1. Collimation MDs LHC Study Working Group 19.04.2011 Daniel Wollmann for the Collimation-Team, BLM-Team, Impedance-Team, … LHC Study Working Group, 19.04.2011

2. Outline Nominal Collimation settings with parallel impedance measurement Quench test in the DS of IR7 Daniel Wollmann 2

3. Collimator Settings – Intermediate as currently in the machine Injection optics Squeezed optics Energy [GeV]4503500 Primary cut IR7 (H, V, S) [ σ ]5.7 Secondary cut IR7 (H, V, S) [ σ ]6.78.8 Quaternary cut IR7 (H, V) [ σ ]10.017.7 Primary cut IR3 (H) [ σ ]8.012 Secondary cut IR3 (H) [ σ ]9.315.6 Quaternary cut IR3 (H, V) [ σ ]10.017.6 Tertiary cut exp. (H, V) [ σ ]132611.8/26/11.8/11.8 TCSG/TCDQ IR6 (H) [ σ ]7/89.3/9.8 Intermediate: keep distance to primary collimators constant in millimeters during the ramp Nominal: keep distance to primary collimator constant in beam sigma during the ramp Daniel Wollmann 3

4. Better cleaning with nominal collimation settings Daniel Wollmann 4 Tight: Best performance but increasingly tight tolerances. R.W. Assmann, 2009 Factor >2 better cleaning at 3.5TeV predicted better worse

5. Nominal Collimator settings 3.5 TeV Max Intensity: 3e11p Close gaps of collimators in steps from operational, intermediate settings to nominal settings Tune shift observations during step wise movement of collimator families Qualification with loss maps (B1/B2 h/v, one off- momentum) If time: test 7TeV (factor 1.4 smaller) settings with low emittance LHC beam Daniel Wollmann 5

6. Quench test in the DS of IR7 Losses into DS of IR7 are predicted to define the collimation dependent intensity limit Measured as predicted: Losses of single diffractive protons in DS (off-momentum particles, loss positions independent of plane of losses) Quench test will allow to better specify the collimation dependent intensity limit. Optimization of BLM threshold in the DS Results will possibly impact the collimation upgrade scenarios Daniel Wollmann 6

7. Single Diffractive Protons lost in DS Zoom IR7-IR8 Daniel Wollmann 7 Losses of single diffractive protons after interaction with primary collimator (off-momentum protons)

8. Losses during stable beams (336b) - Today Daniel Wollmann 8 IR7 IR6 IR3 Luminosity dependent losses in the DSs of the experimental IRs (off-momentum particles)

9. Quench test in the DS of IR7 3.5 TeV (450GeV not sufficient, need single diffractive losses) Max Intensity: 1e13p Create high losses at primary collimators in IR7 Maximum losses in cold aperture expected to appear in DS Produce realistically distributed losses in DS (dilution, loss spots, … ); not possible with bump Daniel Wollmann 9