Gun summer shutdown New NEG’s - Ten 9.5” strips New NEG tube – 27 hr. sputtering time New cathode – “yellow” 25 deg SS polished to 1um, 100kV New cesiator strips Sacrificial bulk w/ large Ta cup Bakeout good – no leaks Bulk activation 4% at 670 nm w/ UHV ~ 5nA baseline (ELOG ) HiPot stalk out 120kV OK vac burst 110kV & stalk in 110kV OK – cathode OK SVT4722#2 loaded No hydrogen cleaning In solder – no heat in air 5 mm polished Ta cup Stalk#4 Loaded into Gun3 on 8/11/04 Bakeout good – no leaks Cathode heat C Activation OK - 5% at 655 nm and 0.65% at 769 nm Preliminary SVT4722#2-GUN3 Status (1/12/05)
Hall A 776 nm Hall B 655 nm Hall C 782 nm Gun3 SVT4722#2 Heat 45 min up Cool Reactivate ~15 yo-yo’s Vacuum < 20 nA Hi-Pot Stalk Out - OK Stalk In - OK Typ. 60 A leakage
Notably good injector setup… Measured beam polarization, surface charge limit, analyzing power Calibrated HVPS against Pcup Early demonstration of possible “Qweak”-type beam
ELOG# SVT4722#3VGUN (Reblochon)
Calibrate laser power vs. attenuator over relevant range… Measure photocurrent vs. laser power twos ways… 200 A ramp 100 A A ramp
QE vs. laser power at 776 and 782 nm one makes sense, the other less so…
Analyzing power is low, but not zero… A ~ 2.1% B ~ 0.2% C ~ 2.2%
Physics started Saturday, but poor transmission…
No more orbit shifts. Good transmission. Sunday, on-call Corrected orbit at 1I03/1I04 – transmission fully restored (good) Hall B1 picomotor to reach 30 nA – too far (spot move!)
Hall A 776 nm Hall B 655 nm Hall C 782 nm
QE vs. Time (yet), because… Daily charge plot app not working – Bickley will fix… StripTool “archiver feature” does not dump data… Archiver for gun current is running at 5 Hz (eek!) – too much data, too late… Hall B “spot move” New “starting line”
Efficiency numbers… BulkStrainedSuperlattice Max. P 35%75%85% QE* [%/mW] At Max. P 6%0.2%0.6% Sufficient “I” Experiments 12%56%72% Limited “I” Experiments 0.7%0.1%0.4%