4 mirrors high finesse optical cavity to produce
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4 mirrors high finesse optical cavity to produce high gamma ray flux at ATF Japanese Labs. : KEK, ATF group, Hiroshima University French Labs. : LAL (Orsay) in Collaboration with CELIA (Laser lab. , Bordeaux) and LMA (mirror coatings Lab. , Lyon) • R&D description • Schedule
New R&D : start february 2008 after 6 th PCRD contract 2005 -2008 1. Setup the following system at Bordeaux/Orsay CELIA Oscillator =1 W, 1030 nm Dt~5 ps frep=178. 5 MHz From Onefive compagny >100 W-200 W Amplifier LAL/KEK/LMA Fabry-Perot cavity Gain~10000 Rod type photonic fiber Yb Doped LAL Numerical feedback Goal : Laser average power >1 MW inside the cavity… 2. Installation of the system at ATF/KEK
R&D at KEK : Cavity installation on the Accelerator Test Facility (ATF) . ～ 54 m cavity Beam Energy → 1. 28 Ge. V ～ 30 m Beam Size → 100μm× 10μm Emittance → 1. 0 x 10 -9 rad. m 1. 0 x 10 -11 rad. m (Ultra Low !!) (H. Shimizu)
The laser amplification R&D Max published E. Cormier (CELIA) One. Five laser Dt=2 -5 ps, 178. 5 MHz, 1 W F. Röser et al. Optics letters, 30, p 2754, 2005 Laser Diode No compressor needed Possible average power 100 W-300 W (simulation) Doped rod type photonic fibre: Large core diameter & monomode developed for CELIA Gold grating-based strectcher gives negative chirp for spectral compression
Choice of the cavity geometry Interaction plane must be horizontal 2 choices 2 D 3 D Main constraint: 5 mm vertical slit width • Optical path length = c/178. 5 MHz~1. 6 m • 4 mirrors needed to reduce the laser spot size • Power/polarisation stabilisation with 3 D configuration
Implementation studies at ATF has started Cavity drawing has started
Rough schedule • Year 2008 : – Mechanical Design and installation plan studies in closed Collaboration with KEK-group • Meetings – LAL group visited KEK in Nov. 2007 – KEK visited LAL in Feb. 2008 – Next LAL visit at KEK: June 2008 to finalise mechanical drawings & participation to POSIPOL workshop at Hiroshima – Webex meetings – Laser Amplification studies at CELIA – Feedback studies & mechanical drawing/construction at LAL • Year 2009 (mid 2009 hopfully, end 2009 probably) – Transport of the system to KEK and installation on ATF