IR7 Impedance Upgrade in HL-LHC: Installation Slots and Baseline Considerations

2. TCSPM Scenarios with New WP5 Baseline A. Mereghetti, on behalf of the LHC Collimation Team A.Mereghetti

3. HL-LHC IR7 Impedance Upgrade Still to be decided! A.Mereghetti • Recent change of baseline of the IR7 impedance upgrade in the context of the HL-LHC project: 9 TCSPMs instead of the 11 initially foreseen; • 4 TCSPMs will be installed during LS2; • 5 TCSPMs will be installed during LS3; • 2 slots will remain equipped with the present hardware; • The installation slots for the LS2 upgrade have been identified by optimizing impact on impedance while taking into account also: • Expected cleaning performance – no particular change expected; • Expected levels of energy deposition and foreseen deformations; • The most exposed MoGr TCSPMs (first TCSG slot) is subject to a total jaw deformation of 500mm towards the beam in case of 0.2h BLT with HL-LHC beam parameters – present tolerance: 100mm; • We decided not to install the TCSPM in LS2 in this slot (first TCSG); • Elastic deformation: the collimator deforms during the load, but then recovers the initial condition  no permanent damage; • Considerations on MKD-TCSG phase advance and likelihood of direct beam impacts (e.g. injection failure scenario, asynchronous beam dump); • Final installation slots: • TCSG.D4L7.B1 / TCSG.D4R7.B2 (IV IR7 TCSG); • TCSG.B4L7.B1 / TCSG.B4R7.B2 (V IR7 TCSG); • TCSG.E5R7.B1 / TCSG.E5L7.B2 (last but one TCSG); • TCSG.6R7.B1 / TCSG.6L7.B2 (last TCSG); • More details available in CERN-ACC-2019-0001;

4. Run III IR7 Layout A.Mereghetti • Foreseen IR7 layout for Run III: • 4 TCSPMs per beam; • 2 TCPPMs per beam will replace the present TCP.D (V plane) and TCP.C (H plane) – thanks to the Consolidation project; • A TCLD per beam in-between two 11T dipoles in cell 9 – improvement of IR7 cleaning;

5. Choice of Slots for Installation in LS3 B2 • The first and third TCSGs are those most exposed to energy deposition; • Choice of LS3 installation slots based on total Endep in collimators in case of 2015 proton quench test, B2H; Does the pattern change with losses on the vertical plane? A.Mereghetti • Installation slots for LS3 still to be identified; • We can deal with the problem as choosing the two slots not to be upgraded; • As for the installation slots of LS2, a choice based on optimizing impedance may conflict with a choice taking into account energy deposition considerations; • In the following: we consider as post-LS3 baseline all TCSGs replaced by TCSPMs but the two most exposed to energy deposition; • Impact on impedance evaluated by S. Antipov (see next presentation): • He will compare the present post-LS3 baseline scenario against two others, where he focuses on optimizing impedance only;

6. Choice of Slots for Installation in LS3 (II) Total Endepin collimators (SixTrack-Fluka coupling  Fluka) in case of 2015 proton quench test Inelastic interactions in collimators, HL-LHC, v1p3, all TCSPs B2 B1 BLM signals from qualification LMs, 2018, post-TS1, B1 • Qualitative pattern from total endep is reproduced by BLM signals also for a different optics, jaw material and beam; • BLM pattern at TCSGs does not qualitatively change with the plane of losses; Most exposed TCSGs are the first and third one A.Mereghetti • No detailed endep simulations in case of B2V losses; • We cannot check that also for Ver losses the first and third TCSGs are the most exposed TCSGs; • …but BLM signals qualitatively reproduce the total load on the collimators;

7. Post-LS3 IR7 Upgrade Baseline In the present post-LS3 baseline, IR7 TCLAs (1m, Inermet) will not be replaced, and the TCLD (0.6m, Inermet) is kept between 11T magnets in cell 9; In the following, we will show reference loss maps (simulated) for this baseline A.Mereghetti

8. Simulation Set Up ~10M primary protons per case, 1% surviving at most In addition to the presented baseline, settings with 1s-retraction (referred to eN=3.5mm) are also explored (only IR7 TCSGs/TCSPMs settings are changed), as option for a pushed collimation configuration; A.Mereghetti • HL-LHC v1p3, 7 TeV, b*=15cm; • B1H / B1V LMs with 2s-retraction settings; • TCLD between 11T dipoles in cell 9; • Fluka-SixTrack coupling  get LMs and touches for endep simulations; • High luminosity IRs: • Horizontal TCTs in CuCD, Vertical TCTs in Inermet180; • All TCLs are in Inermet180; • Collimator settings: usual 2s-retraction (referred to eN=3.5mm) configuration;

9. B1 LMs – Post-LS3 Baseline – 2s B1H B1V Clean machine, as expected A.Mereghetti

10. B1 LMs – Post-LS3 Baseline – 1s B1H B1V 1sretraction settings make the machine even cleaner wrt 2s retraction, as expected A.Mereghetti

11. B1 LMs – Post-LS3 Baseline – 2s B1H B1V Location of highest cold losses at upstream 11T (as expected): average cleaning inefficiency at 7-8 10-6 m-1, peak at 2-310-5 m-1; A.Mereghetti

12. B1 LMs – Post-LS3 Baseline – 1s B1H B1V Location of highest cold losses at upstream 11T (as expected): cleaning inefficiency lower than with 2s retraction settings, i.e. average at 4-6 10-6 m-1, peak at 1-2 10-5 m-1; A.Mereghetti

13. B1H LMs – Post-LS3 Baseline – 1s vs 2s Higher load on TCSGs when using 1s-retraction settings wrt 2s-retraction ones, up to x2.5 1s-retraction 2s-retraction A.Mereghetti

14. Further Cases Studied Cleaning inefficiencies in the IR7 DS are expected to change very little with TCSG material, whereas loads on TCSGs can change more clearly; A.Mereghetti • The previous analysis shows that: • Presented post-LS3 baseline keep the machine clean; • Overall, B1V losses are slightly lower than B1H; • Overall, 1s-retraction settings are more effective than 2s-retraction settings; • Actual margins to quench in IR7 DS should be assessed taking into account also particle-showers  simulations with FLUKA; • In addition to the presented baseline, alternative configurations have been explored, where the material of the first and third TCSGs changed, in the effort of mitigating the large jaw deformation expected for the most exposed TCSG: • Mo-coated, MoGr(as all the other TCSGs) – this configuration, taken as reference, corresponds to the previous upgraded baseline; • R4550 TCSGs – coated and uncoated; • Post-LS2 scenario is shown as well, as reference; • LMs are available in the back up slides; • Results shown in the following concentrate on variations wrt post-LS2 baseline with 2s-retraction settings;

15. Average Cleaning Inefficiency in IR7 DS 2s-retraction 1s-retraction • Wrt the post-LS2 configuration, any post-LS3 configuration with 2s-retraction settings brings a minor (almost negligible) improvement; • Using 1s-retraction settings clearly improves the cleaning wrt 2s-retraction settings no matter the scenario; • Results for the various scenarios with 1s-retraction settings can be regarded as basically equivalent; • Results rely on a statistics of <1k protons locally lost; B1H B1V A.Mereghetti

16. Peak Cleaning Inefficiency in IR7 DS 2s-retraction 1s-retraction • Results rely on a statistics of ~20 protons locally lost (10cm binninb); • Wrt the post-LS2 configuration, no definite trend is there for post-LS3 configurations • Using 1s-retraction settings clearly improves the cleaning wrt 2s-retraction settings no matter the scenario; • Results for the various scenarios with 1s-retraction settings can be regarded as basically equivalent; B1H B1V A.Mereghetti

17. Load on TCLD 1s-retraction 2s-retraction B1H B1H B1V B1V • As for the average cleaning inefficiency, wrtthe post-LS2 configuration, any post-LS3 configuration with 2s-retraction settings brings a minor (almost negligible) improvement; • Using 1s-retraction settings clearly improves the cleaning wrt 2s-retraction settings no matter the scenario; • Results for the various scenarios with 1s-retraction settings can be regarded as basically equivalent; A.Mereghetti

18. Load on IR7 TCSGs – 2s Installation in LS2 Installation in LS2 B1H First TCSG affected only by change of its own jaw material Installation in LS3 Lower loads on TCSPMs already installed in LS2 B1V Higher loads on TCSPMs installed in LS3 Installation in LS3 A.Mereghetti

19. Load on IR7 TCSGs – 1s 1s-retraction settings imply generally higher loads on all secondary collimators; If compared to post-LS2, 1s-retraction settings, the pictures is very similar to the plots in the previous page; Installation in LS3 B1H First TCSG affected only by change of its own jaw material Installation in LS2 B1V Installation in LS2 Installation in LS3 A.Mereghetti

20. Load on IR7 TCSGs A.Mereghetti • The post-LS3 baseline (i.e. replacing 5 TCSGs with TCSPMs in the chosen slots) will imply higher total loads on the exchanged collimators and lower loads on the TCPMs installed in LS2, no matter the retraction settings; • As expected, since we equip some collimators with a material with higher density than the present one; • Estimated numbers are based on number of inelastic events; • Actual numbers should be evaluated with Fluka simulations, since change of jaw material changes also development of secondary particle showers, especially in a region where cross-talk is important, as in IR7; • Changing the material of the first and third TCSGs them in Mo-coated MoGr, graphite or Mo-coated Graphite implies an increase in their total loads, especially on the first one, and a re-distribution of the loads on the downstream collimators; • Again, final numbers to be computed with Fluka; • Inputs for Flukaendep studies available; • Important to estimate the deformation of the jaw, and its impact on cleaning performance;

21. Conclusions A.Mereghetti • The post-LS3 IR7 baseline has been presented; • Wrt the post-LS2 configuration, 5 TCSPMs are planned for installation in LS3; • The first and third TCSGs are planned to be kept as they are, to avoid big elastic deformation in case of BLT drops to 0.2h; • B1H/V LMs with post-LS3 upgrade have been presented; • HL-LHC v1p3, b*=15cm, 2s-retraction settings; • Input for endep studies with Fluka available  important to finalise estimation of jaw deformation and definition of tolerances; • B2H/B2V still to be simulated; • Simulations with 1s-retraction settings (pushed cleaning perfromance) have been simulated as well for comparison; • Load on TCSGs is expected to increase – number of inelastic interactions increase by at most x2.5; • Options with different jaw materials for the un-changed TCSGs have been explored; • Inputs ready for endep simulations with Fluka;

22. Back-up Slides A.Mereghetti

23. B1H LMs – Post-LS2 Baseline – 2s A.Mereghetti

24. B1V LMs – Post-LS2 Baseline – 2s A.Mereghetti

25. B1H LMs – 11 TCSPMs – 2s A.Mereghetti

26. B1V LMs – 11 TCSPMs – 2s A.Mereghetti

27. B1H LMs – 2 R4550 TCSGs – 2s A.Mereghetti

28. B1V LMs – 2 R4550 TCSGs – 2s A.Mereghetti

29. B1H LMs – 2 R4550 TCSGs Mo-coated – 2s A.Mereghetti

30. B1V LMs – 2 R4550 TCSGs Mo-coated – 2s A.Mereghetti

31. B1H LMs – Post-LS2 Baseline – 1s A.Mereghetti

32. B1V LMs – Post-LS2 Baseline – 1s A.Mereghetti

33. B1H LMs – 11 TCSPMs – 1s A.Mereghetti

34. B1V LMs – 11 TCSPMs – 1s A.Mereghetti

35. B1H LMs – 2 R4550 TCSGs – 1s A.Mereghetti

36. B1V LMs – 2 R4550 TCSGs – 1s A.Mereghetti

37. B1H LMs – 2 R4550 TCSGs Mo-coated – 1s A.Mereghetti

38. B1V LMs – 2 R4550 TCSGs Mo-coated – 1s A.Mereghetti