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Study the effects of a Robinson wiggler at SOLEIL towards brightness increase H. Abualrob, P. Brunelle, M. Labat, L. Cassinari, M.A. Tordeux, L. Nadolski, R. Nagaoka, A. Nadji, M.E. Couprie, O. Marcouillé

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Outline Synchrotron radiation & its properties Robinson wiggler & emittance reduction Experimental observation of Robinson SOLEIL Predicted influence of a Robinson wiggler on the spectral performances Preliminary magnetic design of Robinson wiggler H. Abualrob Journées Accélérateur, Roscoff, october 20132

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Light source A bright photon beam is: Intense Emitted from a small size and low divergence source Monochromatic H. Abualrob Journées Accélérateur, Roscoff, october 20133

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Synchrotron SOLEIL H. Abualrob Journées Accélérateur, Roscoff, october Energy2.75 GeV Circumference354 m Emittance H3.9 nm.rad Emittance V39 pm.rad Current500 mA Beam lifetime (bare machine) 15 h beamlines26 Spectral rangeIR to hard X-ray

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Beam Brightness and emittance H. Abualrob Journées Accélérateur, Roscoff, october Effective electron beam emittance Effective photon beam emittance Beam size Beam divergence high brightness low emittance e-e-

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Energy spread & bunch length H. Abualrob Journées Accélérateur, Roscoff, october Number of electrons Energy of electrons Bunch length in seconds Energy spread Synchrotron frequency Momentum compaction factor L L+ΔL Energy spread

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Emittance reduction: motivation Spectroscopy high spectral resolution high flux through narrow slit Crystallography high angular resolution wavelength matching to crystal dimensions High flux within small beam size and divergence H. Abualrob Journées Accélérateur, Roscoff, october High brightness low emittance (H & V)

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Emittance reduction methods Increasing the number of dipoles: MAX IV S. Leemans, Phys. Rev. Spec. Topics AB 12, , Introducing a transverse gradient in the dipoles: ALBA D. Einfeld, Status of ALBA project, IPAC10, Japan. Installing tens of meters of damping wigglers: PETRA III M. Tischer, Damping wigglers for PETRA III light source, proceeding PAC05, Knox ville, Tennessee. Installing a Robinson wiggler H. Abualrob Journées Accélérateur, Roscoff, october 20138

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Robinson wiggler Compact, less expensive, can be adopted by compact & large machines H. Abualrob Journées Accélérateur, Roscoff, october ParameterEquationpresentWith Robinson wiggler Damping partition Horizontal emittance Energy spread s x B dB/dx<0 Robinson wiggler: magnetic system of alternated field gradient superimposed to the main field, to be installed in a non-zero dispersion straight section (1) (1 ) K. W. Robinson, Radiation effects in circular electron accelerators, physical review, vol. 111, number 2, 1958.

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Previous projects First Cambridge Electron Accelerator (CEA) A. Hofmann, Design and performance of the damping system for beam storage in the CEA, ICHEA, Cambridge, Installtion in the CERN showing 50% horizontal emittance reduction Y. Baconnier et al, Emittance control of the PS e+/e beams using a Robinson wiggler, Nucl. Instr. and Meth. in Physics Research A234 (1985) H. Abualrob Journées Accélérateur, Roscoff, october

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Experimental study of Robinson effects on: -The horizontal emittance -The energy SOLEIL Experimental study of Robinson effects on: -The horizontal emittance -The energy SOLEIL H. Abualrob Journées Accélérateur, Roscoff, october

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Robinson SOLEIL Robinson SOLEIL Presently, there is no Robinson SOLEIL ! IDEA… Use the 4 undulators U20 to obtain a strong periodic magnetic field Simultaneous off-axis propagation in the 4 undulators to create a periodic field gradient Measure the transverse beam size using a pinhole camera Measure the bunch length using a streak camera H. Abualrob Journées Accélérateur, Roscoff, october e-

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The in vacuum undulator U20 H. Abualrob Journées Accélérateur, Roscoff, october Gap5.5 mm B max 0.97 T K1.8 Period length20 mm No. of periods 98

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Beam size measurement to deduce the emittance variation Beam size measurement to deduce the emittance variation H. Abualrob Journées Accélérateur, Roscoff, october Beam size measurement using a pinhole camera

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Bunch length measurement to deduce the energy spread variation H. Abualrob Journées Accélérateur, Roscoff, october Bunch length measurement using a streak camera

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Emittance reduction, energy spread increase & spectral performances with a Robinson wiggler Assuming that a Robinson wiggler is SOLEIL Assuming horizontal emittance reduction by a factor of 2 (from 3.9 nm rad to 1.95 nm rad) Assuming energy spread increase by (from to ) H. Abualrob Journées Accélérateur, Roscoff, october

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Photon flux calculation/low energy range H. Abualrob Journées Accélérateur, Roscoff, october UndulatorHU640 TypeHelical/EM Period (mm)640 Bz (T)0.15 K8.9 Flux calculation with SRW (1) through an aperture of 0.1 * 0.1 mm 2 10 m from the source (1) O. Chubar, Accurate and efficient computation of synchrotron radiation in the near field region, EPAC 98, Stockholm.

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Photon flux calculation/high energy range H. Abualrob Journées Accélérateur, Roscoff, october undulatorU20 Typeplanar/PM Period (mm)20 Bz (T)1.08 K2 Flux calculation with SRW through an aperture of 0.1 * 0.1 mm 2 10 m from the source

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19 Brightness calculation Brightness decrease for low energy range (HU640) 90% Brightness increase for high energy range (U20) Remember that H. Abualrob Journées Accélérateur, Roscoff, october 2013

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Robinson wiggler...preliminary magnetic design H. Abualrob Journées Accélérateur, Roscoff, october Gap6 mm B max -2.5 T 193 T 2 Period length164 mm Wiggler length2 m Design performed using RADIA code. O. Chubar, Computing 3D magnetic fields from insertion devices, PAC 1997, Vancouver, Canada. e-

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Conclusion Robinson effects on reducing the emittance and increasing the energy spread were observed and validated experimentally, for the first time, in a synchrotron light source at SOLEIL. Considering a Robinson wiggler at SOLEIL reduces the emittance, leading to brightness increase “in the high energy range”. However, Robinson wiggler increases the energy spread leading to flux reduction. H. Abualrob Journées Accélérateur, Roscoff, october

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Thank you for your attention H. Abualrob Journées Accélérateur, Roscoff, october

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