[d2n-analysis-talk] BB H2 tracks

[posik at jlab.org]

Hi all,

  So for our H2 coin runs, I have selected protons in the LHRS by using
the cuts described in our last meeting. I then looked at these proton
events in the Big Bite. Brad suggested last time to look at how many of
the good proton tracks in the bigbite are left after a target cut.To do
this I did the following:

    First I plotted the z-vertex with no cuts (left) and then the z-vertex
with the proton cut (right). This is in BB_vz.png

    Next I looked at the LHRS proton tracks (far right plot). Then seen
how many show up in the Bigbite (far left plot) and then how many of
these show up with a z vertex cut "abs(BB.tr.vz[0])<0.2" (center
plot). This can be seen in BB_vz_track.png. Using this target cut
there are about 7% of events lost, mostly 0 tracks (ie no track
events). This is also consistent with when I made a proton cut + BB 1
track cut and found about 92% of the good proton LHRS tracks were left
in the BB.

If I plot the events in the bigbite using the proton cut + vz cut + 1
track cut and compare to the events left after a proton cut + 1 track cut.
I find less than 1% of events are lost with the target cut.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: BB_vz.png
Type: image/png
Size: 3484 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20100507/56c19012/attachment.png 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: BB_vz_track.png
Type: image/png
Size: 3129 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20100507/56c19012/attachment-0001.png