1. Coronagraph for beam halo observation for the HL LHC
And
X-ray interferometer for the measurement of extremely small apparent beam size in FCC-ee

2. 1. Coronagraph for the observation of beam halo at HL LHC

3. 1-1. What is the coronagraph?
an introduction

4. Diffraction pattern (with interference fringe) taken by sCMOS low noise and high dynamic range camera at ASLS

5. Diffraction fringes
Gaussian beam profile
Convolution between diffraction fringes and beam profile

6. Diffraction fringes
Gaussian beam profile
Convolution between diffraction fringes and beam profile
Blocked by opaque disk

7. Optical system of Lyot’s corona graph
Objective lens
Field lens
Baffle plate (Lyot stop)
Relay lens
Opaque disk
Many of idea such as baffle plates, light trap material, anti-reflection disk etc. are applied to reduce background scattering light.

8. 3 stages-optical system in the Lyot’s coronagraph
1st stage : Objective lens system
2ed stage : re-diffraction system
3ed stage :
Relay lens

9. Observation in PF, KEK 2005
Beam core (superimposed) + halo
Observation with better than 6 order of magnitude

10. Beam tail images in the single bunch operation at the KEK PF measured at different current
Multi-bunch
bunch current 1.42mA

11. Observation for the more out side
Single bunch 65.8mA
Exposure time of CCD : 3msec
Exposure time of CCD : 100msec
Intensity in here : 2.05x10-4 of peak intensity
2.55x10-6
Background leavel : about 6x10-7
Far tail
Observation for the more out side

12. 1-2. Plan of halo observation by using the coronagraph in HL LHC
Phase1: Test observation ( ),
Designed and constructing a coronagraph by modifying the coronagraph constructed in 2005 in the KEK.
Aiming a halo observation with 103 to 104 contrast to the beam core, and it will set in B2 SR monitor line.
Phase2: Design and construct an optimum coronagraph for the LHC,
aiming 105 to 106 contrast.

13. 1-3. Key conditions for design the coronagraph for LHC (2015).
LHC(B2)
Distance between source point and objective lens
28.5m
Beam size in horizontal
(1s of beam core)
330mm/3.75mmrad
270mm/2.5mmrad
Beam size in vertical
430mm/3.75mmrad
350mm/2.5mmrad
Minimum size of opaque disk against beam core
5 s of beam core

14. The optical design of phase 1 coronagraph
LHC(B2)
Focal length of objective lens
2000mm
Objective lens aperture
25 x 25 mm
Transverse magnification
0.0754
Opaque disk size
0.2-2mm
Focal length of field lens
816mm
Movable range of Lyot stop
2 x 2mm to 20 x 20 mm
Focal length of relay lens and
Magnifier lens
500mm mm

15. 1-4. Diffraction in
Coronagraph

16. Opaque disk
Objective
lens

17. Re-diffraction optical system
Opaque disk
Re-diffraction optics system
Field lens
Objective system
Re-diffraction optical system
Function of the field lens : make a image of objective lens aperture onto Lyot stop

18. Diffraction in re-diffraction system

19. Lyot stop at +/-5mm

20. Re-diffraction optical system
Opaque disk
Lyot stop
Re-diffraction optics system
Objective
lens
Re-diffraction optical system
Blocking diffraction fringe by

21. Lyot stop
Field lens
Blocking diffraction fringe by

22. Lyot stop at +/-5mm

23. Diffraction background at 3ed stage in log scale
3.7x10-4

24. Background from diffraction is depending to leakage of diffraction fringes in inside of Lyot stop

25. 1-5. Mie-scattering noise from optical component surface

26. Background source in coronagraph
Noise from defects on the Objective lens surface (inside) such as scratches and digs.
2. Noise from the optical components (mirrors) in front of the coronagraph.
3. Reflections in inside wall.
4. Noise from dust in air.
5. Rayleigh scattering from air molecule.
6. Turbulence of the air

27. Background source in coronagraph
1.Noise from defects on the Objective lens surface (inside) such as scratches and digs.
2. Noise from the optical components (mirrors) in front of the coronagraph.
3. Reflections in inside wall. Apply baffles and anti-reflection materials
4. Noise from dust in air. Apply dust filter
5. Rayleigh scattering from air molecule.
Not significant in few meter optical path
6. Turbulence of air Not significant in few meter optical path

28. Digs on glass surface of scratch & dig 60/40
The optical surface quality 60/40 guarantees no larger scratches than 6mm width, and no larger dig than 400mm.
5mm
200mm

29. Simulation result of background produced by dig on objective surface

30. Example of Mie-Scattering noise

31. How to eliminate Mie scattering??
A careful optical polishing for the
objective lens.
Reduce number of glass surface.
use a singlet lens for the objective lens.
3. No coating (Anti-reflection, Neutral density etc.) for objective lens.

32. Comparison between normal optical polish and careful optical polish for coronagraph
S&D 60/40 surface of the lens
Surface of the coronagraph lens

33. 1-5. Optical testing of Phase 1 coronagraph with 30m optical testing line

34. 30m Optical testing line for Phase 1 coronagraph

35. Light source

36. Phase 1 coronagraph set on one end of optical line

37. Diffraction without Lyot stop
Exposure time 200msec

38. Elimination of diffraction with Lyot stop
Exposure time 500msec

39. 2x10-7 to the peak intensity
425mm Exposure time 10sec
1x10-4 to the peak intensity

40. Artificial halo source, plastic plate with some finger prints.

41. 425mm 500msec Artificial halo

42. Summary for expected performance for phase 1 coronagraph
The diffraction background in phase1 coronagraph is estimated to 3.7x10-4 (experimentally 1 x 10-4 ).
Except 2 fringes in the centre, most of diffraction fringes have intensities of 10-5 to range.
From Optical testing, Mie-scattering noise from the extraction mirror seems negligible.

43. 2. X-ray interferometer for the measurement of extremely small apparent beam size in FCC-ee

44. 2-1. Parameters of FCC-ee at source point
Bending magnet length
24.585m
Bending radius m
Magnetic field strength
0.0503T
Bending angle
2.144mrad
Beam energy
and current
175GeV mA
45GeV mA
emittance
1.3pmrad
Estimated vertical beam size
sy =5.1mm / b=20m
=0.05mrad / 100m

45. 2-2. Expected spectrum from the bending magnet FCC-ee
45GeV
175GeV
Brightness (photons / mrad2 1%bandwidth)
Frequency integrated power
6.5W/ mrad for 175GeV
5.6W/mrad for 45GeV
Photon energy (keV)

46. 175GeV r=11590.8m 0.1nm Divergence of beam Order of 10-7rad
Divergence of SR
Order of 10-5rad
q in rad

47. 2-3. Extraction of hard X-rays from the ring
Light source:
last bending magnet in Arc.
45-50mm
Estimated vacuum duct
in the straight section after the last bending magnet

48. Bending radius m
24.858m
2.144mrad
1.072mrad
100m
107.2mm
Geometrical condition for the extraction of SR from the last bending magnet
Enough separation between orbit and extraction structure of the vacuum duct is necessary to escape from corrective effect.
Some similar structure such as crotch absorber and branch optical beam line seems necessary to protect the crotch of the vacuum chamber from strong irradiation of SR.
50m
53.6mm
Source point: center of the magnet

49. Apparent size of object
Long distance
Short distance
Observation point

50. Angular diameter Angular diameter is given by, q=a/d or qs=s/d a q d
Object locates having a size a at certain distance d
Angular diameter is given by,
q=a/d or
qs=s/d

51. wavelength Visible light imaging 500nm 50 500 5000 X-ray pinhole 0.1nm
method
wavelength
measurable minimum beme size in angular diameter in mrad
Corresponding size in 100m in mm
Corresponding size in 1000m in mm
Visible light imaging
500nm 50
500
5000
X-ray pinhole
0.1nm
0. 5
FZP imaging
Of soft X-ray
0.35nm
0.3 30
300
Visible light
interferometry
400nm
0.47 47
470
Interferometry
with imbalance input
0.2
(scaled)
No measurement 20
200
Coded aperture
0.3nm
0.5
0.1
(estimation) 10
100
X-ray
(new method)
0.01 1
10mm

52. 2-4. Simple double slit X-ray interferometer (Young type)
Double slit D=20-few100mm, a=8mm
K-edge filter
Be-window

53. We do not need selection of polarization
q in rad
175GeV
r= m
Double slit location
We do not need selection of polarization
Iv / Ih =0.016

54. Double slit of interferometer will not miss the beam size information
Divergence of SR
Order of 10-5rad
Divergence of beam
Order of 10-7rad
Double slit of interferometer will not miss the beam size information

55. Spatial coherence vs. beam size D=300mm, f=100mg
Beam size (mm)
l=0.1nm

56. Expected interferogram for g=0.65 (beam size of 5mm at 100m)
Double slit a=5um, D=300um f=100m
Monochromatic l=0.1nm

57. Krypton gas filter has a nice window around 10keV

58. With quasi-monochromatic ray Kr gas filter 100mm
Dl/l=20%
Dl/l=50%

59. Double slit interferometer (Young type) with total reflection mirror
Double slit D=20-100mm, a=8mm
K-edge filter
Be-window
deg
Totally reflection mirror
Length of 1m
g-ray

60. Background subtraction
Interference fringe which is observed by the simple Young type double slit interferometer has no reference baseline

61. we can identify the background as an background with no input light.
We can crosscheck this issue with observing a single slit diffraction pattern by hiding one slit of double slit

62. Summery for FCC e-e
X-ray interferometer has a good resolution for 5mm beam size in FCC e-e with distance of 100m.
2. The system seems very simple, and easy to construction.
3. A similar system such as crotch absorber etc. are necessary to safety extraction of X-rays.
4. Mechanical vibration issue is very important due to shorter wavelength. Carful design of mechanical structure is necessary.

63. Thank you for your attention

64. Instantaneous diffraction pattern at focus point of Objective lens is given by,
Apparent diffraction pattern on focus point is given by integrating instantaneous diffraction pattern in incoherent manner ,

65. Disturbance of light on Lyot’s stop by re-diffraction system is given by;

66. How is the performance of coronagraph limited?
1-6. Phase 2 coronagraph
How is the performance of coronagraph limited?

67. Corse period correspond to inner aperture diameter
Fine period correspond to outer aperture diameter

68. Back to diffraction fringe on Lyot　stop
0.162mm
0.6mm
1.0mm

69. Back to diffraction fringe on Lyot　stop
0.162mm
0.6mm
1.0mm
Larger opaque disk has small diffraction fringe

70. Phase 2 coronagraph
1. The leakage of diffraction fringe reduces by increase of opaque disk diameter.
We can realize better contrast with larger transverse magnification.
We should design the focal length of objective lens longer.
2. Chromatic shift on optical axis is given by focal length divided by the Abbe number, designing long focal length increases drastically increase the chromatic foal shift.
We should apply reflector focusing system for the objective instead of the objective lens system in phase 2.

71. 16000mm
8000mm
4000mm
5000mm
Coronagraph having a magnification of 0.5 (about 7 times larger transverse magnification)
Objective lens
Opaque disk
Lyot stop
Field lens
relay lens

72. Reduction the actual length of long focus of the simple objective lens with a combination of focus and defocus lenses.
Telephoto type lens

73. Telephoto type with reflectors
First mirror
concave
Second mirror
convex
Focus of first mirror
Synthesized focus of two mirrors

74. Optical design Entrance pupil for the first stage
Objective mirror system f=8000mm
Magnification ≈0.5
First mirror
concave
R=4000mm
Second mirror
convex
R= -800mm
Entrance pupil for re-diffraction system
Field lens
Lyot stop
8mm x 8mm
Relay lens
Magnification =1
5000mm
5200mm
1700mm

75. Diffraction background at 3ed stage
In Log scale x10-6 to 10-7

76. Expected performance of Phase 2 coronagraph
The diffraction background in phase1 coronagraph is estimated to 2x10-6 to
Gaussian appodization at relay lens aperture can improve the contrast of noise diffraction down to 10-9.
Such appodization increase width of diffraction for halo image, and will reduce spatial resolution.