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FMCG/Operating procedure: Difference between revisions
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# Clicking the LabVIEW '''Run''' button will begin the ramp. Results for each trace will be plotted in the XY Graph window. A .dat file containing all of the data collected (Thermistor resistance and 4 channels of voltage data) is recorded on the file in '''Path Out'''.
=Balancing the
Before magnetometry can be performed, the detector on each channel should be balanced, ie adjusted so equal light is incident on each photodiode. '''Make sure the pump laser is off when the following is being performed'''.
# On the array, switch the detectors to DIFFERENCE mode. This is the middle set of header pins, and is indicated by a '''Δ''' or '''-''' symbol. The signal being sent out of the room to the current to voltage converters is now the ''difference'' in currents from the two photodiodes.
# Repeat on the other detectors as needed.
=Nulling the fields=
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.
# If it hasn't been done already, enable the TEC and LD current on the pump LDC501 (left hand side). The D1 resonance line of the pump is near 8.4 kΩ when the laser is being driven at 170.00 mA.
# Open up the TA-7600 pump tapered amplifier controller application on the computer (shortcut on the taskbar). Take note of the status message in the upper right corner.
## '''Not Connected''': The USB cable is not properly plugged into the computer or the controller (black box on the rear of the rack.
## '''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.
#
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