Optics Meeting Jun 6 2023 200PM ET

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  1. (David) Updates on field limits of spectrometer
  2. (Vassu) Smaller hole studies for Sieve[1]
  3. (Bill) GEM drift region into remoll


Dvid, Kate, Kent, Paul S., Zuhal, Andrew, Jim, Sayak, Vassu, Miike D., Bill


  1. (Juliette via David) - have confirmed with the engineers that the spectrometer magnets (i.e. their power supplies) will be able to be operated at upt to +10% and down to -50% of their nominal currents (i.e. magnetic fields). A few caveats - at lower currents the power supply is less efficient, so for cost reasons don't want to run there for "long" periods of time. Also, regulation of power supply will be to +- 1A, regardless of actual current, so stability will be proportionally a bit worse at lower fields. Note that can scale existing field maps in remoll with a scale factor. Juliette is working on implementing separate field maps for each stage of the magnet(s), which would allow us to turn off one selected stages in the simulation. We should think of a plan for exploring in simulation what can be learned in tracking data with such field settings.
  2. (Vassu) Have tried comparing 5 mm diameter holes to 9 (and 6) mm holes. Improves ability to separate two different 12C foils, esepcially at middle radial location. but doesn't allow them to be distinguished at smallest scattering angles. We decide to go to only measuring single 12C foils at a time. To decide on whether or not to go to smallest possible diameter (5 mm) for all holes or not, will look at the holes at largest scattering angles (i.e. worst case for slit scattering), and compare 5 mm vs. 9 mm diameter holes, Use the most downstream foil.Look at 5mm with tilt, 5mm without tilt, 9mm with tilt, 9mm without tilt, where tilt is the central angle for a foil at the center of the lH2 target. Make 1D plots of r and r’ for this one hole image at the GEMs. Look to see if the centroid shifts from the nominal, additional tails in distribution, rate.
  3. (Kent) Would like to see the sieve hole pattern in the r,phi plane for the case of 5-pass beam on the 12C trgte, one foil - this will provide additional sense of whether we can/should add additional holes to the pattern.
  4. (David) Is metrology for the sieve holes part of the prject? Kent says yes, as part of the Q/A, but the spectrometer System Requirements Document (SRD) may need to be updated to provide more details. We would want to know the hole diameters, centroids for both entrance and exit faces (i.e. to get hole tilts).
  5. (Bill) Has implemented one layer of GEM drift volume of Ar/CO2 gas into remoll. At the moment, this geometry does not the spacers (probably not important) nor the frames (this is something we would like included).

Meeting link information

See email invitation, or contact David Armstrong, Kate Evans or Jennifer Finch for Zoom link