Observables2

Azz is an asymmetry so take advantage of numerator denominator systematics cancellation:

1.) Measure Np and Nu with same cup same exact material
2.) Use same B-field
3.) Use NMR on both to measure polarization and un-polarization
4.) Let beam heating an off larmor microwave control un-polarization
5.) Keep both cold (~1K)
6.) Switch from pol to unpol frequently

Additionally:

Multiple ways to measure b1, Azz
t20 for elastic or quasi still very accessible