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Concluding Remarks

Concluding Remarks. Workshop Goals. 1) Take stock of the situation of the different machines, schemes, studies and R&D’s. 2) Gather information on the new technologies (fiber laser, mirrors…). Define the possible associated R&D’s.

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Concluding Remarks

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  1. Concluding Remarks

  2. Workshop Goals 1) Take stock of the situation of the different machines, schemes, studies and R&D’s. 2) Gather information on the new technologies (fiber laser, mirrors…). Define the possible associated R&D’s. 3) Find the overlap with the undulator solution, both for funding (EU FP7…) and common work. 4) Benchmark of the GEANT4 polarized version. 5) Review the industrial – medical applications of Compton machine (extremely important for R&D fund request). CLIC - Redefine the parameters. Analyze the differences from the earlier proposal and have a first “feasibility” scheme. ILC • Converge towards a scheme that can produce a valid “alternative” design and clearly assess what R&D’s are necessary to validate the scheme. • Point the way to EDR • Study the possibility of a demonstrator experiment • Define the aspects of the schemes that still need answering (stacking, costing…) and make a work plan SuperB - Introduce the new machine and address the case of polarized positrons. Introduce the FP7 design study

  3. 1st: Physics (users) • Physics = f( L,P,E) => Flexible machine= flexible (POLARISED) positron source. • Is there a ~ factor 3 rule? • f = ? In te different cases….

  4. space for spin rotators must be foreseen K. Moffeit et al., SLAC-TN-05-045 Layout of positron damping ring system showing the parallel spin rotation beam lines for randomly selecting positron polarization direction. A pair of kicker magnets is turned on between pulse-trains to deflect the beam to the spin rotation solenoids with negative B-field.

  5. Take stock of the proposed solutions & technology • Projects : ILC, CLIC ….SuperB 1 CLIC => New parameters : three schemes proposed

  6. Major CLIC parameters changes In January 2007, new CLIC key parameters have been adopted: Accelerating gradient: 150 MV/m => 100 MV/m RF frequency: 30 GHz => 12 GHz => All CLIC study is today under revision, in particular the CLIC Injector complex and the e+ production (polarized and unpolarized).

  7. Main beam parameters comparison At the entrance of the Main Linac for e- and e+

  8. The CLIC Injector complex (Compton)  30 m  30 m e- Main Linac e+ Main Linac e- BC2 e+ BC2 12 GHz 2.3 GV 12 GHz 2.3 GV 12 GHz, 100 MV/m, 21 km 12 GHz, 100 MV/m, 21 km 9 GeV 48 km 3 TeV Laser Compton configuration Booster Linac 6.6 GeV 3 GHz  360 m e+ BC1 e- BC1  10 m  10 m 3 GHz 162 MV 3 GHz 162 MV 2.424 GeV 360 m 2.424 GeV 360 m e+ DR e- DR e+ PDR and Accumulator ring e- PDR 2.424 GeV 2.424 GeV Injector Linac 2.2 GeV 1.5 GHz RF gun  150 m e- Drive Linac 1.3 GeV Compton ring e+ Target Laser 3 GHz Pre-injector Linac for e+ 200 MeV Pre-injector Linac for e- 200 MeV g DC gun Polarized e- Stacking cavity Laser 1.5 GHz 1.5 GHz  15 m  15 m

  9. 2 ILC baseline and alternative

  10. Undulator The asymmetries preliminary preliminary

  11. Compton Ring

  12. POSIPOL07. Compton Ring Lattice.

  13. MARS (Multiturn Accelerator-Recuperator Source) ~1Å 8 GeV ~12Å 2.6 GeV E = 1.8 GeV G. N. Kulipanov, A. N. Skrinsky and N. A. Vinokurov, 1997 Injector Beam dump ERL

  14. Selection of bunch repetition: frep 3 factors to determine frep ERL bunch charge 163 MHz preferable Laser & optical cavity e+ stacking 40.8 MHz preferable 40.8 MHz preferable

  15. Quantitative agreement of the BNL experiment results e-beam - size 60 m (RMS), charge 0.2 nC, duration 3.5 ps (FWHM); laser - energy 2 J, size 35 m (RMS), duration 5 ps (FWHM). LINAC Agrees with experiment • Conclusions: • 15% of the x-ray energy goes into harmonics • The x-ray signal filtered by the 10-mm Ag foil consists primarily of harmonics • 0.2 nC bunch contains 1.25109 electrons, i.e. 4 times the number of photons generated at IP. However, due to the approximately two times bigger cross-section of the e-beam compared with the laser focus, only ~¼ of the total electrons in the bunch participated in scattering. • Thus, we conclude that x-ray yield is close to Ng/Ne~1, as is required for ILC.

  16. Polarized Electrons: Yes And what about positrons? • Is a polarized positron source interesting for the SuperB factory? • Yes! SUPERB

  17. 2) Gather information on the new technologies (fiber laser, mirrors…). Define the possible associated R&D’s. • Technical aspects • LASERS!!!!!! • CAVITIES (electronics, mechanics…) • Polarimetry • Mirrors • Too much to say only few snapshots

  18. ANR LAL / Amplitude Systemes • PM-LMA fiber ampli. • High pump absorption • Polarized output beam • PCF-Fiber amplifier • High launch power • >800W pump power • Reduced non-linearities Grating stretcher Femtosecond oscillator Compressor Fiber amplifiers Laser Diode PM - LMA fiber PCF fiber OI High power Laser Diode • > 300W average power • Linearly polarized beam

  19. plane mirror plane mirror Y X Y P2 V1 P1 X f V2 Z S1 S2 spherical mirror spherical mirror f0  3D cavity 3D cavity

  20. Substrate Sample Holder (Simple rotation) Assist + - + - + O2 Source - + + + - - - Quartz Ar Neutralizor Sputtered Particles O2 Targets + - + Sputtering + - + + + + Ar Source - - - - SiO2/Ta - - Ar Neutralizor Low Loss Coatings : Ion Beam Sputtering

  21. 4) Benchmark of the GEANT4 polarized version. Knowledge & simulations • POLARISED GEANT/EGS/NEW SOFT • CAPTURE • TARGETS

  22. Baseline Target Design • Wheel rim speed (100m/s) fixed by thermal load (~8% of photon beam power) • Rotation reduces pulse energy density from ~900J/g to ~24J/g • Cooled by internal water-cooling channel • Wheel diameter (~1m) fixed by radiation damage and capture optics • Materials fixed by thermal and mechanical properties and pair-production cross-section (Ti6%Al4%V) • Wheel geometry (~30mm radial width) constrained by eddy currents. • 20cm between target and rf cavity. T. Piggott, LLNL Drive motor and water union are mounted on opposite ends of through-shaft.

  23. Depolarization of positrons in bremsstrahlung

  24. Initial Pol. Vs Energy of Captured Positron Beam

  25. Beam parameters III Parameters of the positron beam at the exit of the solenoid (z = 3085 cm) and of the Capture Section (z = 3436 cm) Z= 3085 Z= 3436 Total capture efficiency ~ 2,05 %

  26. Spot size of photon and positron Due to multi-scattering, positron beam spot size is bigger than photon beam spot size when photon beam is small. Due to lower probability of pair production from lower energy photons in the outer skirt of photon beam, the positron beam spot size is smaller than photon beam when photon beam spot size getting bigger. 0.4 r.l. titanium target, Drift to target: from 10cm up to 500cm

  27. Compton scattering & medical / industrial applications • Extremely important : more and more fundamental science needs applications. 3 talks • Jeff Rifkin • Sakae Araki • Philippe Balcou

  28. Recommendations • How to proceed.

  29. ILC • Baseline : need for E166 published result (V Important also for simulation benchmark) • Find the common work topics (not an intellectual exercise …funding) Attempt : Capture section (simulation and prototyping), target (repository as suggested by I. Bailey), Polarization generation, transport and manipulation. • Alternative : Proceed towards STACKING simulations, Optimization, explore the different schemes and converge to a single proposal => COSTING CLIC : Definition of a “polarised” scheme with the new parameters. What could be a demonstrator experiment? SuperB : New entry…to be supported.Evaluate the feasibility of a polarised solution

  30. Recommended and supported R&D’s Lasers & cavities: LAL : 200W fiber laser, 10exp4 gain cavity, 4 mirror cavity at high finesse, full digitalized feedback KEK (very important) : Cavity in ATF (very important) CO2 : demonstrator of intra cavity CO2 laser (dedicated test stand, non linear optics, damages) Mirror damages @ High frep Target : ILC demonstrator Accelerators tech: High rep frequency and high charge per bunch e- guns ALL this need coordinated effort of the POSIPOL community

  31. Let’s add boxes… SuperB….

  32. Undulator : • Ring : • ERL: • LINAC :

  33. Thank you And.. R.Chehab, A.Vivoli, F.Zomer, C. Eguren, B.Renard, Missions Service…..I surely Forgot someone

  34. And thank you to you all for participation

  35. PosiPol 2008 • Hiroshima Univ. proposes to hold PosiPol 2008 in Hiroshima with support of KEK. • The period will be May or June, which will be fixed later. Hi Itsukushima Shrine Hiroshima Atomic Bomb Memorial Dome KEK Tokyo 2 world heritages

  36. ILC Positron Source Group Meeting September 17 - 19, 2007Argonne National Laboratory • The next ILC Positron Source Group Meeting will be held at Argonne National Laboratory, Chicago, IL, on September 17 - 19, 2007. • Please visit this site for more detailed information which will be posted in a few weeks. • https://www.hep.anl.gov/ILC-positron

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