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Test Beam 2002. Pixel Response Simulation: Update. Paul Nilsson, SPD Group Meeting , August 26, 2003. Jan Conrad (CERN, Pixel Group) SPD general meeting November, 2004. Side remark. Ivanov’s talk: parameterization of errors on reconstructed points
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Test Beam 2002 Pixel Response Simulation: Update Paul Nilsson, SPD Group Meeting , August 26, 2003 Jan Conrad (CERN, Pixel Group) SPD general meeting November, 2004 P. Nilsson, SPD Group Meeting
Side remark • Ivanov’s talk: parameterization of errors on reconstructed points if response working, this can be done by MC (true-rec for different cluster sizes) get parameterizations as function of incident angle and different cluster sizes. Simulation Reconstruction Probably better: data analysis see talks of Domenico, Daniela,Pål P. Nilsson, SPD Group Meeting
Contents • Main news: • Diffusion is included and working P. Nilsson, SPD Group Meeting
Diffusion in AliRoot (Dubna) model • Energy is deposited in steps in the sensor volume (15-20 steps) • Charge sharing done by diffusion (see next slide). Dependence on bias voltage. P. Nilsson, SPD Group Meeting
Diffusion • Gaussian diffusion: charge cloud spreads out during the particle’s traversion • σdiff = k (T ldr,)1/2 • k = (2D/vdr)1/2D = 11cm2/s • vdr = μ E μ = 450 cm2/Vs • E = Vbias /dsensor σdiff dsensor / √Vbias ≈ 5 – 15 μm P. Nilsson, SPD Group Meeting
What is in the simulation @ present (default) ? • Charge sharing geometrical (Ba/Sa model) • Coupling parameters: 0. (no coupling) • Threshold: 2000 e, • noise/threshold 280 e • no dependence on bias voltage • no dependence on temperature P. Nilsson, SPD Group Meeting
Geometry 2002 Trick: whole ladder Si (for segmentation, BN) No scintillators,no PCB VTT ladder: 300μ Chip: 725 μ Telescope: 300 μ Chip: 725 μ P. Nilsson, SPD Group Meeting
Simulation • assume 300 mu detector, 80 V bias • threshold: 2300 e , Noise: 300 e • file: biasscan_chip03_th200_14-07 2002.root P. Nilsson, SPD Group Meeting
Cluster Sizes including diffusion Long dimension Short dimension P. Nilsson, SPD Group Meeting
How does it look without diffusion? No diffusion diffusion P. Nilsson, SPD Group Meeting
Scans(slide taken from last SPD general meeting) Simulation ThresholdScan BIAS VOLTAGE? Data Angle Scan P. Nilsson, SPD Group Meeting
Scans: present status P. Nilsson, SPD Group Meeting
δ rays • Generated on correct level: • rule of thumb: 1 δ ray per mm Si per incident particle. P. Nilsson, SPD Group Meeting
Status summary and outlook • Cluster sizes 1 and 2 reproduced (zero tilt) • There is still a problem with cls >3 • Trigger simulation • more material details • FLUKA (M. Noriega) • More long term: • more effective diffusion routine ( CPU diff/nodiff = 7) • 2003 ! P. Nilsson, SPD Group Meeting