Difference between revisions of "Aug 12, 2019"
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| − | [[ | + | [[Aug_8%2C_2019|previous meeting]] << >> [[Aug_19%2C_2019|following meeting]] |
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Agenda: | Agenda: | ||
| − | Recent results: | + | Recent results discussion: Eric, Paul |
| − | + | Systematics Discussion: Don [https://hallaweb.jlab.org/dvcslog/moller/190812_150816/Moller_Systematics_Discussion(1).pdf], Simona [https://hallaweb.jlab.org/dvcslog/moller/190812_150728/moller_syst_studies_malace.pdf] | |
| − | + | ||
| − | Systematics Discussion: Don | + | |
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Minutes: | 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/stable 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. | ||
| + | *Our setup procedure continues to be dipole rate scan to find max rate followed by a Q1 rate scan. Setting Q1 3.5% above the rate maximum (which is more like the start of a plateau region) is safe. | ||
| + | |||
| + | 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. | ||
| + | |||
| + | Takeaways: | ||
| + | *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. | ||
| + | *Setup procedure=dipole rate scan to find max rate followed by a Q1 rate scan. Setting dipole at max rate point and Q1 3.5% above its rate maximum puts us in a flat Azz region with little Levchuk correction | ||
Latest revision as of 15:39, 12 August 2019
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Original Moller Polarimeter Page
Agenda:
Recent results discussion: Eric, Paul
Systematics Discussion: Don [1], Simona [2]
Connection details:
Meeting URL https://bluejeans.com/388466836
Meeting ID 388 466 836
US toll free phone 1.888.240.2560
Dial in, type in the meeting ID and then press ##
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/stable 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.
- Our setup procedure continues to be dipole rate scan to find max rate followed by a Q1 rate scan. Setting Q1 3.5% above the rate maximum (which is more like the start of a plateau region) is safe.
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.
Takeaways:
- 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.
- Setup procedure=dipole rate scan to find max rate followed by a Q1 rate scan. Setting dipole at max rate point and Q1 3.5% above its rate maximum puts us in a flat Azz region with little Levchuk correction
