Start of shift: Beam to Halls B & D; Hall C down in CA for target ladder issues.
The following cavity histories have been updated:
2L11-1
Username: kerns
Date/Time: 05-07-26_23:19:04
RF Status: Good
Tuner Status: Good
Comment: HV dropped in zone after klystron resistor blew apart. Alex S. replaced and recovered.
Special Instructions:
Maintenance Tag: Component: 50 Ohm Resistor
Searching through the BPM values just before losing B beam, it looks like the orbit in the injector suddenly shifted starting at the 1I07 horizontal BPM shifting ~1 mm to the left, and everything downstream went with it. The Injector SME is on-site and investigating now.
Replaced load resistors for cavities 1 and 3. Cavity 3 was already bypassed for RF drive issues, so pulled the jumper for it to reduce the risk of another unnecessary drop. Will leave the PTW on issue until end of day tomorrow just in case there are any emergent issues with the cavity 1 replacement resistor.
After opening up the CPS to investigate, the 50 ohm load resistor for cavity 3 (front left in figure) was found to have destructively reached the end of its lifespan. Cavity 1 (front right, not pictured) was also noted to be flaking apart and measured well over 100 ohms. Whether the blast crater in the figure was from it or a previous resistor is unclear, but replaced both just to be sure and vacuumed up the debris.
| Shift | Owl |
|---|---|
| CEBAF Program | |
| MCC Crew Chief | Howard |
| MCC Operators | Price, Chaudhary, Christian |
| Program Deputy | Drury |
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