sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

Agenda: https://indico.bnl.gov/event/4581/

(1) We've discussed whether we should open up the doghouses to try to see whether we can fix the voltage taps  and possibly the temperature sensors of TT1786/7.
The general consensus seems to be "yes" and the following are some main considerations :

--- It seems that there is not much real risk in general. 

--- Dave went to check this morning that if we want to move the one piece of roof-steel at lead-end, we need to take away the Valvebox.
People are worried that if we breaks the Valvebox open and take it away, the Magnet would be exposed in a few years before it's installed in 1008. 
   *** But we can easily put "bland" at the flange to cover it up.
   *** Mike Anerella told us that even the RHIC spare magnets were open anyway.  This is probably not a big issue.

---  One advantage to do it now, is that we'll have a lot of time to investigate and won't regret if we find something surprising in 2 or 3 years' time
that we didn't open it up in 2018 summer.   And now, we still remember this issue relatively freshly and people have not retired --- which may not
be the case in 2 or 3 years' time.

(2) Therefore, it's decided to open it up now.    We probably will add another VT11.  If we can fix the existing VT11, we can have redundant.

In fact, Jim Mills said that we should see whether we should add new/redundant ones since we open the doghouses.

(3) The plan is that:

(i)  Dave Phillips will try to arrange the riggers to take away the non-lead-end wall steels and lay those wood/mat on the inside.   Dave has said that he try to
put it on the schedule for the next week.  ( But it may not happen that fast ... but we have time :-)

(ii) Then, Ray Ceruti will go there to take a look to see whether he/his team can open up the doghouse reasonably comfortably  without
     taking away the roof-steel.  Essentially, Ray will decide whether we'll need to take away the Valvebox.
(iii)  When it's ready, if the temperature is still too low, Paul Orfin (Cryo) will do the necessary to warm it up to room temperature by flushing
it with nitrogren etc.
(iv) Then, we can open up the doghouses and Carl Schultheiss and others can go to try to investigate/fix.


(4) Jim Mills reminded us to  charge 18093 for this "repairing" effort, not the "167*" account for the 1008 business.

(5) It's stated again in the meeting that we don't need to design to keep the Magnet cold in the Assembly Hall.  [ By the way, the temperature
sensors around the magnet coils are ~150 to 200K depending which one you look at, after we stopped cooling it since about Feb. 20, almost 2.5 months.  ]

The Cryo group will try to leave the T's/taps in Assembly Hall wherever they're convenient/easy/cheap to do.

(6) Paul Orfin asked whether the Magnet (and therefore all the other Cryo pipes etc.) in the sPHENIX experiment will be moved from time to time.  Don Lynch
and others express that there is no such plan.   But probably, it's the inaccuracy while doing the installation for the 1st time  necessitates including some tolerance
in the design.