I just looked into the reason for a delay of beam delivery to BLAST last
night. A Combination of hardware problem and over extending of a planned
cycling test of the snake quad delayed the beam delivery to around 4:00
am this morning. I remind you that cycling difficulties of this quad was
responsible for the mysterious short lifetime of the stored beam last
week after a mini power glitch.
Here is the chronological story of last night:
- Genya finished tuning of the ABS transitions for deuterium around 8:30
pm.
- LSOL1 tripped ~8:00 while ramping up, under control around 11:00
- measurement of on the holding field and the effect of BLAST on the
Hall probe reading , finished around 11:00 pm
- closed Hall and BLAST ramp up ~00:30
- snake quad cycling tests and the lifetime measurement that was planned
at the 15:30 daily BLAST meeting for the early evening. Finished the
test around 3:30 am.
- beam to the experimenter around 4:00 am.
The oversight and breakdown of communication was mainly on the operation
side. In view of the delays last night, we should have terminated the
quad test and scheduled for a later time. The understanding was to do
the 1-2 hours snake quad test early evening after the hall was secured.
This morning I gave instructions to the operation crew and the
accelerator physicists that the number one priority should be delivering
beam to BLAST.
Manouchehr
Electronic Log Book wrote:
>
> Operators: clasie clasie nikolas
>
> Deuterium data taking most of this 4hour shift.
> CCR had asked for "same conditions" as last night, including H2 target and 2-state flipping, in order to study an effect relating to cycling the quads of the snakes. Didnt sound like "Blast people" had any prior knowledge of this "need", nor did it sound necessary at the time, having just tuned D2 n all...
> We yielded anyway.
> Assuming Genya's tuning from earlier Wednesday was reflected in the ABS setpoints, we set D2 back as target, got plasma and set the same three state flipping sequence as before the change.
> WC tripped like mad as stated in the logbook.
> Lifetimes were bad to really bad (14min to 8min at peak current)
> Phys 0 rates up to 1KHz at beginning of fill. See log.
> Took runs 4873-4881 with l2trig. Data is crunching.
--____________________________________________________________________ Manouchehr Farkhondeh manouch@mit.edu Principal Research Scientist Division Head of Physics, Accelerator MIT, Bates Linear Accelerator Center tel (617)253-9298 Middleton, MA 01949 fax (617) 253-9599 ____________________________________________________________________
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