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ALEXEI SYTOV Research Institute for Nuclear Problems, Belarusian State University

CRYSTAL-BASED COLLIMATION SYSTEM AS AN ALTERNATIVE WAY TO SOLVE THE COLLIMATION PROBLEM FOR FUTURE HIGH ENERGY ACCELERATORS. ALEXEI SYTOV Research Institute for Nuclear Problems, Belarusian State University. The LHC luminosity upgrade. The beam luminosity will increase with a factor 10 !.

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ALEXEI SYTOV Research Institute for Nuclear Problems, Belarusian State University

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  1. CRYSTAL-BASED COLLIMATION SYSTEM AS AN ALTERNATIVE WAY TO SOLVE THE COLLIMATION PROBLEM FOR FUTURE HIGH ENERGY ACCELERATORS ALEXEI SYTOV Research Institute for Nuclear Problems, Belarusian State University

  2. The LHC luminosityupgrade • The beam luminosity will increase with a factor 10!

  3. Absorber Absorber Collimation system for removing halo particles • Halo particles can damage the LHC equipment because of their large amplitude of betatronoscilla-tions. So we should remove them using collimation system: old collimationsystem(after the LHC luminosity upgrade becomes insufficient) new collimation system

  4. The remarkable feature of crystals in high energy physics is very strongelectricfields applied to particle beam with accuracy of Angstrom. How can we deflect high energy particles using bent crystal?

  5. Different effects in crystal θL0 Volume reflection Channeling

  6. Advantages and disadvantages of different effects Channeling in Bent crystals─ large deflection, but small acceptance VR─ large acceptance, but small deflection

  7. Advantages and disadvantages of different effects Channeling in Bent crystals─ large deflection, but small acceptance VR─ large acceptance, but small deflection MVR─ large acceptance, increased deflection MVR indeed increases reflection angle 5 timesin comparison with VR

  8. Multiple Volume Reflection (MVR)* Axes form many inclined reflecting planes <111> Θx Θy Z Y *V. Tikhomirov, PLB 655 (2007) 217; V. Guidi, A. Mazzolari and V. Tikhomirov, JAP 107 (2010) 114908 X

  9. A trajectory θY μrad δθX,Y, θX

  10. Angular acceptance increase by MVR*) Channeling VR Crystal with cut MVR *)MVR orientation with ΘX0 = -273μrad, ΘY0 = 100μrad and R=2m

  11. A technique to improve crystal channelingefficiency of charged particles till 99,9%* • A narrow plane cut near the crystal surface considerably increases the probability of capture into the stable channeling motion of positively charged particles. Crystal z Beam cut z2 z3 z1 0 *V. Tikhomirov . JINST, 2 P08006, 2007. zc

  12. Conclusion 1. MVR is very good for collimation because of high collimation efficiency. We can increase the collimation efficiency by application of channeling regime if we solve some additional problems.

  13. Problems of the channeling effect for the collimation

  14. experiment simulation UA9experiment at SPS (CERN) * • Dependence of inelasticnuclear interactionnumber of protonson the angular position of the crystal C1: The UA9 experimental layout: *W.Scandale et al. Phys. Let., B692 78-82, 2010.

  15. Miscut angle

  16. First crystal hit

  17. First crystal hit UA9: more than 90% of particles for both miscut cases

  18. Probability of nuclear reactions in the crystal collimator vsmiscut angle at perfect crystal alignment* *V. Tikhomirov, A. Sytov. arXiv:1109.5051 [physics.acc-ph]

  19. Probability of nuclear reactions in the crystal collimator vsmiscut angle at perfect crystal alignment* ×4,5 *V. Tikhomirov, A. Sytov. arXiv:1109.5051 [physics.acc-ph]

  20. Probability of nuclear reactions in the crystal collimator vsmiscut angle at perfect crystal alignment* UA9 ×4,5 *V. Tikhomirov, A. Sytov. arXiv:1109.5051 [physics.acc-ph]

  21. What is the miscut influence at the LHC?

  22. Particle distribution in impact parameter for the UA9 (SPS) and the LHC* miscut influence zone miscut influence zone average impact parameter average impact parameter *V. Tikhomirov, A. Sytov. arXiv:1109.5051 [physics.acc-ph]

  23. Conclusion 2 • Both the positive and negativemiscut angles can be the reason of considerable decreasing of the collimation efficiency. • The usual miscut angle can increase the probability of nuclear reactions with a factor 4,5 for the UA9 case. • The LHC functioning will not be considerably disturbed by the influence of crystal miscut. • In addition, the performance of the crystal collimator can be drastically improved by the narrow plane cut.

  24. Conclusion 2 • Both the positive and negativemiscut angles can be the reason of considerable decreasing of the collimation efficiency. • The usual miscut angle can increase the probability of nuclear reactions with a factor 4,5 for the UA9 case. • The LHC functioning will not be considerably disturbed by the influence of crystal miscut. • In addition, the performance of the crystal collimator can be drastically improved by the narrow plane cut.

  25. Conclusion 2 • Both the positive and negativemiscut angles can be the reason of considerable decreasing of the collimation efficiency. • The usual miscut angle can increase the probability of nuclear reactions with a factor 4,5 for the UA9 case. • The LHC functioning will not be considerably disturbed by the influence of crystal miscut. • In addition, the performance of the crystal collimator can be drastically improved by the narrow plane cut.

  26. Conclusion 2 • Both the positive and negativemiscut angles can be the reason of considerable decreasing of the collimation efficiency. • The usual miscut angle can increase the probability of nuclear reactions with a factor 4,5 for the UA9 case. • The LHC functioning will not be considerably disturbed by the influence of crystal miscut. • In addition, the performance of the crystal collimator can be drastically improved by the narrow plane cut.

  27. What is crystal application for the ILC?

  28. What is crystal application for the ILC? • speeding up of the electromagnetic showers generation. • e± crystal collimation • decrease of size of electromagnetic calorimeters • polarization generation/measurement • positron source for ILC

  29. Summary • Both the MVR and channeling phenomena can be successfully used for the crystal collimation at the LHC. • The channeling can provide better efficiency than the MVRbut the MVR is easier to use with high efficiency. • There are many additional crystal applications for the ILC.

  30. Thank you for attention!

  31. Particle distribution in deflection angle for the UA9 (SPS) and the LHC* *V. Tikhomirov, A. Sytov. arXiv:1109.5051 [physics.acc-ph]

  32. Average impact parameter vs average beam diffusion step for the SPS UA9 and the LHC* *V. Tikhomirov, A. Sytov. arXiv:1109.5051 [physics.acc-ph]

  33. Measured in cm average length <Δz> of scattering of particles entering the crystal through the lateral crystal surface vs both miscut angle and diffusion step at perfect crystal alignment*

  34. Miscut angle Uncaptured particles after the first crystal passage: ~92% UA9: ~95%

  35. First MVROC observation W. Scandale et al, PLB 682(2009)274 MVROC indeed increases reflection angle 5 times

  36. Phase space in accelerator at the crystal coordinate

  37. Distribution of angle of deflection by crystalafter the first crystal passage - - - - { { { { - - - - 3 4 3 3 4 3

  38. Crystal thickness choice Crystal thickness Crystal thickness Crystal 0.05 mm 0.5 mm 1.0 mm 0.3 mm 0.05 mm 0.05 mm Count 0.5 mm 1.0 mm 0.3 mm 0.3 mm 1.0 mm 0.5 mm x', μrad Volume reflection Channeling amorphous x, mm θdef,μrad

  39. Dependence of inelasticnuclear interactionfraction of protonson the crystal thickness fraction Dcr=∞ Dcr, mm

  40. Absorber Secondary beam problem Secondary beam Particles flowing from the opposite side of the crystal W.Scandale et al. Phys. Let, B692 78-82, 2010. the experimental equipment hit

  41. UA9 experiment interpretation* experiment count simulation My simulation: θmc=0μrad Miscut angle: θmc=+200μrad θmc=-200μrad θmc=+200μrad (Crystalwidth=2mm) *W.Scandale et al. Phys. Let., B692 78-82, 2010. θcr,μrad

  42. z=z1 z=z2 z=0 1 2 3 Phase space transformations θ/θch z>z1 z>z2 2' 4 θ/θch x, Å θ/θch With cut z=zc z=zc Without cut 3' 5 θ/θch θ/θch *V.V.Tikhomirov . JINST, 2 P08006, 2007. x, Å x, Å

  43. Dependence of the 7 TeV proton dechanneling probability in a 1cm bent Si crystal on the r.m.s. incidence angle* Without cut With cut *V.V.Tikhomirov. JINST, 2 P08006, 2007.

  44. UA9 collaboration references: • W. Scandale et al. PRL 98, 154801 (2007) • W. Scandale et al. PRL 101, 234801 (2008) • W. Scandale et al. PRL 101, 164801 (2008) • W. Scandale et al. PRL 102, 084801 (2009) • W. Scandale et al. Phys. Let. B688, 284 (2010) • W. Scandale et al. Phys. Let., B692 78 (2010) V.V.Tikhomirov’s references: • V.V. Tikhomirov.Phys. Lett. B655 (2007), 217 • V.V.Tikhomirov . JINST, 2(2007), P08006 • V. Guidi, A. Mazzolari, V. V. Tikhomirov. J. of Phys. D: Applied Physics, 42 (2009), 165301 • W. Scandale, V.V.Tikhomirov. Phys. Lett. B. 682 (2009), 274 • V. Guidi, A. Mazzolari, V.V. Tikhomirov. J. Appl. Phys. 107 (2010), 114908 • W. Scandale et al…V. V. Tikhomirov. EPL, 93 (2011), 56002

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