sPHENIX discussion of the superconducting solenoid

["Yip, Kin" <kinyip AT bnl.gov>]

Hi,

Since I last reported, the magnet tripped at 7:22 am on Mar. 26 (fast 
discharge) due to "Cryo Interlock" which happened to be sudden
pressure rise in phase-separator > 1.7 atm.   See attached plot 
("phae-separator-pressure-rise.jpg").

Though Roberto didn't fully understand why this could happen, he found a 
valve (3692) which opens very slowly and he
increased the opening rate by 10 folds or so.   ( Before this, there 
were some occassional spikes in pressure and also temperatures;
after this, the spikes seem gone.  Though this could be also due to more 
stable Cryo in RHIC as both rings were getting cold. )

The magnet was ramped back up ~2:54 pm that day (Mar. 26) and it's 
remained so.  I've attached the current plot.

Last night (Mar. 27), the chiller #3 failed --- a problem we're trying 
to deal with with the AC shop and C-AD (Marianna & Kevin et. al.).
The water-cooled-bus water and the water for the Magnet Power Supply all 
relied on the chiller (for sPHENIX Electronic-Cooling-Water system).
I almost wanted to did a slow ramp-down on the Magnet.  I kept in touch 
with Tim Costanzo who gave me second-by-second info. on whether
the AC shop had arrived ...  At the end, after I told 1008 that I was 
going to ramp down the Magnet, the AC shop fellow arrived in time to
reset this chiller #3 so that the temperature dropped instantaneously, 
and thus I didn't need to ramp down the magnet.

Our trip-point for the Magnet water temperature is 60 C and it normally 
was ~30C or so.  Last night, it went above 41 C.


Kin

Attachment: phase-separator-pressure-rise.jpg
Description: phase-separator-pressure-rise.jpg

Attachment: Fri_Mar_28_114631_2025.2298957.png
Description: Fri_Mar_28_114631_2025.2298957.png