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- In field B apply RF field to material at Larmor frequency ω_0
- Coil of L_0 perpendicular to B_0 to induce spin flip
- LCR circuit (so that ω_0=1/√LC ) to observe change in impedance with frequency
- As frequency changes: circuit response to Q-curve and polarization signal
- Sweep frequency around ω_0 to integrate in ω
Microwave setup
Dynamic Nuclear Polarization System
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Covariance Matrix
Parameters (Characteristics of Q-Meter) to be included in the Q-Curve Covariance Matrix:
V - Input voltage
C_knob - tuning capacitance
trim- cable length defined by nλ/2 (n/2 is the trim, and λ is the Larmor frequency of the material)
η - Filling factor of the coil
∅ - phase offset
C_stray, Stray capacitance – parasitic capacitance of the system
Phase cable length, QMeter temp, noises, and other factors
Hessian Fit with Covariant Matrix results performed using the Iminuit python library.
Target Polarization Systematics
- Signal covariance matrix (Per each channel): Depends on proton/deuteron signal line-shape
- Magnetic field inhomogeneity
- Microwave distribution inhomogeneity
- Polarization decay in x, y, z directions over time (with modifications to the calibration insert)
- Uncertainty from the Calibration Constant
Temperature: Based on the cernox sensors and (or) Helium vapor pressure
Area under the signal: associated systematic uncertainty
Online Polarization Crosscheck:
Calibration constant was re-calculated by taking the average area and average He4 Temperature directly from the available NMR data - Online CC and the recalculated CC were almost the same as below:
NMR Polarization Display Panel
How Polarization was achieved during SpinQuest Commissioning runs:
Offline Polarization Measurements: Area under the NMR Signal
- Plot the Baseline:
2. Plot the RawSignal
3. Get the difference of Baseline and the RawSignal and plot the difference
4. Select a suitable data range on left and right wings of the plot and make a polynomial fit (or apply a Voigt fit) for the selected data
5. Plot the residuals (Difference between Polynomial fit and the Baseline-RawSignal plot). Apply a cut for both sides of the wings and calculate the area under the curve
