Magnetic Equation of State of a Gas of Spin-Polarized Atomic Hydrogen

The magnetic equation of state of spin-polarized atomic hydrogen is reported, relating density to magnetic field ($B\lesssim 10.5$ T), temperature ($T\gtrsim 300$ mK), and atomic flux used to fill the sample cell. Densities greater than ${10}^{16}$ atoms/${\mathrm{cm}}^3$, more than two orders of magnitude greater than initial observations, have been achieved. Results are also presented on the buildup and decay of the density as a function of external conditions. Preliminary observations on the Fermi fluid, atomic deuterium, are reported.