[Shms_users] Draft Hall C proposal

[Garth Huber]

Dear Collaborator:

We are writing to bring to your attention a draft proposal we have prepared for 
JLab PAC 29.  We are proposing to measure the Longitudinal Photon, Transverse 
Target Single-Spin Asymmetry in Exclusive Pi- production.  The experiment would 
make of a new, high luminosity polarized 3He target under development at the 
University of New Hampshire, to achieve acceptable errors in a reasonable 
beamtime.  Another crucial aspect of our experiment is the Rosenbluth L/T 
separation, making use of the SHMS+HMS.

The Longitudinal Photon, Transverse Target Asymmetry in exclusive pion 
production is thought to be one of the best observables with which to gain 
experimental access to the Generalized Parton Distributions.  It is expected to 
scale precociously at moderate Q^2~4 GeV^2, making it relevant for study at 
JLab.  Our proposed experiment would be the cleanest possible measurement of 
this observable and will allow access to the polarized GPDs, E~ and H~.  This 
observable is also relevant to studies of the pion form-factor, in that 
constraints on H~ will give one further insight into non-pion-pole backgrounds 
contributing to the longitudinal p(e,e'pi+)n cross section, and so improve the 
confidence of the Fpi extraction from the cross section data.

The draft proposal can be downloaded from:
    http://lichen.phys.uregina.ca/~huberg/atpi/pac12_draft.pdf

Please feel free to send us your comments prior to the proposal submission 
deadline of May 4.  In particular, please let us know if you would be interested 
in being included in the collaboration list.

        Regards,

          Dipangkar Dutta, Dave Gaskell, Bill Hersman and Garth Huber

-- 
Dr. Garth Huber, Dept. of Physics, Univ. of Regina, Regina, SK S4S0A2, Canada.
tel: 1-306-585-4240. fax: 1-306-585-5659.