| The Higgs particle is the last elementary particle found in the standard model,marking the success of the standard model and explaining the source of mass of elementary particles.Accurate measurement of the properties of Higgs particles has very important scientific significance.In the current international research,lepton collision,as a Higgs particle production method with a clean background,is a relatively competitive Higgs particle research method.There is currently no lepton collider dedicated to the study of Higgs particles in the world,and a chance appears in the field.Under this background,China's high-energy physics community has proposed the Circular Electron Positron Collider(hereinafter referred to as CEPC),and aims to build a "Higgs particle factory" in China to produce a large number of Higgs particles for further research.The CEPC uses the particle flow algorithm(PFA)to reconstruct the energy of the particle of final state,and combines the information from tracker detectors to distinguish the various components in the jet to obtain a higher resolution of the jet energy.For implementing particle flow algorithms,fine-grained imaging calorimeters are essential.For the electromagnetic calorimeter,the scintillator solution has the advantage of lower cost.At present,only the CALICE cooperation group has built a physical prototype of the solution to verify the feasibility of the principle.However,it has not studied how to implement the readout electronics of the fine-grained electromagnetic calorimeter.This paper designs a readout electronics system based on SPIROC chip for the prototype of the scintillator-based imaging electromagnetic calorimeter.The system supports the reading of 6300 channels of SiPM,and has functions such as electronic self-check,gain monitoring,and temperature compensation.The front-end part adopts a modular design and consists of 30 front-end readout modules.Each module completes 210 channels of SiPM signal amplification,shaping filtering and digitization.The module is highly compact,and the detector and electronics are closely integrated,realizing an average 1 channel/2cm3 high-density readout.The back-end part is based on the FELIX architecture and consists of a data acquisition board(DAQ)and FELIX nodes.It has the functions of clock synchronization distribution,state handshake and data transmission.Both the upstream data channel and the downstream data channel can reach a data transfer rate of up to 9.6Gbps.In this paper,after the realization of the electronic system,the electronic test,radioactive source test and cosmic ray joint test are carried out.Tests have shown that the electronics system operates normally,the electronics equivalent charge noise is less than 90fC,the dynamic range is about 300pC,the integral nonlinearity is not more than 1.6%,and the relative standard deviation of the gain inconsistency after correction is about 1%.The single-channel time measurement accuracy is about 2.5ns,the integral nonlinearity is less than 0.2%,and the linear coefficient inconsistency does not exceed 2%.The overall system time measurement accuracy is about 7ns.Under the framework of the prototype,10 layers of the 30 layers front-end readout module were selected for cosmic ray testing.The measured signal-to-noise ratio of the MIP signal can reach more than 20,and successfully reproduced the cosmic ray track.The temperature compensation system works normally.After the correction,the uncertainty of SiPM gain can be controlled within 5.5%when the ambient temperature changes by 4?.In this work,a readout electronics solution for a fine-grained scintillator electromagnetic calorimeter is designed and its feasibility is verified in a joint test with a prototype.This provides a technical reference for the CEPC scintillator electromagnetic calorimeter readout electronics solution. |
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