Setup Of A PMT Test System For LHAASO-KM2A And STAR-iTPC MWPC Prototype Design And Performance Measurement

This thesis consists of two parts:(1)Setup of a PMT test system for LHAASO-KM2A;(2)STAR-iTPC MWPC prototype design and performance measurement.1.Setup of a PMT test system for LHAASO-KM2A.Large High Altitude Air Shower Observation(LHAASO)is a proposed cosmic ray experiment which will be built in Daocheng,China.The main array of LHAASO,Kilometer-square Array(KM2A)is focused searching for galactic gamma ray sources above 30 TeV in the northern hemisphere and expand research on cosmic ray physics.It consists of 5261 electromagnetic particle detectors(ED)and 1146? detectors(MD).The ED is scintillator detector that consists of 4 rectangle plastic scintillation tiles(25cm*100cm).32 Wavelength-shifting fibers are embedded in each tile to collect the scintillation light and transfer to a 1.5 inch diameter head-on type photomultiplier tube(PMT).The quality of PMT will affect directly to the ED's performance,should be strictly controlled.In order to finish the work of quality control,a multi-function PMT test system was setup.This part of thesis work including 3 parts:the design of the PMT test platform,development of software and the research of measurement method.A multi-function light tight box with 3 stepper motors was designed,which can hold 16 PMTs.The 3 stepper motors and 16-channel fiber optical transfer scheme made it possible for the test and scan.The electronics of the system contains VME and NIM based modules,including QDC?TDC?scaler?LTD?CFD,gate generator,etc.The charge,time of PMT anode output signals are measured.The software system consists of 3 parts:control system and data acquisition(DAQ)and offline data analysis.The control system realizes the remote monitor and control of system run according to the measurement procedure.The DAQ system was designed based on VEM-BUS protocol and it was developed with C under Linux OS.The main function of it is used to transport the readout raw data of electronics to the workstation.Offline data analysis based on CERN ROOT package was used to analyse and depict the test results.The candidate PMTs for KM2A ED were measured with the system,including:Hamamatsu R11102,ET 9903KB,Photonis XP2012.It focused on measurement meth-ods and characteristics studies,including absolute gain(SPE spectrum),gain vs.voltage,cathode uniformity scanning,linearity dynamic range,time transit time spread(T.T.S),cathode time transport difference(CTTD),etc.The PMTs can be measured with high precision and the system can work efficiently with long time stability.2.STAR-iTPC MWPC prototype design and performance measurement.The STAR collaboration proposed a second phase of the Beam Energy Scan program at RHIC(BES Phase-?)to answer compelling questions about the phase structure of QCD matter.It requires an upgrade of the STAR inner sector TPC(STAR-iTPC)to extend the capabilities of the TPC in many ways:improved dE/dx and momentum resolution,as well as tracking at higher pseudorapidity(|?|?1?|?|?1.5).STAR-iTPC upgrade will renew all of 24 inner sectors of wire chambers.Shandong University,as a collaborator of STAR-iTPC group,mainly responsible for the mass production of wire chamber and the performance measurement.This thesis work includes:developing the software of the control system of the wire-winding machine,setup of a wire tension test system,design and construction of the iTPC wire chamber prototype,experimental setup and performance measurement for the iTPC prototype based on cosmic ray ?.The iTPC wire chamber is a type of multi-wire proportional chamber(MWPC).For the MWPCs' mass production,I developed an automatic software for a wire-winding machine.With the function of tension control,it can wind wires with approximately constant tension.I also design and develop of a wire tension measurement platform.The platform can scan the wire plane,automatically,in a single run and obtain the wire tension on each wire with high precision.The iTPC MWPC essentially consists of 3 planes of wire(Anode?cathode and gate),a signal readout padplane and a strongback.The process of wire-wind was a wire-transfer frame first.Then it transferred the wire plane to the iTPC module.The combs fabricated with high-accuracy was used for the wire pitch adjustment when it fixing on the module.To make performance study of the iTPC prototype,an measurement system was setup based on the cosmic ray ?.Experimental setup mainly including drift chamber design,gas system,electronics and trigger.Using it,signals from multi-pad were read and a cosmic ? track was reconstructed.The test results show the performance of the prototype fulfill the iTPC design.