CEBAF Guns July 1999 Present Present JLab VentBake
CEBAF Guns July 1999 - Present
Present JLab “Vent/Bake” Polarized Electron Gun Cathode Anode (Ga. As) 4 days to load, bake, prepare new photocathode Laser e Cs NF 3 (leaky) (F. E. ) -100 k. V
New Load Lock Gun Assembled & Running Spring ‘ 06 Heat/activation chamber Goal: 8 hours swap photocathode Present: ~12 hours x 4 Small bake Load region Suitcase NEG-coated HV chamber
Experimental Setup High Voltage (-100 k. V) Laser (1 W @ 532 nm) & attenuators Faraday Cup (450 C bake) NEG pipe Activation (Cs/NF 3, Mask=5 mm) Solenoid Centering Spot Size Adjustment Load lock port (Ga. As on puck) 7 Precision Ion Pump Supplies 350 mm 1500 mm
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 Ga. As lifetimes, & up to 10 m. A 13 m. A!
Future: High Current & High Polarization Programs Qweak to test standard model >200 m. A at 85% polarization Proposed e-/ion collider facilities JLab ELIC (>1 m. A), BNL e. RHIC (>50 m. A) ~20 C/day Circulator <1 C/day Linac >100 C/day
Now: High Current & High Polarization Ingredients: Good gun, good photocathode, powerful laser 14 pairs 100 nm NEW Load Lock Gun Superlattice Ga. As: Layers of Ga. As on Ga. As. P chekc No strain relaxation QE ~ 1% Pol ~ 85% @ 780 nm Fiber-based Laser
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 m. A (2 days, 70 C) Lifetime 250 -1000 C (translates > 1 week running/spot) ELIC Circulator Ring Demonstrated 1 m. A (10 hr, 30 C) Lifetime ~200 C
- Slides: 8