MainDriftChamber(MDC)Cos0=0.83Cos0=0.93Interaction point43(8+12+16+7)sensewirelayersgroupto11superlayerCell is nearly square in shapecos0from-0.93to0.93He + C3H8 (60%+40%)
Main Drift Chamber (MDC) ❖ 43 (8+12+16+7) sense wire layers group to 11 superlayer ❖ Cell is nearly square in shape ❖ cos from -0.93 to 0.93 ❖ He + C3H8 (60%+40%) Interaction point Cosθ=0.83 Cosθ=0.93 6
MDCCalibrationTo (Time offset)calibration:To isdetermined cell by cell usingthedifferencebetweenmeasurementdriftdistanceanddoca(distanceofclosestapproach)Calibrationof Time-to-distancerelation (X-Trelation)UseBhabhaeventstodoinitialcalibrationUsepionsampletocalibrateX-TfunctionswithlargeentranceangleCalibration of Q-T function:to calibratethe correlationbetweentiminacdifferarferand mralse height of the signalQ-Tfunction(layer29)angleinlayer40po-5.466±0.06967p1155.4±1.8812.550-30°<α<-200-20<0<-10°Twalk = Po + pr / N4001.5-10°<0<0(su)(su)0<α<1001o10<α<20°0.520<0<30°-0.5100910103004005006007008009001000110012001300Driftdistance (mm)ADCcounts
MDC Calibration ❖ T0 (Time offset) calibration: T0 is determined cell by cell using the difference between measurement drift distance and doca (distance of closest approach) ❖ Calibration of Time-to-distance relation (X-T relation) ⚫ Use Bhabha events to do initial calibration ⚫ Use pion sample to calibrate X-T functions with large entrance angle ❖ Calibration of Q-T function: to calibrate the correlation between timing difference and pulse height of the signal X-T functions of different entrance angle in layer 40 Q-T function (layer 29) 0 1 / walk T = + p p Q 7
8Performancefrom Bhabha eventsForBhabhafrom2s) data,K10spatialresolutionis136m86321952505400-01Pisand0.138RMSN,+N6.605e-04±26200ForBhabhafromJIdata,N,/N+N2.7007±0.000spatialresolutionis135m1500339109000g= 135 μmPisand1002111ForBhabhafrom50data,spatialPisresolutionis138mand-0.8-0.6-0.40.20.40.60.8R2idual (m0)1.565sae6000α=1.4576+/-0.0085e-P=0.011343+/-0.0000301.5614000P=1.547811+/-0.00003712000nm1.019+/-0.0131.555100001.558000P60001.54540001.54200001A1.5351.451.51.55651.6P (GeV/c)(rad)
= 135 m ❖ For Bhabha from 2s) data, spatial resolution is 136 m and P is ❖ For Bhabha from J/ data, spatial resolution is 135 m and P is ❖ For Bhabha from data, spatial resolution is 138 m and P is Performance from Bhabha events 8
9Calibration Monitoringanea1.571.5651.565551.551.545J/yscan1.541.5351.539900100001010010200103001040010500Run180)oose1701601501401301201101009900100001010010200103001040010500Run
Run Peak value of Bhabha momentum Run distribution (GeV/c) Spatial resolution (m) Calibration Monitoring J/ scan 9
MDC M.C. Tuning (1)layer2recEffvsdocalayer29recEffvsdoca000.80.0.Ipi_data pi_datapi_mc。pi_mc0.doca(mmdoca(m工T0.90.80.7pi_data0.6pi_mc0.5100.4
MDC M.C. Tuning (1) 10