1 R.W. Assmann, V. Boccone, F. Cerutti, M. Huhtinen, A. MereghettiSimulations 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

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

3 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

4 D1 field Latest field map obtained from P. Hagen FLUKA fieldmapR. Bruce

5 New collimator implementationMore 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

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

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

8 Starting conditions IR5Right of IR5 X (cm) Left of IR5 Y (cm) Z (cm) R. Bruce

9 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: 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

10 Energy spectra Similar shape for all three casesNo biasing used, cut-off at 20 M R. Bruce

11 Energy spectra R. Bruce

12 Radial energy distributionsMost of the energy in the center of the beam pipe R. Bruce

13 Radial energy distributionsmuons R. Bruce

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

15 Inelastic beam-gas simulationsNew 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

16 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

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

18 Energy spectra R. Bruce

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

20 Radial energy distributionR. Bruce

21 Energy distribution for primary interaction along zSimilar 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

22 Energy distribution for primary interaction along zR. Bruce

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

24 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 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