JLabCLAS

1
JLab dedicated DVCS experiments in 2004 - 2005

• Dedicated, high statistics, DVCS experiments
  
• ? Detection of 3 particles e, p and ? in final
  state
• ? Firmly establish scaling laws (up to Q2 5
  GeV2),
• if observed, or deviations thereof
  understood,
• first significant measurement of
  GPDs.
• ? Large kinematical coverage in xB and t
• leads to femto-tomography of the
  nucleon

JLab/CLAS
JLab/Hall A
Calorimeter and superconducting magnet within
CLAS torus
424 PbWO4 crystals
HRS PbF2 Plastic Scintillator H(e,egp) D(e,e
gN)N
Details in talks by M.Mazouz and R.Niyazov
2
Hall A at 6 GeV, future ideas

• Extend current configuration to xBj0.6, Q24.0
  GeV2
• Add magnetic field near target to suppress Møller
  electrons. Increase luminosity to 1038/cm2/sec
• H,D (e,eg)X s(MX2) ? 0.2 GeV2 lt (Mmp)2-M2
• Add Magnetic field and tracking detectors in
  front of calorimeter sufficient to identify
  charge of ee- pairs
• H(e,eee-)p at small ee- mass ? ?GPD/?xxx
• Access to qq-bar content of proton
• (Suppress p0 Dalitz decay by missing mass).

3
DVCS in Hall A/C at 11 GeV
Spectrometer (HRS at Ebeam8.8 GeV,
HMS/SMHS/MADat 11 GeV) Calo Scintillator
array at 1037/cm2/sec (Higher luminosity
possible with Solenoidal field on target)
Asinf term in Helicity-dependent cross
section. Bsin2f term determined to 10 of A. 400
hours
xBj0.5
Design studies underway for full acceptance
dedicated detector at 1037/cm2/sec (Dec 2004
LOI).