Tracking Simulation in North America

1. Tracking Simulationin North America Norman A. Graf ALCPG Meeting, SLAC January 8, 2004

2. Overview • Improving Detector Response Simulation • Intrinsic (Geant4, dedicated simulations) • Digitization (pixel size, strip pitch, orientation) • “Raw data” hits • Including Detector Backgrounds • Noise, machine and physics • Pattern Recognition • Track Fitting

3. Tracker Hits • Defer digitization to post-Geant4 to speed up simulations and investigate effects of readout. • e.g. Si strip pitch, TPC pad size, CCD pixel size. • Have defined “generic” tracker hit information for full simulation output. • SimTrackerHit in common LCIO format. • In studies to-date, hits have simply been smeared by expected resolutions. • No hit-merging or ghosting.

4. VXD CCD Digitization • Near-term focus on improving digitization. • Defined interface for pixelizing hits. • First implementation incorporates pixel distributions from SLD into simulations as functions of track parameters (Nick Sinev UO.) • Implementing pixel clustering and hit position and uncertainty determination. • Being incorporated into mainstream code.

5. Si -strip Digitization • Defined interface for hitsstrips w/ADC. • First implementation uses software based on BaBar code (C. Flacco, UCSC). Includes diffusion, charge expansion, noise. • Implementing strip clustering and hit position and uncertainty determination. • Being incorporated into mainstream code.

6. TPC Digitization • Dan Peterson presented a nice talk on work he has been doing to digitize the TPC hits. • Will collaborate with him (and others, e.g. M. Ronan, D. Karlen) to get this feature into the mainstream code. • Personally not sure how to correctly include time offsets for overlaid events…

7. Backgrounds • Much recent work has been done to systematically generate backgrounds from e+e-& +- pairs and hadrons (T. Barklow, T. Maruyama). • Mask & BDS elements have been included in GEANT4 using LCD XML detector description plus dedicated drivers for the masks, luminosity monitors and beam delivery system (T. Behnke). • G4 event source reads in GuineaPig output (TB). • Started generating data samples. • Machinery to overlay events exists.

8. SiD Barrel • Extend VXD-found tracks into SiD Barrel, picking up additional axial hits (S. Wagner). • Axial-only track finding in Barrel (SW). • Find MIP-clusters in EM Calorimeter (M. Charles). • Study alternate geometries? • Number & placement of barrels. • Strip pitch, z segmentation, stereo layers.

9. SiD Forward • Study effects of disk tiling and strip orientations. • Understand impact of ghosts when creating 3D hits vs. adding strip hits to VXD tracks. • Characterize robustness in presence of backgrounds (physics and machine). • Investigate alternate geometries. • Inner pixels, outer strips?

10. Alternate Detector Designs • Revisit the VXD design with an eye towards improving its pattern-recognition capabilities. • longer inner layer at larger radius? • better forward performance • larger outer radius? • better b and V performance • additional layer(s), forward disk elements? • redundancy • protection against possible layer 0 degradation • better b and V performance

11. Summary • Near term emphasis on improved detector digitization. • Active work on CCD, TPC, Si -strips • ~Full background sets available, being pushed through the full simulation. • Aiming for results at LCWS incorporating realistic hit reconstruction from “raw” data and in the presence of full backgrounds.