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LHC TI2/TI8 TL Stability check during Run II

LHC TI2/TI8 TL Stability check during Run II. ABTEF meeting Presents: MOISES BARBERA RAMOS 03/09/2019. Supervisor: Chiara Bracco (CERN). OUTLINE. Personal Introduction ---------------------------------- 3

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LHC TI2/TI8 TL Stability check during Run II

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  1. LHC TI2/TI8 TL Stability check during Run II ABTEF meeting Presents: MOISES BARBERA RAMOS 03/09/2019 Supervisor: Chiara Bracco (CERN)

  2. OUTLINE • Personal Introduction ---------------------------------- 3 • Scope ---------------------------------- 4 • Injection process --------------------------------- 5 • Objectives ---------------------------------- 7 • MIA analysis ----------------------------------- 8 • MADX simulations ----------------------------------- 9 • TI2 study and comparison with RUN I --------------------- 11 • TI8 study and comparison with RUN I --------------------- 15 • Conclusion ---------------------------------- 18

  3. Introduction: Moises Barbera Ramos • Final year student of a master integrated in Physics by the University of Liverpool. • CERN Summer Student since the 17th of June 2019. • Mentor at HIPY.uk, teaching along with professors and PhD students how to implement programming on scientific research to students. • Professional magician with more than 100 shows of experience in front of crowds over 8,000 people around Europe. International award - 2017.

  4. Scope The injection process in the LHC is critical in terms of loss minimisation and preservation of the beam quality. During the last two runs, the injection phase was identified as one of the main limiting factors for a fast turnaround time. This presentation shows the analysis of the stability of SPS to LHC transfer lines during Run II (2015-2018) and aims to compare the results with RUN I.

  5. Injection process: SPS-to-LHC Transfer Lines • TI2: • - Transports the beam from the SPS Long Straight Section (LSS) 6 to the clockwise LHC ring. • Extraction section from SPS called TT60. • TI8: • - Transports the beam from SPS LSS4 to the counter clockwise LHC ring. • - Extraction section from SPS called TT40. Each transfer line (TL) ≈ 3 km long.

  6. The Beam Position Monitors (BPMs) • BPMs record the vertical and horizontal position of the beam in the TL. • LHC BPM data returns the bunch-by-bunch trajectory data triggered at the moment of injection. • TI2: presents 59 BPMs. • TI8: presents 51 BPMs.

  7. Objectives • Get familiar with TL optics and MIA analysis: • Use MADX to simulate 100 transfers of protons through TI2 & TI8 with a random kick from the MSE of a few μrad. • Perform MIA analysis of the data set simulated. • Perform MIA analysis of real CERN data from RUN II and superpose results with the simulated trajectories to find a possible source matching. • Evaluate results on stability across RUN I & II.

  8. MIA (Model Independent Analysis) • Consider, a sequence of M BPMs for P injections is constructed as: B(P,M) Use Singular Value Decomposition (SVD) to identify vectors • Returns the eigenvalues () and temporal () and spatial () eigenvectors. Position of BPM in the TL Time evolution

  9. MIA simulated data TI2 On MAD-X, applying a source of error of σ = 50 μrad as the mean of a gaussian distribution, at the start of the TL. Eigenvalues () from simulated analysis for RUN I and II show one significant mode, we must only have one to identify a single source causing trajectory oscillation.

  10. Trajectory obtained from the 1st spatial eigenvector (). • Spatial mode normalised by the square root of beta function. • A sine fit confirms betatron oscillation. • As there is only one significant eigenvector. • The source can be predicted by fitting a simulated kick trajectory.

  11. Real-data RUN II study • Observables relevant for the analysis: • The position of the BPMs and the H-V position of the beam at each BPM. • Transfers above 12 bunches only (1.1E11 p per bunch = 1.32E12 p). • Exclude spurious readings of data in the H-V position above |5|mm. • The injection oscillations are calculated by the module as the difference between the orbit and the average of the trajectory. • Values above 3 sigma of the trajectory excluded from the study.

  12. Eigenvalue analysis: TI2 • All fills performing proton physics and scrubbing. • More than one dominant singular value in almost the whole analysis. • May 2017 only significant difference between 1st to 2nd dominant singular values.

  13. TI2 Eigenvalue comparison RUN I & II • As a general trend over Run II several eigenvalues above noise are found. • For this Run II special case, the result is equivalent to what was observed in Run I where the MSE was identified as main source of shot-to-shot trajectory variations. 76% 78%

  14. Best source matching attempts for TI2 • For only one dominant eigenvalue we could simulate a trajectory with a kick on one of the elements of the TL and plot it with the trajectory. • As we have several dominant values, even the best matching trajectories, share phase but not trajectory through the totality of the TL. BPM location [m]

  15. Amplitude analysis: TI8 • All fills performing proton physics and scrubbing. • More than one dominant singular value in almost the whole analysis. • October 2017 only significant difference between 1st to 2nd dominant singular values.

  16. TI8 Eigenvalue comparison RUN I & II • As a general trend over Run II several eigenvalues above noise are found • For this Run II special case, the result is equivalent to what was observed in Run I where the MSE was identified as main source of shot-to-shot trajectory variations 47% 63%

  17. Best source matching attempts for TI8 • For only one dominant eigenvalue we could simulate a trajectory with a kick on one of the elements of the TL and plot it with the trajectory. • As we have several dominant values, even the best matching trajectories, share phase but not trajectory through the totality of the TL. BPM location [m]

  18. Conclusion • Simulations with MADX allowed to set up the environment for the MIA analysis of Run II experimental data. • The analysis was performed binning monthly data during proton physics fills and scrubbing runs. • From this analysis we observe that during Run II in general there is no singular dominant Eigen mode (single source). • In only one case per line, a single source could be identified and seems to be due to the MSE as observed in Run I. • Further analysis is needed to conclude on Run II performance with respect to the last years of Run I (after MSE PC improvements).

  19. References • [] LeneNorderhaugDrøsdal, “LHC Injection Beam Quality During LHC Run I”, CERN-THESIS-2015-254 24/08/2015. • [] J. Irwin, C. X. Wang, Y. T. Yan, K. L. F. Bane, Y. Cai, F.-J. Decker, M. G. Minty, G. V. Stupakov, and F. Zimmermann, Model-independent beam dynamics analysis, Phys. Rev. Lett., vol. 82, pp. 16841687, Feb 1999. • [] V.Mertens et al., “Status and Plans for the SPS to LHC Beam Transfer Lines TI 2 and TI 8”, EPAC’04, Lucerne, July 2004. • []CAS 2017

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