Hi Brad,<div><br></div><div> I do not understand the large change in the pion rejection from PMT 14,16. I spent a lot of time last night looking into it, but could not conclude why. I talked to Dr. Meziani about it and said he needed to think about it. Do you have any ideas? I should also mention that pmts 11,12 and 18 had no events left in the pion sample after I applied the Cerenkov cut to them. </div>
<div><br></div><div>The errors that I had on the pion rejection factors were not completely correct. Since I am plotting N_p/N_e, where N_p is my initial pion sample, and N_e is the number of events left after my Cerenkov cut, then my error should be </div>
<div><br></div><div>(1/N_e)*sqrt(N_p)</div><div><br></div><div>My most recent version of the talk that I just sent out has this plot with the errors above on it. The error bars are hidden due to the log scale. But the ranged on average from 1-20.</div>
<div><br></div><div>For the pion rejection, I used the T6 and the initial pion sample on the small angle side ranged from ~5000-3000 events per mirror, with pmt 8 having 400 events. And for the large angle side the initial pion sample ranged from 3000-900 events per mirror, with pmt 18 having 200 events.<br>
<br></div><div>Thanks</div><div>-Matt</div><div><br><div class="gmail_quote">On Tue, Dec 7, 2010 at 9:12 AM, Brad Sawatzky <<a href="mailto:brads@jlab.org">brads@jlab.org</a>> wrote:<br><blockquote class="gmail_quote">
<br>
The change in pion rejection for PMTs 14,16 are pretty strange. Any<br>
idea why? I presume the large error bars are due to using T1 or T6<br>
data? (Which is fine, I'm just checking.)<br>
<br>
-- Brad<br>
<div><div></div><div class="h5"><br>
On Mon, 06 Dec 2010, <a href="mailto:posik@jlab.org">posik@jlab.org</a> wrote:<br>
<br>
> So I added some error bars to the BB cerenkov pion rejection factors<br>
> that I showed last week. I also redid the rejection factor vs BB Cer<br>
> photo electron cut using the pion selection of E/p<0.8 and 10 <<br>
> preshower < 250.<br>
><br>
> So the plot pion_selection.eps shows my pion sample selection.<br>
><br>
> I then looked at how many particles from the pion sample were passing<br>
> through the geometrical location of a Cerenkov mirror, I called this<br>
> variable N_p. I then how many of the N_p particles also fired the Cerenkov<br>
> ADC and TDC and called this number of events N_e. I then defined my pion<br>
> rejection factor as<br>
><br>
> pion_rejection = N_p/N_e, and following Dr. Meziani's advice took the<br>
> Sqrt(N_p) as my error.<br>
><br>
> I did this for each pmt, see cer_pi_rej.eps for the small angle side and<br>
> rhrs_cer_pi_rej.eps for the large angle side. The different data markers<br>
> represent the rejection factor at different BB Cerenkov ADC photo-electron<br>
> cuts. I also plotted the average rejection factor for each side of the<br>
> Cerenkov as a function of photo-electron cut, see cer_avg_pi_rej.eps and<br>
> rhrs_cer_avg_pi_rej.eps.<br>
><br>
> I am now going to do a similar thing for the electron efficiency.Please<br>
> let me know what you think of these plots.<br>
<br>
</div></div><font color="#888888">--<br>
Brad Sawatzky, PhD <<a href="mailto:brads@jlab.org">brads@jlab.org</a>> -<>- Jefferson Lab / Hall C / C111<br>
Ph: 757-269-5947 -<>- Fax: 757-269-5235 -<>- Pager: <a href="mailto:brads-page@jlab.org">brads-page@jlab.org</a><br>
The most exciting phrase to hear in science, the one that heralds new<br>
discoveries, is not "Eureka!" but "That's funny..." -- Isaac Asimov<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Matthew Posik<br>Email: <a href="mailto:posik@temple.edu">posik@temple.edu</a><br>Temple University Physics Dept.<br>Office: BA-319<br>Office #: 215-204-1331 <br>
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