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ANALYSIS OF SOME LHC FILLS WITH AND WITHOUT TRANSV. EMIT. BLOW-UP

ANALYSIS OF SOME LHC FILLS WITH AND WITHOUT TRANSV. EMIT. BLOW-UP. Elias Métral. Info from Gianluigi : Fills with blow-up 1731 (36 bunches/train) – 480 bunches 1736 (72 bunches/train) – 480 bunches => BU or not? => No data 1744 (72 bunches/train) – 624 bunches

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ANALYSIS OF SOME LHC FILLS WITH AND WITHOUT TRANSV. EMIT. BLOW-UP

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  1. ANALYSIS OF SOME LHC FILLS WITH AND WITHOUT TRANSV. EMIT. BLOW-UP EliasMétral • Info from Gianluigi: • Fills with blow-up • 1731 (36 bunches/train) – 480 bunches • 1736 (72 bunches/train) – 480 bunches => BU or not? => No data • 1744 (72 bunches/train) – 624 bunches • 1756 (72 bunches/train) – 768 bunches => No data • Fills with no-blow-up • 1732 (36 bunches/train) – 480 bunches • 1736 (72 bunches/train) – 480 bunches => BU or not? => No data • 1745 (72 bunches/train) – 624 bunches => Fill not found • 1755 (72 bunches/train) – 768 bunches • Some other fills with in particular the fill 1802 (rec. lumi of ~ 1.1E33, i.e. good) and the fill 1803 where BU has been observed

  2. Fill # 1731 => BU 480 bunches with 36 / train (13 × 36 + 12) B1H mainly Fill # 1732 => No BU 480 bunches with 36 / train (13 × 36 + 12)

  3. Fill # 1744 => BU 624 bunches with 72 / train (8 × 72 + 1 × 36 + 12) B1H mainly Fill # 1755 => No BU 768 bunches with 72 / train (10 × 72 + 1 × 36 + 12)

  4. CONCLUSIONS • It seems that for the cases where transverse emittance blow-up was observed, some coherent motions were also observed from the BBQ: • With trains of 36 bunches => After ~ 9 trains, i.e. ~ 4E13 p total intensity • With trains of 72bunches => After ~ 6 trains, i.e. ~ 5.5E13 p total intensity • We will see later that with trains of 108 bunches => After ~ 2-3 trains, i.e. ~ 3-4E13 p total intensity • We will also see that it usually starts in the H plane of either B1 or B2

  5. Meas. on 19/05/2011 (1/9) • LHC injections with batches of 108 bunches => Started at ~ 17:20 • Chroma ~ 2 in both planes and beams and TD gain ~ 0.25 in both planes and both beams. • 1092 on B1 at 17:55 • 1092 on B2 at 17:56 => New record (it was 1020 for the scrubbing run) • Transverse emittances meas. by Kevin => Seems to reveal ~ 2.5 microm on B1 and ~ 3.5-4 on B2 with ~ constant values along the batch => No instability! • Finished with ~ 1300 bunches in both beams without strange signals on the BSRT

  6. Meas. on 19/05/2011 (2/9) 1092 bunches with 108 / train (10 × 108 + 12)

  7. Meas. on 19/05/2011 (3/9)

  8. Meas. on 19/05/2011 (4/9)

  9. Meas. on 19/05/2011 (5/9)

  10. Meas. on 19/05/2011 (6/9)

  11. Meas. on 19/05/2011 (7/9)

  12. Meas. on 19/05/2011 (8/9) • We had to kick (without beam) as we were close to a time-out for the injection kicker => After this we saw some losses increasing on the TCTV.4R8 and we lose on B2, which is the bigger beam • We got the OK to inject more bunches and we will try and do this soon (19:24)

  13. Meas. on 19/05/2011 (9/9) 1200 bunches with 108 / train (11 × 108 + 12)

  14. 2nd meas. on 19/05/2011 (1/3) • 768 bunches, with batches of 72 bunches, in stable beams => ~ 7.5E32 peak luminosity

  15. 2nd meas. on 19/05/2011 (2/3) • 768 bunches, with batches of 72 bunches, in stable beams => ~ 7.5E32 peak luminosity

  16. 2nd meas. on 19/05/2011 (3/3)

  17. Fill # 1802 on 23/05/11 with peak lumi ~ 1.1E33 (1/2) • 912 bunches, with batches of 108 bunches (874 colliding pairs), in stable beams => ~ 1.1E33 peak luminosity, which would mean ~ 2.5 microm transverse emittances => 1st time we went above 1E33!

  18. Fill # 1802 on 23/05/11 with peak lumi ~ 1.1E33 (2/2)

  19. Fill # 1803 with BU (1/6) • 912 bunches, with batches of 108 bunches (874 colliding pairs), in stable beams => ~ 0.85E33 peak luminosity, which would mean larger transverse emittances as before (~ 3.2 microm) and therefore BU!

  20. Fill # 1803 with BU (2/6) Activity in B2H just after 2nd batch injected for B2

  21. Fill # 1803 with BU (3/6)

  22. Fill # 1803 with BU (4/6) 08:19:56 => Black 08:19:58 => Blue 08:19:56 => Black 08:20:07 => Green Appearance of some lines here (-1, 0, 1) 08:19:56 => Black 08:20:19 => Red Mode 0 growing faster Inj. of 2nd batch at ~ 08:19:53

  23. Fill # 1803 with BU (5/6) 08:20:01 => Purple 08:20:13 => Light blue

  24. Fill # 1803 with BU (6/6) • => Some lines (-1, 0, 1) seem to appear but there is no beam loss during this process, only some transverse emittance blow-up • Mode 0 seems to grow faster than the others • I would expect some beam losses from the TCBI… Furthermore, the instability rise-times predicted are smaller than 1 s, whereas here it seems to be several s • Could this be due to some ecloud activity? • Could this be due to some residuals from the injection (from the longitudinal plane as observed during the scrubbing run, or due to the undamped oscillations, or from the injection or abort gap cleaning)??? • => To be followed up

  25. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (1/14) Fill # 1802 NicolasM

  26. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (2/14) Fill # 1803 NicolasM

  27. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (3/14) Fill # 1802 NicolasM

  28. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (4/14) Fill # 1803 NicolasM

  29. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (5/14) Fill # 1803 NicolasM

  30. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (6/14) Fill # 1802 NicolasM

  31. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (7/14) Fill # 1803 NicolasM

  32. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (8/14) Fill # 1803 NicolasM

  33. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (9/14) Fill # 1802 NicolasM

  34. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (10/14) Fill # 1803 NicolasM

  35. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (11/14) Fill # 1803 NicolasM

  36. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (12/14) Fill # 1803 NicolasM

  37. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (13/14) Fill # 1802 NicolasM

  38. Comparison between fill 1802 good and 1803 bad, both with 920 bunches (14/14) Fill # 1803 NicolasM

  39. 24/05/11: 1st bad fill and then refill and good fill (1/4) UTC time here, i.e. – 2 h!!!

  40. 24/05/11: 1st bad fill and then refill and good fill (2/4)

  41. 24/05/11: 1st bad fill and then refill and good fill (3/4)

  42. 24/05/11: 1st bad fill and then refill and good fill (4/4)

  43. 29/05/11: 1st a bad fill and then a good one (1/?)

  44. 29/05/11: 1st a bad fill and then a good one (2/?)

  45. 29/05/11: 1st a bad fill and then a good one (3/?)

  46. 29/05/11: 1st a bad fill and then a good one (4/?)

  47. 29/05/11: 1st a bad fill and then a good one (5/?)

  48. 31/05/11: Good and bad fills again BUT at different positions (1/?) This beam was not accelerated due to BU. Note that usually the activity was after ~ 2 batches whereas it is the 4th in this case (and it is B2V 1st here)

  49. 31/05/11: Good and bad fills again BUT at different positions (2/?) Excellent fill

  50. 31/05/11: Good and bad fills again BUT at different positions (3/?) The activity is now observed after the 8th batch! (B1H) Some pbs seen on this fill but it nevertheless gave an initial peak lumi of ~ 1.2E33! (only a bit less compared to the previous one)

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