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FMCG/Operating procedure: Difference between revisions
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# Repeat on the other detectors as needed.
=
Once the detectors are balanced, the magnetometer is "activated" by turning on the optical pumping laser.
Once the detectors are balanced, the process of nulling the fields (necessary for the SERF regime) can begin. One detector will be nulled using the "global" '''room coils''', and the other one(s) with the "local" '''shell coils'''. Nulling one channel with the room coils will bring the fields at the other channels ''near'' zero, and the remaining field can be shimmed using the local coils.▼
The following will assume the room coils are connected to the single-channel '''"Wyllie Supplies"''' and each individual set of shell coils is connected to the appropriate port on the back of the main control box.▼
# Close the door to the MSR, either using the automatic switch, or manually using BRUTE STRENGTH.
## '''Key Locked''': The enable key on the controller is in the '''disabled''' position. Turn the key 90 degrees clockwise to enable.
## '''Amplifier Off''': The amplifier is ready is turned off, but ready to be activated.
# Check the '''Input Power (mW)''' display. The input power must be at least 10 mW, but with good coupling, we usually see closer to 20 mW of input light. If the input power is less than 15 mW or so, adjust the coupling from the pump diode into the fiber (top shelf of rack, nearer set of optics).
# The output power of the TA can be adjusted using either the slider or the input box above the two power guages. '''1000-1200 mA''' is a good drive current to start at.
# Once you are satisfied with the settings, the pump light can be applied to the magnetomers by clicking the '''Amplifier On/Off''' button. After a brief countdown, the TA will activate.
# Once the TA is active, you should see the difference signal (henceforth referred to as the "magnetometer signal") swing as the device begins to actively sense fields.
=Field Nulling=
▲
▲The following will assume the room coils are connected to the single-channel '''"Wyllie Supplies"''' and each individual set of shell coils is connected to the appropriate port on the back of the main control box.
The process of nulling the fields is very much
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