Recoil Plots for PRC Oct 2008

This is a working page which will continuously change. The content is not reviewed and is intended for people working on this specific topic.

Page maintainer: Caro

Last update: Aug 2, 2008 Back to Recoil Status

Introduction

This page is an old working page which will not be updated anymore. It lists all Recoil plots proposed for the Oct.2008 PRC. Please see also the Recoil Status page. The proposed studies depend to a certain extent on the open points as of Augst 1, 2008

Available Manpower

• Charlotte, Roberto, Weilin, Jonathan, Didi; David (Xianguo)
• Fidi, Hyon-Suk, Alberto
• Andreas, Caro, Sergey (Achim, Polina, Rebecca for summies projects)

Basic detector quantities

• First higher calibration of all 3 detectors has been performed (Andreas/Didi, Weilin, Charlotte)
• PID probability distributions have been obtained (Weilin, Xianguo)
• SFT plane-by-plane efficiency vs. ($\phi$, $\theta$, p, ZVx), for protons and pions (Roberto)
• $\pi ^{0}$ reconstruction with the photon detector (Charlotte)
  • M(bar)x2 vs. M-pizero2
• Missing momentum distribution of protons (towards tagged SFs) (Andreas)
  • Literature 1: DC50
  • Literature 2: Jan Visser's PhD thesis
• 2-, 3- and 4-spacepoint track "topologies" (multiplicity, missing layers of reconstructed tracks, clones?, ...) in combination with DVCS event in the front. (David)
  • This study is supposed to be the starting point for other exclusive studies.

Exclusive Events

• e-p elastic ($M_{x}^{2}\equiv W^{2}$) (Sergey, Achim + 1 summer student)
  • Correlations between scattered beam lepton and target proton (phi, theta, p...)
  • MC/data absolute x-section comparison
• DVCS (Caro, Weilin, Didi)
  • Acceptance and efficiency studies on Mx2 distribution
    • Needs definition of best coplanarity cut(s) "$\Delta \phi$" (tighten Mx2 cut for this?)
    • Needs definition of "recoiling proton reconstructed" YES/NO (using: PID info; ZVx correlation with front spectrometer; single track events?) Is of course known for MC!
    • Needs definition of fiducial volume Didi's Mail Aug 1, 2008

Plot usual Mx2 distro. 
Plot Mx2 distro only for events with vec(p) in fiducial volume (FVC) of recoil. (the expected vec(p) can be calculated from the kinematics in the front)
Plot Mx2 distro only for events with recoiling proton reconstructed. Consider long AND short tracks, M7 has now also 2SPs
We introduce a new variable: M(bar)x2 = missing mass AFTER inclusion of recoil kinematics (track momentum) 
Plot M(bar)x2 vs. delta(phi) 
This is a plot on track level! 
The missing mass has different "hypotheses" if there is more than one recoil track in the event
The 2-dim presentation should well separate off ghost tracks (not clone tracks, as their momentum is almost identical) 
Is a bump seen at M(bar)x2 = pizero mass?? 

• • The same Mx2 study on Monte Carlo (from new to-come productions)
  • A_LU with and without requiring recoil tracks
    • Can directly follow after Mx2 study, applying what was learned there
    • Also look to gmc_DVCS (new production)
• Hard Exclusive Meson Production (Andreas, Caro, Polina, Rebecca + 2 summer students)
  • Feasibility studies: exclusive and fragmentation products off neutron target
  • fragmentation: x_F<0
  • background for tagged structure functions (neutron fragments)