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BDSIM at LHC G. A. Blair, L. Deacon RHUL CERN, 25 th June 2009

BDSIM at LHC G. A. Blair, L. Deacon RHUL CERN, 25 th June 2009. Introduction to BDSIM Use in ILC Recent use in CLIC BDS Progress in implementing LHC Summary. Fast accelerator-style Tracking within beam-pipe ‘Normal’ G4 tracking outside. BDSIM. I. Agapov G. Blair,

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BDSIM at LHC G. A. Blair, L. Deacon RHUL CERN, 25 th June 2009

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  1. BDSIM at LHCG. A. Blair, L. DeaconRHULCERN, 25th June 2009 • Introduction to BDSIM • Use in ILC • Recent use in CLIC BDS • Progress in implementing LHC • Summary

  2. Fast accelerator-style Tracking within beam-pipe ‘Normal’ G4 tracking outside BDSIM I. Agapov G. Blair, J. Carter, L. Deacon, S. Malton, (RHUL) + R. Appleby (UMAN)… + O. Dadun (LAL)… All secondaries tracked https://www.pp.rhul.ac.uk/twiki/bin/view/JAI/Simulation ERLP LHC ILC, CLIC ATF, PETRA

  3. Basic Structure of Code Object oriented approach natural for beamline structure Acc. Comp. geometry Acc. Comp. beamline Stepper

  4. G4 Stepper Post-step x,xp,y,yp,z,E Multipole Stepper Step-size from physics process Each volume can have its own field or stepper Pre-step x,xp,y,yp,z,E Multipoles up to Octupoles included so far

  5. “Fast” Tracking Sector Bend Accuracy of volume intersection Delta-chord Performance depends crucially on these parameters… Can still be further optimised... Drift

  6. Synchrotron Radiation Generator of H. Burkhardt Implemented for all components Based on local curvature Individual photons from individual parents Primaries and secondaries tracked

  7. Muon Showers The muons are in addition to the electrons (doesn’t conserve energy) correct spectra via track weighting: Increase statistics for Bethe-Heitler by forcing

  8. TESLA: Muon Trajectories Concrete tunnel 2m radius BDS No offset from centre View from top

  9. TESLA: Muons at IP 10-3 Halo bunch 82% e’s Lost in BDS Nμ per lost e = 0.6 10-5 (Bethe-Heitler only) (TDR used 1.4 10-5 incl. other mechanisms) Tunnel Diameter 4 m

  10. Interaction Region in BDSIM • Full IR Geometry modelled in BDSIM • Using MySQL geometry database • Currently using the “Stahl” design for L* = 4.1m • Includes a full Solenoid Field Map Z Component Screenshot of an IR Design in BDSIM Radial Component at 1m from beamline

  11. 100W/m hands-on limit Losses in ILC extraction line 20mrad 20mr: losses < 100W/m at 500GeV CM and 1TeV CM2mr: losses are at 100W/m level for 500GeV CM and exceed this level at 1TeVRadiation conditions and shielding to be studied Losses are mostly due to SR. Beam loss is very small 2mrad 250GeV Nominal, 0nm offset 100W/m 45.8kW integr. loss Losses are due to SR and beam loss J. Carter, I. Agapov, G.A. Blair, L. Deacon (JAI/RHUL), A.I. Drozhdin, N.V. Mokhov (Fermilab), Y.M. Nosochkov, A.A. Seryi (SLAC) J. Carter

  12. CLIC BDS

  13. LHC Beamline • Beamline converted from MADX to GMAD format • Beam 1, interaction region 7 (betatron cleaning section), from first primary collimator (TCP.D6L7) to final coll. before IP7 • Primary vertical collimator aperture and material (carbon) defined • Section shown is ~200m long. Image not to scale (vertically stretched). space for secondary collimators primary collimators quads dipoles L. Deacon

  14. Particles • 7 TeV protons hitting primary collimator • Particle distribution from existing simulation data (Chiara Bracco) • Hadronic interactions turned on • Secondaries produced (green = neutral, blue = positive, red = negative charge) primary collimator L. Deacon

  15. Tracking • Particles tracked along beam line • Energy loss recorded in magnets, beam pipe, collimators • Particle positions, energies etc. can be sampled at any location L. Deacon

  16. Energy loss histogram primary collimators other components • Preliminary results • Secondary and absorber collimator apertures are yet to be defined in the simulation quads L. Deacon

  17. Next steps • Check physics processes • Define collimator apertures and materials • Extend beamline to detectors – mainy ATLAS • Run on computing Grid Summary • BDSIM is ideal for full simulation of LHC beamline including full secondary production and tracking • Interfaces to Sixtrak output have been defined • First simulations are now underway • ATLAS interfaces planned • Well defined programme; work has started…

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