1. 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

2. 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,

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 fieldmap
R. Bruce

5. 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

6. 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,

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

8. Starting conditions IR5
Right 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 cases
No biasing used, cut-off at 20 M
R. Bruce

11. Energy spectra
R. Bruce

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

13. Radial energy distributions
muons
R. Bruce

14. 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,

15. 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

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 spectra
All 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 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

20. Radial energy distribution
R. Bruce

21. 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

22. Energy distribution for primary interaction along z
R. Bruce

23. 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,

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