1. PNPI Gatchina Crystal Farm
Yuri M. Ivanov, PNPI

2. Milestones
1985 – by initiative of A.I.Smirnov and O.I.Sumbaev the crystal-optics fabrication at PNPI was organized by outstanding engineer Yu. P. Platonov (worked under D. D. Maksutov who founded large astronomic optics production in USSR).
– design and fabrication of elastic quasimosaicity quartz crystals and bending devices for 5 meter crystal diffraction spectrometer to study exotic atom X-rays. Precise measurements of K- and Σ- masses at IHEP.
– design and fabrication of silicon crystals to focus particle beams (invented by A.I.Smirnov). Experiments with focusing crystals at IHEP.
– design and fabrication of silicon O-crystals for charged particle beam multi-turn extraction and collimation. Experiments with O-crystals at IHEP, BNL, FNAL.
– design and fabrication of elastic quasimosaicity silicon crystals. Experiments with X-rays at PNPI and with 70 GeV protons at IHEP. Observation of volume reflection effect.
Yuri M. Ivanov
CERN, 9-10 March 2006

3. Samples of precise crystal diffraction units for X-rays
Quartz plate sizes 1x120x120 mm3
Bending radius 5 meters
Elastic quasimosaicity 3”-20” ( μrad)
3 units made
Yuri M. Ivanov
CERN, 9-10 March 2006

4. Focusing crystals for charged particle beams
A.I.Smirnov Experiment PNPI-IHEP 1991
F2 = 4r2 – R2
F - focal distance
R - bending radius of the crystal
r - radius of the exit crystal face
Yuri M. Ivanov
CERN, 9-10 March 2006

5. Deflection and transformation of divergent beams
Experiment IHEP-PNPI 1995
Possibility to form secondary particle beams with focusing crystals
Yuri M. Ivanov
CERN, 9-10 March 2006

6. Samples of focusing crystals
About 10 crystals made
Yuri M. Ivanov
CERN, 9-10 March 2006

7. Multi-turn extraction of proton beam with short bent crystals
IHEP-PNPI
Bent crystal to deflect beam into septum aperture
Magnet system to extract beam
Yuri M. Ivanov
CERN, 9-10 March 2006

8. O-crystal design Typical dimensions: 5 x 5 x 50 mm3 Yuri M. Ivanov
CERN, 9-10 March 2006

9. Samples of O-crystals prepared at PNPI in 1998
Typical interference pattern from a bent face of the O-crystal
Yuri M. Ivanov
CERN, 9-10 March 2006

10. O-crystals prepared at PNPI in 1999 for experiment at RHIC BNL
Slide taken from report to EPAC02 (Paris, France) on Crystal Collimation at RHIC
Yuri M. Ivanov
CERN, 9-10 March 2006

11. O-crystals prepared at PNPI in 2003-2004 for using in IHEP ring
20 crystals made
Yuri M. Ivanov
CERN, 9-10 March 2006

12. Main results with O-crystals at IHEP
Length along beam > 3 mm
Extraction efficiency < 70%
Intensity of extracted beam < 2 x 1012
Radiation hardness ~ 1020
Still working with efficiency ~ 40%
Yuri M. Ivanov
CERN, 9-10 March 2006

13. New approach – to use Sumbaev (elastic quasimosaicity) effect
Studied by O.I.Sumbaev in 1957
Resulted in broadening of gamma-ray diffraction peaks from bent quartz plates
Caused by bending of the reflecting atomic planes (initially flat and normal to large faces of plate) due to crystal anisotropy
Depends on choice of crystallographic plane and orientation angle of plate cutting relative to a normal to the chosen crystallographic plane
Figure from article: O.I.Sumbaev, Reflection of gamma-rays from bent quartz plates, Sov. JETP 32(1957)1276
Yuri M. Ivanov
CERN, 9-10 March 2006

14. Idea
Detailed description of deformed crystal plate done by V.M.Samsonov in 1975
Resulted in predictions of elastic quasimosaic effect for some other quartz and silicon plate orientations
Large elastic quasimosaicity for (011) plane of silicon predicted
Zero result in first experiment in 1999
New calculations: (111) plane, not (011)
Figure from article: V.M.Samsonov and E.G.Lapin, On some possibilities and pequliarities of a curved crystal use in crystal diffraction instruments, 1980
Yuri M. Ivanov
CERN, 9-10 March 2006

15. Crystal design
Yuri M. Ivanov
CERN, 9-10 March 2006

16. Bending of Si(111) planes in dependence on cut angle φ
Dq = 2k9 T , where
T – thickness of plate
k9 – deformation coefficient
For bending radius R = 1 m
(relationship from:
V.M.Samsonov and E.G.Lapin, Preprint LIYaF-578, 1980 )
Yuri M. Ivanov
CERN, 9-10 March 2006

17. Cut  = 0 for Si(111) planes
Yu.M.Ivanov, A.A.Petrunin, and V.V.Skorobogatov, JETP Lett. 81(2005)99
Yuri M. Ivanov
CERN, 9-10 March 2006

18. Different cuttings of Si platej
= 30
= 0
<0
0 1> (1 1 1)
<1
1>
1 0)
Cutting with quasimosaicity
Cutting without quasimosaicity
Oriented ingot
Yuri M. Ivanov
CERN, 9-10 March 2006

19. Production of elastic quasimosaicity crystals at PNPI in 2002-2005
2002 – 4 crystals (0.4 mm, 0.7 mm)
2 for studies of elastic quasimosaicity effect with X-rays
1 for channeling studies with external 70 GeV p-beam
1 for collimation studies in U-70 ring
2003 – 3 crystals (0.3 mm, 2.7 mm)
3 for collimation studies in U-70 ring
2004 – 1 crystal (2.7 mm)
1 for high intensity beam extraction (4x1012)
2005 – 1 crystal (0.4 mm) – not used
1 for reflection/channeling studies with external p-beam
Yuri M. Ivanov
CERN, 9-10 March 2006

20. Crystal design for experiment at SPS30 60
Crystal plate sizes 1x30x55 50
Yuri M. Ivanov
CERN, 9-10 March 2006

21. Oriented piece of silicon ingot prepared
Yuri M. Ivanov
CERN, 9-10 March 2006

22. Billet for plates cut from oriented piece
Yuri M. Ivanov
CERN, 9-10 March 2006

23. Grinding and polishing of (111) faces of billet completed
Yuri M. Ivanov
CERN, 9-10 March 2006

24. Measurement of (111) orientation with respect to face using double crystal diffraction scheme for X-rays and optical autocollimation
Miscut angle ~4” (20 μrad)
Yuri M. Ivanov
CERN, 9-10 March 2006

25. Face flatness check: ~0.2 μm
Yuri M. Ivanov
CERN, 9-10 March 2006

26. Face non-parallelism check: ~3”
Yuri M. Ivanov
CERN, 9-10 March 2006

27. Rocking curve measurement: width ~10”, polishing should be continued
Yuri M. Ivanov
CERN, 9-10 March 2006

28. Further steps To complete polishing of (111) billet faces
To measure widths of rocking curve from (111) faces of billet.
To cut billet for plates.
To grind and to polish large faces of plates providing necessary orientation of crystallographic axes.
To bend plates providing 100 μrad bending angle for (111) planes.
To investigate bent crystals with X-rays.
To complete first crystal in April, second one – in May
Yuri M. Ivanov
CERN, 9-10 March 2006