When the fridge is in Hold Cold Mode, it means we have a liquid in the fridge nose and holding target material
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. In that case, we
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must keep the target material to preserve the paramagnetic centers.
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In the Hold Cold Mode, you will see the fridge parameters as follows:
We fill the fridge to Heat-Ex Top for the Cold Hold Mode and close the Run and Bypass valves. To reduce LHe consumption in the fridge nose, set the GV bypass opening at 8.1% at the lowest opening to keep the fridge pressure flat.
Keep monitoring the target parameters, say Insert#7, Insert #8, Annealing A, and Annealing B. Where Insert #7 and Insert# 8 are the Cernox (CX-1030) sensors on the Top and Bottom cup of the target insert. Where Annealing A and Annealing B are the metal temperature in the fridge, monitor these four target parameters. Where Insert#7 and Insert# 8 are in resistance (Ohm) and Annealing A and Annealing B are in temperature (K). Please see a screenshot below for these target parameters:
You can see below the conversion table for the Cernox (CX-1030) from resistance to temperature.
- Run and Bypass valves are closed.
- Separator Flow set at 7slm
- The GV bypass can be set at 8% or fully open. It does not matter what the GV bypass opening is.
You can see the Fridge Parameters on the Strip Charts Fridge 2x3 (fnal.gov):