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JC and Marina 12/18/00. Pixel Detector Simulation with Magnetic Field. Effects with magnetic Field Deflection Effective mobility Non-constant Hall mobility Comparison with magnet run. Magnetic Field. 0 V. n +. . e. e. B y. e. e. n. e. e. . e. e. e. e. e. e. e.
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JC and Marina 12/18/00 Pixel Detector Simulationwith Magnetic Field • Effects with magnetic Field • Deflection • Effective mobility • Non-constant Hall mobility • Comparison with magnet run
Magnetic Field Syracuse University
0 V n+ e e B y e e n e e e e e e e e e p+ -V Deflection in Magnetic Field Effect of magnetic field Effect of incident angle Syracuse University
Deflection in Magnetic Field Assumption: mH = constant meff = m The charge distributions are the same with B or q Syracuse University
Effective Mobility Very small effect: B field Cloud drifts slower Larger Spread Syracuse University
P+ side larger E N+ Side Smaller E E-dependent Mobility Larger E Smaller mHall Smaller deflection Syracuse University
Effect of Magnetic Field With non-constant mHall(E), and meff The charge distributions are slightly different Syracuse University
Conclusion We Don’t expect the magnetic field will reduce the ratio between two-pixel clusters and one-pixel clusters Syracuse University
Magnet Run • Track at 1.3 angle ( ~ 0.242 Tesla ) • Measurement: Rmin = 0.193 • Simulation ( Qth= 2.5Ke ): Rmin = 0.250 What is wrong ? Syracuse University
Magnet Run • Track at 1.32 ( 23 mrad ) ( ~ 0.245 Tesla ) • Measurement: Rmin = 0.193 • Simulation ( Qth= 4.0Ke ): Rmin = 0.197 Just to Play around But there is no other evidence that threshold was wrong Syracuse University
Magnetic Field • Measured with Gauss meter: 45A 0.585 Tesla • Assume overall scale of the magnetic field uncertain • Use MC simulation to fit 0.517 Tesla (error?) • Error of Hall factor (mHall/m =1.15) can make up the difference Syracuse University
Summary • MC simulation accurate both for drift and B field simulation • Magnet Run data is not fully understood yet Syracuse University
Lorentz Angle Lorentz angle is not a constant along z, shown are overall effects Larger bias voltage Larger E field Smaller mobility Smaller Lorentz angle Syracuse University
Lorentz Angle Comparison Magnetic field: 1.4 Tesla Udepletion is calculated with effective thickness of the sensor Syracuse University
Diffusion Constant Einstein equation: D = k T m / q Reduce Teff from 390K to 300K Reduce fraction of doublet by 1.4% Syracuse University
Angular Fit with Distribution FPIX0-Pstop Normal Incidence Data • MC: 0.5 interval, interpolation between points • Normal incident data: = (1.77 0.09) Syracuse University
15° Data 20° Data 10° Data 5° Data Angular Fit with Distribution FPIX0-Pstop Syracuse University
Detector Inclination Angle • In Minuit fit, the beam is assumed to normal incident on the first SSD, the overall rotation of the detector can not be fitted • In fit, interpolation between MC points (0.5° interval) is used • The error from the fit is about 0.1°, which should be smaller than error from MC model Syracuse University