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</style><article id="node-712304" class="node node-logentry contextual-links-region article ia-n clearfix" role="article"><header class="node-header"><h1 class="node-title">
<a href="https://logbooks.jlab.org/entry/3639399" rel="bookmark">Initial CCAL (NPS prototype) calibration and energy resolution</a>
</h1>
</header><div class="contextual-links-wrapper"><ul class="contextual-links"><li><a href="https://logbooks.jlab.org/entry/3639399/edit?destination=email/send">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/3639399/delete?destination=email/send">Delete</a></li></ul></div>
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<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/3639399" class="lognumber" data-lognumber="3639399">3639399</a>. Submitted by <a href="https://logbooks.jlab.org/user/somov">somov</a> on <time datetime="2018-12-16T13:32:13-0500" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1544981533&end_date=1544988733&book=HDCCAL&book=HDLOG">Sun, 12/16/2018 - 13:32</a></time>. </p>
<table class="field-vitals"><tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/hdccal">HDCCAL</a> <a href="https://logbooks.jlab.org/book/hdlog">HDLOG</a></td></tr><tr><th>Entry Makers: </th><td>somov, berdnik</td></tr></table></div>
<div class="logentry node-content">
<p>I ) In order to equalize gains on CCAL modules<br />
we performed a HV scan for each module (runs<br />
51824 - 52004). Each CCAL module was positioned<br />
to the photon beam. Energy of beam photons was<br />
determined using tagging detectors. HVs were<br />
computed according to the required energy range:</p>
<p>- energy deposition of a 10 GeV photon<br />
is required to be around fadc count 3100<br />
(note, the maximum fadc range is 4096 counts)</p>
<p>- we set voltages by requiring the average fadc<br />
amplitude for 4.2 GeV photons to be 1267 fadc<br />
counts. </p>
<p>--------------</p>
<p>After setting voltages, we checked the calibration<br />
(runs 2216 -22364)</p>
<p>Fig 1. FADC amplitudes of CCAL modules corresponding<br />
to 4.2 GeV photons. Sigma of the distribution is<br />
about 1.3 % </p>
<p>Fig. 2 FADC amplitudes of CCAL modules corresponding<br />
to ~10. GeV photons</p>
<p>Fig. 3.The amplitude ratio (A (10 GeV) / A (4.2 GeV)<br />
The relative width of the distribution is about 0.4 %<br />
(relatively stable performance of all modules).</p>
<p>The HV setting procedure worked well for most<br />
modules except of 10:</p>
<p>We didn't calibrate two modules (5,4) and (-2,-6).<br />
There are 7 suspicious modules (-4,6), (-2,6), (-6,5),<br />
(-4,4), (4,-2), (-6,-4), (5,-5).</p>
<p>For these modules, we adjusted voltages "by hand".<br />
We'll check calibration after we finish with<br />
Compton production runs.</p>
<p>-----------</p>
<p>II ) We used the initial gain calibration to estimate<br />
the energy resolution of CCAL</p>
<p>Fig. 4 Energy distribution for 4.2 GeV photons</p>
<p>- energy deposited in the single CCAL module (curve on the left)</p>
<p>- total energy deposited in 5x5 cells (curve on the right). The<br />
relative energy resolution (width of the distribution over the<br />
mean value is about 2%)</p>
<p>We checked different regions in the detector. The typical<br />
energy resolution for 4.2 GeV photons is 2 - 2.3 %</p>
<p>Fig. 5 Energy distribution for 10 GeV photons</p>
<p>- the typical energy resolution is 1.4 - 1.6 %</p>
<p>The energy resolution can be improved after we refine gain<br />
calibration. Two things have to be done: </p>
<p>- gain can be refined by fitting energy distributions in 5x5<br />
modules to the shower profile </p>
<p>- data have be taken in a raw fadc mode<br />
(in Fig. 3 and Fig. 4 the fadc threshold for each module<br />
was set to 27 MeV)</p>
</div>
<div class="attachment-box">
<div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2018/12/3639399/gain_calib_amp_4_2.png" width="598" height="374" alt="" title="Fig 1. FADC amplitudes of CCAL modules corresponding to 4.2 GeV photons. " /></div> <div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2018/12/3639399/gain_calib_amp_10.png" width="598" height="374" alt="" title="Fig. 2 FADC amplitudes of CCAL modules corresponding to ~10. GeV photons" /></div> <div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2018/12/3639399/gain_calib_ratio.png" width="598" height="374" alt="" title="Fig. 3 The amplitude ratio (A (10 GeV) / A (4.2 GeV) The relative width of the distribution is about 0.4 % (relatively stable performance of all modules)." /></div> <div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2018/12/3639399/row_n4_col_n1_en_4GeV.png" width="498" height="374" alt="" title="Fig. 4 Energy distribution for 4.2 GeV photons. Energy deposited in the single CCAL module (curve on the left). Total energy deposited in 5x5 cells (curve on the right) " /></div> <div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2018/12/3639399/row_n4_col_n1_en_10GeV.png" width="498" height="374" alt="" title="Fig. 5 Energy distribution for 4.2 GeV photons. Energy deposited in the single CCAL module (curve on the left). Total energy deposited in 5x5 cells (curve on the right) " /></div> </div>
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