R. Nagaoka, A. Nadji, M.E. Couprie, O. Marcouillé 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

H. Abualrob Journées Accélérateur, Roscoff, october 2013 Outline Synchrotron radiation & its properties Robinson wiggler & emittance reduction Experimental observation of Robinson effect @ SOLEIL Predicted influence of a Robinson wiggler on the spectral performances Preliminary magnetic design of Robinson wiggler H. Abualrob Journées Accélérateur, Roscoff, october 2013

Light source A bright photon beam is: Intense Emitted from a small size and low divergence source Monochromatic H. Abualrob Journées Accélérateur, Roscoff, october 2013

H. Abualrob Journées Accélérateur, Roscoff, october 2013 Synchrotron SOLEIL Energy 2.75 GeV Circumference 354 m Emittance H 3.9 nm.rad Emittance V 39 pm.rad Current mA Beam lifetime (bare machine) 15 h beamlines 26 Spectral range IR to hard X-ray H. Abualrob Journées Accélérateur, Roscoff, october 2013

Beam Brightness and emittance 𝝈𝒑𝒉 𝝈 ′ 𝒑𝒉 e- Effective emittance is the beam size 𝝈𝒑𝒉 times the angular divergence 𝝈 ′ 𝒑𝒉 Effective photon beam emittance Effective electron beam emittance Beam size Beam divergence high brightness low emittance  H. Abualrob Journées Accélérateur, Roscoff, october 2013

Energy spread & bunch length Number of electrons Energy of electrons Energy spread L L+ΔL Momentum compaction factor Bunch length in seconds Energy spread Synchrotron frequency H. Abualrob Journées Accélérateur, Roscoff, october 2013

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 High brightness  low emittance (H & V) H. Abualrob Journées Accélérateur, Roscoff, october 2013

Emittance reduction methods Increasing the number of dipoles: MAX IV S. Leemans, Phys. Rev. Spec. Topics AB 12, 120701, 2009. 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 2013

H. Abualrob Journées Accélérateur, Roscoff, october 2013 Robinson wiggler Robinson wiggler: magnetic system of alternated field gradient superimposed to the main field, to be installed in a non-zero dispersion straight section (1) Compact, less expensive, can be adopted by compact & large machines s x B dB/dx<0 Parameter Equation present With Robinson wiggler Damping partition Horizontal emittance Energy spread (1) K. W. Robinson, Radiation effects in circular electron accelerators, physical review, vol. 111, number 2, 1958. H. Abualrob Journées Accélérateur, Roscoff, october 2013

H. Abualrob Journées Accélérateur, Roscoff, october 2013 Previous projects First observation @ Cambridge Electron Accelerator (CEA) A. Hofmann, Design and performance of the damping system for beam storage in the CEA, ICHEA, Cambridge, 1967. Installtion in the PS @ 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) 224-252. H. Abualrob Journées Accélérateur, Roscoff, october 2013

H. Abualrob Journées Accélérateur, Roscoff, october 2010 Experimental study of Robinson effects on: -The horizontal emittance -The energy spread @ SOLEIL H. Abualrob Journées Accélérateur, Roscoff, october 2010

Robinson effect @ SOLEIL Presently, there is no Robinson wiggler @ 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 e- H. Abualrob Journées Accélérateur, Roscoff, october 2013

The in vacuum undulator U20 Gap 5.5 mm Bmax 0.97 T K 1.8 Period length 20 mm No. of periods 98 H. Abualrob Journées Accélérateur, Roscoff, october 2013

Beam size measurement to deduce the emittance variation Beam size measurement using a pinhole camera H. Abualrob Journées Accélérateur, Roscoff, october 2013

Bunch length measurement to deduce the energy spread variation Bunch length measurement using a streak camera H. Abualrob Journées Accélérateur, Roscoff, october 2013

H. Abualrob Journées Accélérateur, Roscoff, october 2013 Emittance reduction, energy spread increase & spectral performances with a Robinson wiggler Assuming that a Robinson wiggler is installed @ 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 1.01 10-3 to 1.428 10-3) H. Abualrob Journées Accélérateur, Roscoff, october 2013

Photon flux calculation/low energy range Undulator HU640 Type Helical/EM Period (mm) 640 Bz (T) 0.15 K 8.9 Flux calculation with SRW (1) through an aperture of 0.1 * 0.1 mm2 located @ 10 m from the source (1) O. Chubar, Accurate and efficient computation of synchrotron radiation in the near field region, EPAC 98, Stockholm. H. Abualrob Journées Accélérateur, Roscoff, october 2013

Photon flux calculation/high energy range undulator U20 Type planar/PM Period (mm) 20 Bz (T) 1.08 K 2 Flux calculation with SRW through an aperture of 0.1 * 0.1 mm2 located @ 10 m from the source H. Abualrob Journées Accélérateur, Roscoff, october 2013

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

Robinson wiggler...preliminary magnetic design Gap 6 mm Bmax -2.5 T 193 T2 Period length 164 mm Wiggler length 2 m e- Design performed using RADIA code. O. Chubar, Computing 3D magnetic fields from insertion devices, PAC 1997, Vancouver, Canada. H. Abualrob Journées Accélérateur, Roscoff, october 2013

H. Abualrob Journées Accélérateur, Roscoff, october 2013 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 2013

Thank you for your attention H. Abualrob Journées Accélérateur, Roscoff, october 2013