sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

Hi,

I just came back from Bldg. 912 after the OFFICIAL pressure test --- witnessed by Mike Gaffney --- and leak check for our new
welding (in the cryo line for the sPHENIX Magnet) was completed successfully ~2:45 pm (Mike, Roberto, Paul Orfin and
Mark Sardzinski started before noon).   

There were a high pressure test (>100 PSIG) and low pressure test (30 PSIA) for the two different lines.  When I arrived, they
had already finished the high pressure test and were doing the low pressure test.   The vacuum level was ~4E-8 Torr (I hope
my unit is correct) during the test --- it rose a bit at the beginning but then came down.   It's declared as success => the welding
done last week is good !

I've learnt a couple more things from Roberto (ie. a couple facts that I was totally ignorant of) :

--- for the ASME standard, the vacuum level just needs to be ~E-3 Torr for the pressure test and we do the more stringent
leak check for our benefit to make sure that there is no leak for the insulating vacuum.
 
--- near the valve box, we still have some cryo connections to be made for the warm piping which will require another pressure test.
The warm pipeline is needed because we need to cool or warm up the solenoid magnet in a controlled fashion, ie. with a temperature
gradient < 40 K for the entire Magnet, by mixing the warm gas with the cold gas.


Your enthusiastic reporter,

Kin Yip