Slide 1

3.9 GHz Cryomodule Shipment to DESY E.Harms on behalf of the Third Harmonic Effort Team (AD & TD, with help from PPD, FESS, BS) Slide 2 What is the 3.9 GHz Effort? Fermilab has constructed a third harmonic accelerating (3.9GHz) Superconducting cavity and cryostat for a new generation high brightness photo-injector. This system will compensate the nonlinear distortion of the longitudinal phase space due to the RF curvature of the 1.3 GHz TESLA cavities prior to bunch compression. The cryomodule, with four 3.9GHz cavities, will be installed in DESYs TTF/FLASH photoinjector downstream of the first eight cavity, 1.3 GHz cryomodule. Four 3.9 GHz cavities will provide the energy modulation, ~20 MV, needed for compensation. Part of Technical agreement with DESY as part of Tesla Technology Collaboration Slide 3 General Parameters The Third harmonic system (3.9GHz) is proposed to compensate the nonlinear distortion of the longitudinal phase space due to cosine-like voltage curvature of 1.3 GHz cavities. It will linearize the energy distribution upstream of the bunch compressor thus allowing allowing the achievement of extremely small normalized emittance ~1.10 -6 m*rad (few time less than without). Parameter List for ACC39 V 3 =V 1 / 9 Number of Cavities4 Active Length0.346 meter Gradient14 MV/m Phase-179 R/Q [=U 2 /(wW)]750 E peak /E acc 2.26 B peak (E acc = 14 MV/m) 68 mT Q ext 1.3 X 10 6 BBU Limit for HOM, Q