Minutes: |
- Dave Mack: We will need to build a faraday cup and invent a 10^-4 level luminosity monitor; perhaps a large angle muon telescope behind a concrete wall. There will need to be geant simulations. We have to build a low power (5 kW?) faraday cup. The positron runs will need a 50 kW cup and Dave has a 10 kW cup in storage from DESY. We will need to get the general specs (80-120nA usually with 200 mA occaissionaly) to the engineers and designers. It will be installed downstream. Depending on specs it could be a defacto beam dump or might be on a little elevator to remove from the beam. This has all been done before, atleast at the 3 kW level in hall, so should not be a huge problem.
- has been going thru the old docs. Primary concern of the conditional review is tensor polarization. Just need to show you have a technical solution for polarization. Prepare a presentation, worth mentioning low power faraday is needed since existing monitors will drift by atleas 0.1% over 8 hrs. We can mention that Dave is the contact on this effort. Not sure if we will build new or use an old DESY cup. The lumi's will be trickier and details will be needed for ERR, but not conditional review. The existing BCMs will not work to 0.1% over 8 hrs. But this conditional review "is not an ERR". For the eventual ERR, JLab will want the cost of the experiment to be well defined.
- Next 1-2 years will be NPS followed by LAD. ERR is usually needed before getting on the schedule officially.
- Nathaly S: One possibility is when Moller runs (in 3 years?) since they need high current and we are low current. Dave: Moller is huge endeavor and may experience delays. They will also require 100% longitudinal polarization and typical running is limited to polarized beam to 2 halls. (Not clear that this is any problem for us)
- Dave M: suggest to contact Jay B for the status of chicane. Dave Gaskell is beamline owner. David Flay may also be involved.
- issue of beads settling over time. Might not be a problem if we wait to settle or actively "settle them". Chris suggests disks. Lumi needed to monitor these types of changes. KS: we are also considering to address this by using shorter polarization cycles than 8 hours or two in-line target cells. Each brings unique challenges.
- z-target resolution: y-target resolution is crappy 1-2 mm. Lorentzian with long tails. z-targ then depends on angle.
- Dave will look at the error propagation. 2 targets will have 1% luminosity difference. He has a difficult time getting around the slow drifts. Thought about maybe monitoring a g1-type asymmetry but it is convoluted with the tensor asymm. This experiment was difficult when we proposed it, but is fairly typical for positron experiments and JLab will definitely need a faraday cup for those runs.
- KS : we received two invitations to the Hall A/C meeting; one on the experiment status and one on target. Experiment talk should be a rapid overview with discussion of recent progress. Target talk should highlight the overall good progress in made by Dustin/UVa, and also Ellie/UNH independent lineshape modeling progress.
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Attendees: |
Dave Mack, Karl Slifer, Elena Long, Allison Zec, and Nathaly Santiesteban
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