[BLAST_SHIFTS] ABS status 2002-12-13

From: Hauke Kolster (hauke@lns.mit.edu)
Date: Fri Dec 13 2002 - 00:42:14 EST


Hello everybody.
Today we have continued to map out the position of the ABS nozzle in
respect
to the skimmer. We have collected about 8 data points that showed a
picture
that is consistent with a misalignment of about 1mm of the nozzle after
pumping and cooling of the nozzle. One can clearly see the loss of beam
due
to the overlap of the nozzle and the skimmer. However the overall signal
in the target chamber remained small.

Unfortunately at about 9 pm we discovered that the glass tube coolant
in the
dissociator leaked into the dissociator can (the one that contains the
rf cicuit)
and we had to pull the dissoiator to protect the other chambers from a
spill.
This sets us back for some time but also enables us to make the
decision for
an alternative solution on the dissociator top flange. Ernie and I
agreed today
to use the original top flange from Amsterdam. This flange enables a
tilt of the
rf can and also results in a motion of the nozzle in respect to the
skimmer
under roughing vacuum conditions so that an alignment of the nozzle can
be
done much faster. With the new pushers we have control over a x-y motion
and a tilt as well as the distance from the skimmer in much shorter
time. The
time estimate is that the flange can be modified by Friday evening and
all
components back in the ABS during the weekend. The alignment of the ABS
through the theodolite is still set up so that the top flange and the
plummet
can be adjusted within a much shorter time now.

In the meantime the dissociator will be cleaned and critical parts
replaced
to get good initial conditions for the upcoming run. Ernie's estimate
was that
the ABS should be operational by the beginning of next week so we can
pick up the studies to find sufficient target density.

The target field is operationl for the longitudinal and transverse
direction
and can be set to L: 250A, T: 500A for an spinangle of 45 deg in the
cell center. The resulting field is in the order of 375 Gauss. For the
exact
calibration please contact Vitaly Ziskin.

I have already tuned the MFT 12-23 transition and written two short
macros
that control the injection states for polarized running:
MFT off: states 1 and 2, average injected polarization P_e = 0.7, P_z =
0.15
MFT on: state 1 only, average injected polarization; P_e = 1, P_z = 1
After taking into account that there are molecules injected in the cell
(P=0)
and also relaxation effects one can expect a polarization of:
MFT off: P_e = 0.5, P_z = 0.25
MFT on: P_e= 0.6, P_z = 0.6
as a realistic number.

Hauke
   



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