Hello:
this is to summarize the final numbers for the target spin angle:
We agreed to use the ed elastic tensor asymmetry to first determine the ed
elastic yield-weighted average, and then deduce theta_nominal for the
considered profile [theta_nominal = theta(z=0)].
Doug's profile should be used. It is in cvs at
exp/analysis/macros/target_spin_angle.C.
It requires a global alignment given by "theta_nominal" which is the
profile's value at z=0. While the same theta_nominal applies to all
reaction analyses, each resulting yield-weighted average angle can
vary individually. For use in DGen, I've added the 32 and 47 deg profiles
with proper values for "theta_nominal" (see below) into kine.init just as
a grid z:theta, uncomment the lines to activate. I've generated the lines
in kine.init with the macro exp/analysis/macros/DPprofile_to_kineinit.C,
find both in the latest cvs.
Results:
For the "32" degree setting, theta_nominal = 34.12 +- 0.43
For the "47" degree setting, theta_nominal = 48.84 +- 0.45
Chi recommends to generally quote an error of 0.5 degrees to be on
"the conservative side and and to partially reflect the fact that
there are conflicting results" [with ep elastic when it is used to
determine the spin angle].
In the table below, compare <th>_yield between "map" and "asym": it
tells by how much a given map needs to be shifted to comply with the
physics of tensor ed elastic. The error is given by the uncertainty
with which the overall alignment can be determined from the ed elastic
tensor asymmetry and is on the order of 0.5 degrees, while the error on
the "shape" of the profile(s) is on the order of 0.1 deg or less and
hence negligible.
32 degrees setting: ed elastic
==============================
Ed-elastic yield-weighted average angle for original maps from survey:
<th>_yield <dth>_yield theta_nominal(z=0) Comment
31.2(map) -2.89 34.09 original Jan2005 map
30.6(map) -2.75 33.35 original Jun2005 map
"map" is the yield-weighted average angle for a given original map
----------------------------------------------------------------------
Angle from tensor asymmetry analysis and resulting theta_nominal:
<th>_yield <dth>_yield theta_nominal(z=0) Comment
31.3(asym) -2.89 34.19 shifted Jan2005 + 0.1
-2.75 34.05 shifted Jun2005 + 0.7
-2.82(av.) ->34.12 nominal angle for DH's profile
31.7(oldasym)
"asym" is the yield-weighted average angle from asymmetry analysis
(asym=v3_4_18, oldasym=online crunch version)
==> theta_nominal = 34.12 degrees
Error on theta_nominal: statistical: 0.35
tracking: 0.20
false asym: 0.10
theory: 0.10
TOTAL: 0.43
======================================================================
======================================================================
47 degrees setting: ed elastic
==============================
Ed-elastic yield-weighted average angle for original maps from survey:
<th>_yield <dth>_yield theta_nominal(z=0)
47.0(map) -1.5 48.5 original Jul2004 map
46.7(map) -1.5 48.2 original Jan2005 map
46.2(map) -1.32 47.52 original Jun2005 map
"map" is the yield-weighted average angle for a given original map
----------------------------------------------------------------------
Angle from tensor asymmetry analysis and resulting theta_nominal:
<th>_yield <dth>_yield theta_nominal(z=0)
47.4(asym) -1.5 48.9 shifted Jul2004 + 0.4
-1.5 48.9 shifted Jan2005 + 0.7
-1.32 48.72 shifted Jun2005 + 1.2
-1.44(av.) ->48.84 nominal angle for DH's profile
47.8(oldasym)
"asym" is the yield-weighted average angle from asymmetry analysis
(asym=v3_4_19, oldasym=online crunch version)
==> theta_nominal = 48.84 degrees
Error on theta_nominal: statistical: 0.45
tracking: 0.12
false asym: 0.01
theory: 0.10
TOTAL: 0.45
======================================================================
======================================================================
Best regards,
Michael
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