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Halo scraping and loss rates at collimators

Halo scraping and loss rates at collimators. F. Burkart R. Assmann, R. Bruce, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino, D. Wollmann. 1. Introduction 2. Halo scraping measurements 3. Results of data analysis from measurements

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Halo scraping and loss rates at collimators

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  1. Halo scraping and loss rates at collimators F. Burkart R. Assmann, R. Bruce, M. Cauchi, D. Deboy, S. Redaelli, A. Rossi, G. Valentino, D. Wollmann

  2. 1. Introduction 2. Halo scraping measurements 3. Results of data analysis from measurements 4. Collimation losses during high-luminosity fills 5. Results of data analysis from physics fills 6. Conclusion 7. Future work Outline Florian Burkart 2

  3. Why halo scraping? • Understand population and repopulation speed of the beam halo at 3.5 TeV → extrapolate the results to 7 TeV → loss rates at collimators → minimum instantenious lifetime of the beams • Calibrate BLM-signal at primary collimator [Gy/s] to a particle lossrate [p/s] → compare to losses seen in collimation region during high-luminosity runs → distinguish between hor.,ver. and skew losses Florian Burkart 3

  4. Halo scraping procedure • Move single jaw of a primary collimator into the beam halo • with different step sizes (5 micron, 20 micron, 40 micron) • at different intensities • in different machine states (injection, collision) - measure beam intensity (FBCT) → loss rate - measure BLM-signals • Most EoF-studies after physics → beam dumped by BLMs Florian Burkart 4

  5. Usage of different step sizes 10 μm step size 5 μm step size Florian Burkart 5

  6. C-BLM: 8.5E+11 p/Gy D-BLM: 1.7E+12 p/Gy BLM-response Scraping with TCP.D B1, running sum: 1.3 s Signal in TCP.C-BLM dominated by vertical losses Florian Burkart 6

  7. 1.3s: 8.5E+11 p/Gy 10.24ms: 3.4E+12 p/Gy BLM-response for different running sums Scraping with TCP.D B1 Loss rate diluted in large running sums Florian Burkart 7

  8. Calibration factor Halo scraping RS09 / RS06 Variation up to a factor 6.6 → to be understood → impact parameter → error in lossrate due to 1 Hz FBCT-signal Florian Burkart 8

  9. Overview of different scrapings variation up to a factor 6.6 → not understood Florian Burkart 9

  10. Measure BLM signals [Gy/s] on Collimators (TCP.C) Measure Beam Intensity (FBCT) [p] → steady state lossrate [p/s] (dominated by losses at collimators) → calibration factor [p/Gy] Collimation losses during high-luminosity fills – steady state Florian Burkart 10

  11. Losses with colliding beams Fill 1722, 336 bunches IR7: ~87% Linear scale! IR8: ~6% IR3: ~2.5% IR1: ~1% Courtesy D.Wollmann Florian Burkart 11

  12. Beam Intensity versus time Fill 1749, B1 Intensity [p] 7.6*10^13 7.1*10^13 Time [s] 14 h Florian Burkart 12

  13. Loss rate versus time Fill 1749, B1, running average 240sec Lossrate [p/s] 4*10^8 1*10^8 Time [s] 14 h Florian Burkart 13

  14. BLM-signal versus time Fill 1749, B1 BLM-signal [Gy/s] 0.0006 0.0001 Time [s] 14 h Florian Burkart 14

  15. Average value B1: 2.2E+12 p/Gy B2: 1.54E+12 p/Gy Variation : 6,5 (B1), 3,4 (B2) Calibration factors (stable beams) Florian Burkart 15

  16. Minimum Lifetime RS09 (1.3 s) • 624 b, 768 b Florian Burkart 16

  17. Comparison Min.Lifetime B1 RS09, RS06 Min. Lifetime for multiturn losses → RS06 Florian Burkart 17

  18. Comparison Min.Lifetime B2 RS09, RS06 Florian Burkart 18

  19. Overview of physics fills RS09 Florian Burkart 19

  20. Overview of physics fills RS06 Courtesy D.Wollmann Florian Burkart 20

  21. Halo scrapings For vertical losses BLM at TCP.C shows highest signal More scraping experiments needed More usable data points per experiment → sufficient loss rate Variation of calibration factors (~ 6.6) Physics fills Losses mainly appear at collimators (IR7: ~87%) Average calibration factor B1: 2.2E+12 p/Gy Average calibration factor B2: 1.54E+12 p/Gy Min. Lifetime B1 > 1.3 h (RS06) Min. Lifetime B2 > 1.15 h (RS06) Conclusion Florian Burkart 21

  22. Analysis of other integration times Analysis of other BLM-signals e.g. TCHSV (physics fills data, scraping data) More scrapings with different step sizes → understand variation of calibration factor Scrapings with different optics (squeezed, collision) Measure repopulation speed Future work Florian Burkart 22

  23. END Thank you for your attention! Florian Burkart 23

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