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Logistic information

 Toll-Free Number (U.S.&  Canada):  888-240-2560
 PARTICIPANT CODE:                  # 887 194 559
 Room IRL:                            <none>


Please post slides in haplog or docdb, before the meeting

  1. Kent: recap FOM calculation for estimated rates and Q2
  2. Ryan: summary of new Q2 determination HALOG:3756934
  3. Ryan: Update FOM calculations for averaging over acceptance [1]
  4. Siyu: tests of optics database, pointing, Ca-48 dp spectra (maybe no data to use yet)?
  5. Devi: summary of Q2, alignment, and sieve in measurements (task from last meeting) CREX Optics Runlist
  6. Devi: [2] [3]
  7. Devi: progress toward acceptance symmetry estimate: vs sieve hole or over acceptance.


  1. FOM: <comments by KP> Ryan's new calculation seems to predict rates pretty well. This gives us some confidence on our estimates of sensitivity and FOM. But we still need to make sure we understand this - it could be coincidental. If you take what we _think_ we know now, we correspond to the error bar we expected when we changed the experiment to run at 5 degrees.
  2. Inelastic states, reconstruction and alignment.
    • Q2 measurements on the right and left now agree well, within about 0.6% of each other. HALOG:3756934
    • Devi estimated dispersion at the detector plane using dp vs x_detector plot to be 14.3m. haplog:3987
    • Then he showed that this dispersion matches the inelastic peak locations in x_detector for 12C
    • The result also looked plausible on Ca-48.
    • The dp plots on the left arm shows inelatic peaks clearly. Marking locations of inelastic levels, it looks like the dangerous 3- is slightly larger rate than the 2+, but it is pretty close.
    • Devi also logged plots of the Ca-48 dp spectra with cuts on the quartz ADC spectra. haplog:3988 These can help check KP's rough estimate from the x_detector distribution of a few tenths of percent 3- contamination.
    • The right HRS showed a big problem in the dp spectrum - looked totally wrong.
      • Siyu found the right HRS db had been mistakenly changed, and corrected the problem, so we should be able to look at reconstructed variables on the right arm again.
    • Siyu will look at Ca-48 dp spectra to try to get an estimate of the contributions of the various inelastic states
    • Siyu will also show us plots to help quantify the quality of the new Tune E optics data base.
  3. FOM calculation (Ryan) - haplog:3989
    • now averaged over acceptance, showed angle, Apv, and sensitivity plots
    • The sensitivity changes very rapidly with angle, energy, Q2.
      • Bob points out this ultimately can contribute to systematic uncertainty, so we need to evaluate if there are further auxillary studies to be done.
      • We also need to confirm that we have estimated our angle, energy, and Q2 distributions correctly so far, so that we can have confidence that we have roughly the right FOM calcuation. The problem seems to be primarily in knowing the sensitivity vs the rate.
    • The simulation disagrees on scattering angle, but the most obvious difference is an offset explained by the difference in the central angle definition between the simulation and the data optics db.
    • The rate measured by counting is uncertain by charge monitor calibration. The rate estimated by the width is 54 MHz, nearly exactly matching the simulation estimate - with the caveat that the simulation may not match the acceptance of the real data well, so we still need to study to be sure this isn't a coincidence.
    • The simulation also calculates Q2, rate, asymmetry, fom, sensitivity from the "vertex" kinematics, not the external kinematics. Obviously, the data uses the external kinematics. Ryan will try to compare vertex vs external kinematics using his simulation.
  4. Watercell data: Not yet analyzed. Siyu will look at Dec 15 water cell data. Raster correction can be performed for the carbon with/without raster data to benchmark raster correction technique.
    • we noted that the raster correction may also clean up the PREX watercell data
  5. The CREX Optics Runlist has been updated to include some alignment runs. We should make a new tab in the spreadsheet to accomodate this list.


Devi, Ryan, Siyu, Chandan, Sanghwa, Dustin, Bob, CIp, Don, Kent, Krishna