A novel approach was developed to probe density compression of liquid deuterium ($L\mathrm{\text{−}}{\mathrm{D}}_2$) along the principal Hugoniot. Relative transit times of shock waves reverberating within the sample are shown to be sensitive to the compression due to the first shock. This technique has proven to be more sensitive than the conventional method of inferring density from the shock and mass velocity, at least in this high-pressure regime. Results in the range of 22–75 GPa indicate an approximately fourfold density compression, and provide data to differentiate between proposed theories for hydrogen and its isotopes.

• Received 23 July 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.035505