UV/X-ray Diffraction radiation for non-intercepting beam size measurement

T. Aumeyr1, L. Bobb1, 2, M. Billing3, E. Bravin2, P. Karataev1, T. Lefevre2, S. Mazzoni2, H. Schmickler2

John Adams Institute at Royal Holloway, Egham, Surrey, United KingdomCERN European Organisation for Nuclear Research, CERN, Geneva, SwitzerlandCornell University, Ithaca, New York, USAODR Beam Size Monitor

T. Aumeyr, 30th January 2013, CLIC Workshop1MotivationBasic concept of DR beam size measurementDR angular distributionOptical setupSimulationsGoals of phase 1 testInstallation in CESROperation of set-upResultsOutlook and future workConclusionContentsT. Aumeyr, 30th January 2013, CLIC Workshop2E. Chiadroni, M. Castellano, A. Cianchi, K. Honkavaara, G. Kube, V. Merlo and F. Stella, Non-intercepting Electron Beam Transverse Diagnostics with Optical Diffraction Radiation at the DESY FLASH Facility, Proc. of PAC07, Albuquerque, New Mexico, USA, FRPMN027.

A.H. Lumpkin, W. J. Berg, N. S. Sereno, D. W. Rule and C. Y. Yao, Near-field imaging of optical diffraction radiation generated by a 7-GeV electron beam, Phys. Rev. ST Accel. Beams 10, 022802 (2007).

Most recent experiments using Optical Diffraction Radiation (ODR) for beam diagnostics

P. Karataev, S. Araki, R. Hamatsu, H. Hayano, T. Muto, G. Naumenko, A. Potylitsyn, N. Terunuma, J. Urakawa, Beam-size measurement with Optical Diffraction Radiation at KEK Accelerator Test Facility, Phys. Rev. Lett. 93, 244802 (2004).y = 14 m measured ATF2@KEK T. Aumeyr, 30th January 2013, CLIC Workshop3

Motivationhttp://www.clic-study.org/Section of machineBeam Energy [GeV]Beam size [m]RequirementPDR (H/V)2.8650/10Micron-scale resolution DR (H/V)10/1RTML (H/V)2.86 - 910/1Drive Beam Accelerator2.3750 -100Non-invasive measurementTransverse beam size requirements for the Compact Linear Collider (Table 5.62 CDR Volume 1, 2012):Baseline high resolution non-interceptive beam profile monitor:Laser Wire Scanners

S. T. Boogert et al., Micron-scale laser-wire scanner for the KEK Accelerator Test Facility extraction line, Phys. Rev. S. T. Accel. and Beams 13, 122801 (2010)T. Aumeyr, 30th January 2013, CLIC Workshop44E (GeV)H (m)V (m)CesrTA2.13209.25.3250065Project aim:To design and test an instrument to measure on the micron-scale the transverse (vertical) beam size for the Compact Linear Collider (CLIC) using incoherent Diffraction Radiation (DR) at UV/soft X-ray wavelengths.Our experimentD. Rubin et al., CesrTA Layout and Optics, Proc. of PAC2009, Vancouver, Canada, WE6PFP103, p. 2751.Cornell Electron Storage Ring Test Accelerator (CesrTA) beam parameters:

http://www.cs.cornell.eduT. Aumeyr, 30th January 2013, CLIC Workshop5Principle: Electron bunch moves through a high precision co-planar slit in a conducting screen (Si + Al coating).Electric field of the electron bunch polarizes atoms of the screen surface.DR is emitted in two directions: along the particle trajectory Forward Diffraction Radiation (FDR) In the direction of specular reflection Backward Diffraction Radiation (BDR)Diffraction Radiation0ye-

DR Angular distributionImpact parameter:

Generally:DR intensity as slit size hT. Aumeyr, 30th January 2013, CLIC Workshop

6Vertical Beam Size Measurement using the Optical Diffraction Radiation (ODR) model + Projected Vertical Polarisation Component (PVPC)

P. Karataev et al.Vertical polarisation component of 3-dimensional (x, y, Intensity) DR angular distribution.PVPC is obtained by integrating over x to collect more photons.Visibility (Imin/Imax) of the PVPC is sensitive to vertical beam size y.T. Aumeyr, 30th January 2013, CLIC Workshop7

Beam size sensitivity at CesrTA

To compare with TR intensities:

Measureable visibility for initial test at parameters: = 200 - 400 nma = 0.5, 1 mmy = 50 m T. Aumeyr, 30th January 2013, CLIC Workshop8

Optical System

Far-field Condition:

2.1 GeV5 GeV200 nm0.54 m3.18 m400 nm1.08m6.37 mCompact optical system (distance to

Detector )Long-range optical system (distance to

detector ) Bi-convex lens required with camera in back focal plane.Far-field zoneDual purpose:Image targetImage DR angular distributionDR observation wavelengths: = 200 nm, 400 nmIn footprint of target mechanism ( < 1m)Determined by L and spatial constraints. given and : L = distance from source of DR to detector.

Compact optical system is in the prewave zone

(Pre-wave zone effect in transition and diffraction radiation: Problems and Solutions -P. V. Karataev).T. Aumeyr, 30th January 2013, CLIC Workshop9

Imaging the slit

ViewportFold mirrorAchromatic lensThorlabs AC254-150-A150 mm, 25.4mmT. Aumeyr, 30th January 2013, CLIC Workshop10

Beam passes through slit

Simulating DR from a single electron paraxial thin lens0.5 mm slitSourceDetectorT. Aumeyr, 30th January 2013, CLIC Workshop11Biconvex lens removes all spatial information and transforms distribution into a purely angular one.11ODR angular distribution is very sensitive to distances away from the focal plane. The detector must therefore be exactly in the back focal plane.

Simulating DR from a single electron real lensBiconvex lensCVI Melles GriotBICX-50.0-308.5-UV308.5 mm, 50mm0.5 mm slitSourceDetectorT. Aumeyr, 30th January 2013, CLIC Workshop12Simulations where to go from hereComparing analytical equations for angular distributions with ZEMAX simulations (single particle, finite beam size)Using real setup, understanding diffraction limitsQuantifying measurement sensitivity limitations with respect to deviations from the perfect real setupDevelop system for = 200 nm to measure smaller beam sizesT. Aumeyr, 30th January 2013, CLIC Workshop13