,compact space size,large number of readout channels and high data bandwidth,etc.Traditional electronic architectures,such as fastBus,VME and PXI,can no longer meet the needs of further development of physical experiments.Facing this situation,CERN developed the FELIX(FrontEnd LInk eXchange)system for the specific application requirements of ATLAS upgrade.The FELIX system has the characteristics of high integration,large data bandwidth,many channels,high expansibility,flexible working mode and adaptability to different front-end ASIC chips,which also meet the requirements of readout electronics system for MPGDs.Based on sufficient investigations of the developments of readout electronics system architecture for physical experiments at home and abroad,a FELIX-based readout electronics system for MPGDs is proposed in this paper,with the target of providing a universal solution for MPGDs with different needs,in different fields,different stages of research and applications.This readout electronics system has characteristics of large data bandwidth,large number of channels,high compatibility,good expansibility,robustness,flexible working mode and suitable price,etc.The idea behind the system is to build a universal virtual hardware channels(Elink)from software to front-end ASICs with industry protocols and commercial devices,wich makes readout electronic system a part of the computer architecture.The specific work in the system is done by software,such as ASIC configuration,electronics system condition monitoring,data reading,etc.Because of this design concept,the readout system is flexible in working mode,scalable,and has good supports for different front-end ASICs.This readout electronics system can adapted to applications of MPGDs in different fields,different devices and different working modes.The system adopts mature technologies and products in the industry,which makes the system robust and suitable for long-term operation.The system can be further upgraded and developed with the progress of electronics in the industry,so as to meet the increasing needs of physics experiments.The prototype of the system consists of Chip Carriers,GBT boards,FELIX and back-end DAQ system.The function of a Chip Carrier is to complete detector analog signal shaping and digitization.Chip Carriers are equipped with different multi-channel charge measurement ASIC chips,and are usually close to or mounted on the detector.A GBT board is mainly used as a transparent data channel between multiple Chip Carriers and FELIX.Multi virtual channels are constructed in GBT by Time Division Multiplexing(TDM)to meet the requirements of large channel numbers.A FELIX consists of a commercial server FELIX server and a PCIE extension card FLX.It is a data node between front-end electronics and back-end DAQ system,adopting mature high-speed industrial technologies such as PCIE interface,fiber transmission and commercial switch.In this paper,AGET Chip Carriers and MICROROC Chip Carriers are used to build two sets of prototype readout electronics for MPGDs,which can realize 10240 MICROROC channels and 4096 AGET channels respectively.A set of cosmic ray track detection device has been constructed with the prototype readout electronics and Micromegas detectors developed by USTC.Electronic tests were completed as well as the reconstruction of cosmic ray track,which verified the extensibility of this architecture and support for different front-end ASIC.The feasibility of two-dimensional encoded multiplexing readout for MPGDs is also verified in the test.The results shows the FELIX-based readout electronics system is feasible for MPGDs applications.The universal and scalable readout electronics system designed in this paper can be easily extended to application with larger number of channels,and each part can be easily upgraded to improve the system performance and meet the requirements of MPGDs applications in defferent fields.In addition,this architecture has good versatility and can not only be applied to microstructural gas detector,but also be extended to other detectors,such as semiconductor detector,silicon pixel detector and so on.