1. Using crystals facilitates the LHC upgrade the LHC upgrade Victor Tikhomirov Institute for Nuclear Problems Minsk INP

2. Outline The LHC luminosity upgrade Beam halo scraping by crystals Volume reflection of particles in bent crystals Volume reflection amplification by crystal axes Channeling capture increase by the crystal cut Conclusions

3. Luminosity upgrade: Fifteen years of planning and R&D, followed by over 10 years of construction, should be followed by a comparable period of exploitation. Energy upgrade: What is better? The LHC upgrade need INP

4. ssss Luminosity upgrade in more effective at M < 3.5 TeV

5. ssss Statistics is too low for a clear separation among possible models at integrated luminosity of 100fb -1

6. ssss Thus, the luminosity upgrade have to be very effective INP

7. ssss However luminosity increase will intensify the beam halo formation INP

8. ssss Halo sources: – beam physics and operational instabilities – intra beam scattering – scattering with residual gas – synchrotron radiation – collective instabilities … INP

9. ssss Collimation is used to scrape the halo

10. ssss Crystals improve collimation efficiency

11. ssss Crystals are used in both channeling and volume reflection regimes

12. ssss Crystals bending

13. ssss How it must look at the LHC crystal Proton absorption INP

14. ssss Background reduction by channeling at FNAL INP Deflection of channeling protons reduce the background more than 4 times

15. ssss Volume Reflection prediction A.M.Taratin and S.A.Vorobiev, Phys.Lett. A119 (1987) 425 and A.M.Taratin and S.A.Vorobiev, NIM in PR B26 (1987) 512 INP

16. ssss Volume reflection CERN H8-RD22 experiment Sept 2006 channeling Volume reflection INP Volume capture

17. ssss Volume reflection by crystal axes INP

18. ssss Axes form reflecting planes INP

19. ssss INP Protons are reflected from many crystal plane sets of one crystal

20. ssss Reflection from many crystal planes increase VR angle 4 times - 1 INP

21. ssss INP Reflection from many crystal planes increase VR angle 4 times - 2

22. ssss Typical distribution of multiple reflected protons

23. ssss INP Reflection from different crystal planes allows to increase the volume reflection angle about 4 times

24. ssss INP The capture probability can be increased by a plane cut

25. ssss INP The cut diminishes the potential energy conserving the transverse kinetic one Transverse energy reduction by the cut - 1

26. ssss INP Transverse energy reduction by the cut - 2 Only 1-2% of protons avoid the transverse energy reduction by the cut

27. ssss Protons are moved away from the high nuclear density regions Proton phase space transformation by the cut

28. ssss INP Dechanneling suppression by the cut The cut decreases the dechanneling probability from 18 to 1-2%

29. ssss A pair of crystals with cuts bent in orthogonal planes allows to deflect 99.9% of protons

30. ssss INP The cut allows to increase the proton (nuclei) deflection efficiency and to decrease the accompanying proton absorption by 1-2 orders of magnitude

31. ssss INP Conclusion: The LHC luminosity upgrade acquired new technical means which need further investigation