Beam-background simulations at IP1 & 5: a first discussion on 2011 priorities

1. Beam-background simulations at IP1 & 5:a first discussion on 2011 priorities • In this meeting today: a first look at... • the topics that need to be covered • the external inputs needed (e.g. vacuum) • the priorities • the amount of work involved (FTE’s) • This will then be iterated (in parallel) within • ATLAS • CMS • the collimation group • the LBS before it is finalized... moderated by W. Kozanecki

2. Immediate Priorities: overview • Complete the ongoing collimator-halo simulation • estimated workload • RB: ff FTE • target delivery date: dd/mm/2011 • Sensitivity to inelastic beam-gas btwn TCT & experimental cavern • estimated workload: • RB: ff FTE • target delivery date: dd/mm/2011

3. Immediate Priorities (1) • Complete collimator-halo simulation • beam conditions: 3.5 TeV/beam. b* = 3.5 m • source: collimator halo impinging on the TCT, from the worst source: • B1 at IP1 • B2 at IP5 • main deliverable: particle fluxes @ interface plane, biasing off • external inputs still required: none?

4. Immediate Priorities (2) • Sensitivity to inelastic beam-gas btwn TCT & experimental cavern • beam conditions: 3.5 TeV/beam. b* = 3.5 m • source: beam-gas scatters between TCT and interface plane • pressure profile • uniform, so as to easily produce a source distribution (= background flux as a function of scattering location along beam line) • external inputs still required • reference gas species? • b*: 3.5 m (2010) or 1.5 m (2011?) • main deliverable: particle fluxes @ interface plane, biasing off, uniform p distribution, including scattering history per particle • may require cross-checks on effect of • transverse offsets, large alignment errors, aperture model • b*, beam tails

5. Medium-term priorities: overview (in arbitrary order) • Absolute prediction of inelastic beam-gas backgrounds btwn TCT & experimental cavern • Extend sensitivity study of inelastic beam-gas to scatters beyond the TCTs & (some distance) into the arcs • IR FLUKA inputs from collimation halo tracking w/ 2011 optics • allows rough scaling of 2010 halo results to 2011 conditions • FLUKA runs for collimation halo on TCT's with2011 low b* (2011) are considered lower priority by the experiment • Extend the collimation halo study to the 2nd beam • B2 @ IP1, B1 @ IP5 • Background implications of smaller IP beam pipes • collimation halo background with baseline optics at that time? • background impact of tighter TCT settings under those circumstances?

6. Medium-term priorities: detailed issues • Absolute prediction of inelastic beam-gas backgrounds btwn TCT & experimental cavern

7. Medium-term priorities: detailed issues • Extend sensitivity study of inelastic beam-gas to scatters beyond the TCTs & (some distance) into the arcs

8. Medium-term priorities: detailed issues • IR FLUKA inputs from collimation halo tracking w/ 2011 optics • allows rough scaling of 2010 halo results to 2011 conditions • FLUKA runs for collimation halo on TCT's with2011 low b* (2011) are considered lower priority by the experiment

9. Medium-term priorities: detailed issues • Extend the collimation halo study to the 2nd beam • B2 @ IP1, B1 @ IP5

10. Medium-term priorities: detailed issues • Background implications of smaller IP beam pipes • collimation halo background with baseline optics at that time? • background impact of tighter TCT settings under those circumstances?

11. Tentative conclusions (after discussion) from this meeting