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CEBAF Guns July 1999 - Present

CEBAF Guns July 1999 - Present. Cathode (GaAs). 4 days to load, bake, prepare new photocathode. Anode. Laser. -. e. -100 kV. Cs. (F.E.). NF. 3. (leaky). Present JLab “Vent/Bake” Polarized Electron Gun. New Load Lock Gun Assembled & Running Spring ‘06.

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CEBAF Guns July 1999 - Present

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  1. CEBAF Guns July 1999 - Present

  2. Cathode (GaAs) 4 days to load, bake, prepare new photocathode Anode Laser - e -100 kV Cs (F.E.) NF 3 (leaky) Present JLab “Vent/Bake” Polarized Electron Gun

  3. New Load Lock Gun Assembled & Running Spring ‘06 Goal: 8 hours swap photocathode Present: ~12 hours Heat/activation chamber x4 Small bake Load region NEG-coated HV chamber Suitcase

  4. Experimental Setup Faraday Cup (450 C bake) Laser (1 W @ 532 nm) & attenuators High Voltage (-100 kV) NEG pipe Activation (Cs/NF3, Mask=5 mm) Solenoid Centering Spot Size Adjustment 7 Precision Ion Pump Supplies 350 mm 1500 mm Load lock port (GaAs on puck)

  5. Benchmarking the NEW Load Lock Gun (2006-2007) • CEBAF ~2500 C/year • LL Gun ~ 2500 C/week • No RF structure • Low-P wavelength • Demonstrated world best • GaAs lifetimes, & up to 10 mA 13 mA!

  6. Future: High Current & High Polarization Programs Qweak to test standard model >200 mA at 85% polarization Proposed e-/ion collider facilities JLab ELIC (>1 mA), BNL eRHIC (>50 mA) Circulator <1 C/day Linac >100 C/day ~20 C/day

  7. Fiber-based Laser Superlattice GaAs: Layers of GaAs on GaAsP chekc 100 nm 14 pairs No strain relaxation QE ~ 1% Pol ~ 85% @ 780 nm Now: High Current & High Polarization Ingredients: Good gun, good photocathode, powerful laser NEW Load Lock Gun

  8. Friday, Saturday & Sunday • Brief opportunity to use one of the fiber lasers, before installed into CEBAF on Monday: • Superlattice high-P material (85%) • Very good QE ~1% in New Gun • First running with 499 MHz RF • Qweak Demonstrated • 250 mA (2 days, 70 C) • Lifetime 250-1000 C • (translates > 1 week running/spot) • ELIC Circulator Ring Demonstrated • 1 mA (10 hr, 30 C) • Lifetime ~200 C

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