1. Historical Perspective and First Experiments with Bent Crystals
E. Tsyganov
The University of Texas Southwestern Medical Center at Dallas
and
Joint Institute for Nuclear Research, Dubna
March 7, 2005

3. Channeling at Fermilab, 1977

4. Drift chambers for K -- e experiment at 250 GeV

5. Solving cross-talk problem

6. Continuum potential energy for protons channeled in the (110) planes of Si.
D. S. Gemmel, Reviews of Modern Physics, 46 (1974) 129.

7. What will happen with channeled particles if we
bend the crystal?

9. Quotation:
“What will happen with the trajectory of the channeled particles if we bend the crystal?
Up to some critical value of the bending radius a particle trajectory will repeat the shape of a bent crystal.
This unexpected phenomenon caused by the fact that the particle in this case gradually goes to high electric field of the atoms. It then starts to be bent in the direction of the crystal bending. A stabile trajectory in this case goes away from the potential minimum, in the region where electrical fields are strong enough to create the necessary transverse acceleration. The critical radius of bending is given by the following expression:”

10. The paper was rejected by Phys. Rev. Lett.
6 - MEMBER SCIENTIFIC PANEL HELD AT FERMILAB
(including Prof. D. S. Gemmel from Argonne National
Laboratory) REJECTED PROPOSAL TO
DEFLECT HIGH ENERGY BEAM USING BENT
CRYSTAL
The paper was rejected by Phys. Rev. Lett.
Prof. Alexis A. Maraddudin from UC Irving proved that
the paper is scientific absurd, silly, unintelligent,
bizarre proposal.

11. Channeling at Dubna synchrophasotron
8.4 GeV protons

12. CERN COURIER, September 1977:

13. Goniometer

14. Si crystal, semiconductor detector and bending device

15. Ionization losses in Si crystal
random direction
(110) plane aligned

16. Beam deflection in bent silicon crystal
low ionization
all particles

17. Beam deflection in bent silicon crystal

18. Effect was lost after 12 mrad bending!

19. Beam deflection in bent silicon crystal

21. BEAM EXTRACTION:
FIRST EXPERIMENT

22. Schematics of beam extraction from synchrophasotron

23. 4.2 GeV
Rcr = R mm

24. Beam extracted!
4.2 GeV
Rcr = R mm

25. More beam extracted!
4.2 GeV
Rcr = R mm

26. bent crystal extraction is proved! (1984)
7.5 GeV
bent crystal extraction is proved! (1984)
Rcr = R mm

29. Double Crystal Halo Extraction Efficient Crystal Scraper

32. Crystal mirror concept

33. Angular distributions of outgoing particles for the cases when the tungsten crystal planes (110) are tilted (a) by 0 mrad, (b) by 8.5 mrad, (c) by mrad, and (d) by 68 mrad relative to the direction of an incident 900 GeV-protons. Thickness of the crystal is 24 mm.

34. Impact parameter for different crystal mirrors SC2: a - silicon, b - tungsten.

35. Quotation:
“The device is suitable for cleaning up the proton beam halo
(a clean crystal scraper), or for useful extraction of the
proton beam halo particles with a 99% efficiency. When it
is used as a clean scraper, it could work as an efficient
clean radiation drain preventing radiation due to a proton
beam loss that now is spreading around the Tevatron.
The device is suitable to be used at the LHC collider for both circulating proton beams. It could reduce the background radiation due to a beam halo loss by a factor of about 100.”

36. thank you for your attention!