High-precision, room-temperature pressure standards to 300+ GPa from ramp-compression experiments

Magnetically driven ramped (quasi-isentropic) dynamic compression experiments at the Z machine have fulfilled their promise of precise (standard deviation under 2% in pressure), absolute measurements of solid-phase compressibility up to 100s of GPa, where isothermal diamond-anvil cell (DAC) techniques have limited pressure accuracy due to reliance on theoretical equations of state to deduce room-temperature calibration standards from shock data. With proper accounting for strength effects, a pressure-strain compression isentrope can be extracted from measured window-interface velocity waveforms either analytically using inverse Lagrangian analysis (ILA) or computationally using Bayesian model calibration (BMC), with only a small correction needed to obtain the room-temperature isotherm. After a very brief review of results already published on platinum, we present preliminary results on one or more other standard metals (from among rhenium, gold, iridium, aluminum, or tungsten) for which Z experiments have been performed.