[Frost] Possible polarization problems and data request

[Michael Dugger]

Hi,

Here at ASU we are seeing a need to renormalize the polarization for 
circular beam - longitudinal target data. The shift in polarization that 
we see is large. The renormalization is about an 8% effect! The problem 
could very well be in our code, but we are having a difficult time finding 
an error that could cause this 8% shift.

We would like to compare ASU results for the pi+ n and pi0 p reactions 
with that of our fellow collaborators. In the past, we were able to see 
that we roughly agree with the results from Hideko's pi0 p, and Steffen's 
pi+ n analyses, but would like to do a more precise comparison. In order 
to make a better comparison, we need to have the actual numbers for the E 
observable for the pion reactions. Figures of the E observable are not 
sufficient for us to determine if there is an overall 8% shift.

If there is any other group that has looked into the pion measurements, we 
would greatly appreciate obtaining those preliminary data as well.

Our plan is to bin the ASU pion E observable identical to any data that 
has been shared with us. We will then concentrate on the central 
center-of-mass angles (where the measurements are robust) and make 
division plots. We will take the shared preliminary pion E results and 
divide them by the ASU results for as many energy bins as possible and see 
if there is any overall features that point to a problem with the ASU 
code.

If we find that the ASU pion results agree with those of other groups we 
would have strong evidence of a problem with the polarization values. If, 
on the other hand, we see systematic disagreement between the results 
from ASU and other groups, we will have a better handle on where to look 
for problems with the ASU code.

Thanks for your time.

Sincerely,
Michael