[d2n-analysis-talk] BB shower calibration

[posik at jlab.org]

Hi all,

  Sorry I could not get this ready in time for the analysis meeting
yesterday, but I was running around teaching and tutoring all day.

  So I have just plotted some the the results of the 4pass 3He BB shower
calibration. You can find the plots that I am talking about here:

http://jlab.org/~posik/d2n/BB/4pass_sh_cal/2060_plots/

The plots labeled psh_const_hist.gif and sh_const_hist.gif, show a
histogram of the preshower and shower energy coefficients.

I should mention that for all of the plots, I have applied single track
cut, track quality cuts, vertex cut, charge cuts and a momentum cut  of  
0.5<p<2.0.

The plot called "energy.gif" This shows the calibrated total energy in red
and the reconstructed momentum in blue. The striking thing here is that
the momentum seems to jump near 900 MeV. This is using the momentum that
Diana had fixed.

Next  I looked at the E/p. The plot Ep_p.gif shows the E/p vs the
momentum. I had used some electron cuts on this plot. ( that is prehsower
>500 and the particles passing through the cerenkov mirror location, and
the BB_cer adc and tdc firing). There is a faint line with a slight slope
just below E/p=1 , I think that this may be due to pions, I will show why
shortly.

Following this I then looked at the energy vs momentum, this can be seen
in E_p.gif. This appears to be pretty linear. I again put the following
cuts on it   (  prehsower >500 and the particles passing through the
cerenkov mirror location, and the BB_cer adc and tdc firing)

I was then curious to see how the E/p and the E/p vs p distribution would
change with PID cuts. So to look at this I plotted the E/p with no PID,
PID=electron (cuts are: BB cer_mirror cut + preshower>500) and PID=pion
(cuts are: BB_cer_mirror cut+ preshower <500).

These can be seen on the left  column of  "EP_pid_no_cer.gif"  The right
column shows the E/p vs p for the 3 PID cuts.

I then look again at the E/p and the E/p vs p distribution, but using BB
Cerenkov in the PID cuts. Looking at the Ep_pid_cer.gif , the left is
again E/p and the right is E/p vs p
   -No PID cut (Top): Cut was just that the event had to pass through
location of the BB cer mirror

  -PID=electron (middle) Cut was event had to pass through BB cer mirror
location fire the BB cer ADC , fire the BB cer TDC and preshower >500

-PID = pion (bottom) Cut was event had to pass through the BB cer mirror
location, not fire the BB cer  TDC, not fire the BB cer ADC and preshower
< 500

-matt