[d2n-analysis-talk] BB shower

[posik at jlab.org]

Hi all,

 I have taken a look some of the individual block amplitudes in the big
bite shower to see if I can see why I am getting negative calibration
coefficients. For all amplitudes I make a vertex cut, an invariant mass
cut, E/p and a preshower energy cut, as well as require at least one
reconstructed track. The block which gave me a negative coefficient are
blocks 1,4,5,28,37,76,130 and 163. The shower geometry for the blocks can
be found here:

https://hallaweb.jlab.org/wiki/images/1/13/Shower.pdf

Most of the negative blocks are on the upper (physically looking at the
detector) edge which since we are at low energy (1.2GeV) we would expect
low statistics in this region, so maybe some are negative due to lack of
events. The first figure shows the amplitude of block 1 with and without
cuts. You can see that there is almost no signal there. The Second plot
shows several blocks all with cuts and you can see that the two blocks
near the physical bottom of the detector (blocks 26,97) have a good signal
near channel 1000.

 I think that the negative coefficients is due to a cut conflict in the
energy reconstruction script, because I was not able to include an E/p
cut when running the reconstruction script; It generated a divide by zero
error. I am not plotting "BB.tr.n" applying the cut I want to use, and
then going into the reconstruction script and using that same cut. If all
is good with the cuts, the events on the T->Draw("BB.tr.n") and that
recorded by the reconstruction script should match. This will let me iron
out the cut conflict.

-Matt


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