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<a href="https://logbooks.jlab.org/entry/4338462" rel="bookmark">Conclusion of ECal test</a>
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<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/4338462" class="lognumber" data-lognumber="4338462">4338462</a>. Submitted by <a href="https://logbooks.jlab.org/user/jonesdc">jonesdc</a> on <time datetime="2025-03-12T07:43:29-0400" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1741776209&end_date=1741783409&book=HALOG">Wed, 03/12/2025 - 07:43</a></time>. </p>
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Last updated on <time datetime="2025-03-12T07:44:52-0400" pubdate="pubdate">Wed, 03/12/2025 - 07:44</time> </p>
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<tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/halog">HALOG</a></td></tr>
<tr><th>Entry Makers: </th><td>jonesdc</td></tr>
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<p>The ECal heater system has been turned off. Here are some observations and conclusions we can take away.<br />
1. The burn off is complete and the VESDA levels have stabilized at the 1bar barely visible level and seem to be going down even with the doors all closed. We can run in a beam configuration without alarming the VESDA system.<br />
2. We easily reached 290 degC on the front plates of the supermodules and 230 degC on all but 3 of the edge aluminum bar heater zones. Of the three that did not reach their final set point, one likely would have and the other two probably would have stabilized 10 to 20 degC lower due to their position. These temperatures setpoints were chosen because they were used to reach the desired crystal temperatures in the prototype.<br />
3. The 290 degC on the front plates of the supermodules appears to be insufficient to reach 220 degC on the fronts of the crystals even though it did in the prototype. The crystal temperatures were largely in the 170 to 190 degC range on the hot end and although still rising when I turned off the heaters, were doing so very slowly much less than 1degC per hr.<br />
4. The enclosure temperature is also hotter than the prototype. This is partially due to the PMTs+bases that were not present. The addition of the air conditioner helped but temperatures particularly on the upper half were elevated to point we would not want to run that way.<br />
5. A large temperature gradient exists in the enclosure with temperatures at 20 deg C near the bottom and above 50 degC at the top. The cooling exhaust at the end of the exhaust pipe measures 53 degC! It appears that the convective heat loss is much higher in the actual ECal detector than the prototype creating cooler crystals and a warmer enclosure. Plans are underway to mitigate the enclosure temperature with further cooling focused at the top. However, there is very little headroom for further heating on the hotter side of the crystals closer to the target since the detector was designed with an upper bound of 300 degC for materials, so we may not reach much above 190 degC on the hot side.</p>
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