1 / 39

Pressure observations in the LSS of the LHC Octavio Domínguez

Pressure observations in the LSS of the LHC Octavio Domínguez. Acknowledgements H. Bartosik, G. Iadarola and G. Rumolo. e- cloud meeting, 22 November 2013 . Outline. Pressure observations in the LSS of the LHC. I. Bunch intensity thresholds for 50 ns II. Conditioning over time

aerona
Download Presentation

Pressure observations in the LSS of the LHC Octavio Domínguez

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. Pressure observations in the LSS of the LHC Octavio Domínguez Acknowledgements H. Bartosik, G. Iadarola and G. Rumolo e-cloud meeting, 22 November 2013

  2. Outline Pressure observations in the LSS of the LHC • I.Bunch intensity thresholds for 50 ns • II.Conditioning over time • III.Behavior during pre-ramp and energy ramp • IV. Conclusions O. Domínguez – e-cloud meeting – 22 November 2013

  3. Outline Pressure observations in the LSS of the LHC • I.Bunch intensity thresholds for 50 ns • II. Conditioning over time • III. Behavior during pre-ramp and energy ramp • IV. Conclusions O. Domínguez – e-cloud meeting – 22 November 2013

  4. Nb thresholds 50 ns 450 GeV • Maximum activity for Nb=1.3-1.4 • Thresholds around dmax ≈ 1.45 – 1.55 O. Domínguez – e-cloud meeting – 22 November 2013

  5. Nb thresholds 50 ns 4 TeV • Maximum activity for Nb=1.3-1.4 • Thresholds around dmax ≈ 1.45 – 1.55 O. Domínguez – e-cloud meeting – 22 November 2013

  6. Nb thresholds 50 ns emax=230 eV sz,450 GeV= 10 cm sz,4 TeV= 9.5 cm ex= 2.4 mm ey= 2.9 mm Ø = 80 mm • The maximum e-cloud activity occurs at Nb = 1.3-1.4 ∙1011 ppb. • Thresholds are quite similar for all bunch populations. • Despite a stronger activity at 4 TeV (photoelectrons), threshold values are very similar at both energies O. Domínguez – e-cloud meeting – 22 November 2013

  7. Outline Pressure observations in the LSS of the LHC • I. Bunch intensity thresholds for 50 ns • II.Conditioning over time • III. Behavior during pre-ramp and energy ramp • IV. Conclusions O. Domínguez – e-cloud meeting – 22 November 2013

  8. Conditioning over time • Pressureriseswerethefirst ECE observed in the LHC with 150 and 75 ns • I focusedonpressure gauges located in warm-warmtransitions (VGI type): • They are more accurate than other types of gauge in the machine • They are all located in the same type of module (with simple geometry) StSt – Cu coated Ø 80 mm O. Domínguez – e-cloud meeting – 22 November 2013

  9. Conditioning over time • Pressureriseswerethefirst ECE observed in the LHC with 150 and 75 ns • I focusedonpressure gauges located in warm-warmtransitions (VGI type): • They are more accurate than other types of gauge in the machine • They are all located in the same type of module (with simple geometry) • These modules are located between two 7 m NEG-coated beam pipes > 7 m NEG coating > 7 m NEG coating There are few exceptions where one side is shorter • There are 173 gauges of this type around the ring (easier comparison and extrapolation) • For the conditioning I’ll focus on beam 1 (68 gauges), although conclusions are equivalent for both beams. O. Domínguez – e-cloud meeting – 22 November 2013

  10. Conditioning over time • I base my observations on 50 ns on following fills: • 2124: 19 September 2011 (before MDs with 25 ns) • 2240: 22 October 2011 (between 14 October MD and 24 • October MD) • 2261: 27 October 2011 (after 25 ns MDs) • Nb≈1.37e11 ppb for all three • 2736: 16 June 2012 (Nb≈1.47e11 ppb) • 3000: 24 August 2012 (Nb≈1.52e11 ppb) • 3135: 6 October 2012 (Nb≈1.63e11 ppb) • 3185: 15 October 2012 (Nb≈1.58e11 ppb) • 3236: 28 October 2012 (Nb≈1.65e11 ppb) • 3286: 14 November 2012 (Nb≈1.65e11 ppb) • 6 random long physics fills during 2012 operation • I’ll show observations of 25 ns for the 24-25/10/11 MD O. Domínguez – e-cloud meeting – 22 November 2013

  11. Conditioning over time Fill 2124 (19 Sep.) 1-2 2011 2012 sz O. Domínguez – e-cloud meeting – 22 November 2013

  12. Conditioning over time Fill 2124 (19 Sep.) 1-2 2011 2012 sz We observe different behaviors  Different conditioning states? O. Domínguez – e-cloud meeting – 22 November 2013

  13. Conditioning over time Fill 2240 (22 Oct.) 1-2 2011 2012 sz DP after 5th injection No DP for the rest of the gauges There is a visible conditioning effect after the MD on 14 October with 25 ns O. Domínguez – e-cloud meeting – 22 November 2013

  14. Conditioning over time MD 25 ns (24-25 Oct.) 1-2 2011 2012 With 25 ns we observe DP in all the gauges O. Domínguez – e-cloud meeting – 22 November 2013

  15. Conditioning over time Fill 2261 (27 Oct.) 1-2 2011 2012 sz No e-cloud related DP observed in any of the gauges  Clear improvement after conditioning O. Domínguez – e-cloud meeting – 22 November 2013

  16. Conditioning over time Fill 2736 (16 Jun., Nb≈1.47∙1011ppb) 1-2 2011 2012 sz DP after 5th injection Nb≈1.47∙1011 ppb, but it seems that some deconditioning took place in gauge VGI.137.7R1.B O. Domínguez – e-cloud meeting – 22 November 2013

  17. Conditioning over time Fill 3000 (24 Aug., Nb≈1.52∙1011ppb) 1-2 2011 2012 sz DP after 4th injection DP after last injection Nb≈1.52∙1011 ppb, DPFill3000> DPFill2736 some deconditioning without 25 ns beams? O. Domínguez – e-cloud meeting – 22 November 2013

  18. Conditioning over time Fill 3286 (14 Nov., Nb≈1.65∙1011ppb) 1-2 2011 2012 sz Nb≈1.65∙1011 ppb. It has a higher threshold. All gauges must be below this threshold O. Domínguez – e-cloud meeting – 22 November 2013

  19. Conditioning over time Fill 2124 (19 Sep.) 2-3 2011 2012 Similar behavior as in sector 1-2 O. Domínguez – e-cloud meeting – 22 November 2013

  20. Conditioning over time Fill 2240 (22 Oct.) 2-3 2011 2012 Similar behavior as in sector 1-2 (some conditioning observed after MD with 25 ns) O. Domínguez – e-cloud meeting – 22 November 2013

  21. Conditioning over time MD 25 ns (24-25 Oct.) 2-3 2011 2012 Again, with 25 ns we observe DP in all the gauges O. Domínguez – e-cloud meeting – 22 November 2013

  22. Conditioning over time Fill 2261 (27 Oct.) 2-3 2011 2012 • Still some DP after 25 ns MDs • 20 gauges along the machine Again, conditioning observed after MDs with 25 ns. O. Domínguez – e-cloud meeting – 22 November 2013

  23. Conditioning over time 3-4 Fill 2261 (27 Oct.) 2011 2012 After the 25ns MDs, there are two gauges still showing large DP O. Domínguez – e-cloud meeting – 22 November 2013

  24. Conditioning over time 3-4 Fill 3286 (14 Nov., Nb≈1.65∙1011ppb) 2011 2012 Nb≈ 1.65∙1011 ppb. It has a higher threshold, but still some gauges show DP O. Domínguez – e-cloud meeting – 22 November 2013

  25. Conditioning over time 6-7 Fill 2124 (19 Sep.) 2011 2012 All gauges show DP before the 25 ns MDs O. Domínguez – e-cloud meeting – 22 November 2013

  26. Conditioning over time 6-7 Fill 2261 (27 Oct.) 2011 2012 No visible DP after the 25 ns MDsEnhanced conditioning in sector 6-7? O. Domínguez – e-cloud meeting – 22 November 2013

  27. Conditioning over time Summary of results Scrubbing campaigns No measurements possible MDs This values correspond to gauge VGI.141.6L4.B, which shows the worst state of conditioning over time. O. Domínguez – e-cloud meeting – 22 November 2013

  28. Conditioning over time LSS5 Fill 3557 (12 Feb., Nb≈1.2∙1011ppb) 2011 2012 2013 Systematic behaviour for this gauge After 2012 scrubbing run with 25 ns, no e-cloud related DP can be observed in the entire machine with 50 ns… O. Domínguez – e-cloud meeting – 22 November 2013

  29. Conditioning over time LSS4 Fill 3557 (12 Feb., Nb≈1.2∙1011ppb) 2011 2012 2013 After 2012 scrubbing run with 25 ns, no e-cloud related DP can be observed in the entire machine with 50 ns… Excepting 5 gauges in LSS4 (was it opened during the WS?) O. Domínguez – e-cloud meeting – 22 November 2013

  30. Outline Pressure observations in the LSS of the LHC • I. Bunch intensity thresholds for 50 ns • II. Conditioning over time • III.Behavior during pre-ramp and energy ramp • IV. Conclusions O. Domínguez – e-cloud meeting – 22 November 2013

  31. Pre-ramp and ramp Fill 2261 (27 Oct.) 2-1 2011 2012 In this example, none of the gauges exhibit DP during injection and all detect some DP during the ramp (at about 2.4 TeV) O. Domínguez – e-cloud meeting – 22 November 2013

  32. Pre-ramp and ramp Fill 2124 (19 Sep.) 2-3 2011 2012 No clear response to the ramp • Not all gauges show a response to the ramp (especially the most active at injection) • “Funny” DP behavior before the ramp  Uncaptured beam? O. Domínguez – e-cloud meeting – 22 November 2013

  33. Pre-ramp and ramp VGI.804.4R6.B Fill 2261 (27 Oct.) 2011 2012 Good example of the DP likely caused by uncaptured beam O. Domínguez – e-cloud meeting – 22 November 2013

  34. Pre-ramp and ramp VGI.141.6L4.B Fill 2124 (19 Sep.) 2011 2012 sz Yet “another” pre-ramp behavior P follows sz (usual behavior for many guages) O. Domínguez – e-cloud meeting – 22 November 2013

  35. Pre-ramp and ramp 6-7 Fill 2124 (19 Sep.) 2011 2012 No effect during the energy ramp (likely due to higher pressures) O. Domínguez – e-cloud meeting – 22 November 2013

  36. Pre-ramp and ramp LSS5 Fill 2736 (16 Jun., Nb≈1.47∙1011ppb) 2011 2012 Systematic behaviour for this gauge Symmetric gauges (both in inner ring) Some symmetric DP can be observed in IPs 1 and 5 O. Domínguez – e-cloud meeting – 22 November 2013

  37. Outline Pressure observations in the LSS of the LHC • I. Bunch intensity thresholds for 50 ns • II. Conditioning over time • III. Behavior during pre-ramp and energy ramp • IV. Conclusions O. Domínguez – e-cloud meeting – 22 November 2013

  38. Conclusions • Nb thresholds are between 1.45 and 1.5 for Nb=1.0-1.6∙1011 ppb • Thresholds at 450 GeV and 4 TeV are very similar • Different gauges in the warm-warm straight sections show different behaviors • Conditioning effects seem to be stronger for some gauges • The DP diminishes for increasing Nb, as predicted by simulations • No DP during 2013 pp fills with 50 ns can be appreciated, excepting 5 gauges in LSS4 • There are some behaviors during pre-ramp and ramp that are not fully understood yet (uncaptured beam, sz, photoelectrons) • Some symmetries can be observed between gauges around IPs 1 and 5 O. Domínguez – e-cloud meeting – 22 November 2013

  39. THANKS FOR YOUR ATTENTION

More Related