<br><br><div class="gmail_quote">On Fri, Dec 17, 2010 at 12:47 PM, Brad Sawatzky <<a href="mailto:brads@jlab.org">brads@jlab.org</a>> wrote:<blockquote class="gmail_quote">
Some of your plots seem to indicate E/p is happening for more than 10%<br>
of physics triggers that have a track. Is that really the case?<br>
Are those E/p==0 values correlated with cosmics? (ie. the frequency of<br>
the problem will get larger at higher LHRS p0 setting, beta will be<br>
negative, the track will probably not reconstruct to the target).<br></blockquote><div><br></div><div>using EDTM==0,T3 trigger, VDC one cluster (for each plane), I plotted L.tr.n for each kinematic. I compared that number to the same histogram with the same cuts plus the cut E/p==0 (and taking the ratio, with E/p==0 events being 'bad'):</div>
<div><br></div><div><div>kin | p | E | Bad/Total (%)</div><div>0 0.60 4.73 9.05</div><div>1 0.60 5.89 9.43</div><div>
2 0.80 4.73 8.68</div><div>3 0.90 5.89 9.27</div><div>4 1.13 5.89 9.83</div><div>5 1.20 5.89 10.09</div>
<div>6 1.27 5.89 11.01</div><div>7 1.42 4.73 13.21</div><div>8 1.42 5.89 12.99</div><div>9 1.51 4.73 16.78</div>
<div>10 1.51 5.89 15.15</div><div>11 1.60 4.73 22.52</div><div>12 1.60 5.89 19.80</div><div>13 1.70 5.89 25.07</div>
</div><div><br></div><div><br></div><div>Now, to investigate the correlation to cosmics, I added the cut L.tr.beta>0 to the above histograms:</div><div><br></div><div><div>kin | p | E | Bad/Total (%)</div>
<div>0 0.60 4.73 8.91</div><div>1 0.60 5.89 9.29</div><div>2 0.80 4.73 8.39</div><div>3 0.90 5.89 8.87</div>
<div>4 1.13 5.89 8.84</div><div>5 1.20 5.89 7.92</div><div>6 1.27 5.89 8.57</div><div>7 1.42 4.73 8.10</div>
<div>8 1.42 5.89 8.68</div><div>9 1.51 4.73 9.05</div><div>10 1.51 5.89 8.75</div><div>11 1.60 4.73 11.37</div>
<div>12 1.60 5.89 10.60</div><div>13 1.70 5.89 13.45</div></div><div><br></div><div>So it seems that cosmics do play a role to some degree here. </div><div>
<br></div><div>I've also constructed a raw sum of the PRL ADCs (see file 1, which also has a sample L.tr.n plot (total events in black, E/p==0 in red, and a sample beta plot for the E/p==0 events). I've verified the pedestal subtracted sums, so I have confidence that this is correct (see second file which shows the pedestal subtracted sum from my code as a 1D histo, along with the plot vs. the energy, determined by the analyzer; plots of L.tr.n and beta are shown again). The last file shows the ADC pedestal subtracted sum determined by the analyzer. </div>
<div><br></div><div>The 2D plot of the raw ADC sum vs. the energy (calculated by the analyzer) shows something that looks to be fairly ok; however, there were instances (from my output to the screen) where the energy was identically zero while the ADC sum in either of the layers was not zero. </div>
<div><br></div><div>For instance:</div><div><br></div><div><div><div>======================== Event: 171472 ========================</div><div><br></div><div>PRL1 Block: 16 ADC value: 506.0000</div>
<div>ADC sum value: 506.0000</div><div>Energy Sum: 0.0000</div><div>======================== Event: 171473 ========================</div><div><br></div><div>PRL1 Block: 8 ADC value: 533.0000</div>
<div>ADC sum value: 533.0000</div><div>Energy Sum: 0.0000</div></div></div><div><br></div><div><div>======================== Event: 1108548 ========================</div><div><br></div><div>PRL1 Block: 8 ADC value: 533.0000</div>
<div>ADC sum value: 533.0000</div><div>PRL1 Block: 16 ADC value: 508.0000</div><div>ADC sum value: 1041.0000</div><div>PRL1 Block: 24 ADC value: 489.0000</div>
<div>ADC sum value: 1530.0000</div><div>Energy Sum: 0.0000</div></div><div><br></div><div><br></div><div>From my pedestal subtracted sums: </div><div><br></div><div><div>======================== Event: 1408639 ========================</div>
<div><br></div><div>PRL1 Block: 2 ADC value: 11.0000</div><div>ADC sum value: 11.0000</div><div>Energy Sum: 0.0000</div><div><br></div></div><div>which leads me to believe that the occurrence of E==0 for the raw sum (above) was pedestal events -- maybe the pedestals for some of these blocks are not perfectly subtracted so that they sit at zero, or maybe a binning issue?</div>
<div><br></div><div>I'm still digging around the source code for the ExTgtCor_L.p variable so I can see how it's set to kBig...</div></div><br>-- <br>-----------------------------------------------------------<br>
David Flay<br>Physics Department<br>Temple University<br>Philadelphia, PA 19122 <br><br>office: Barton Hall, BA319<br>phone: (215) 204-1331<br><br>e-mail: <a href="mailto:flay@jlab.org">flay@jlab.org</a> <br>
<a href="mailto:flay@temple.edu">flay@temple.edu</a><br><br>website: <a href="http://www.jlab.org/%7Eflay">http://www.jlab.org/~flay</a><br> <a href="http://quarks.temple.edu">http://quarks.temple.edu</a><br>
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