Hello All,
This afternoon Doug determined the optimal wire position (-1.0 mm) with the
magnetic field off with slit setting of 0,14,5,-3 for L,R,T,B
respectively. This was done by examining the effects of wire position on
beam lifetime. For the evening shift, the magnetic field was turned on to
see its effects on background. However, the large magnetic field had
caused the read back value to drift from its fully retracted position of
-25.0 to 8.0 mm which would be deep in the beam. This was determined to
be a read back problem only and not a shifting of the wire itself. There
were two solutions, shielding the linear voltage displacement transducer
with a mu metal and a controls (software) fix. Peter Bins came in and did
the shielding which turned out to be unsuccessful however Dan Cheever was
abe to perform the temporary software fix that allowed us to continue. This
problem had eaten up most of the evening shift.
Since the beam position changes with the field on, the slits and wire
position were optimized again. The slits are at 1,14,5,-3 for L,R,T, B
respectively and a wire position of -0.6 mm. After optimization two runs
were taken:
Run 1822:
trigger =any_coincs_lowt
Torroid Current =6730 Amps
Sense,Field, Guard = 3700,3570,1900
Run 1823:
trigger=elastic_tof10-15~0001
Torroid Current =6730 Amps
Sense,Field, Guard = 3700,3570,1900
I did not have time to look at them in any depth.
Adam
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:28 EST