X-ray interferomety for the FCC-ee Beam emittance (size) diagnostic T. Mitsuhashi and K. Oide KEK E. Bravin, G. Trad, F. Roncarolo and Frank Zinmmerman CERN Mark Boland ASC Parameters of FCC-ee Bending magnet length Bending radius 24.585m Magnetic field strength 0.0503T Bending angle 2.144mrad Beam energy and current 175GeV 6.6mA 45GeV 1500mA emittance 1.3pmrad Estimated vertical beam size sy =5.1mm / b=20m =0.05mrad / 100m 11590.8m Review for existing methods method wavelength measurable minimum beme size in angular diameter in mrad Corresponding size in 100m in mm Visible light imaging 500nm 50 500 5000 X-ray pinhole 0.1nm 0. 5 50 500 FZP imaging Of soft X-ray 0.35nm 0.3 30 300 Visible light interferometry 400nm 0.47 47 470 Visible light Interferometry with imbalance input 400nm 0.2 (scaled) No measurement 20 200 Coded aperture 0.3nm 0.5 0.1 (estimation) No measurement 50 10 Corresponding size in 1000m in mm 500 100 Angular diameter a q d Object locates having a size a at certain distance d Angular diameter is given by, q=a/d method wavelength Visible light imaging 500nm 50 500 5000 X-ray pinhole 0.1nm 0. 5 50 500 FZP imaging Of soft X-ray 0.35nm 0.3 30 300 Visible light interferometry 400nm 0.47 47 470 Visible light Interferometry with imbalance input 400nm 0.2 (scaled) No measurement 20 200 Coded aperture 0.3nm 0.5 0.1 (estimation) No measurement 50 10 500 100 X-ray Interferometry 0.1nm 0.01 1 10mm (new method) measurable minimum beme size in angular diameter in mrad Corresponding size in 100m in mm Corresponding size in 1000m in mm Beam in phase space and Angular divergence and spectrum of Synchrotron Radiation Beam profile in phase space b=20m a=2 Y’ (rad) a=1 Y (m) a=0 175GeV r=11590.8m 0.1nm Divergence of beam Order of 10-7rad Divergence of SR Order of 10-5rad q in rad Expected spectrum from the bending magnet FCC-ee Brightness (photons / mrad2 1%bandwidth) 45GeV 175GeV Photon energy (keV) Character of bending magnet in FCC-ee 24.858m or 2.144mrad Bending radius 11590.8m Bending angle of 2.144 mrad is 100 times larger than tail to tail opening of SR at 0.1nm (0.02mrad). So, this bend is classified as long magnet. SR and TR from magnet edge is week enough in X-ray region. Extraction of hard X-rays from the ring Light source is assumed to the last bending magnet in Arc. Estimated vacuum duct 45-50mm 100m 50m 107.2mm 1.072mrad 53.6mm 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. 24.858m 2.144mrad Bending radius 11590.8m X-ray interferometer Simple double slit X-ray interferometer (Young type) K-edge filter Double slit D=20-few100mm, a=8mm Be-window 100m 50-100m 175GeV r=11590.8m Double slit location Iv / Ih =0.016 D=300mm We do not need selection of polarization q in rad 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 Spatial coherence vs. beam size D=300um, f=100m g l=0.10nm Beam size (mm) Expected interferogram for g=0.65 (beam size of 5mm at 100m) Double slit a=5um, D=300um f=100m Monochromatic l=0.1nm Quasi-monochromatic ray at 0.1nm Absorption of Krypton gas K-edge filter (1 atm, 100 mm pass). Krypton gas filter has a nice window around 10keV How to eliminate shorter wavelength component Using the critical angel of total reflection in X-ray Elimination of shorter wavelength component with total reflection mirror K-edge filter Double slit D=20-100mm, a=8mm g-ray 1.0-1.5deg Be-window 100m Totally reflection mirror Length of 0.3m 100m With quasi-monochromatic ray Kr gas filter 100mm Dl/l=20% Dl/l=50% Interference fringe which is observed by the simple Young type double slit interferometer has no reference baseline Escape from the shift in two optical axis Elliptically deformed total reflection mirror Interferogram by elliptically deformed total reflection mirror Double slit interferometer (Young type) with curved total reflection mirror (mechanically vended) K-edge filter Double slit D=20-100mm, a=8mm g-ray 1.0-1.5deg Be-window 100m Totally reflection mirror Length of 1m 100m Since long distance between total reflection mirror to observation plane will enhance the geometrical aberrations of the mirror, following position seems better K-edge filter Double slit D=20-100mm, a=8mm Totally reflection mirror 1.0-1.5deg Be-window 100 m 100 m few m Summery for FCC e-e 1. 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.Angle between beam duct and X-ray branch beam line is very small (1 mrad without total reflection mirror, 1deg with total reflection mirror) , some difficulty will be expected for duct design for example, connection flange. Comment for longitudinal and dynamical diagnostics Streak camera and fast gated camera for observation of bunch by bunch longitudinal dynamical observation. Visible SR beam line should be necessary. Heat deposit onto the SR extraction mirror is not so larger than existing SR machine, so we can use mirror design in SR facilities. The spatial-temporal measurement of beam dynamical behavior. Head-tail motion observed with the streak camera Turn by turn image of injected beam into storage ring Optimization of injection Proposal for Test of the X-ray interferometry at the Imaging and Medical beamline at the Australian Synchrtron Parameters at the Source Point on IMBL. Length of magnets 1.55 m Max. magnetic field strength 4.2 T Nominal user field strengths 1.4, 2, 3, 4 T Period 52 mm Critical energy limit 25 keV @ 15.2 mm Source point lattice parameters (0.01% emittance coupling) Max. stored e-beam current sy = 1.6 mm / b y = 2.42 m = 0.051 mrad at 140 m 200 mA Spectrum of SR at the Source Point on IMBL Possible configuration of X-ray interferometer at IMBL K-edge filter Double slit D=20-600mm, a=8mm Totally reflection mirror g-ray 1.0 -1.5deg Be-window 31m 39m 101m Vertical position in mm A calculated interferogram for a 1.6 mm beam at 101 m downstream from the double slit. The double slit separation is 0.3mm Summary for Australian Synchrotron We can test the performance of X-ray interferometer by using the long-range IMBL beamline for medical imaging at Australian Synchrotron. We can locate the double slit at 31 m downstream from the source point, and another 109 m distance is available for the observation of the interferogram. The expected beam size is 1.6 mm to 16 mm. The corresponding angular diameter is 0.051 mrad, and this angular diameter is similar in the FCC-ee. We propose a test of the X-ray interferometer design on the IMBL beamline with a simultaneous cross check with the visible interferometer on the neighbouring ODB beamline at the Australian Synchrotron. Thank you very much for your attentions Measurement of beam size in the FCC-hh Parameters of FCC-HH Bending magnet length Bending radius 14.3m Magnetic field strength 15.85T at 50TeV 0.951T at 3TeV Bending angle 1.36mrad Beam energy and current emittance 50TeV 500 mA 3TeV injection 20pmrad Estimated beam size sy =30mm / b=60m sy ≈200mm / high b sx =30mm / b=60m sy ≈200mm / high b 10514.7m Brightness (photons / mrad2 1%bandwidth) Expected spectrum from the bending magnet FCC-HH at 50TeV Frequency integrated power 217W / mrad at 50Tev Photon energy (keV) 50TeV r=11590.8m l=0.1nm 50TeV r=11590.8m l=500nm Comparison l=0.1nm l=500nm 500nm 0.1nm Brightness (photons / mrad2 1%bandwidth) Expected spectrum from the bending magnet FCC-HH at 3TeV Visible light Photon energy (keV) Brightness (photons / mrad2 1%bandwidth) Expected spectrum from the bending magnet FCC-HH at 3TeV Visible light X-ray is not available at injection energy! Photon energy (keV) Brightness (photons / mrad2 1%bandwidth) 50TeV 40TeV 30TeV 20TeV Photon energy (keV) Summary of SR in FCC h-h 1. Visible SR is available for all energy range. 2. X-ray is available in higher than 30TeV For the SR source, the complicated scheme as in LHC; Wavelength shifter for injection energy Edge radiation for middle energy range Bending radiation for high energy range are not necessary. Possible diagnostics system using visible SR in the LHC will be useable for all Energy range. Imaging system Coronagraph Streak camera We need High-b section for SR source point to obtain larger beam size SR Interferometer etc. Heat deposit onto SR extraction mirror is very larger than LHC due to hard X-ray component, but not larger than existing SR facilities. But still direct cooling for mirror seems key issue. Summery for FCC H-H 1.We can use visible SR for all energy range for diagnostics. 2. The hard X-ray is available higher than 40TeV. 3. Many diagnostics system using visible SR in the LHC will be useable for all Energy range. For the convenience of diagnostics, we need high b-section to obtain a large beam size at the source point. 4. Simple pinhole camera should be convenient for beam size measurement at 40-50TeV. For the pinhole camera, we need to optimize lattice parameter at the source point. 5. For the visible SR extraction, heat deposit onto the extraction mirror is larger. We need to consider direct cooling of extraction mirror. More information for FCC-hh, please see Conceptual design of SR monitor in the FCC Beam emittance (size) diagnostic By T. mitsuhashi, K. Oide and F. Zinmermann in proceedings of IPAC 2016, Busan Comment for X-ray pinhole camera Start with physics of pinhole. A simple X-ray pinhole camera should be convenient for beam profile/size monitor in high energy range Representation of the pinhole in the phase space and matching between the source point y’ y’ y’=(-y+h)/s pinhole h/s h On the source point y h On the pinhole y Pinhole in phase space on source point h 1 s y = y' 0 1 y' p h=y+sy’ y’=(-y+h)/s y’ y’=(-y+h)/s In the case of longer wavelength, ellipsoid will smeared by large opening angle of radiation h/s In the case of short wavelength such as Xray h y Phase space plot of proton beam Diffraction phenomena in pinhole camera Intensity of diffraction is given by Fresnel transform of pupil function F of the pinhole ik 2 2 I( x, y) = F( x 0 , y 0 ) exp x 0 - x y 0 - y 2z dd Thus, in the case of simple circular hole J Rr dr Ix, y = 2 exp izr 2 0 2 2 t=f/(a2/l)<1 Fresnel like region t=f/(a2/l)>3 Franhofer like region For example, l=0.1nm, a=2mm Franhofer region > 0.12m In most case, pinhole with x-rays should be Franhofer region. l=0.1nm a=2mm (D=4mm) F=10m 100mm Diffraction patterns for several pinhole size 3mm 1mm 2mm 4mm 5mm Diffraction width as a function of pinhole diameter l=0.1nm, F=10m 400 350 Geometrical resolution becomes higher 300 Diffraction resolution higher 250 200 150 100 50 0 0 1 2 3 4 pinhole diameter (um) 5 6 An example of pinhole camera measurement setup Diffraction size should be 100mm Pinhole D=4mm Observation plane at 10m Beam 1s=10mm 1m 10m Result of beam size should be 14mm without convolution of pinhole diameter Geometrical magnification=10 Geometrical image size should be 100mm Without convolution between pinhole diameter Large transverse magnification will necessary for obtaining an enough image size vs. diffraction width. Where we can insert the pinhole?? 100m 50m 107.2mm 1.072mrad 53.6mm 24.858m 2.144mrad Some special structure, near by the beam, we mast great take care for corrective effect to the beam in Electron machine. Small impedance (smooth structure ) is strictly necessary! Assuming we can set a pinhole at 35mm from the beam ( almost same condition in SR extraction mirror in the B-factory), corresponding distance from the source point is 35m, and putting a image sensor at 100m downstream, geometrical magnification is 1.857, so image size for 5mm beam is 9.3mm. Diffraction width of pinhole with 10mm diameter at 67m downstream is 600mm. So, 9.3mm image size is hopeless to measure. Total reflection by surface of pinhole blocks Good surface should be necessary to make small gap of two blocks 10mm gap with 3mm length 3.33mrad Totally reflection by surface of pinhole blocks Good surface should be necessary to make small gap of two blocks 10mm gap with 3mm length 3mrad It’s smaller than total reflection critical angle for heavy metal
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