R.W. Assmann, V. Boccone, F. Cerutti, M. Huhtinen, A. Mereghetti Simulations of beam-halo and beam-gas at 3.5 TeV for IP1 & IP5 (progress report) R. Bruce R.W. Assmann, V. Boccone, F. Cerutti, M. Huhtinen, A. Mereghetti

Outline Introduction Improvements in FLUKA model Beam-halo simulations at 3.5 TeV, beta*3.5 m Inelastic beam-gas simulations with homogenous pressure profile Conclusions R. Bruce, 2011.07.11

Introduction Simulating shower of particles going through the interaction region into the ATLAS and CMS detectors with FLUKA. To be used by experiments for detector simulation. Several parts: Beam-halo Inelastic beam-gas Elastic beam-gas Status last time: beam-halo simulations done for IR1 and IR5, both sides, 2010 machine Simplified inelastic beam-gas simulations with homogenous pressure done for IR1 and IR5 Agreed work tasks Implement field map in the D1 (highest priority) Re-run simplified beam-gas simulation with higher energy cutoff and better statistics Status today: These goals have been achieved. R. Bruce 2011.07.11

D1 field Latest field map obtained from P. Hagen FLUKA fieldmap R. Bruce 2011.07.11

New collimator implementation More accurate model of TCT implemented by V. Boccone. Depth of tungsten independent of jaw opening Updated IR5 model with this collimator OLD NEW R. Bruce 2011.07.11

Outline Introduction Improvements in FLUKA model Beam-halo simulations at 3.5 TeV, beta*3.5 m Inelastic beam-gas simulations with homogenous pressure profile Conclusions R. Bruce, 2011.07.11

Cross-check: rerun beam-halo simulation for IR5 L Impacts dominated by impacts on vertical TCTV from horizontal halo (surprising!) R. Bruce 2011.07.11

Starting conditions IR5 Right of IR5 X (cm) Left of IR5 Y (cm) Z (cm) R. Bruce 2011.07.11

Normalization For simplicity and easy comparison, showing particle fluxes normalized per initial hit on TCTs (including both H and V) Normalization to get time rates: Particles @ interface plane /s = Conversion factors (TCT hits/ lost particles) Beam 1 Beam 2 IR1 1.0e-5 2.3e-5 IR5 4.6e-5 4.9e-6 R. Bruce 2011.07.11

Energy spectra Similar shape for all three cases No biasing used, cut-off at 20 M R. Bruce 2011.07.11

Energy spectra R. Bruce 2011.07.11

Radial energy distributions Most of the energy in the center of the beam pipe R. Bruce 2011.07.11

Radial energy distributions muons R. Bruce 2011.07.11

Outline Introduction Improvements in FLUKA model Beam-halo simulations at 3.5 TeV, beta*3.5 m Inelastic beam-gas simulations with homogenous pressure profile Conclusions R. Bruce, 2011.07.11

Inelastic beam-gas simulations New cases run: IR5 as before (20 MeV cutoff, nitrogen) but with D1 field map IR5 as before (nitrogen) but with D1 field map and 1 GeV cutoff IR5 as before but with D1 field map and 1 GeV cutoff and hydrogen - preliminary Sampling forced inelastic interactions homogenously along ideal orbit, between s=22.6 m and s=149.6 m Equivalent to assuming a homogenous pressure profile Real inhomogeneous pressure profiles can be accounted for by weighting the particles according to the initial interaction point, or selecting events with a probability according to pressure profile No biasing used R. Bruce 2011.07.11

Orbit geometry For the moment, no crossing angle (no corrector field) Accuracy: Particle tracked with FLUKA from TCT has a 3µm horizontal offset at interface plane. triplet D1 Interface plane X (cm) Outgoing beam MADX Incoming beam MADX Incoming beam FLUKA TCTs Z (cm) R. Bruce 2011.07.11

Results - energy spectra All cases similar in shape Less energy when using 1 GeV cutoff – reasonable also in high- energy spectrum? Energy @ interface plane for N and H respectively: 764 GeV vs 645 GeV with 1 GeV cutoff. 1.1 TeV with 20 MeV cutoff R. Bruce 2011.07.11

Energy spectra R. Bruce 2011.07.11

Radial energy distribution Impinging energy on interface plane strongly peaked in the center Falls off more rapidly at high radii with a 1 GeV cutoff R. Bruce 2011.07.11

Radial energy distribution R. Bruce 2011.07.11

Energy distribution for primary interaction along z Similar pattern for with and without field map Less energy with 1 GeV cutoff For muons, interactions farther away seem more important Expanding the geometry in z seems reasonable For other particles, interactions after D1 most important R. Bruce 2011.07.11

Energy distribution for primary interaction along z R. Bruce 2011.07.11

Outline Introduction Improvements in FLUKA model Beam-halo simulations at 3.5 TeV, beta*3.5 m Inelastic beam-gas simulations with homogenous pressure profile Conclusions R. Bruce, 2011.07.11

Conclusions New simulations presented for beam-gas and beam-halo presented D1 field map included New model of TCT 1 GeV cutoff in beam-gas simulation Using hydrogen instead of nitrogen in beam-gas simulation No dramatic differences seen w.r.t. old results All data files available on http://macbe13119 Feedback from experiments wanted: Are these new data files useful for your purposes? Is there anything strange in the results? What improvements are needed? R. Bruce 2011.07.11