[Cuga] Change of the Accelerator Energy Gain per Pass- a message from Rolf Ent and Arne Freyberger for the Nuclear Physics Experiment

[Lorelei Carlson]

MEMORANDUM
Date: March 5, 2019

Within the past week, C100 cryomodules 1L25 and 1L26 in the North Linac had a combined loss of 32
MeV of energy gain per pass. This loss is due to contamination of the SRF cavity surface and cannot be
recovered without removal of the entire cryomodule from CEBAF. The North linac had no headroom
going into this event; there is no choice but to lower the accelerating gradient of both linacs. The
research program, with modification as describe in the next paragraph, will continue once CEBAF has
been configured at the lower energy.

The energy gains of 1000 MeV and 1020 MeV in the North and South Linac respectively have been
chosen as the values that provide the highest energy possible with good likelihood of completing the
research laid out for this run cycle. The chosen gradients affect negatively some of the experiments in
Halls B and C but will allow completing other parts of them.

Using the lessons learned during this run cycle, our effort has now shifted to understand our options,
schedule the necessary module repairs and maintenance to achieve the Fall run cycle energy
requirements.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/cuga/attachments/20190305/9e98a076/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 20190305.2_Memo.pdf
Type: application/pdf
Size: 48919 bytes
Desc: 20190305.2_Memo.pdf
URL: <https://mailman.jlab.org/pipermail/cuga/attachments/20190305/9e98a076/attachment-0001.pdf>