Knobs
inversion is COMPUTED from the cascade (trapped-field 3p fraction), not a knob — the whole point.
At the probe
The scaling spectrum: $I_{589}$ vs $n_\text{Na}$ on log-log. The local slope is the regime exponent. slope 1 = incoherent N; slope > 1 = cooperative/pooling; slope → 2 = Dicke N²; slope rolls over (even negative) where the Na₂ dimer sink (∝$n^2$) depletes the free radiating Na. The device walks the ladder; the slope tells you which rung. Superradiance is GATED per-cell by $\tau_R < \min(T_2, )$ and Arecchi-Courtens $\tau_E = L/c < \tau_R$ — earned where the chemiluminescent inversion beats dephasing, absent in the thermalized bulk (Gross-Haroche; Rajabi-Houde).