Hello,<br><br>In run 1530 pre-shower sum was not included in trigger and pions are plenty.<br>Attached is pre-shower and shower energy distribution with Cerenkov cut Diana had in her macro.<br>TCut = cer_cut = basic_e&&cer_tot&&"abs(BB.tr.p-0.6)<0.1";<br>
<br>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<br>in pre-shower to give total energy around 0.6 GeV. As you can see if one removes the pion peak from shower energy<br>
distribution the remaining spectrum in shower looks symmetric and in pre-shower too. <br>Also it can be seen that the blue pion peak is centred at around 0.5 GeV and looking at <br><a href="https://hallaweb.jlab.org/wiki/images/e/e0/Bbsimulation_new.pdf">https://hallaweb.jlab.org/wiki/images/e/e0/Bbsimulation_new.pdf</a> page 2 left blue spectrum one can see that there is similar peak in around 0.5 GeV.<br>
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 <br>pions that deposit more than 0.1 GeV energy in pre-shower. <br>
<br>I still think that Cerenkov adc cut was not enough to remove much pions as Mattew showed in page 11 of his report.<br>I estimated Cerenkov rejection power to be 1:5.5 from run 1530.<br>According to Wiser parametrization there are about 24 pions for each electron in BigBite acceptance, so roughly <br>
there are 4.3 pions for each electron and taking account that most pions are at lower energy, this number is higher.<br>
<br>Best regards,<br>Vahe<br>