Log entry time 18:47:04 on March 23, 2011

Entry number 352998

Followups:

• 353058 03/24/11 10:43 yez L-HRS: Cerenkov ADC overfload. Need to recude the HVs

After I calibrated Cer and PRLs, I studied the PID of Left HRS and found
some issues:
 
 1,I cut on a small spot on PRL2.vs.PRL1 to select electrons, and look at
the L.cer.asum_c (blue line). As you can see, there still have many low
ADC channels in Cerenkov SUM, which means that from Cer, there are still
many Pions. After I cut on L.cer.asum_c at >300, where the single
electron peak is, the efficiency of electron already reduces to 97%.
[[Image:L.prl.cer.png]]

 2, I did the reverse way by cutting on high ADC channels of Cer Sum
(4000~5900), which indicates that most of them should be electrons.
However, when I cut on the electron peaks of PRL1&2, there are only 87%
of electrons. It looks like some pions deposite very big energy in
Cerenkov, which does not make sence since their energy must be very huge
to produce big signals in cerenkov PMTs.  
[[Image:L.prl.eff.png]]

 3, I look at the L.tr.beta (raw beta before timing calibration). As you
can see, even I cut on PRL1.vs.PRL2 to pick electrons, in the beta
spectrum, the peak of pion is still very comparable to electron peaks.
[[Image:L.beta.eff.png]]

 4, After only applying cut on L.cer.asum_c>4000, which basically can
remove most of pion, I plot of L.tr.beta,and still find that there is a
pion peak.
[[Image:L.beta.eff2.png]]

 In a word, it looks like the ADC signals of Cerenkov and PRL do not look
normal. Is there any problem with the synchronization of ADCs and triggers?

L.cer.eff.png

L.prl.eff.png

L.beta.eff.png

L.beta.eff2.png