Agenda

MOLLER related Beam Tests: (Note: laser is back to 249.5 MHz, need to switch to low-rep laser (need one shift))
1. Study photocathode effects from KLong beam
2. Deliver Hall D Low-rep Rate and High Bunch Charge Beam to Hall
Hall D Bleed-through:
1. RF bleed-through results from bad RF Separator phasing in Beam Switch Yard. This can be eliminated.
2. Bleed-through that originates at injector because each drive laser produces some dc beam that bleeds across all three chopper slits. We measured bleed-through in injector using different lasers (Mode-Locked laser vs. Gain-Switched laser), but found the same level of bleed-through as our Gain-Switched based drive lasers. All Hall D empty RF buckets will be filled with bleed-through current from Hall D laser in addition to the bleed-through from the other lasers. Other halls worried about effect on polarization, otherwise no issues. KLong should worry about accidentals and timing. Accelerator wants a requirement document. Bleed-through can be measured in injector. We will need to submit a beam test request. KLong DAQ should also receive a 15.6 MHz timing signal from Injector.

Minutes

Present: Vitaly, Beni, Tim, Josh, Hovanes, Igor, Riad, Pavel, Edy, Mikhail, Marshall, Sashi, Moskov

Riad discussed the plans for the beam tests during 2025 runs. He thinks he would need two "beam study days" to get reasonably conclusive results.
Riad pointed out that these measurements were planned earlier but were not done due to a lower priority assigned to them. The priority of these tests is affected by the Physics Division input, and we would need to be a high priority item on the Physics Division list not be bumped off the schedule for the beam studies.
Edy can help some of us be included in the meetings of the "BTeam".
Riad expects that the bleed-through will be on the level of 1%. Hovanes asked why it should not stay at ~3nA as measured during KLF instead if the slit aperture is not changed. Beni commented that for KLF the DC beam-current will be the sum of the other halls, as for GlueX, plus leakage from KLF laser. Riad expects that Hall D laser for KLF may substantially change the DC-beam-current and increase the bleed-through. The dark current level of KLF laser can be measured at the injector.
Injector group would like to have specs for bleed-through from KLF. This could be a slide describing the impact of the bleed-through and the maximum bleed-through current that could be tolerated by KLF. Moskov and Vitaly commented that they have estimated the impact of 0.1% bleed-though. At this time KLF does not have specifications for the out-of-time bleed-through current.