Re: [BLAST_SHIFTS] Shift summary 11/26/2003 F (20-24)

From: Manouch Farkhondeh (manouch@mit.edu)
Date: Thu Nov 27 2003 - 08:58:48 EST


Hi BQM values:

Reading the shift summaries and talking to L. Longcoy (chief) last night
and this morning, it seems that the high BQM values are most likely due
to warming up of the target cell that started yesterday afternoon when
Ernie turned the target cooling off. It was done so to have it at room
temperature by Friday morning to work on the cell to fix the thermal
contact between it and the cold head. In hind sight, it was a mistake
to start it Wednesday afternoon; they should have turned the target
cooling off this morning and 24 hours would have been more than adequate
for warming up.

The elevated vacuum pressures in the scattering chamber with ligit in 7
scale and others in 8-9 scales instead of 10 (according to Larry) must
have been caused by outgasing of the cell. I see no other reason for
elevated BQM values that basically made the overnight background studies
useless.

Manouchehr

Tancredi Botto wrote:
>
> to add to my notes below,
> nozzle chjamber pressure stayed in low e-8, so presumably cryo still on at
> 6000 A.
>
> -- t
> ________________________________________________________________________________
> Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
> research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> On Thu, 27 Nov 2003, Electronic Log Book wrote:
>
> > Operators: seely yxiao ----
> >
> > until 8 pm continued on NC's, flasher runs (see logbook)
> >
> > We start taking beam. CCR tuning takes 1+ hrs, with final BQM norm rates
> > of T=180, L=70, B= 77, R=45. Note: comunicating slit positions has little value.
> > We want to minimize bqm rates !
> > Left slit position found at +3 mm from -25, not typical (motor steps ??)
> >
> > AFter that realize no dcct. D-tunnel. Chase cables. The dcct has been disconnected at the rsb side of patch!!! Nothing I can do about it. So no charge
> > measurament (including dead time).
> >
> > Try to take empty target runs anyways, with 2nd level trigger. Trigger may be
> > fine but running very hard because of wch trips.
> > On right, channels 5 of slots 3 and 7 (box R30), on left, channels 1,5 of slot 0 (sense wires). Disabling right channels works. It does not work on left...
> >
> > Also, beam background is very unstable. Beam rates come in splashes,
> > with many wires tripping. Not going to be a good night for the chambers either.
> > Maybe this is due to so and so vacuum. No beam data tonight.
> >
> > Yuan stays, he will work on ion pol neutron detectors, including hall
> > access and if possible field off data.
> >
> >
> >
> >
> >
> >
> >



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