1. Cosmic Rays for ATLAS Commissioning Commissioning Meeting ATLAS Physics Workshop Athens May 2003 Halo+Cosmics group: M.Boonekamp, F.Gianotti, R.McPherson, P.Nevski, J.Pinfold, R.Soluk Cosmics Info: http://cern.ch/rmcphers/atlas/cosmics/

2. Athens May 2003ATLAS Physics Workshop2 Overview  Scheduled ~ 40 days of cosmic running end 2006  Could also imagine cosmic running with only calorimeters earlier, and further running in January—March 2007 (machine cool down) IS IT USEFUL?  Study: Cosmic rates entering ATLAS cavern Hit or Geant “Digit” rate in different detector elements Calorimeter energy deposition (Triggers) (Offline Reconstruction)

3. Athens May 2003ATLAS Physics Workshop3 ATLAS Geometry SX1 PX14 PX16 PX15 UX15 USA15  Shafts (PX14 and PX16)  Large windows Critical to include in simulation  G3 Geometry Surface buildings PX14, PX16 Shielding Concrete …

4. Athens May 2003ATLAS Physics Workshop4 Current Geant 3 simulation Rock ~ Silicon 600m x 600m x 200m deep (2.33 g/cm 3 ) Air Concrete Density = 2.5 g/cm 3 Surface building PX14/16 shielding PX14 (14 m Inner Dia.) PX16 (10 m Inner Dia.) Full ATLAS Geant 3 Simulation (atlsim) - Release 6.0.3 - Initial detector - Full B fields

5. Athens May 2003ATLAS Physics Workshop5 In progress: refined description  Ground density variation with depth  Suspension halls  Other caverns (USA15, US15) Being implemented by R.Soluk and J.Pinfold in consultation with CERN civil engineers Can be used for later simulations

6. Athens May 2003ATLAS Physics Workshop6 Cosmic  Flux  Two generators used so far PDG approximation formula Single muon flux (Energy, cos  ) Neglects muon decay-in-flight Fit to measured fluxes Code from Alois Putzer (ALEPH simulation) Agrees at few % level with measured fluxes  Allkofer et al, Phys. Lett. 36B (1971), 425; A. Dar, Phys. Rev. Lett. 51 (1983), 227 For E  > 50 GeV Agreement < 20% level between 2 generators  Third generator also under study (Soluk) “CORSIKA” full cosmic ray shower program Useful for cosmic ray physics studies with ATLAS Includes “multi-muon” events, not present in other generators

7. Athens May 2003ATLAS Physics Workshop7 Sample studied  PDG single  flux with cuts: SURFACE : 0.35 < cos  < 1  (above 70 o hit earth’s curvature) 50 GeV < E  < 5000 GeV -300 m < X 0 < +300m -300 m < Z 0 < +300m  (allow  at 70 o to enter ATLAS cavern) ATLAS Y=0: use speed-up cuts (track extrapolation) -30 m < X(Y=0) < +30 m -30 m < Z(Y=0) < +30 m SURFACE RATES (before Y=0 cuts): 3 x 10 -4  / (cm 2 s) 1 x 10 6  / s CURRENT SAMPLE: 1.2 x 10 9  18 min)

8. Athens May 2003ATLAS Physics Workshop8 Cosmics  in 0.01 sec

9. Athens May 2003ATLAS Physics Workshop9 Kine Distributions … “Cavern”: ATLAS G3 volume  E, cos  of  entering cavern

10. Athens May 2003ATLAS Physics Workshop10 Kine Distributions … “Digit”: Any G3 digit (mostly MDT)

11. Athens May 2003ATLAS Physics Workshop11 Kine Distributions …  Through-going RPC digit, Y>0 RPC digit, Y<0 ID Digits  Can(?) adjust LVL1 RPC trigger for these

12. Athens May 2003ATLAS Physics Workshop12 Kine Distributions …  Through-going RPC digit, Y>0 RPC digit, Y<0 Pixel Digits  LVL1 RPC trigger should work (with timing adjustments)

13. Athens May 2003ATLAS Physics Workshop13 Digit Distributions …  Detector planes From digit counting Number of “ihit=1” hits

14. Athens May 2003ATLAS Physics Workshop14 Digit Distributions …  Detector planes From digit counting Number of “ihit=1” hits

15. Athens May 2003ATLAS Physics Workshop15 Digit Distributions …  Detector planes From digit counting Number of “ihit=1” hits

16. Athens May 2003ATLAS Physics Workshop16 Digit Distributions …  Detector planes From digit counting Number of “ihit=1” hits

17. Athens May 2003ATLAS Physics Workshop17 Digit closest to (0,0,0)

18. Athens May 2003ATLAS Physics Workshop18 EM Cal Transverse Energies  EM endcaps and barrel  ECALREC for reconstruction and clustering  EM Scale

19. Athens May 2003ATLAS Physics Workshop19 Tile Energy  Tile calorimeter  Used DIGI(4) for energy  EM Scale

20. Athens May 2003ATLAS Physics Workshop20 HEC Energy  Hadronic EC  Used DIGI(4) for energy  EM Scale

21. Athens May 2003ATLAS Physics Workshop21 FCAL Energy  Forward Cal  Used DIGI(4) for energy  EM Scale

22. Athens May 2003ATLAS Physics Workshop22 Rates Summary SystemCondition Rate (Hz) ATLAS Cavern --3400 Any G3 Digit --1450 Through RPC Y>0 x RPC Y 0 x RPC Y<0 x ID DIGI13.7 Going RPC Y>0 x RPC Y 0 x RPC Y<0 x PIX DIGI0.34 Passed |Z DIGI | < 300, |R DIGI | < 60 cm 6.05  origin  origin |Z DIGI | < 100, |R DIGI | < 30 cm 1.12 |Z DIGI | < 60, |R DIGI | < 20cm 0.32 E T CELL > 5 GeV 0.09 EM Cal E T CLUSTER > 5 GeV 0.21 E TOTAL > 5 GeV 0.36 Tile Cal E TOTAL > 20 GeV 1.37 HEC 0.14 FCAL 0.015 Rate error (generator comparisons)  20%

23. Athens May 2003ATLAS Physics Workshop23 Summary, Plans  Working cosmic  G3 (atlsim) MC for ATLAS Different generators 4-vectors samples of muons entering cavern ZEBRA event files for offline studies  Rates seem to be large enough for initial electronics shake-down Dead channel maps, electronics+DAQ checks, etc.  To-do: triggers and offline reconstruction … Simplified trigger studies: have input already for LVL1 RPC (Gianpaolo Carlino, Leandro Nisati, Stefano Veneziano) and Tiles (Alan Watson), and also from Nick Ellis Full trigger studies: switch to full ATHENA trigger simulations, currently under development Many issues for both triggers and reconstruction due to non- pointing, out of time tracks must be studied Studies: reconstruction, alignment, calorimeter calibration …