1 / 9

50 ns Back-up Solution - Summary

50 ns Back-up Solution - Summary. V. Kain, B. Salvant , B. Goddard, W. Hofle , G. Iadarola , T. Pieloni , G. Arduini , M. Meddahi , G. Rumolo , J. Wenninger. Résumé of 25 ns possible issues. Machine protection due to increased energy density: probably solvable

gerodi
Download Presentation

50 ns Back-up Solution - Summary

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 50 ns Back-up Solution - Summary V. Kain, B. Salvant, B. Goddard, W. Hofle, G. Iadarola, T. Pieloni, G. Arduini, M. Meddahi, G. Rumolo, J. Wenninger

  2. Résumé of 25 ns possible issues • Machine protection due to increased energy density: probably solvable • Beam inducedheating: similar for 25 ns and 50 ns • UFOs: to be seen in LHC run 2 • Possible only real threat: e-cloud RLIUP workshop - Archamp

  3. The only real threat: E-Cloud • Significant increase of heat load (~ factor 4) in arcs during ramp • Coming only from e-cloud in the dipoles • Does not decrease over time at flattop (no scrubbing at flattop ?) • Underlying mechanism to be understood • Assuming 2012 scrubbing situation: • Limited to 50 % of nominal number of bunches for 25 ns spacing • Mitigation: • Remove e-cloud “completely”in dipoles: doublet beam scrubbing • To be tried in 2015 • HL era: Cryo cooling power upgrade? RLIUP workshop - Archamp

  4. 50 ns alternative RLIUP workshop - Archamp

  5. Integrated luminosity estimate - assumptions • Physics Efficiency = time in stable beams / total available time • Use 2012 physics efficiency: 0.37 • Pessimistic/realistic fill length distribution: exponential distribution • Average fill length ~ 6 h (2012) • Remark: uniform distribution: ~ 15 % more performance • Assume luminosity lifetime = 9 h (const.) • Simplistic assumption • 160 days of physics operation • Pile-up limit 140  50 ns leveled to half the 25 ns leveled luminosity Exponential fill length distribution 2012. J. Wenninger RLIUP workshop - Archamp

  6. Efficiency – 50 ns HL parameters 2012 efficiency For 50 ns crab cavities NOT big impact on performance (for small efficiencies). Efficiency is key. Target 25 ns meets target at ~ 47 % efficiency. 50 ns would need ~ 80 % !!! RLIUP workshop - Archamp

  7. Upgrades for 50 ns in injectors? Does anything else help? Status August 2013 • Sdf • Consider performance with post-LS2 50 ns parameters • Same assumptions as before for physics efficiency, average fill length • But assume 40 % emittance growth in LHC due to higher brightness Full HL-LHC 50 ns scenario & crab: yearly Lint≈ 123 fb-1 50 ns post-LS2 with planned injector upgrades & crab: ≈ 113 fb-1 Only 10 % difference  50 ns parameters after planned upgrades & crab cavities give (almost) as good results as proposed HL parameters… RLIUP workshop - Archamp

  8. Conclusion • 25 ns preferred but still to be proven in operation – still some unknowns • E-cloud could still be a show-stopper for this beam in the LHC. • 2015 will tell us • 50 ns could be an alternative – worked at 4 TeV to 1.8×1011 ppb…but… • Efficiency is key – to become comparable to 25 ns performance, an efficiency in the range of 70-80 % needed (which is totally unrealistic) • 50 ns means less integrated luminosity: ~ 60 % of 25 ns performance • No clear-cut additional upgrades identified for 50 ns • Efficiency and crab cavities in LHC more important than 'stretching’ injector performance • Beam stability with high bunch intensities might be an issue • Need to understand 2012 instability mechanism 2015 beam tests • Input for damping requirements or impedance reduction RLIUP workshop - Archamp

  9. RLIUP workshop - Archamp

More Related