[d2n-analysis-talk] Pions from run 1530 where pre-shower sum was not included in trigger

[Vahe Mamyan]

 Hello,

In  run 1530 pre-shower sum was not included in trigger and pions are
plenty.
Attached is pre-shower and shower energy distribution with  Cerenkov cut
Diana had in her macro.
TCut = cer_cut = basic_e&&cer_tot&&"abs(BB.tr.p-0.6)<0.1";

Since I applied a cut on BB.tr.p to be around 0.6 GeV the blue peak
corresponds to pions that have a sharp red peak
in pre-shower to give total energy around 0.6 GeV. As you can see if one
removes the pion peak from shower energy
distribution the remaining spectrum in shower looks symmetric and in
pre-shower too.
Also it can be seen that the blue pion peak is centred at around 0.5 GeV
and looking at
https://hallaweb.jlab.org/wiki/images/e/e0/Bbsimulation_new.pdf page 2 left
blue spectrum one can see that there is similar peak in around 0.5 GeV.
The peak in page 2 is not as visible as in run 1530 because pre-shower sum
was included in the trigger and momentum cut abs(BB.tr.p-0.6)<0.1 takes
only
pions that deposit more than 0.1 GeV energy in pre-shower.

I still think that Cerenkov adc cut was not enough to remove much pions as
Mattew showed in page 11 of his report.
I estimated Cerenkov rejection power to be 1:5.5 from run 1530.
According to Wiser parametrization there are about 24 pions for each
electron in BigBite acceptance, so roughly
there are  4.3 pions for each electron and taking account that most pions
are at lower energy, this number is higher.

Best regards,
Vahe
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20111202/37cdcdc0/attachment.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pre-shower_shower_energy.gif
Type: image/gif
Size: 11944 bytes
Desc: not available
Url : https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20111202/37cdcdc0/attachment.gif