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<p class="MsoNormal" style="text-autospace:none"><b><span style="font-size:12.0pt;font-family:"TimesNewRomanPS-BoldMT","sans-serif";color:#00000A">MEMORANDUM<o:p></o:p></span></b></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:#00000A">Date: March 5, 2019<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:#00000A"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">Within the past week, C100 cryomodules 1L25 and 1L26 in the North Linac had a combined loss of 32<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">MeV of energy gain per pass. This loss is due to contamination of the SRF cavity surface and cannot be<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">recovered without removal of the entire cryomodule from CEBAF. The North linac had no headroom<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">going into this event; there is no choice but to lower the accelerating gradient of both linacs. The<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">research program, with modification as describe in the next paragraph, will continue once CEBAF has<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">been configured at the lower energy.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">The energy gains of 1000 MeV and 1020 MeV in the North and South Linac respectively have been<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">chosen as the values that provide the highest energy possible with good likelihood of completing the<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">research laid out for this run cycle. The chosen gradients affect negatively some of the experiments in<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">Halls B and C but will allow completing other parts of them.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">Using the lessons learned during this run cycle, our effort has now shifted to understand our options,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">schedule the necessary module repairs and maintenance to achieve the Fall run cycle energy<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"TimesNewRomanPSMT","sans-serif";color:black">requirements.</span><o:p></o:p></p>
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