Karl Slifer
discussed his work on target thickness and cross sections:
Karl looked
at the thickness along the beam line before and after scattering.
He discovered that Be window was 15
mil, and Ed had never used a 10 mil
window. By comparing previous
values with Karl's thickness values, Karl
found that the after scattering values
are similar, but the before scattering
thickness increased by 30%.
Karl gave an
overview of the procedure to calculate the Born cross
section from the raw cross section.
He also discussed the calculation of
the errors.
A spectrometer
comparison for Jin, a cell for which the thickness is known
well, shows that the difference
between the cross sections is only 2.5 to 5%.
But for Armageddon the thickness is
not known well, and the difference in the
cross sections is much larger.
Karl will check
the effect of the radiation length increase due to the 15 mil
Be window and rerun the cross
sections with the correct RL. He will soon
start the 3He GDH analysis.
The collaboration
will discuss the second paper on structure functions
next
week on Friday, December 13, 2002, since Zein-Eddine Meziani
could not
make to the meeting:
Nilanga Liyanage
discussed the third paper on twist expansions/duality:
Nilanga will
have more results for the next meeting.
The
collaboration discussed upcoming and new experiments:
Doug Higinbotham
talked about the approved 3He(e,e'd) experiment. The
experiment will measure the Ax
and
Az asymmetries to pin down the error
from the nuclear polarizations.
Big Bite will be used 1 meter from the target.
Gordon Cates
discussed the preparations for GEn at high
Q2. Magnetic field
calculations are being done to find
a way to compensate for the gradient field from
Big Bite. For the experiment
the laser hut and current scattering chamber will not
be used. To compensate for the
gradient, a new idea is being considered to replace
the coils with plates and to wrap
the coils around the plates.
Xiaodong
Jiang, discussed a new proposal that will be presented at the next
PAC. The proposal will measure
the transversity of the neutron. The experiment
will use Big Bite to detect electrons,
and the HRS to detect charged pions. Big Bite
will be located 1.5 meters from the
target, where gradients are not expected to be
a large problem.
JP Chen discussed
conferences for 2003:
JP
suggested that members of the collaboration think about possible
conferences
to which they would like to go and to let him know of any
conferences
not included on the list. JP will send out an updated list, when
he gets all
the information together.
Back
to
Main Minutes page.