Topics:
Visit of D.Philips
Kinem Corrections
Wch Calibration
Spin angle
Inclusive and N-Delta analysis
------
Visit of D. Philips
_ Present T20, focus on details of normalization
_ show normalization, step by step, eq by eq
_ overview available theories
_ their consistency with Q-moment
_ their consistency with BLAST data
_ size of T21 corrections and other theory systematic
uncertainties
_ systematic uncertainties related to analysis/calibration
issues
_ Shorter presentation for AM, VZ, WX
_ agenda will be sent out soon
Kinem Corrections
AM: fixed p_e, p_p to Q2 values predicted by blastmc for the
quasi-elastic channel
_ extracted correction factors range up to 10 %
_ correction was significantly different L,R sectors
_ average values close to guess 1.05 and 1.0 correction factor
used so far which was dominated by low-Q statistics
_ hence correction lined Q2 values but did not change polarization
value
_ corrections used on Gen analysis, improved X2 values but change in
Gen value buried in statistical error bar
_ T20 insensitive since it only uses theta_e
_ Kinematical corrections are really only momentum corrections.
They effectively include eloss
TB: wish to compare to hydrogen based corrections (waits for eugene)
DH: we can only use one set of corrections for H and D
Wch Calibrations:
No plan to redo t2d-residual fit (chi, aki)
B=0 runs: DH suspects some offsets not right, needs to work on it more
FFitter: DH neural net not good enough to be used
TB: expect may have to redo tracking even new offsets come from B=0.
That would mean new t2d fits and kinematical corrections
Spin Angle value for next run
Chi: on going to 45 deg
expect imrpoved statistic error bar
minimizes systematic correction due to T21
poorer spin angle (1 deg)
will quantify these numbers before run
VZ: does not care
Spin Angle correction
_ everybody aware of oop angle, and event by event th_spin, th_q difference
_ z-dependence ready in analysis to be switched on
_ discussion about field map follows
Aki: present analysis of field map data
existing grid of x-z data, estimated uncertainty +- 5 gauss
tosca model: only one available parameter to vary in global fit
fits very purely
no time to fudge around with tosca input params, very slow
DH: suggest that different B(H) could explain some of disagreement
Aki: show results of biot savart calculation, much better agreeement
suggests to forget tosca, just spline the field map data
Then you have only one strenght parameter to play with to fix
the average angle to "observed" value of 31.5 deg (from 47 deg)
discussion:
TB: agree, with that procedure you can have a field map to start with
You will have to do event by event correction anyhow, so better
start now, even if before "final" field map data.
VZ "how can I average spin angle weighing with density distribution ?"
TB: sigh. Density distribution (1-|z|/L), 2L = cell lenght. Just do it.
VZ: but scaling with current is non linear, in a Z-dependent way
TB: yes, but only true for Bz while you need to scale Bz. Event by event
z-dependent spin angle corrections should be included right now, even
if you can't see what you don't want to see.
Inclusive + N-Delta analysis :
NM: talked with TB yesterday, work in progress
TF: needs 2 weeks before presenting results
YX: working on incorporating blastmc. Nothing to show this week
-- ________________________________________________________________________________ Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124 research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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