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- When the magnet LHe level is approaching 0%, the first indication will be the Tank B temperature. If you start seeing Tank B reach jumps up from 4.7 5 K, then immediately coordinate with the Target Expert and Target Helper on shift to get ready for a magnet LHe fill using this procedure → Filling Magnet Helium Space without Lowering the Liquifiers Pressure
Here is an example: https://e906-gat1.fnal.gov/data-summary/e1039/target-all.php?Y0=2024&M0=03&D0=23&h0=00&m0=00&s0=00&Y1=2024&M1=03&D1=23&h1=15&m1=00&s1=00&Cryo+Temperature_Tank+B
- The 2nd indication will be the magnet return flow. It will start decreasing to ~0.
In this example, you can see that the magnet level starts decreasing when Tank B increases from 4.9 K to 5.0K (this may happen when Tank B is around 4.8 K, so as soon as you see the jump 4.6 K → 4.7 K, then get prepared for a magnet LHe fill):
https://e906-gat1.fnal.gov/data-summary/e1039/target-all.php?Y0=2024&M0=03&D0=23&h0=00&m0=00&s0=00&Y1=2024&M1=03&D1=23&h1=15&m1=10&s1=00&Cryo+Temperature_Tank+B&Cryo+Flow_MagRetBypass+Return
- The 3rd indication will be the Separator return flow. You will notice that the spread of the separator flow will start decreasing.
In this example, the Separator flow was set to 20slm (you can notice the average of the spread is 20slm).
https://e906-gat1.fnal.gov/data-summary/e1039/target-all.php?Y0=2024&M0=03&D0=23&h0=12&m0=00&s0=00&Y1=2024&M1=03&D1=23&h1=15&m1=20&s1=00&Cryo+Flow_Separator+Return
- If all the above three observations are "true", then you will need a magnet LHe fill immediately. As mentioned in the 1st observation, you will have to arrange (or start preparing for) filling the magnet with LHe as soon as you start seeing Tank B temperature increase from 4.5 K → 4.6 K, but you will have time (~ 3-4 hrs since the time you start seeing 4.5 K → 4.6 K jump) until it reaches ~5.0 K to start the magnet LHe fill. But, please start closely monitoring while you are getting ready for a fill.
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