Jianchun Wang Marina Artuso Syracuse University 11/06/00 MC Simulation of Silicon Pixel Detector
Jianchun (JC) WangSyracuse University2 Readout Signal Simulation ee Track E Energy deposition by charged track along its path length, and production of electron/hole pairs Electron clouds drifting towards readout pixel in electric field (corresponding to doping and bias voltage applied) Electron cloud spread due to diffusion Magnetic field deflection (our sensors will be in dipole field of 1.6 T) Realistic front end electronics (noise, threshold, digitization accuracy)
Jianchun (JC) WangSyracuse University3 Energy Deposition Density effect: At high , radiative losses need to be considered (+7%) Thin material (280 m silicon): = 5.0 keV, / I 0 = GeV/c
Jianchun (JC) WangSyracuse University4 Production of -ray Number of -ray: 0.5 (T cut =10 keV, d=280 m) Kinetic energy according to dN/dT Polar angle is calculated Azimuthal angle generated isotropically
Jianchun (JC) WangSyracuse University5 Ionization of -ray The -ray range is calculated The length of -ray Survival probability function Ionization uniformly -ray escape (only 1/4 of energy collected)
Jianchun (JC) WangSyracuse University6 Excitation and Ionization Urbán model (thin material: /I = 29 for 280 m silicon) Excitations: E 1 E 2 Ionization: E 3 Cross-sections dE/dx: C· (1 r) for excitation and C·r for ionization
Jianchun (JC) WangSyracuse University7 Total Charge Total Charge (ke) Landau function
Jianchun (JC) WangSyracuse University8 Electric Field n+n+ n p+p+ -V 0 V EZEZ Z n + on n p + on n p+p+ n n+n+ +V 0 V
Jianchun (JC) WangSyracuse University9 Mobility T = 300 K V applied = 140 V V depletion = 85 V d = 280 m
Jianchun (JC) WangSyracuse University10 Magnetic Field
Jianchun (JC) WangSyracuse University11 Charge Cloud Spread Radius of ionization trail: R = hc / I (~2 m) Diffusion: D = kT / q, X = Y = sqrt(2Dt)
Jianchun (JC) WangSyracuse University12 Electronics Noise (preamplifier, ADC) Non-uniform threshold Gain uncertainty ADC precision
Jianchun (JC) WangSyracuse University13 Cluster Algorithm Similar as test beam offline analysis Plan: study overlapped cluster This might also improve the resolution by reducing the effect of -ray
Jianchun (JC) WangSyracuse University14 Charge Sharing FPIX0 CiS p-stop Q th = 2500 e V bias = 140V V depl = 85V Simulation Measurement Fraction of Cluster (row) size
Jianchun (JC) WangSyracuse University15 Large Size Cluster Simulation has less large size cluster than measurement Source ? FPIX0-pstop
Jianchun (JC) WangSyracuse University16 Charge Sharing FPIX1 Seiko p-stop Q th = 3780 e V bias = 75V V depl = 45V Simulation Measurement Fraction of Cluster (row) size
Jianchun (JC) WangSyracuse University17 Reconstruction Linear correction applied X residual = X track - X recon
Jianchun (JC) WangSyracuse University18 Resolution vs angle No track projection error subtracted from the measurement Resolution distribution agrees with simulation Binary resolution degraded from 8-bit ADC FPIX0 p-stopFPIX1 p-stop
Jianchun (JC) WangSyracuse University19 Summary New version simulation program works quite well There are not much can be tuned Plug the code into BTeV simulation Two approaches need to be evaluated – Use GEANT simulation in energy deposition – Use the energy deposition simulation of this program
Jianchun (JC) WangSyracuse University20 Beam Test Track Angle Precision of the alignment is about 0.1 (i.e. Four runs of FPIX1 P-spray at 15 : 15.16, 15.22, 15.25, 15.16)