Activity expansion calculation of shock-compressed helium: The liquid Hugoniot

The Hugoniot of shock-compressed liquid helium was calculated using the activity expansion dense plasma program. The predicted maximum compression is at 100 GPa and 58 000 K, at a density nearly six-fold that of the initial state. Comparisons are made with recent path-integral Monte Carlo simulations, which predict a smaller maximum compression of 5.24-fold, near 360 GPa and 150 000 K.