FN_RHO# FN_RHO = <Quantity 1.6726e-16 g / cm3># Mass density normalization for MAS. \(\rho_0 = m_p\,n_0 \approx 1.67 \times 10^{-16}\) g cm⁻³, assuming a fully ionized hydrogen plasma where the mass per particle is the proton mass.
