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A proposal for the first facility to be installed at ELI Romanian pillar: A simple, compact and very bright 1-30 MeV gamma ray source based on Compton.

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Presentation on theme: "A proposal for the first facility to be installed at ELI Romanian pillar: A simple, compact and very bright 1-30 MeV gamma ray source based on Compton."— Presentation transcript:

1 A proposal for the first facility to be installed at ELI Romanian pillar: A simple, compact and very bright 1-30 MeV gamma ray source based on Compton scattering Guy Wormser LAL Director LAL-Orsay. IN2P3-CNRS

2 Everything said in one slide We have learned that ELI could be interested in a 1-30 MeV intense Compton source It so happens that LAL Orsay with a strong team of collaborators is presently designing the most ambitious X ray Compton source in the world (10**13 photons per second in the 100 keV range) –Very detailed Conceptual Design Report now available –Top level expertise in laser, cavity, accelerator –Technical Design Report ready by end 2010 –Experimental results on 1.3 GeV ring in Japan starting from summer 2010 Our X ray source design can be easily adapted to produce 1-30 MeV photons with similar performance –Ease the ring design and dynamics (250 MeV-1 GeV ring) If there is interest from your side, we are happy to explore collaboration possibilities to build such a machine for/with you.

3 Our general idea There will be a photonuclear program in ELI nuclear physics pole Ultimaltely the Compton source will be produced by the 10 PW laser, coupled with a electron source from an accelerator or another laser (or the same laser) One should not perform difficult measurements with a new source being commissioned at the same time Seems therefore very wise to start the experimental program with a good performance stable « classical » source of moderate cost Ideal first step : Ring based Compton source, totally decoupled from the PW laser program

4 Why this presentation Extract from ELI scientific committee [c] Photonuclear physics Methods to produce monoenergetic directed brilliant pulsed gamma- rays have been already discussed earlier in Subsecs.[a] and [b]. The principal approach is to utilize the intense laser backscattered on high energy electron bunch to produce such gamma-rays by the Compton backscattering process. This method is proven and has been already employed several laboratories around the world to produce some promising results in exploring nuclei by high energy photons. In this technique, for example, a large amount of MeV gamma-rays with the above characteristics may be generated. MeV is the energy range where typical nuclear reactions and nuclear excitations take place. We are currently designing a compact X ray source ThomX capable of delivering 10** keV photons per second! We know how to build a very intense MeV Compton source!

5 Brief LAL Orsay presentation LAL Orsay is the largest CNRS/IN2P3 laboratory devoted to particle physics and cosmology LAL is a Joint Research Unit between CNRS and Paris Sud 11 University 100 physicists, 220 Engineers and technicians Annual consolidated budget: 20 M€ –Mostly coming from IN2P3 but now with important funds coming from other sources as well: European Union, National Research Agency, Paris region, etc…. Strong implication in HEP experiments across the world with large technical contributions No more local accelerators but many accelerator R&D activities

6 LAL technical know-how Mechanics –60 technicians and engineers with a strong local workshop –Very large construction hall (Hall André Lagarrigue) Electronics –60 technicians and engineers, 50 cards per year –Microelectronics excellence pole 10 ASIC top level designers Computing –A Tier2 Node for LHC –Local software development (CMT, graphics, databases,..) Accelerator R&D (70 people including 20 acc. Specialists) Administration

7 LAL Accelerator projects XFEL (DESY) : delivery of all 800 power couplers for LINAC CTF3 (CERN) : Delivery of Drive beam and Probe beam photo-injectors PHIL (LAL) : Photo-injector test bench: 10 MeV Linac ILC-GDE : Power couplers, Beam Delivery system ATF2 (KEK) : Optics study at the IP SuperB (Frascati) : Positron source, vacuum, IP studies

8 Outline of this talk Presentation of Compton sources ThomX: a vey bright compact X ray source –General design –Laser system –Resonant cavity –Accelerator system –Cost and schedule Some results from ATF ring Adaptation to MeV source How to proceed Conclusion

9 ThomX CDR now available

10 The ThomX Team LAL CNRS, Université Paris-Sud 11, Batiment 200, Orsay, France: C.Bruni, R.Chiche, R.Cizeron, Y.Fedala, J.Haissinski, M.Jacquet, D.Jehanno, M.Lacroix, L.Meignien, B.Mercier, B.Mouton, Y.Peinaud, C.Prevost, R.Roux, V.Soskov, A.Variola, G.Wormser, F.Zomer, Synchrotron-SOLEIL,Saint-Aubin, France : P.Brunelle, M.E.Couprie, J.C.Denard, J.M.Filhol, N.Guillotin, P.Lebasque, A.Loulergue, P.Marchand, O.Marcouillé, F.Marteau, R.Nagaoka, Centre Lasers Intenses et Application, CNRS – Université de Bordeaux 1: P.Balcou, E. Cormier, M.C. Nadeau, C2RMF-UMR171 du CNRS/Ministère de la Culture : P.Walter, ILE, Ecole Polytechnique, CNRS, Palaiseau, France : N. Artemiev, L.M.A. CNRS, 7, Avenue Pierre de Coubertin VILLEURBANNE, France : R. Flaminio, C. Michel, L. Pinard, B. Sassolas, THALES : J.P. Brasile

11 The Compton effect : its use for X,  rays sources Compton backscattering is the most efficient « frequency amplifier »   diff =4  2  laser, ThomX =>  but very weak cross section: cm 2 Therefore for a powerful light source, one needs beaucoup d’électrons qui collisionnent avec beaucoup -lots of electrons -lots of photons -very small collision volume -very high repetition frequency electron Laser  laser Rayon X :  diff (scattered electron)  =E électron /m e c 2  diff

12 Main features of the Compton effect between 1 electron and 1 photon 1)Outgoing photon frequency = Laser frequency* 4  2 (tunability thru either laser or electron energy) 2) Directivity= >  around the electron direction 3) Energy/angle dependance => monochromaticity thru diaphragm 4) Polarisation if needed 5) Further tunability by relationship between electron and laser collision angle

13 But: Collision imply an electron bunch and a laser pulse. Everything gets somewhat smeared and coupled: a) energy, angles, polarisation, (convolution) b) effect of the collision angle (luminosity loss, energy shift, jitter) c) Focalisation => hourglass effect N.Artemiev

14 The ThomX project compact electron ring = e bunches withy a high rep rate laser system with similar high f rep and large AVERAGE power coupled to a high finesse Fabry-Prot resonator Source X energy50-90 keV* Flux10 11 – ph/s Frequency width10 %** Divergence < 2 mrad Cost (excluding Manpower) < 5 M€ Accélerator and laser Ring and injector energy50 MeV Charge 1 nC Emittance (rms normalised)< 5  mm mrad  * 10 cm =>IP ~ 70  m Average power inside cavity> 100 kW Bunch length, rms5-10 ps* Compton f rep MHz Collaboration between: LAL Orsay, SOLEIL, CELIA Bordeaux, ILE, LMA, Thales A compact X ray source

15 Compton source characteristics Photon flux : 10**13 /s Laser characteristics : 50 MHz, 1 micron, 100 W, 5 ps (fiber-doped) Time structure: 1 bunch every 20 ns (50 MHz)  Energy: 1-30 MeV Natural energy spread : 2-3% –Possibility of collimation down to 0,1% –Linear loss on the rate Beam spot at the IP : 50 microns Beam divergence at the IP : few mrads

16 Laser beam Linac +RF gun Electron beam pipe Electron Storage ring Collision point Electron beam dump Four mirrors Fabry Perot cavity X rays ThomX general scheme

17 Comparison with other light sources Flux is of course smaller than in large (and expensive) synchrotron sources,but in this energy range, very important applications for a compact source M.E.Couprie, O.Marcouille

18 ≈ n*10 MHz, n*10 2 W (amplification inside cavity 10000) => 100kW -MW!!!!!!! Fabry-Perot cavity  2 Super mirrors  4 for mech stability Electron bunch The Fabry Perot resonator Resonant pile-up Fréquence du laser frequency= c/2 L (L = cavity length) Laser pulse a few ps E beam n*10  F.Zomer

19 30000 finesse Dec 08 : World record! Previous world record: by LAL:3000 Test bench cavity results at LAL

20 Oscillator LD VBGVBG Output to FP ANR MightyLaser goal 200 W To get amplified in the Fabry perot cavity Very high quality beam, monomde, small phase jitter P.Balcou, E.Cormier

21 Two Prototype Cavities 4-mirror cavities w/LAL 2-mirror cavity high enhancement small spot size sophisticated control moderate enhancement moderate spot size simple control (Hiroshima / Weseda / Kyoto / IHEP / KEK) demonstration of  ray gen. accum. exp. w/ cavity and acc. intense  ray generation

22 The most delicate : putting everything together Stabilisation of the cavity frequency (40 MHz with a few mHz precision) Integration in an accelerator environment Digital feedback system F.Zomer, P.Balcou

23 Integration in the electron ring optimised to limit the impact of the photon beam divergence M.Lacroix

24 Energy (MeV)70.4 Normalized emittance (  mm.mrad) 4.5 Transverse size (mm)0.9 Bunch length (ps)4.5 Energy spread (%)0.57 Energy (MeV)50.4 Normalized emittance (  mm.mrad) 4.2 Transverse size (mm)1.2 Bunch length (ps)4.5 Energy spread (%) MeV => ~40 keV Photoinjector new design 70 MeV => ~80 keV R.Roux The Accelerator system : The linac

25 Injection and transport line No time for damping ! R.Roux

26 Circumference (m)14.47 Nominal energy (MeV)50 Betatron tunes x, z 3.4 / 1.4 Beta max x,z (m)11 / 11 Dispersion max (m)0.9 Beta, IP (m)0.1 / 0.1 / 0 Momentum Compaction Factor RF frequency (MHz)500 RF harmonic24 RF voltage (kV)300 Period (ns) / Revolution frequency (MHz)48.5 / 20.6 Natural chromaticities-3.2 / -8.2 Dipole number, family & field (T)8 / 1 / 0.5 Quadrupole number, families & field (T/m) 24 / 6 / <3 Sextupole number, families & field (T/m 2 ) 12 / 2 / <30 A.Loulergue, C.Bruni Characteristics of the electron ring 3 m diameter!!

27 Dynamics and Instability studies C.Bruni, A.Loulergue Désadaptation résiduelle => Effets collectifs Zone « stabilisée » Wake fields …………….interaction Compton

28 Magnetic systems Novel idea of the cavity integration into the ring Solves many problems! A.Loulergue, P.Lebasque

29 RF systems  t = 20 ms Fig. 3 : shape of the 500 MHz ELETTRA-type cavity with a cut-off pipe diameter of 60 mm. C RF cavity ( kV at 500 MHz) to reduce the compression factor and limit the bunch lenghtening induced by the Compton scattering Critcial to lwoer HOM impact to stabilise the electron beam P.Marchand

30 Detailed layout of the THomX machine 7m 10m Canon RF a forte brilliance LINAC 3 GHz – 50 / 70 MeV Anneau de stockage Zone d interaction Compton Cavité et laser Utilisateurs Y.Peinaud, M.Lacroix

31 Cost and Manpower Photoinjector422 LINAC1176 Transport line219 Ring1919 Fabry Perot339 Laser246 control systems and synchro490 Infrastructure and cabling200 Extraction and caracterisation of X rays200 Spares222 Total (k€ - HT) [1] [1] 5433 Machine Cost (Preliminary) FTE FTE (BE) Photoinjector LINAC Ring and transport line Fabry Perot0.1 Laser Control systems 1.0 Infrastructure, support & câblage Total102.6 ~70% of this manpower has been identified TDR phase personnel needs

32 ThomX Planning Detailed study Machine construction Experimental Hall Assembly, test, commissioning, X ray characterisation Jan2010Jan 2013 Oct 2013 Oct 2010

33 Experimental R/D in ATF. Make a fist prototype 2-mirror cavity Put it in ATF ring Hiroshima-Waseda-Kyoto-IHEP-KEK L cav = 420 mm

34 Laser Power enhancement 250

35 Flat mirror Spherical mirror 8°8° Central support Spherical mirror R. Cizeron LAL 30/01/2008 Staus of the LAL cavity French colleagues visited KEK in July. discussed detail of the installation procedure setting up at the ATF beam line The cavity will be installed on ATF ring in summer 2010 (2 GeV e-) and will produce 100 MeV photons

36 If we want 1 MeV photons the best way is to increase the beam energy (we should also reduce the laser wavelength but remember that for a ring =>higher the energy easier the operation due to Touschek, gas scattering, instabilities….) So with an easy scaling for 1 MeV photons we need 250 MeV electrons. This will imply also a lower B field in the Q poles for the focalisation sections. The emission cone will be reduced from 10 mrad to 2 mrad (sigma) with a consequent increasing of the brillance. But remember that the 1 MeV photons will be located close the axis. Diaphragm effects on the energy spectrum are expected close to the 50 MeV case The expected flux is bigger (>  /s)or equivalent to the ThomX one Dynamics will be different !!!!! Maybe we can use the Syncrotron damping with an important gain in stabilization. If this is the case we can reduce the frequency of injection to reduce the Linac cost that will be increase by the bigger required injection energy Extension to 1 MeV source

37 MC simulations – e beam at 250 MeV, laser ~1.37eV Emitted photons emittance Emitted spectrum Photon tracking without and With diaphragm Photons angle energy correlation Energy cut ~ 1.25 MeV

38 Potential use Fundamental studies –Photonuclear scienecs on stable nuclei Photonuclear sciences on instable nuclei –Waste material –Coupling with accelerators to excite nuclei ??? Applied science

39 Potential collaborations C.J. Barty et al. (GRLS)

40 Energy range 1 MeV gamma : 250 MeV electron ring 16 MeV gamma : 1 GeV electron ring –Similar to many damping rings (PEP-II) –30 m circonference 32 MeV gamma : 1 GeV electron ring and 500 nm laser

41 How to proceed ! Is there an interest for ~1 MeV Compton source? Critical : Main specifications –Energy (Nominal-Range-Tunability) – Energy width (in %) –Photon intensity –Temporal characteristics (pulse width-Frequency) –Spatial characteritics (beam spot) What we can offer –If confirmed interest from ELI, make a complete study for such a machine in (cost ~0,5 M€) –Full experimental tests in summer 2010 at KEK of the laser/cavity system –Build a 1 MeV Compton source –Commissionning (in Orsay or in Romania?) –Transport to Romania –Could be ready in 2015 –Cost not known yet Cooperation agreement would need to be worked out

42 Conclusion We have learned that ELI could be interested in a 1 MeV intense Compton source It so happens that LAL Orsay with a strong team of collaborators is presently designing the most ambitious X ray Compton source in the world –Lot of expertise in laser (CELIA), cavity-accelerator (LAL), ring (Soleil) –End of technical design report fall 2010 –Experimental results on 1,3 GeV ring in Japan starting from summer 2010 Our X ray source can be easily adapted to produce 1 MeV photons –Ease the ring design and dynamics (250 MeV ring) –Cost not known yet –4 year construction time If there is interest from your side, we are happy to explore collaboration possibilities to build such a machine for you.


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