DEPFET Vertex Detector Simulation Status 26/09/2005 Ariane Frey Daniel Britzger MPI für Physik

Standard VXD Geometry Driver Simple cylinders, no support structures, layer thickness 0.1% X0 5×5000 e+/e-Background 4T Magnetfeld

DEPFET Ladder Geometry Pixel sensor (50 µm) Readout chip (50 µm) Frame with holes Si Frame (300µm) r=15 mm IP 8 Laddders in Layer 1

Implementation of DEPFET module Top Wafer – 50µm Si-Frame – Lower Wafer – 250µm Si sensor Boolean Solids Materials and dimensions from MySQL database Sensor mit Pixels Read out Chip

Simulated Ladder Mirrored Ladder Ladder for Layers 2-5

DEPFET Vertex Detector Ladder-gap Layer 1

Correction for overlaps in r done

How are hits determined ? Whole pixel sensor is one volume 1 hit per track, independent of crossing angle Each pixel is simulated separately Each crossed pixel gives 1 hit, however, no charge drift etc taken into account

Problems with single pixel simulation Of course, don’t want to have that many volumes (speed) Problem if track leaves sensor at the edges (in direction of G4Replica) Longer term goal: realistic readout/digitization simulation

What do the others do ? Example: CMS Pixel detector Get from GEANT entrance/exit point and energy loss in volume Track inside volume is split in 10 m subsegments Each fragment is assigned a fraction of the energy (Landau fluctuations) Charge is drifted to the detector surface (magnetic field, Lorentz angle) with diffusion (Gaussian) Mapping to pixel grid Noise added (assumed to be Gaussian) Digitization

„Occupancy“ pro mm2 Bei 25000 e+/e- Mean: 0.07 particles/mm2 Erwartet; ~125000 e+/e-Background pro BX Entspricht: 0.35 particles/mm2/BX Zusätzliche Integration ×20

MySQL Datenbank Datamembers und Typen Verschiedene Datenbanken DEPFET VXD Datenbank Strukturierte Daten Datenbank “Tables” Zentrale Datenbank über Internet pollin1.in2p3.fr