Analysis meeting minutes:
Attending EG, NM, TF, TA, DH, BT, AS, CC, MK.
-"Big" Analysis meeting scheduled for Wednesday 4/61/2005
(*not* Thursday!!)
-EG:
+Finds discrepancy for (e,e'n) yields from flr and dst for runs in
the 8000's, however those still have no useful dst, only after
recrunch. Should use new runs of this year instead which do have
proper dst.
+Reports (e,e'n) yields have decreased this year compared to last
year because of lower target density (this may depend on particular
run numbers), however relative to proton yield it is unchanged.
+Should investigate if this also applies to the forward LADS wall
(above Q2=0.4, or cut on L15), when normalizing (e,e'n) yields to the
(e,e'p) rate in order to see if installing the lead
shieldings/converters had any effect
+Will get started with Tosca soon
-TF:
+Presenting inclusive-ep beam-target asymmetries compared to MC
with MAID implemented.
+Aleft and Aright for different trigger types, also A_TT' and A_TL'
+Trigger type 7 agrees with MC
+TF-MC and AS-MC agree
+Trigger type 1 asymmetry is shifted to negative direction.
Qualitative understanding is that the radiative tail of elastic
scattering events contributes to the inclusive yield in the
Delta-region, however only in trigger 1 and not in 2 (e,e'n) or 7
(singles). Asymmetry attributed to elastic events is negative.
Somewhat but not drastically different asymmetry of tail-events
compared to unradiated events expected due to kinematics effect (q2
different)
+AS claiming that radiative tail does not explain quantitatively the
discrepancy of measured asymmetry and MC.
+In order to gain confidence into the implementation of MAID into
BLASTMC, one needs some benchmarking. Possible checks are comparison
of BLASTMC with MAID prediction for pointlike kinematics at prominent
points (at top of Delta). MAID may not be the last word for
polarization observables and the multipoles probed. The unpolarized
case is much better known. Since the electron efficiency for
inclusive scattering should be on the order of 80% and for a
luminosity taken from ep elastic scattering, one could determine the
differential cross section (unpolarized) to some limited precision
which should be reproduced by MAID (dominant M1 multipole).
+Different trigger types have different backgrounds; background may
even be polarized as in above case. Polarized radiative-tail
background should be handled in BLASTMC with MAID+radiation tail in
generator.
-NM:
+Made MASCARAD to work, converted to C++ from Fortran. MASCARAD
accounts for the Mo and Tsai radiative effects for elastic
scattering including the helicity-dependent part.
-We should have radiative effect in generator. May not be so important
for asymmetries in elastic scattering, however it is important for
the estimate of the contribution by radiated elastic events in the
Delta region.
-CC:
+Showing ep elastic data and MC asymmetries and polarizations
+Slight disagreement between MC and Hoehler-pointlike
+Some cluster-like over-and undershooting of the Hoehler curve
+Q2-dependence of PbPt gone after cutting more strictly on
wirechamber hits. Data sample became smaller, polarization higher.
+Kinematical corrections: Trust angles, calculate momenta from angles
for elastic scattering -> p_exp-p_calc(the):the etc. for eleft,
pright and vice versa. Seems to observe somewhat different results
than EG (needs to be compared explicitly.)
+p_exp-p_calc(theta):p_exp for eleft, pright, eright and p_left
should be plotted and made available as a third set of kinematical
corrections and be compared to the ones by AM and EG.
+z_electron-z_proton is not zero and has opposite sign when sectors
are flipped. Possible explanation may be a transverse offset of the
target, beam, or wire chamber. If so, dz versus theta should cross
zero at 90 degrees.
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 | | +-------------------------------------+--------------------------+
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:32 EST