1. A.Variola Motivations…from D.Hitlin Talk The polarized positron source

2. A.Variola ILC - Polarised positron source based on Compton scattering (alternative solution) Different advantages in respect of the undulator baseline solution: Source independence from the main LINAC – no interference with the main e- beam No need of deceleration for low center of mass energy collisions. Timing can be adjusted with the DR injection. No extra delay lines Easy to switch the polarisation (switch the laser polarisation). Less energy deposition per pulse in the target Compactness (no long transport lines) Possible demonstrators prior to ILC Applications as hard-x /gamma source for other physics field

3. A.Variola Status An international community has start to collaborate (KEK, LAL, INFN, CERN etc..) This year the second “Posipol” workshop in Orsay (May 23-25) Different kind of schemes and machine under evaluation (Compton ring, ERL, Linac) A lot of synergies and R&D with laser and optical cavity community Experiment are performed in ATF-KEK and LAL Orsay on high gain cavities and their application on Compton collision

4. A.Variola Electron polarised (unpolarised) source Polarised positron source – Compton cavities + ERL. (Splitting = Multi-injection in both rings) Positron damping ring Linac 1.5 GeVLinac 4.75 GeV Target Capture Post Acceleration 250 MeV Compton cavities + bunch compressor Elecrton re-circulation Electron damping ring Linac 5 GeV Actually there is a strong activities in studying the applicability of an ERL machine to suppress the bunch Length effect in the collision point

5. A.Variola ILC and SuperB positron polarized source ILC => 5 Hz, 3000 bunches 2exp10 e+/bunch = ~ 3 10exp14/sec => 1.5 10exp16 gammas/sec (60 % polarization) SuperB = basic requirements 2 10exp12 e+ => 10 exp14 gammas/sec What polarization? (remember…with Compton scattering at 1.3 GeV It is possible to have 30% polarization for free…without gamma preselection). ILC MACHINE = VERY PERFORMANT!!!!!!!! But : SuperB Machine => SAME TECHNIQUE With a good laser + cavity system we can have 10exp8 gamma/collision This means that if it possible to stack in the damping ring 10exp6 injection it is possible in principle to have a 30% polarized beam for the SuperB using a “standard” ERL technology (i.e. JLAB machine)

6. A.Variola SuperB polarized positron source could be a fantastic test facility to test the Compton production scheme for the ILC. Not only at production but polarization preservation in the ring must be studied before ILC. Already two order of magnitude less are a challenge due to the laser+cavity technology and to the collision scheme 30% polarization will be sure….more must be studied Other physics communities (nuclear etc…) are welcome…it would be a first real tunable gamma factory with brilliance near to FEL machines!!!