Here are your 5 duties: Maintain Polarization, Maintain Cryogens, Move Target, Respond to Alarms, Log Everything.
Your first task on shift is to talk to the outgoing target operator and read the Fermilab elog! (https://dbweb8.fnal.gov:8443/ECL/spin_quest/U/login) Find out the following.
The polarization should be your constant worry. Even once you've found a good microwave frequency for the material, be vigilant! This frequency will change as the sample acquires dose!
Your constant attention to the microwave frequency is required! Change it often to ensure you have the highest polarization!
The output frequency of the microwave is automatically controlled by the microwave VI. It takes the real-time polarization data recorded by the PDP via "Data input file".
Call the target expert if
The polarization is going down continuously for longer than 5 minutes.
Interface of Microwave VI
The cryogens are maintained by automatic PID loops. Your job is generally to monitor these loops and step in if they fail.
If the level drops below a target cup, the polarization will drop to zero!
Ensure the levels stay within alarmed levels. If they drop too low or go too high, wait to see if the alarms go away. If they don't contact a target expert.
Space | ID | Low | High | Fill Procedure |
---|---|---|---|---|
Magnet LHe | anifolds Magnet Dewar Level | 10% | 45% | https://seaquest-docdb.fnal.gov/cgi-bin/sso/ShowDocument?docid=9670 |
Magnet LN2 | LL106-N | 40% | 90% | https://seaquest-docdb.fnal.gov/cgi-bin/sso/ShowDocument?docid=10337 |
There are 4 levels to watch
Set of slides with operational settings: QT_Operational_Settings.pdf
The first thing (on the UVA-QT system) to check is the overall status of the system on QT-HMI, and the main part of the screen is the following.
System status: "ON"
Both Liquefiers: "Liquefy" mode (or could be either "Cooldown" or "Manual" mode depending on the current conditions different from "Liquefying").
Purifier A: "Manual" mode
Purifier B: N/A (we don't have a purifier B)
HR3: "ON" + Green check mark.
If you see "Alarm" on any of those status indicators (in the above picture), then that needs to be addressed/fixed soon.
If that's the case, coordinate with the Target Expert on shift to fix the Alarm.
The overview screen (example)
This example picture illustrates that both Liquefiers are "ON". Liquefier A is in "Idle" mode, whereas Liquefier B is in "Liquefy" mode.
("Idle" mode means, the Liquefier is just holding liquid helium at ~4 K but not producing).
Also, you can monitor the LHe, LN2 levels in the magnet, as well as the LN2 level in the purifier as well. Another example image is below.
Check each Liquerfier screens (A & B) at least once per hour. A sample operational screen is below.
The main components to check on the Liquefier screens are below:
1) Mode (top left): Should be Run + Auto + Liquefy mode if it's in the production mode
2) Cold head temperatures: Should be around > 3 Kelvin.
3) Dewar level keeps increasing and does not do frequent large fluctuations between 0-275 Liters. If you start seeing large frequent fluctuations, then contact the Target Expert on shift immediately.
4) Make sure FC501(A/B)I (actual inlet gHe flow) is close to FC501(A/B)Q (gHe set-flow from PID) (see "Settings" screen to check the set values)
5) Make sure FC(A/B)I (actual outlet gHe flow) is close to FC(A/B)Q (gHe outlet set-flow from PID) (see "Settings" screen to check the set values)
In terms of the UVA-QT system maintenance, we need to keep the LN2 levels in the purifier always above 50% for higher production rate.
Fill Procedure | Procedure |
---|---|
Filling LN2 to the purifier (remote: using the outside LN2 tank) | https://seaquest-docdb.fnal.gov/cgi-bin/sso/ShowDocument?docid=10337 |
Filling LN2 to the purifier (in-person: using a portable LN2 Dewar) | https://seaquest-docdb.fnal.gov/cgi-bin/sso/ShowDocument?docid=10053 |
Magnet LHe level: This LHe level should always be > 10% during the operational state. Monitor the level and arrange re-fills in a timely manner.
Note: Maximum level of the magnet is 45% due to the geometrical positioning of the level probe in the magnet.
Purifier liquid nitrogen (LN2) level: This LN2 level should always be > 50%. Monitor the level and arrange re-fills in a timely manner.
Storage tank (gHe) pressure: This should be between 40 PSI and 110 PSI.
If the pressure reaches 110 PSI, then you will need to arrange to vent gHe to the atmosphere.
If the pressure is reaching 40 PSI, you will need to arrange a re-fill of gHe ahead of time.
Before move:
There are 2 NMR coils, one in the Top cup, one in the Bottom.