[g2p_ana] abstract to the GRC

[Jixie Zhang]

Hi,
  I am going to submit my abstract to the GRC. I pasted the tex text
here and also attached the pdf file.  I will send my poster a little bit
later.
Feel free to give comments. Thanks.



 The G2P (E08-027) and GEP (E08-007) was recently completed at Hall A
Jefferson Lab.

The goal of the G2P experiment was to study the spin-denpendent structure
function $g_{2}$

for the proton at resonance region with low momentum transfer ($0.02 <
Q^{2} < 0.2 GeV^{2}$).

The GEP experiement was to meausure the proton elastic form factor ratio at
the same

low $Q^{2}$ region. These 2 experiments shared the same dynamic nuclear
polarized (DNP)

NH3 target except the orientation of the superconducting helmoholtz
magnetic. G2P required

running the target magnetic field pointing to 90 degrees(pointing to
horizontal left if looking downstream

along the beam line) with 2.5 or 5.01 Tesla while GEP required that the
target field stays at 6 degrees

with 5.01 Tesla. Several beam energies ranged from 1.1 to 3.3 GeV have been
used.

G2P experiment are the first Hall A experiments that a transver target
field is used. In order

to compensate the vertical bending of the incident electron beam while
travel through the target field,

a magnetic chicane was placed upstream from the target and a local dump
were newly built and placed

at 79 cm downstream. In order to reach low $Q^{2}$, a pair of septum
magnetics was placed at 157 cm

downstream, which will bend the 5.65 degrees elelctron rays to 12.5 degrees
so that they can

reach the High Resolution Spectrommeter of Hall A. A recoil proton
detector, the 3rd arm, was also

built to monitor the beam and target polalrization. A Gean4 Monte-Carlo
program was

developed for these two experiments to simulate the beam line, target and
septum field, the local dump,

the 3rd arm and HRS detector acceptance. These simulation results will be
present.


-- 
Best Regards,
Jixie Zhang
Jefferson Lab - Hall A - A112,
757-269-5352
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