New emittance monitor beamline
A. Saa Hernandez, N. Milas, M. Rohrer, V. Schlott, A. Streun TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Outline New emittance monitor beamline Layout and working principle New vs. old beamline Basic elements: parameters and some concepts Plan B SRW simulations Different wavelengths Interferometric method Inclusion of mirror misalignments Status TIARA mid-term meeting, CIEMAT, Madrid, June 2012 New emittance monitor beamline
layout: dipole BX-08 exit window finger absorber flat mirror polarizer CCD camera toroidal mirror optical table measurement principle: -polarization method finger absorber focusing element vertical polarizer image plane = CCD camera filament beam spread function visible/UV light: X-rays electron beam (filament beam) horizontal () polarization vertical () polarization TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Why a new emittance monitor beamline? Increase sensitivity to small beam sizes (< 3 m): wavelength independent (only reflective elements are used) allows shorter wavelengths (e.g. 266 nm) allows interferometricmethod Increase measurement precision better magnification ratio Full-time accessible outside the SLS tunnel Cross-check results with the use of different wavelengths and two measurement methods New beamline flat mirror 6.985 image plane 49 0.144 z interference obstacle 0.350 y S1 = m S2 = m 45 4.551 M= 0.595 toroidal mirror finger absorber x Old beamline flat mirror 3.88 image plane z 0.175 y 0.175 4.48 0.44 S1 = m S2 = m flat mirror finger absorber M(=364 nm) = x TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Basic elements image object S1 S2 Rz Rx Toroidal mirror Reflects and focuses the beam Radii of the toroid chosen to correct astigmatism: for an incident angle = 22.5 Rx = m, Rz = m Fx= Fz = m Parameters toroidal mirror Material SiC (silicon carbide) or Zerodur with coating (Al) R [mm] 0.1 D [mm] ~ 20 Surface quality : Slope error ["] Max. peak-valley [nm] or better (/30, for = 632.8) RMS roughness [nm] < 4 TIARA mid-term meeting, CIEMAT, Madrid, June 2012 (Surface quality on mirrors)
RMS roughness [nm] Rp Rv Rp + Rv Max. peak-valley [nm] peak-valley peak-valley Slope error [ " ] TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Dipole BX-08 Finger absorber Flat mirror synchrotron radiation source protects mirror from excessive heat load by blocking x-rays and horizontally polarized visible/UV light reflects the beam Parameters electron beam Parameters finger absorber Parameters flat mirror E [Gev] E/E I[A] ex [nmmrad] ey [pmmrad] L [m] Bz [T] 2.4 0.2 5.5 Material Lx [mm] Lz [mm] Cu 60 4 Material fused silica with Al coating Max. peak-valley [nm]21 or better (/30) Vertical obstruction angle [mrad] 0.45 Obstruction power (400 mA) % of 230 W Parameters bending magnet 3 1.4 Twiss and Dispersion parameters at source point x [m] y [m] Dx [m] Dy [m] 0.452 14.3 0.029 TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Plan B Replace toroidal mirror by a flat one and add a lens to focus = back to refractive optics flat mirror 6.985 image plane 49 interference obstacle 0.144 z lens 0.160 0.190 S1 = m S2 = m y 45 4.551 0.595 flat mirror finger absorber x Parameters lens Material Fused Silica with Al coating Curvature Spherical R1, R2, D Refractive index: n(=266 nm) n( =364 nm) Surface errors: Max. peak-valley [nm]38 RMS roughness [nm] Adjust geometrical parameters of the lens to get magnification ratio ~ -S2/S1 e.g: For R1= R2 = 2.9 m, D=8 mm F(=266 nm) = m M(=266 nm) = F(=364 nm) = m M(=364 nm) = TIARA mid-term meeting, CIEMAT, Madrid, June 2012 Vertical polarization Horizontal polarization
SRW simulations SRW (Synchrotron Radiation Workshop) code developed at SOLEIL and ESRF by O. Chubar and P. Elleaume Signal at image plane (CCD camera) Vertical polarization Horizontal polarization TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Vertically polarized light as a function of the emittance and beam size TIARA mid-term meeting, CIEMAT, Madrid, June 2012 Different wavelengths
For = 266, 340 and 498 nm Used to create look-up tables in monitor TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Interferometeric method 15 mm 20 mm 25 mm TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Interferometer vs. pure polarization method TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Inclusion of mirror misalignments Dy R Tx Dx Ty Dx horizontal offset Dy vertical offset Tx horizontal tilt Ty vertical tilt R rotation around mirror axis TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Inclusion of mirror misalignments 1 - Vertical offset 2 - Horizontal offset TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
3 - Horizontal tilt TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Rotation around optical axis and vertical tilt Both misalignments show the same pattern: mixing of the horizontal and vertical planes TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Status Design almost finished In contact with providers: delivery of all components expected for last months of the year We need just a few more iterations to decide on the mirror alignment tolerances Scheduled installation: 01/13 Commissioning period: 01/1303/13 Measurement period: 04/1306/13 TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Some extra slides TIARA mid-term meeting, CIEMAT, Madrid, June 2012 Can we correct the misalignment from the image analysis?
Vertical offset minimum when brilliance of the horizontal projection is maximum Horizontal offset minimum when brilliance of the vertical projection is maximum Rotation around optical axis is immediately recognizable by the plane mixing: peak asymetry in vertical projection, apearance of double peak in the horizontal projection Gaussian laser for mirror setup TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
Inclusion of mirror misalignments 1 - Vertical offset TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
2 - Horizontal offset TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
3 -Vertical tilt TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
3 -Horizontal tilt TIARA mid-term meeting, CIEMAT, Madrid, June 2012 TIARA mid-term meeting, CIEMAT, Madrid, 12 - 14 June 2012
3 - Rotation around optical axis mixing the horizontal and vertical planes astigmatism will not be corrected any longer TIARA mid-term meeting, CIEMAT, Madrid, June 2012