During SMC the measurement of the N14 polarization was performed[1], also shown in earlier measurements [2]. The measurement indicated that equal spin temperature (EST) is obeyed.  With coupled systems like this that obey EST one knows what the polarization is given the other.  So no real need to measure the polarization in real-time if you know what the proton polarization is. At SLAC, a measurement of N15 where the ammonia spin is carried by the proton also found agreement with EST.  N15D3 was used for the measurement of the spin structure of the neutron. Because the spin of N15 is carried by the proton there is reduced background subtraction for observables like g1 and g2.  For this reason, ammonia that uses nitrogen-15 is a better target and the corrections for an example observable can be found in [3,4].  This approach is very reasonable given some knowledge of the nitrogen cross-section for the process of interest.  For DIS both the cross-section and the partonic effect of the nuclei polarization to the overall asymmetry were known enough to make these corrections to the asymmetry after the experiment.

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