HAPPEXH and HAPPEXHe

1
HAPPEX-H and HAPPEX-He

• E-99-115
• E-00-114

2
Quarks and Gluons Make Protons
Picture of the proton changes with resolution of
microscope
Primary building blocks 2 u-quarks and 1 d-quark
The vacuum is alive with particles
Including heavier quarks
Lightest heavy quark Strange or s-quark
3
Electric and Magnetic Distributions of Protons
Neutrons
Elastic scattering
Measure Scattered Electrons
Map out charge and current distributions protons
and neutrons are not point-like!
Nuclear and nucleon charge distributions
This happens for sure
Does this happen?
4
HAPPEX at JLab
Hall A Proton Parity EXperiment
1998-99 1H, 12.5 degrees 2004-05 1H, 4He, 6
degrees
The HAPPEX Collaboration California State
University, Los Angeles - Syracuse University
- DSM/DAPNIA/SPhN CEA Saclay - Thomas Jefferson
National Accelerator Facility- INFN, Rome -
INFN, Bari - Massachusetts Institute of
Technology - Harvard University Temple
University Smith College - University of
Virginia - University of Massachusetts
College of William and Mary
5
2004 HAPPEX Results 2005 Prospects
6
HAPPEX Subsytems

• Polarized Beam
• Beam Optics and Diagnostics
• Cryogenic Targets
• Spectrometer Magnets
• Detectors
• Electronics and DAQ

7
HAPPEX Special Considerations

• Polarized Source
• Careful alignment of laser optics
• Frequent (mostly automated) small changes to
  laser transport elements
• Injector beamline tune
• Electron Beam Optics Diagnostics
• HAPPEX high resolution beam monitors in injector
  region and Hall A beamline
• Beam optics into Hall A
• Phase advance
• Phase trombone
• Background at Compton IP
• Impact of sweeper magnet and raster on beam size
  at dump

8
HAPPEX Special Considerations (contd)

• Cryogenic Targets
• Large raster critical at high current!
• CHL considerations for He target
• Large radiation load in Hall A careful current
  ramps
• Spectrometer
• New sweeper magnet critical to achieve high
  current with septa
• No expected machine protection issues with
  sweeper to be verified at commissioning.
• Detectors and Electronics
• We care about helicity signals EVERYWHERE!
• DAQ system involves crates in injector and Hall A