Ben summarized the current situation very well in his shifts summary.
Plan is to continue running polarized Deuterium.
We'll watch the drift time spectra on the left and right sector on a
run-by-run basis. The position of the valve in the left sector branch
might have to be readjusted. At present it is half closed, meaning that
the impedance of the left branch should have increased by a factor 2.
If the right sector recovers while the left does not get worse, then we
would have found the quick fix.
If the right branch recovers and the left branch gets worse, we would
have closed the valve too far and would have to readjust it (open it somewhat
further).
If the right sector does not recover and the left one remains fine, then
we would have closed the valve not far enough and would have to readjust
it (close it somewhat further).
If instead the left branch gets worse while the right one remains
unchanged, then there is some poisoning in the right branch that cannot be
solved with a quick fix. Note that it needs some hours before we can tell
any definitive trends. In this case we would open the left-sector valve
again such that the left-sector performance becomes fine again and take
data (those data are still useful for GEn).
In any case, the He-3 test is postponed until next week. This test is also
closely related to active beam tuning and is not suited for weekend and
overnight shifts. Since we still can take useful data with polarized
Deuterium, this is the preferred way.
Plan is also to run for a period of time with the forward LADS (L15)
turned off, for systematic studies on e,e'n rates and possible
detector-related deadtime. I will give instruction on this at given time.
Regards,
Michael
--+-------------------------------------+--------------------------+ | Office: | Home: | |-------------------------------------|--------------------------| | Dr. Michael Kohl | Michael Kohl | | Laboratory for Nuclear Science | 5 Ibbetson Street | | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 | | Middleton, MA 01949 | U.S.A. | | U.S.A. | | | - - - - - - - - - - - - | - - - - - - - - -| | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de | | Work: +1-617-253-9207 | Home: +1-617-629-3147 | | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 | | http://blast.lns.mit.edu | | +-------------------------------------+--------------------------+
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