sPHENIX discussion of the superconducting solenoid

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

Hi,

 

As you may see the outlet temperature is now < 97 K and the temperature has dropped ~24 K in the last ~24 hours (~1 K per hour).  

 

From what Roberto said in his last email and he told me a few hours ago + what I can see now, earlier today they still mixed ~10 K He

(from the Cryo plant) with 80 K He but around 4 pm-ish (as I can see the abrupt change in the curve), they had now used only  the ~10 K

He from the Cryo plant to cool.

 

Now I suddenly understand why Roberto sent us the thermal contraction for Al in his last email.  To get to  90+ K, the contraction is ~3.7%  

of the total length and  to 4 K, the contraction will be ~4.15 %.  So, from 90+ K to 4 K, the contraction is only the last ~0.04%, or 0.04/4 = 10%

of the total contraction.  So, they think that we don’t need to worry about the requirement of the 40 K temperature gradient.

 

Earlier this morning, Paul Orfin told me that he’s observed frost around the current lead (on the platform).   I’ve asked Sonny Dimaiuta

to help check and he found no “short” this morning.  You may read his email below and we should get rid of those frost as much as possible.

Paul Orfin contacted D. Phillips (for removing those yellow barrier over the current lead temporarily) to install heater this afternoon.

 

Kin

 

From: Dimaiuta, Sebastian A
Sent: Monday, March 14, 2016 1:08 PM
To: Yip, Kin
Subject: RE: Frosted leads

 

Hi Kin

               Went and looked at Sphenix leads at 11:20 this morning, the frost should be cleared and dried off as much as possible before running any current on the magnet. Met Paul Orfin in 912 They are blowing a fan on the leads and reducing lead flow, also that Tom Tallerico was looking into a heater to keep the frost down which is a good idea.

                                                                                                                                                                                                                                                                                                           Sonny

                                                                                                                     

 

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