1. Afterglow Studies Eric Torrence University of Oregon 183 nd LMTF Meeting 10 October 2013

2. Eric TorrenceSeptember 2013 2 Overview Test afterglow model by single-bunch addition  Originally studied by Mika  Will need to be used for 25 ns operations Try to test assumptions in method  Afterglow is universal with time and μ  Afterglow is additive to the prompt luminosity signal (not true if there are migration effects) Look at expected afterglow levels in 2015 (using 2012 templates) Look at 2012 25 ns fills

3. Eric TorrenceSeptember 2013 3 Fills Single-bunch templates  r200804 - 2 bunches, μ~20, first fill of 2012  r206717 - 1 bunch, μ~50, high-mu test Test runs  r212529 - 6 bunches in mini-train  r214651 - 50 ns physics fill - during BCM noise period  r215541 - 50 ns physics fill - after BCM noise period  r216399 - 25 ns fill - 97 bunches  r216432 - 25 ns fill - 373 bunches Large range in mu, 3 months apart

4. Eric TorrenceSeptember 2013 4 Details Looked only at OR algorithms (simpler), mainly:  BcmH_EventOR  BcmV_EventOR  Lucid_HitOR No absolute calibrations applied, everything scaled to some relative luminosity Simple log formulas, no complicated Lucid mu dependence L = -ln(1-Rate)

5. Eric TorrenceSeptember 2013 5 BCMV single-bunch response r206717 - BcmVOR Single-bunch, high μ Peak = 1, used to normalize relative response Afterglow falls below noise level after ~500 BCIDs Colliding bunch Afterglow Noise

6. Eric TorrenceSeptember 2013 6 BCMV single-bunch response r206717 - BcmVOR Single-bunch, high μ Averaged over many LBs Afterglow Reflections More plots in appendix...

7. Eric TorrenceSeptember 2013 7 Stability over short time BCMV: http://physics.uoregon.edu/~torrence/BcmVOR.movhttp://physics.uoregon.edu/~torrence/BcmVOR.mov Lucid: http://physics.uoregon.edu/~torrence/r200804_LucORA.movcORA.mov

8. Eric TorrenceSeptember 2013 8 Stability over long times r206717 r200804 BcmVOR ~ identical over x2 in mu and three months!

9. Eric TorrenceSeptember 2013 9 Lucid HitOR r200804 No reflections Short-term falloff Similar mid-term slope Longer tail (or just lower noise?)

10. Eric TorrenceSeptember 2013 10 Single-beam Templates r200804 BCM - 500 BCIDs to reach ~10 -7 level LucidHit - 1500 BCIDs to reach ~10 -7 level (ran into next bunch) Constant background subtracted from -100 BCIDs

11. Eric TorrenceSeptember 2013 11 Maximum BCM afterglow Just add 500 copies of this template (without peak), each shifted by 1 BCID Asymptotic value 0.8% reached in ~200 BCIDs

12. Eric TorrenceSeptember 2013 12 Maximum Lucid Hit afterglow Even with longer tail, less ‘integral’ afterglow (no reflections) Asymptotic value 0.3% reached in ~300 BCIDs

13. Eric TorrenceSeptember 2013 13 50 ns limits BCID-1 works for BCM in 2012! (coincidental, only for BcmV) Afterglow under collisions ~ 10 -3 Difference w/ BCID-1 ~ 1 x 10 -3 (worse in 2011) 0.4% is half of 25 ns limit (expected) colliding bcid ± 1

14. Eric TorrenceSeptember 2013 14 Realistic 25 ns fill pattern 14 25ns_2604b_2592_2288_2396_288bpi12inj.sch 2604 bunches colliding in P1/5 Mostly saturated (except at start-of-train)

15. Eric TorrenceSeptember 2013 15 Data subtraction procedure (per LB) Start with raw luminosity by BCID for each lumi block Identify colliding bunches, and divide out average colliding luminosity from full distribution  not strictly necessary, but useful for averaging over LBs  also avoids need for calibration, everything relative... Build model of afterglow by adding up templates, one template per collision BCID, weighted by relative lumi Subtract this afterglow from raw luminosity in all BCIDs Iterate if desired (practically makes little effect) Measure residual background in abort gap (last 50 BCIDs) Subtract background as well to produce corrected lumi

16. Eric TorrenceSeptember 2013 16 Example 6 colliding bunches (normalized response) 500 BCID template length constant term ‘fit’ here Raw Luminosity After.+Bgd. Prediction

17. Eric TorrenceSeptember 2013 17 Example Zoomed 6 colliding bunches rather excellent agreement between predicted and observed afterglow under collisions

18. Eric TorrenceSeptember 2013 18 Lucid artifacts Finite Lucid template leads to (small) artifacts with few bunches 1500 BCIDs constant term ‘fit’ here

19. Eric TorrenceSeptember 2013 19 Lucid HitOR Prediction close to luminous bunches looks right on (high μ template, 28 tubes)

20. Eric TorrenceSeptember 2013 20 Lucid - 50 ns fill Works fine with full fill pattern Remember: simple log formula applied, no mu dependence

21. Eric TorrenceSeptember 2013 21 BcmV noise comparison During BCM noise period After BCM noise period << 10-3 discrepancies

22. Eric TorrenceSeptember 2013 22 25 ns runs Can’t prove afterglow under collisions is correct, but procedure seems to work fine

23. Eric TorrenceSeptember 2013 23 25 ns runs Can’t prove afterglow under collisions is correct, but procedure seems to work fine Same train length and gap expected in 2015

24. Eric TorrenceSeptember 2013 24 Lucid reduced HV Lucid ran with reduced HV for most runs from r215433, includes all 25 ns runs Template clearly not accurate

25. Eric TorrenceSeptember 2013 25 Lucid reduced HV 2 Scale up fast component (BCID+1, 2) by ~30% Seems to work fine!

26. Eric TorrenceSeptember 2013 26 25 ns Lucid Hit OR Use scaled template to look at 25 ns Lucid data Much larger afterglow (~2%) due to HV settings normalized background error slight mismatch

27. Eric TorrenceSeptember 2013 27 25 ns comparison Compare afterglow-subtracted relative luminosity collisions only Shape looks familiar, but magnitude is larger...

28. Eric TorrenceSeptember 2013 28 50 ns comparison 28 Similar to Benedetto’s plots? Remember, no complicated Lucid corrections, just log formula

29. Eric TorrenceSeptember 2013 29 Trigger Counters Special-purpose counters to look at 6 L1 items before and after veto to study deadtime by BCID Can try to use before veto as a proxy for luminosity Triggers available  Counter 0 is trigger 93 L1_MU11  Counter 1 is trigger 85 L1_EM30  Counter 2 is trigger 102 L1_J50  Counter 3 is trigger 128 L1_FJ75  Counter 4 is trigger 118 L1_XE50  Counter 5 is trigger 97 L1_J10 Must be skeptical, many trigger-related issues with bunch train position... Trigger rates ~1% error per BCID (over many LBs) Most linear with lumi

30. Eric TorrenceSeptember 2013 30 50 ns run L1_EM30 L1_MU11 L1_MU11 low at start of train (retriggering?) L1_EM30 rises in early train (calo noise?)

31. Eric TorrenceSeptember 2013 31 50 ns run L1_EM30 Now referenced to Lucid, L1_MU11 looks pretty OK...

32. Eric TorrenceSeptember 2013 32 25 ns run Back end of bunch train seems to be more consistent with BcmV

33. Eric TorrenceSeptember 2013 33 25 ns run Really had to draw any conclusions from this

34. Eric TorrenceSeptember 2013 34 Conclusions Single-bunch template method seems to work for 2012  Templates quite universal over all 2012 Afterglow error using BCID-1 appears smaller than 2011 for BcmVOR No evidence of anything weird in BCM noise period 25 ns data shows larger (as expected) but manageable afterglow levels, Lucid larger due to HV settings First look at Lucid/BCM ratios is rather alarming, but probably lots to understand here Trigger rates don’t seem to help

35. Eric TorrenceSeptember 2013 35 Appendix A Single-bunch plots Run 200804 2 bunches, μ ~ 20

36. Eric TorrenceSeptember 2013 36 Lucid Hit OR

37. Eric TorrenceSeptember 2013 37 Lucid OR

38. Eric TorrenceSeptember 2013 38 Lucid OR A

39. Eric TorrenceSeptember 2013 39 Lucid OR C

40. Eric TorrenceSeptember 2013 40 Lucid AND Raw rate only!

41. Eric TorrenceSeptember 2013 41 BcmH OR

42. Eric TorrenceSeptember 2013 42 BcmV OR

43. Eric TorrenceSeptember 2013 43 BcmH OR A From Rates: A + C = OR + AND

44. Eric TorrenceSeptember 2013 44 BcmV OR A From Rates: A + C = OR + AND

45. Eric TorrenceSeptember 2013 45 BcmH OR C

46. Eric TorrenceSeptember 2013 46 BcmV OR C

47. Eric TorrenceSeptember 2013 47 Appendix A Single-bunch plots Run 206717 1 bunch, μ ~ 40

48. Eric TorrenceSeptember 2013 48 Lucid Hit OR

49. Eric TorrenceSeptember 2013 49 Lucid AND Raw rate only!

50. Eric TorrenceSeptember 2013 50 BcmH OR

51. Eric TorrenceSeptember 2013 51 BcmV OR

52. Eric TorrenceSeptember 2013 52 BcmH OR A From Rates: A + C = OR + AND

53. Eric TorrenceSeptember 2013 53 BcmV OR A From Rates: A + C = OR + AND

54. Eric TorrenceSeptember 2013 54 BcmH OR C

55. Eric TorrenceSeptember 2013 55 BcmV OR C