Observables

A couple of words about A_xx and how to measure it:

with an absolute systematic uncertainty estimated from,

To obtain tensor polarization by optimizing vector polarization we expect a tensor polarization of P_zz=2-(4-3P²)^1/2 assuming a Boltzman distribution at thermal equilibrium.
But not at thermal equilibrium under experiment (trying not to under estimate error)
Analytic relation not applicable for tensor Optimization (hole burning)

General limitations for all tensor polarized experiments to keep in mind:
1.) Ideal P_zz =2.5%-5%
2.) Vector Optimized P_zz =6.5%-12%
3.) Tensor Optimized P_zz =15%-25%
4.) Negative tensor polarization not yet achieved without hole burning (very unstable)