Aug 12, 2019
Recent results discussion: Eric, Paul
Meeting URL https://bluejeans.com/388466836
Meeting ID 388 466 836
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Minutes: Paul started the discussion with results of the previous weekend. Conclusions:
- We are highly sensitive to the orbit of the beam coming into the solenoid. During our last run on Aug 4, our rates were very low compared to expectation presumably due to misalignment
- One of the correctors previously used in the Moller lock was just upstream of the Moller target and appears to have been sending high angle (~2 mrad) beam into the solenoid. This has been rectified with a new lock using upstream correctors. Presumably this will result in a much more repeatable setup.
- Simulation indicates that Azz is largely insensitive to these alignment issues (phew!)
- Data taken over the weekend matches expectation from simulation very well showing that we are close to a large Levchuk correction (>1%) but if we overtune Q1 from its rate peak we are located in a flat region of Azz with minimal Levchuk correction and sensitivity.
Slides were shown from Don and Simona discussing future systematic studies including target quality and saturation studies, deadtime studies, and a magnetic field reversal. We discussed the interpretive issues surrounding both the saturation test and a field reversal. While no definite conclusions were reached, there seemed to be a consensus that we should do a saturation test, although the exact structure and scope is not yet clear. Further discussion is required before committing to a field reversal. Perhaps more information on solenoid alignment will help inform the decision.
Takeaway: We need to continue doing a beam off bleedthrough test when other halls are running. We can dispense with null asymmetry measurements on Cu as long as we measure both HWP IN and OUT polarizations to measure the null.