-CC reported about present hydrogen running
+>300kC polH2 taken since October
+FOM increased at least by a factor 2.9
+Three methods to extract GE/GM and hPz give hPz=0.465...0.480
+Data excesses GE/GM (Hoehler) above Q2>0.4
+With bin-by-bin superratio method hPz is Q2-dependent
+Data shows evidence for momentum misreconstruction
+Q2 reconstruction is sector-dependent
+If Q2 is determined from th_e only, hPz vs. Q2 is more uniform, but
GE/GM is significantly smaller than 1 (or Hoehler)
+False asymmetries: false beam asymmetries negligible, false target
asymmetries are ~0.4% or 2% relative to measured asymmetry
+Suggestion on how to correct reconstructions. Fit (th,ph,z) for
electrons from 18 Wch hits + TOF info. Calculate (p,th,ph,z) for both
electron and proton using elastic kinematics. Fit for deviation of
calculated (p,th,ph,z) from measured ones.
+Above procedure to be done only after cosmics and zero-field running
has minimized uncertainties on Wch geometry.
+Energy loss needs to be implemented in reconstruction. AM suggested to
parameterize eloss as function of pid, momentum and angle with polynom.
Most of the energy loss happens in the cell wall. Sizeable continuous
eloss of the tracks on their way through the chambers. Eloss can be
simulated as a function of pid, p, th and then be parameterized.
+Use cosmics to determine relative position and orientation of left Wch
vs. right Wch.
+Fit for deltaX and deltaTh of Wch pos and orientation by minimizing chi2
for elastic tracks
+Discussion about spin angle from p(e,e'p)-elastic. For 45 degree runs,
T20 analysis of polD2 data gave a value around 47 degrees with errors of
-2.5%/+3.5%. E-p elastic without further correction gives 43.3+-2.5%.
The asymmetry ratio varies 1% per degree, thus the spin angle is
dominating the systematics. Should use holding field map for spin angle
determination (better than 1 degree).
+Request to map holding field in three dimensions to be able to fit for
spin angle rather than to rely on knowledge of the orientation of the
probe (which would limit the precision in case of a one-dimensional
mapping).
-AS reported about p(e,e'pi+)n event selection, yields and asymmetries.
+Analysis startes from flrpm (one charged track in each sector with
opposite charges)
+Cuts: Reconstructed electron mass < 10MeV, require Cer(e') and
noCer(pi), standard z-cut, low ADC in Hadron-TOF, Mmiss-Cut,
anti-coplanarity.
+Compares beam-target double polarization asymmetry with MAID and
Sato-Lee. If fitting for hPz, getting smaller values 0.25-0.3 than from
ep elastic. Possible reason could be (diluting) background from other
channels within remaining event sample.
+Also shows beam-target asymmetry in p(e,e'p)pi0
-D. Phillips (effective field theories) is giving a talk at Bates on
01/26/2005.
-One more meeting this year (12/22/2004), no meeting on 12/29/2004
-No meeting on 01/05/2005, but an extended analysis meeting on 01/06/2005
prior to the Collaboration meeting on 01/07/2005. People should start to
get prepared for this in time.
-Discussion on how we want to run the analysis meetings:
+I will send a request for contributions on the preceding Friday. People
should get back to me by Monday, a final agenda is to be sent out by
Tuesday
+Presentations of broader topics should be reviewed in advance and
scheduled on a longer-term schedule
+Ongoing topics will always be squeezed in according to the needs
+Will try not to exceed two hours
+Sessions with "Everybody-Contributions" only in those cases where we
don't have anything else prescheduled.
+Suggestions and wishes are welcome
Regards,
Michael
--+-------------------------------------+--------------------------+ | Office: | Home: | |-------------------------------------|--------------------------| | Dr. Michael Kohl | Michael Kohl | | Laboratory for Nuclear Science | 5 Ibbetson Street | | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 | | Middleton, MA 01949 | U.S.A. | | U.S.A. | | | - - - - - - - - - - - - | - - - - - - - - -| | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de | | Work: +1-617-253-9207 | Home: +1-617-629-3147 | | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 | | http://blast.lns.mit.edu | | +-------------------------------------+--------------------------+
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