[Dsg-hallb_magnets] Hall B Solenoid - temperature sensors

[Dave Kashy]

Hi Pablo,
To get below 1K takes very different refrigeration techniques.
Our polarized targets operate at~0.050K using dilution refrigerators 

The lowest temperature you should see on the solenoid is 4.2K if we are venting to atmosphere.
But at 1.2 ATM return pressure it can't go lower than 4.4K

All due to the properties on helium

Dave

Sent from my iPhone

> On Jul 17, 2017, at 5:23 PM, Pablo Campero <campero at jlab.org> wrote:
> 
> Hello Ruben,
> 
> I checked the sensors that is reading back 0.0 K 
> 
> TR8671
> TR8673
> TR8611
> TR8672
> TR8674
> TR8610
> 
> The mentioned sensors are read by the Cryocon Units, so I have to go and check the cryocon units readouts and also make sure that the mentioned temperature sensors are physically connected in the Solenoid Service Tower.  
> PLC is reading  0.0 K values because the Cryocon Unit is reading a real zero (which we know is not possible at this moment) or it has a ''clip'' readback on its channels where the temperature sensors is connected (Most probably for now).
> 
> 
> Best Regards,
> Pablo 
> 
> 
> From: "Ruben Fair" <rfair at jlab.org>
> To: "Pablo Campero Rojas" <campero at jlab.org>, "Probir Ghoshal" <ghoshal at jlab.org>
> Cc: "Scot Spiegel" <spiegel at jlab.org>
> Sent: Monday, July 17, 2017 4:35:26 PM
> Subject: Hall B Solenoid - temperature sensors
> 
> Pablo, Probir,
> 
> All the temperature sensors are now installed and the connectors are still plugged in.
> 
> Please review all the sensors on EPICS and see if they are all reading what you expect.
> 
> If not, please work with each other to assign correct calibration curves.
> 
> I shall disconnect the cables first thing tomorrow morning at 7am as welding will start shortly after.
> 
> Regards
> 
> Ruben
> 
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