Pressure studies and pulsed NMR studies in solid hydrogen

A presentation is made of two studies made on solid hydrogen. In the first study the ortho-para conversion rate was studied at 4.2 K up to a relative density of p/p sub o=1.2, where p sub o is the density at zero pressure. In the second study, the longitudinal relaxation time, T1, and the transverse relaxation time, T2, were studied in low concentration (less than 20% ortho) hydrogen between .4 K and 13.6 K at 5MHz and 29MHz under saturated vapor pressure. The ortho-para conversion rate measurements under pressure were prompted by a prediction that the conversion rate may go through a minimum in the cross over region between the one and two-phonon processes. A high pressure gas handling system capable of reaching 20,000 psi was used to check this prediction.