sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

Hi,

Mike Lenz this morning found that due to the reality how the cables and the support stand are, he has more modifications to do than he expected.  
He won't finish today.    He may finish before lunch on Monday.

I talked with Carl, Pablo and Charlies Theisen (when Zeynep was not in her office), in addition to Paul Orfin.

So, assuming Mike can finish it before/around Monday noon, we'll try to start some testing (interlocks etc.) on Monday at 1 pm.  In case, this doesn't work,
we'll start on 9 am Tuesday morning.

The timing is now important for the Cryo group.  I heard --- may not be the final nos. --- that the He consumption is like 6.5%/hour.   They usually fill up at the maximum
about ~70% full and one needs to slow down/stop when it reaches 10%.   So, the max. we can do is 9-10 hours or so.   The refill rate is like 1% per hour.   We can either
give up the next day (Mon. - Wed. - Fri.) or work a few hours on the next day etc.

So, the Cryo group needs  to prepare ...

There are some temperature sensor readings which are puzzling.  Steve Plates and Roberto Than et. al. are investigating.

Kin


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PS:

Just to remind people that, in BaBar operation, they did the following (one example given in the first chapter of  \\bnl.gov\c-adnas\BaBar P.S. Manual  ) :

after the slow ramp-down (with the free-wheeling diode) for 34.4 minutes, at 1338 A, they'll do fast discharge and that would warm up the entire Magnet/Cylinders
and cause the so-called  "quench-back".    This seems to be their common practice (every time) as they didn't want to wait for multiples of 34.4 minutes.   

I am trying to say, quenches at low current is common practice.


[ I wrote about this in May 2017 : https://lists.bnl.gov/mailman/private/sphenix-magnet-l/2017/000559.html  ]