 Background at CLIC and Requirements on Time Stamping Marco Battaglia UC Berkeley, LBNL and CERN Jean Jacques Blaising LAPP, Annecy and contributions from Daniel Schulte, Albert De Roeck CLIC Meeting CERN, May 14, 2009

 Background Characterisation   hadrons generated using GuineaPig + PYTHIA by Daniel Schulte using Schuler and Sjostrand cross section parametrisation and PS fragmentation; Database of events readable with HADES provided by Daniel; 2.7   hadrons / BX at 3 TeV for 2008 CLIC parameters; Consider only particles with |cos  | 0.2 GeV Nb of Particles Nb of Tracks Energy 11.7/BX8.1/BX27 GeV/BX

 Background Characterisation

Effects from  Background MB and A De Roeck, CERN Detector Effect +   hadrons 25 ns time stamping

Effects from  Background

Energy at ECAL from  Background

Track Occupancy from  Background Overlay   hadrons to e + e  event in PYTHIA using HADES and save BX number for each particle in event record: Full simulation using VXD+FTD+beampipe with B=5 T in Mokka and reconstruction (digitisation + pattern recognition + tracking) in Marlin.

Track Occupancy from  Background R=30 mm -50<z<50mm R=50 mm -125<z<125mm R=70 mm -125<z<125mm Hits/mm 2 /Train~0.20~0.17~0.14 z=200 mm 85<R<140mm Hits/mm 2 /Train~0.04 VXD FTD

SUSY Benchmarks at Point K'

Track Occupancy from  Background VXDFTD

Track Occupancy from  Background ~5500 hits on VXD for 50 BX Full PatRec in VXD only yielding ~450 tracks PatRec efficiency > 90 % for high p t tracks 1 ns 25 ns ~10 ns time stamping capability seems adequate for mitigating the effect of  background on event reconstruction.

Track PatRec with  Background Layer 1 R=30 mmLayer 2 R=40 mmLayer 3 R=50 mm R ROI on Layer 5.0  m6.8  m12.7  m VXD-based Full PatRec assuming 10 ns time stamping on all layers 20 BX Assume here monolithic pixels 0.12% X 0,  point = 3.5  m,  m pixel cell, Main Tracker give unambiguous Layer 5 to Layer 4 hit bundling.

Track PatRec with  Background 10 ns Time Stamp Layer 1 R=30 mm -50<z<50 mm Layer 2 R=40 mm -125<z<125 mm Layer 3 R=50 mm -125<z<125 mm VXD-based Full PatRec assuming 10 ns time stamping on all layers CLIC 3 TeV + 20 BX   hadrons Full VXD PatRec

  hadron background affects mostly channels with missing energy or precise di-jet mass reconstruction because of extra energy injected in the event; occupancy appears negligible in Barrel Cal and modest in Vertex tracking with time stamping ~ ns, preliminary results documented in CLIC Note in preparation; optimisation of time stamping strategy (very precise timing at a single layer or distributed timing in innermost tracking layers) requires to consider constraints from layer material budget, power dissipation and pixel sizes. study pattern recognition efficiency and performance for different VXD concepts (in collaboration with Alex Kluge et al.) on physics benchmarks +   hadrons and PAIR background.