Tancredi Botto and Douglas Hasell on shift
Yesterday we operated the beam quality monitors with the BLAST toroid off
and optimised the slits LVC20 and LVC27 and steering magnets 1 and 2 near
BLAST.
During injection the four beam quality monitor rates were 500 - 1500 kHz.
With stored beam the rates before optimization rates were 1-2 kHz per mA
stored current.
After optimizing the slits rates were 0.1-0.2 kHz per mA stored current.
After optimizing the steering magnets rates were 0.05-0.1 kHz per mA.
Repeated this procedure today with the BLAST toroid on at nominal current
with similar results.
Slit settings for magnet on were 20L = -3, 20R = 6, 27T = 2, and 27B = -3
Further improvements were possible with the steering magnets but they had
to be changed back for injection. Current steering magnets settings give
some improvement in beam quality monitor rates but also permit injection
without changing the settings. Beam lifetime was not optimised for the
BLAST toroid on but 15-20 minutes were typical at 40-50 mA. The steering
magnets and general beam tuning still needs to be done properly with the
toroid on.
Wire chambers were turned on and seemed to hold voltage without drawing
much current but so far haven't been able run with triggers to check signal
to background or "cleanliness" of tracks.
Problem with CODA turned out to be a dodgy cable.
Took runs 80 and 81 with no gas in the target cell. Wire chamber had
signal to background around 10:1 so not too bad. Nsed looked reasonably
clean though lots of triggers without tracks. Wire hit distributions shows
some bad channels which have to be investigated.
Turned on unpolarised hydrogen at 0.05 sccm and started run 82.
Cheers,
Douglas
26-415 M.I.T. Tel: +1 617 258 7199
77 Massachusetts Avenue Fax: +1 617 258 5440
Cambridge, MA 02139, USA E-mail: hasell@mit.edu
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