Vertical Emittance Measurements using a Vertical Undulator K.P. Wootton, G.N. Taylor, R.P. Rassool Uni. Melbourne M.J. Boland, B.C.C. Cowie, R. Dowd, Y.-R.E. Tan Australian Synchrotron Y. Papaphilippou CERN

2Wootton – CLIC DR Meeting – 13/09/2012 Overview Measurement of vertical emittance Undulator spectra Photon beam brilliance Vertical undulators Measurements of undulator spectra Future directions

3Wootton – CLIC DR Meeting – 13/09/2012 Vertical emittance Collider damping rings and Super B-factory storage rings demand pm rad Collective effects lead to growth –IBS, electron cloud Storage ring light sources as test accelerators –SLS, ATF2, CESR, ASLS, Diamond, … (ALS?) Need measurements of vertical emittance

4Wootton – CLIC DR Meeting – 13/09/2012 Indirect measurement Orbit response matrix fitting Touschek lifetime –Eigen as opposed to projected emittances Beam ellipse tilt (bending magnet) Dowd PRSTAB 14, (2011)

5Wootton – CLIC DR Meeting – 13/09/2012 Direct measurement Laser wire scanner Scanning laser waist through electron beam –Inverse Compton gamma rays Shintake monitor –Interference pattern narrower than laser waist Shintake NIMA 311, (1992) Boogert PRSTAB 13, (2010)

6Wootton – CLIC DR Meeting – 13/09/2012 Direct measurement Vertical emittance monitors Andersson, NIMA 591, Scheidt, DIPAC05 CTWM01 Masaki DIPAC01, PS17 Flanagan PAC09, TH5RFP048 Nakamura PAC01, TPAH307

7Wootton – CLIC DR Meeting – 13/09/2012 Undulator diagnostics Focus on odd (useful!) harmonics Horizontal undulators –Imaging –Projection –Absolute spectral brilliance (pinhole flux) Energy spread, dispersion, ‘large’ emittance Moreno JSR, (2012) Hahn JSR 4, 1-5 (1997)

8Wootton – CLIC DR Meeting – 13/09/2012 Undulator beam projection Undulator 25 periods 75 mm period K = 3.85 Pinhole 50 x 50 um 15m distance

9Wootton – CLIC DR Meeting – 13/09/2012 Horizontal undulatorVertical undulator Undulator projection measurements Undulator 25 periods 75 mm period K = 3.85

10Wootton – CLIC DR Meeting – 13/09/2012 Photon beam brilliance Horizontal undulator –No contrast Vertical undulator –Even harmonics

11Wootton – CLIC DR Meeting – 13/09/2012 Photon beam brilliance

12Wootton – CLIC DR Meeting – 13/09/2012 Fitting spectra Convolve beam emittance with undulation ‘It is evident that the second-harmonic brightness is proportional to the beam emittance …’ Dattoli PRE 52(6) (1995) I add to this: … the emittance in the direction of undulations –How do we measure photon beam brilliance? Dattoli PRE 52(6) (1995)

13Wootton – CLIC DR Meeting – 13/09/2012 Advanced Planar Polarised Light Emitter-II Modes of operation

14Wootton – CLIC DR Meeting – 13/09/2012 SXR undulator beamline

15Wootton – CLIC DR Meeting – 13/09/2012 SXR undulator beamline APPLE-II undulator White beam slits first optical element All focussing, monochromator downstream SlitsMonochromatorPhotodiode

16Wootton – CLIC DR Meeting – 13/09/2012 Detector Measuring vertical emittance with one large pixel! Beamline optics –Grating monochromator –Au-coated mirrors –Energy-defining slit –Photodiode (GaAsP, Si) Au-coated mirrors –Transmission varies with photon energy

17Wootton – CLIC DR Meeting – 13/09/2012 Photodiode choice Early experiments –Hamamatsu GaAsP Ratio of peaks Absorption edges –Silicon photodiode Keithley picoammeter –Spans many orders of magnitude in current Krumrey, Tegeler (1992) Rev Sci Instrum 63 (1), p

18Wootton – CLIC DR Meeting – 13/09/2012 Horizontal undulatorVertical undulator Undulator projection measurements K = 3.85 E = 3 GeV 75 mm period

19Wootton – CLIC DR Meeting – 13/09/2012 Measured undulator spectrum Measured Modelled

20Wootton – CLIC DR Meeting – 13/09/2012 Emittance envelopes

21Wootton – CLIC DR Meeting – 13/09/2012 Where to? Fixed pinhole diameter SOLEIL DiagOn (fixed energy eV) SPring-8 BL45XU (vertical IVU) Higher undulator k Lower beam energy (IBS studies) –Same minimum gap, higher undulator k Moreno JSR, (2012)

22Wootton – CLIC DR Meeting – 13/09/2012 Summary