Just so future shifts know: An acceptable beam tune has beam halo monitor
rates of around 150/300/60/60 Hz/mA. So the tune from last night was 4
times worse which is too noisy for the wire chambers.
--On Tuesday, May 6, 2003 8:10 AM -0400 Adam DeGGrush <degrush@MIT.EDU>
wrote:
> Most of the night was spent tuning the beam.
>
> Unable to test minor fixes to HV Gui because route to mysql database
> (blast05) through dblast07 does not work. This probably occured due to
> power failure. Ernie Bission can probably fix it this morning.
>
>
> 4:00 CCR encountered difficulty in beam tuning due to ring vacuum
> problems ( high ligit 106,101 and 102 readings). Ernie Ihloff and Chris
> Vidal came in and fixed the problem. Beam was then tuned using the beam
> halo monitors and the slits were optimized again.
>
> 6:00 AM: CCR was able to provide only 100 mA peak current. We took it
> less our late night shift became an exercise sine sententia
>
>
> The beam quality monitors gave the following scaled counts:
> Top:800hz/mA
> Right:1200hz/mA
> bottom:370hz/mA
> Left:700hz/mA
>
> CCR did not know of values typical of good beam tune. We took runs with
> no gas and with ABS but we believe that we were dealing with a poor beam
> tune which led to higher rates than expected and relativelhy porr S/B for
> the wire chambers. We have then shut off gas and asked CCR to retune the
> beam.
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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