1. Wire Scanners Observations In SPS & LHC G. TRAD Emittance working group 26/08/2015

2. Layout  Quantification of the “crosstalk” effect experimentally with beam in the SPS and LHC WS  Crosstalk seen as an overall signal leakage to adjacent 25 ns slots.  SPS WS studied are 419 and 519 (rotational), according to OP the most frequently used.  LHC WS studied are the 4 active ones, B1H2-B1V2-B2H1-B2V1  Quantification of the impact on trains emittance measurement  Implementation of a possible cure.

3. SPS WS 416

4. Measured Slots Slot 1Slot 2Slot 3Slot 4Slot 5Slot 6Slot 7 Only 1 filled Bucket Experimental Setup Example of a measurement output

5. Bringing these points to zero =>Subtracting the slot 1 profile considered as noise of an empty bucket

6. SPS.BWS.41677.H_ROT IN SCAN 1 IN SCAN 2IN SCAN 3IN SCAN 4

7. SPS.BWS.41677.V_ROT IN SCAN 1IN SCAN 2IN SCAN 3

8. FITTING Example: 'SPS.BWS.41677.H_ROT'

9. 13.7% 4.6% 1.7% 6% ? FITTING - SCANNER 1

10. 'SPS.BWS.41677.V_ROT' 15.1% 5.3% 3% 3% ? FITTING - SCANNER 2

11. SPS WS 519

12. SPS.BWS.51995.H_ROT IN SCANOUT SCAN Almost the same Intensity!

13. SPS.BWS.51995.V_ROT IN SCANOUT SCAN

14. 'SPS.BWS.51995.H_ROT' Slot 1Slot 2Slot 3Slot 4Slot 5Slot 6Slot 7 As if WS slots have wrong delay: Even though it is not the croostalk originating from the system BW, The result is the same WS Slot 1WS Slot 2WS Slot 3WS Slot 4WS Slot 5WS Slot 6WS Slot 7 77.2 % 13 % 5.4 % 2.8 % 1.75 % 1.2 % FITTING - SCANNER 3

15. FITTING - SCANNER 4 'SPS.BWS.51995.V_ROT' 79.8 % 13.1 % 5.4 % 2.6 % 1.5 % Same Issue for the vertical scanner

16. LHC

17. Slot 1Slot 2Slot 3Slot 4Slot 5Slot 6Slot 7 Slot 1793Slot 1794Slot 1795Slot 1796Slot 1797Slot 1798Slot 1799 Measured by : LHC.BWS.5R4.B1H2 LHC.BWS.5R4.B1V2 LHC.BWS.5L4.B2H1 LHC.BWS.5L4.B2V1 Experimental Setup

18. ‘LHC.BWS.5R4.B1H2' 21.07 % 4.4 % 2.4 %

19. ‘LHC.BWS.5R4.B1V2' 26.95 % 4.75 % 2.3%

20. ‘LHC.BWS.5L4.B2H1' 10 % 3.9 % 2.6 %

21. ‘LHC.BWS.5L4.B2V1' 11.6 % 4.7 % 3.2 %

22. IMPACT A train of 72 bunches (25 ns spacing) has to be measured; Assuming realistic but still conservative values: Mean Bunch intensity 1.2 e11 prot (+/- 5 %) Mean Bunch Emittance 2 e-6 m (+/- 8 %) Due to this signal leakage between slots, an error on each bunch profile is introduced by the previous bunches in the train: Slot 1Slot 2Slot 3Slot 4

23. 30% spread peak to peak 20% spread peak to peak

24. IMPACT Slot 1Slot 2Slot 3Slot 4 K1 * Prof S1 K2 * Prof S1 K3 * Prof S1 A train of 72 bunches (25 ns spacing) has to be measured; Assuming realistic but still conservative values: Mean Bunch intensity 1.2 e11 prot (+/- 5 %) Mean Bunch Emittance 2 e-6 m (+/- 8 %) Due to this signal leakage between slots, an error on each bunch profile is introduced by the previous bunches in the train:

25. IMPACT Slot 1Slot 2Slot 3Slot 4 K1 * Prof S2 K2 * Prof S2 A train of 72 bunches (25 ns spacing) has to be measured; Assuming realistic but still conservative values: Mean Bunch intensity 1.2 e11 prot (+/- 5 %) Mean Bunch Emittance 2 e-6 m (+/- 8 %) Due to this signal leakage between slots, an error on each bunch profile is introduced by the previous bunches in the train:

26. IMPACT Slot 1Slot 2Slot 3Slot 4 K1 * Prof S3 A train of 72 bunches (25 ns spacing) has to be measured; Assuming realistic but still conservative values: Mean Bunch intensity 1.2 e11 prot (+/- 5 %) Mean Bunch Emittance 2 e-6 m (+/- 8 %) Due to this signal leakage between slots, an error on each bunch profile is introduced by the previous bunches in the train:

27. Quantified IMPACT Error on the measured emittance in the slot, falsed by crosstalk effects By definition the first bunch has no induced from other bunches since …it is the first A Histogram of the obtained errors to study the distribution patterns

28. SPS.BWS.41677.H_ROT Quantified IMPACT

29. SPS.BWS.41677.V_ROT Quantified IMPACT Error on emittance determination % Bunch slots along the train Error on emittance determination %

30. SPS.BWS.51995.H_ROT Quantified IMPACT Error on emittance determination % Bunch slots along the train Error on emittance determination %

31. SPS.BWS.51995.V_ROT Quantified IMPACT Error on emittance determination % Bunch slots along the train Error on emittance determination %

32. Quantified IMPACT Scanner416 H Rot416 V Rot519 H Rot519 V Rot Max Rel ErrorUp to 21 %Up to 24 %Up to 45 %Up to 48 % SPS summary

33. LHC.BWS.5R4.B1H2 Quantified IMPACT Error on emittance determination % Bunch slots along the train Error on emittance determination %

34. LHC.BWS.5R4.B1V2 Quantified IMPACT Error on emittance determination % Bunch slots along the train Error on emittance determination %

35. LHC.BWS.5R4.B2H1 Quantified IMPACT Error on emittance determination % Bunch slots along the train Error on emittance determination %

36. LHC.BWS.5R4.B2V1 Quantified IMPACT Error on emittance determination % Bunch slots along the train Error on emittance determination %

37. Quantified IMPACT LHC summary ScannerB1H2B1V2B2H1B2V1 Max Rel ErrorUp 24 %Up to 30 %Up to 18%Up to 16%

38. Solution Bunch 1 Profile Bunch 2 Profile Bunch 3 Profile Bunch 4 Profile … Bunch n-1 Profile Bunch n Profile Obtained by Scan Measured Weights Bunch 1 Profile Bunch 2 Profile Bunch 3 Profile Bunch 4 Profile … Bunch n-1 Profile Bunch n Profile Calculated 1 K 1 K 2 K 3 K 4 … K n

39. % SPS 51995 H Rot crosstalk_weights=[0.772; 0.13; 0.054; 0.028 ;0.0175; 0.012]; deconvoluted_buckets=zeros(size(buckets)); for bucketID=1:size(deconvoluted_buckets,1) previous_contributions=zeros(1,size(deconvoluted_buckets,2)); for j=1:length(crosstalk_weights) if bucketID-j>0 previous_contributions=previous_contributions+... crosstalk_weights(j).*deconvoluted_buckets(bucketID-j,:); end deconvoluted_buckets(bucketID,:)=buckets(bucketID,:)-previous_contributions; end Easy cure, just a SW routine Where should it be implemented? FEC or WS applications??