Hello, All:
We started off the night getting Dan Cheever's software fix for the wire
target instability to run. To do so, run medm. Then open the following
file:
/home/locus/cheever/BLAST_wire_target.adl
When this GUI comes up, ignore everything except the box that says Motor
Readback. This box, regardless of what the others say, should equal the
value in the Desired Position box (which is the value that CCR can
adjust).
Due to the power outage last night, the beam was having trouble staying
stable for the first few hours. When stability arrived, we re-positioned
the slits. However, when we went to take a run, the beam instability
arose again, and no beam was available for a hour or so. When it
stabilized, we took a run (1831) with no wire target and with WC voltages
of 3600/3570/1900.
We then re-positioned the slits. There optimal positions are:
L R T B
-2 +19 +7 -10
We then started another run (1832) still with no wire target and with the
WC voltages the same as before.
Looking at the TDC's from the two afore-mentioned runs, a definite slope
is visible. Perhaps the valley of stability isn't quite reached at 3600V.
We also noted, during this process, that all of the runs since 1823 have
not appeared on the SPUD's. Don't know why...
Finally, we tried to put the wire target in. A drop in the lifetime of
about 50% occurred at the wire position of +1.8mm. We then took the
target out (to -25mm) for a fill. When we put it back in to +1.8mm, the
lifetime was unaffected. We moved the target to +1.85 and then +1.90,
and, if anything, the lifetime rose. (???)
A. Maschinot and P. Karpius
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:28 EST