[Halla_running] [New Logentry] RC Report for Sunday, April 24

[vasulk at jlab.org]

Logentry Text:
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Yesterday evening, production data taking on the LH2 target was resumed after the beam was off, since about 9:30 in the morning.
The issue with beam involved a vacuum valve, VBV1L24A being in an indeterminate state.  The resolution is described in this 
ELOG entry: https://logbooks.jlab.org/entry/3402347

Unfortunately, while MCC was working on recovering from this issue, strong storms came through the area yesterday afternoon
disrupting the operation of the C100s.  After the storms passed, the RF stabilized and MCC continued restoration of the beam.
Beam was returned to Hall A around 16:50, which then the Hall A shift crew began the beam restoration procedure.  Production 
on the Loop 3 LH2 target resumed around 18:30, though at only 45 uA due to BLA trips when MCC attempted to run higher current 
to Hall A.  Unfortunately, there was also large bleed through of the Hall A beam into Hall B, but apparently this magically disappeared
on its own:  https://logbooks.jlab.org/entry/3402458   
The resolution however did not improve the BLA trips for running Hall A at higher currents.

Production running continued well through the remainder of Swing into Owl shift.  Then at 00:40, the raster YB power supply failed.  
Bill Gunning came in and replaced both the XA and YB power supplies by 02:10.  See Halog: https://logbooks.jlab.org/entry/3402533. 
The shift crew then proceeded to check the beam spot and raster size by lowering the left HRS momentum to 1 GeV/c to obtain 
some rate to see the carbon hole.  The raster size was restored to 2.5 x 3 (MCC units) to give approximately a 2 x 2 size at the Hall A
target.  The beam position was found not be be centered on the carbon hole.  The positions at BPMA and BMPE were adjusted from
(0.3,-2.4) to (0.0,-2.6).  Production at 45 uA on the LH2 target was resumed at 03:40.  The shift crew asked for MCC to provide 60 uA,
but the beam would trip as they went above 45 uA.  Then after 06:00 the BLA trips got worse, and MCC lowered the Hall A current to
40 uA, which improved the trip rate.

For today through tomorrow morning, we will continue production running on the LH2 target at as high of a current as MCC can delivery.
I still hold out some hope that we can get back to higher currents.    Around 15:30, we will take data for two hours on the 15 cm dummy 
target, and the continue production until 06:00 Monday, when beam goes off.

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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/3402685
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