Hi
the 0-field runs last night as far as I can tell are miserable failures.
live time is low. runs 13846-13849 accumulated gated charge of only 7
Coulumbs despite the 70mA current in the ring. out of 7 coulumbs, I am
expecting 3-4 ed elastive events.
trigger 7, despite being prescaled by 1000, dominates. trigger 7
dominate even among events where both sector contain tracks. so the
background is really really really bad. 10% of the tracked
events have LADS/NC hits even though the HV on them were turned off.
So it is not clear still whether we can do any physics runs without Blast
Field, may it ep elastic or ed elastic or anything. background is a
major problem even though CCR spent quite a while tuning the beam.
If we ever want to do this excercise again, I think we should do it with
better preparation. a new trigger file must be written to take out
anything but trigger type 1. type 1 trigger should be modified to take
only events arround the elastic kinematics. One must make sure that all
irrelevant HV are turned off.
Chi
On Sun, 27 Feb 2005, Michael Kohl wrote:
> We are going to take data with zero BLAST field with ABS D2 (32deg).
> After end of run 13842, Larry Longcoy starts to tune the beam with BLAST
> off, at first with BQMs only. When BQMs are low, the Wch are turned on and
> the tune is refined with help of the Wch scalers. We will start at
> currents 50-100mA and see gradually how high we can get with regard to
> Wch tripping, Wch S/N and overall rates.
>
> Plan is to take zero-field data with ABS-D2 until Monday morning.
>
> Regards,
>
> Michael
>
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>
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