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

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

3. 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

4. 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

5. Simulated Ladder Mirrored Ladder Ladder for Layers 2-5

6. DEPFET Vertex Detector
Ladder-gap
Layer 1

7. Correction for overlaps in r done

8. 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

9. 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

10. 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

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

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