Analysis of Collimator BPMs: Highlights from 2018 Data

2. Analysis of Collimator BPMs A. Mereghetti, on behalf of the LHC Collimation Team A.Mereghetti

3. Outlook A.Mereghetti Introduction Examples of BPM Signals and Checks Highlights from Analysis of 2018 BPM Readouts Conclusions

4. Introduction 16 2 1 1 2 Analysis only on 2018 data from TCTs – Won’t mention anything concerning alignment A.Mereghetti • In-jaw BPMs are relevant for: • Collimator alignment: • Faster than BLM-based procedure; • No beam particles are intercepted; • Allows to reconstruct beam angle by design; • Monitoring of closed orbit at collimators: • Check of collimator centering; • Fill-to-fill reproducibility; • Possibility to implement interlocks on closed orbit; • Collimators with in-jaw BPMs presently installed (2018): • All TCTs – IR1/2/5/8; • IR6 TCSPs; • IR7 TCP.C6L7.B1; • IR7 TCSPM.D4R7.B2 (with third BPM mounted on the tank); • Wire TCLs, i.e. TCL.4L5.B2 (IR5) and TCLVW.A5L1.B2 (IR1);

5. Check of Collimator Centering • Machine local reference system; • Beam direction; • BPM readouts; • Absolute beam position: • Average between up and dw BPMs; • Take into account motor positions; • Ideal for checks of collimator center functions; IR8, R&S, pp run until TS1 • TCT centre functions reproduce very nicely behavior of beam; • Not every single beam manipulation is taken into account  room for improvement; A.Mereghetti

6. Check of Collimator Centering • Machine local reference system; • Beam direction; • BPM readouts; • Relative beam position: • Average between up and dw BPMs; • Ideal for checks of collimator center functions; • Good fill-to-fill reproducibility – within ±100mm (~0.1s) • Spikes correspond to moment of dump; IR5, stable, pp run post-TS2 A.Mereghetti

7. Check of Collimator Angle • Machine local reference system; • Beam direction; • BPM readouts; • Collimator-beam relative angle: • Difference between up and dw BPMs; • Ideal for checks of collimator angle; • Estimation of angle assumes 1m between BPMs  to be refined; • Spikes correspond to transients with BPM signals at 0; IR7 and IR6, R&S, PbPb run, negative ALICE polarity A.Mereghetti

8. Check of 3rd BPM • Machine local reference system; • Beam direction; • BPM readouts; • Beam position as seen by 3rd BPM: • Readout of BPM alone; • Ideal for checks of tank centering; IR7, adjust, 90m run A.Mereghetti

9. Analysis of Signals • Machine local reference system; • Beam direction; • BPM readouts; • Interlock settings (@FT): • IR1/5: 1s; • IR8: 2.5s; • IR6: 1.5s; • Interlock strategy: • Check each BPM (up and dw) singularly; • Trigger a beam dump if both BPMs at the same time are above limit; • In the following, analysis similar to that by G.Valentino when proposing interlocks; • Plots of max(BPM_U,BPM_D) at every TCT, pp-flill lasting until STABLE, for every BP; • Max beam excursion wrt collimator center position; • Plots are grouped by IR and Beam; • Plots of expected number of dumps with 2018 readouts vs interlock setting [mm]: • Interlocks reasonably set; • Overview of signals; • Analysis focused only on TCTs (only had time for that…); A.Mereghetti

10. Max BPM Readout • All 2018 pp fills (221); • For every fill and every BP, take max(BPM_UP,BPM_DW)@TCTs; • H: maxTCTPH; V: maxTCTPV; • NB: (H,V) coordinate represent only max excursion on both planes during a fill; the max did not necessarily take place at the same time! A.Mereghetti

11. Interlock Tuning • All 2018 pp fills (221); • For every fill and every BP, take max(ave(BPM_UP,BPM_DW))@TCTs; • Actual interlock: BPM_UP>interlock && BPM_DW>interlock; • Using the average gives a conservative estimation; A bit of worsening of good collimator centering from BP to BP, and along the year, mainly on IR5 TCTPHs A.Mereghetti

12. IR5 BPMs • Degradation of centering of IR5 TCTPHs: • Increasing along the LHC cycle; • Increasing over the year; • Nevertheless, limited to 100-200mm; Net separation between TCT center function and beam orbit, getting worse at the end of R&S R&S, after TS2 (34 fills) R&S, before TS1 (87 fills) A.Mereghetti

13. IR5 BPMs (II) • Degradation of centering of IR5 TCTPHs: • Increasing along the LHC cycle; • Increasing over the year; • Nevertheless, limited to 100-200mm; Larger excursions between TCT center function and beam orbit STABLE, after TS2 (34 fills) STABLE, before TS1 (87 fills) Worsening can be tolerated A.Mereghetti

14. Alternative Plotting (IR7/IR6) • All 2018 pp fills (221); • For every fill, every BP, get ave(BPM_UP,BPM_DW)@each collimator at each moment; Median Q1-Q3 range outliers Outliers affected by odd signals (noise?) at dump (no check of flag for validity of signal);  Analysis to be refined A.Mereghetti

15. IR6 BPMs • Very stable reading, throughout the LHC cycle and the year: • Very stable collimator centering – centers do not change after EoR&S; • Very stable fill-to-fill reproducibility, getting better along the year! • IR6 BPMs suffer less from spurious signals; STABLE, after TS2 (34 fills) STABLE, before TS1 (87 fills) A.Mereghetti

16. Conclusions A.Mereghetti • In-jaw BPMs are very convenient for collimation purposes in the LHC: • They allow for fast, precise and non-invasive positional/angular alignment; • They allow for monitoring of closed orbit in a reliable way till the deployment of interlocks on closed orbit; • 2018 data at TCTs (mainly): • Analysis on all fills that made it to STABLE BEAMS; • Very stable and reliable readouts; • Fill-to-fill reproducibility and possible drifts of orbit during the year well below interlock level; • Present settings of interlock perfectly sensible – potential for further tightening them? • Any further analysis?

17. Thanks! A.Mereghetti

18. Max BPM Readout • 2018 pp fills before TS1 (87); • For every fill and every BP, take max(BPM_UP,BPM_DW)@TCTs; • H: maxTCTPH; V: maxTCTPV; • NB: (H,V) coordinate represent only max excursion on both planes during a fill; the max did not necessarily take place at the same time! A.Mereghetti

19. Max BPM Readout • 2018 pp fills between TS1 and MD2 (30); • For every fill and every BP, take max(BPM_UP,BPM_DW)@TCTs; • H: maxTCTPH; V: maxTCTPV; • NB: (H,V) coordinate represent only max excursion on both planes during a fill; the max did not necessarily take place at the same time! A.Mereghetti

20. Max BPM Readout • 2018 pp fills between MD2 and TS2 (70); • For every fill and every BP, take max(BPM_UP,BPM_DW)@TCTs; • H: maxTCTPH; V: maxTCTPV; • NB: (H,V) coordinate represent only max excursion on both planes during a fill; the max did not necessarily take place at the same time! A.Mereghetti

21. Max BPM Readout • 2018 pp fills after TS2 (34); • For every fill and every BP, take max(BPM_UP,BPM_DW)@TCTs; • H: maxTCTPH; V: maxTCTPV; • NB: (H,V) coordinate represent only max excursion on both planes during a fill; the max did not necessarily take place at the same time! A.Mereghetti

22. Interlock Tuning • 2018 pp fills before TS1 (87); • For every fill and every BP, take max(ave(BPM_UP,BPM_DW))@TCTs; • Actual interlock: BPM_UP>interlock && BPM_DW>interlock; • Using the average gives a conservative estimation; A.Mereghetti

23. Interlock Tuning • 2018 pp fills between TS1 and MD2 (30); • For every fill and every BP, take max(ave(BPM_UP,BPM_DW))@TCTs; • Actual interlock: BPM_UP>interlock && BPM_DW>interlock; • Using the average gives a conservative estimation; A.Mereghetti

24. Interlock Tuning • 2018 pp fills between MD2 and TS2 (70); • For every fill and every BP, take max(ave(BPM_UP,BPM_DW))@TCTs; • Actual interlock: BPM_UP>interlock && BPM_DW>interlock; • Using the average gives a conservative estimation; A.Mereghetti

25. Interlock Tuning • 2018 pp fills after TS2 (34); • For every fill and every BP, take max(ave(BPM_UP,BPM_DW))@TCTs; • Actual interlock: BPM_UP>interlock && BPM_DW>interlock; • Using the average gives a conservative estimation; A.Mereghetti

26. Alternative Plotting (IR1) • All 2018 pp fills (221); • For every fill, every BP, get ave(BPM_UP,BPM_DW)@each collimator at each moment; Median Q1-Q3 range outliers A.Mereghetti

27. Alternative Plotting (IR2) • All 2018 pp fills (221); • For every fill, every BP, get ave(BPM_UP,BPM_DW)@each collimator at each moment; Median Q1-Q3 range outliers A.Mereghetti

28. Alternative Plotting (IR5) • All 2018 pp fills (221); • For every fill, every BP, get ave(BPM_UP,BPM_DW)@each collimator at each moment; Median Q1-Q3 range outliers A.Mereghetti

29. Alternative Plotting (IR8) • All 2018 pp fills (221); • For every fill, every BP, get ave(BPM_UP,BPM_DW)@each collimator at each moment; Median Q1-Q3 range outliers A.Mereghetti