PREX/CREX Monday, March 30, 2015 3:00pm EDT

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Link to the Meeting page PREX/CREX Teleconferences
Last meeting: PREX/CREX Monday, March 23, 2015 3:00pm EDT

The teleconference info is as follows:
       Phone #: +1-888-240-2560 or +1-408-740-7256 and See International Numbers
       Code: 174599135


Discussion about unified scattering chamber design

Follow-up by Nickie to add MC results and look at Q3 distribution elog-2976

Yuxiang, Ciprian, Seamus, Nickie, Rakitha, Kent, Bob, Caryn, Guido, Dustin



  • Elog 2973 is just an idea to use the Qweak scattering chamber so that qweak target ladder system with xy motion can be employed. Silvu has been using this chamber for his Qweak target ladder for PREX studies. To Do: Need info on exact size of Qweak chamber.
  • Bob's initial estimates on using two target ladder design inside a long cylindrical scattering chamber is shown in the elog 2974. Figures only show two target ladder. The targets would move in a long vertical travel.
  • Then in elog 2975 what if both PREX and CREX run at the same angle and use appropriate beam energies that give optimal figure of merits (FOM) ?
    • Attachments 2 and 3 shows FOM for CREX and PREX at different scattering angles as a function of beam energy
    • PREX will require different beam energy than requested in the proposal in this configuration at 4.5 deg
    • Single collimator design is possible
    • Have to break the vacuum to install CREX target at the end of PREX or vice versa
    • Due to change in angle and beam energy what will happen to radiation load for PREX?
    • Bob mentioned that PREX rates have gone up in this new configuration, what about the effect of increase in rate?
    • The FOM for PREX cut of at 1.2 GeV and Bob will generate beyond 1.2 GeV to see how FOM decrease as increase in beam energy
    • The Optimum beam energy that gives best FOM does not match with the proposed value for 5.0 deg. angle. The expected value is about 1.05 GeV but the plot shows about 950 MeV. Bob will check this mismatch (Seamus: possibly due to using the unshifted acceptance function)
    • What is the possibility of running experiments longer with this same angle configuration?
  • Follow-up by Nickie to add MC results and look at Q3 distribution see elog-2976
    • Added MC results with no raster. There is an offset between data and MC for x,y and angle distributions
    • The data is from optics studies using C target possibly with no raster. Nickie will check this.
    • what is the effect of raster on these detector plane distributions?
    • Will follow-up during next optics meeting and report next week on raised issues.


  • Beam parasitic studies needs a to-do list

TO DO Lists

  • It would be nice to have real-time viewer for optics studies in commissioning (disussed in 01/16/2014 meeting)

TO DO Lists link: PREX, CREX