[Halla_running] [New Logentry] RC Report for Saturday, April 23

[vasulk at jlab.org]

Logentry Text:
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Over the past day there have been a few major interruptions of beam delivery.  The first began around 10:46 in the morning
due to IOC problems.  Then when accelerator began to restore, the beam was suffering from BLA trips, which required a
new calibration of the BLA system.  Unfortunately, as this procedure was in progress, the thunder storms came through the
area and caused the  C100 RF in SL to trip multiple times.  During Swing shift, the BLA calibration was completed and there
were some issues with the 1st and 4th pass separators.  Beam was finally back in Hall A around 19:40 and production was
resumed on the LH2 target.  Altogether beam was done for about 9 hours between 10:46 and 19:40.

>From Swing shift to early Owl shift, beam production running went smooth until the XA/X1 raster power supply failed again.
Unfortunately, we were unable to get a hold of Bill Gunning on Owl shift to come in and replace the failed power supply. 
Bob Michaels was contacted and suggested that we use the remaining X power supply and double the raster size.  The 
relevant ELOG and Halog entries are below.  A total of about two hours was lost on Owl shift due to the raster power supply.

https://logbooks.jlab.org/entry/3402177

https://logbooks.jlab.org/entry/3402183

https://logbooks.jlab.org/entry/3402184

https://logbooks.jlab.org/entry/3402204

https://logbooks.jlab.org/entry/3402227

Here is the raster size from the carbon hole target after the changes: https://logbooks.jlab.org/entry/3402214

Bob Michaels came in this morning and found the spare power supplies: https://logbooks.jlab.org/entry/3402318

In the meantime, Bill Gunning called the Counting House this morning, and he is available if we want him to come
into the lab.  If an opportunity presents itself, such an extended accelerator down period, then we will have him 
replace the X1/XA power supply.

Since 09:15, the accelerator is having issue with a vacuum valve.  An expert has been called and should be here now
to fix the issue.  Last estimate was that beam would be back soon.

Once beam is recovered, we will check the beam spot and resume production.  On Swing, we plan to take 2-3 hours of
15 cm dummy target data at 40 uA, and then resume production on LH2 for the rest of the weekend.

Issues:
1) Raster X1/XA power supply failure.  A plan is in place as a work around, but if an opportunity presents itself, we will
take an access to replace the failed power supply.

2) New BCM receivers were found to be saturated above 40 uA from the BCM calibration completed on Thursday.  Yesterday
before before beam was restored on Swing shift, I adjusted the gain on the receivers from 39 to 19 to avoid the saturation.
If we have time later today, we will ramp the current to provide a mini-BCM calibration of the new receivers against the Unser.
The new receivers are not critical for GMp, since we have three analog signals U1, D1 and D3 that work up to 65 uA.


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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3402319
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