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.

The study of linearity and detection efficiency for 20″photomultiplier tube

Background The linearity and photon detection efficiency(PDE)are important parameters of photomultiplier tube(PMT),which need to be precisely measured with suitable techniques.Purpose To search good methods for linearity and PDE study of newly developed 20-inch PMT.Methods In this paper,we setup a testing system to use the average photoelectrons(P.E.)in pulse mode for linearity measurement with the result corrected for strong light.For the PDE measurement,we developed a relative method with a reference PMT whose efficiency is known to compare the measured PDE with both average charge and hit numbers.Results The measurements of PMT shows only 5%nonlinearity within 1000 P.E.and good PDE,the result of linearity’s corrected definition is closer to the real status of PMT.Conclusions The results show good charge and linearity response for newly developed 20-inch MCP PMT and dynode PMT.The testing techniques discussed in this paper are suitable for the study of PDE and linearity.