The z estimation in the BMU_DtoE has been repaired, and now
seems to make sense. In the upper left
plot (due to Camille: it is a plot based on reconstructed muons)
we see x vs y. The gap at the bottom is where we lack chambers
because of the toroid supports. Notice that most of the stub positions
are exactly where we expect--in a ring. However, 7.5% of them show up
in various places inside the toroid region, including quite a number
at about 1.3 meters radius. I do not yet understand why these nominal
stub positions appear here. When I plot the position of the stub
at the time of stub creation I see only the outer ring.
All but 3 of these curiously placed stubs are
3-hit stubs; which suggests
a place to start looking. See below for solution
The upper right plot
is that of the z of the stubs, which looks
sensible. The spike at the rear of the chambers is due to accidental
matching of a COT track and one of the rear stubs that bedevil us.
The lower left plot shows that the odd x/y positions don't correlate
with z. The lower right shows the chi-squared of the stubs, which are
looking sensible again since the alignment corrections.