Distinguishing between the Frenkel and Widom lines in supercritical Nitrogen

In recent years narrow transitions between gaslike and liquidlike behaviour of fluids at temperatures significantly exceeding the critical temperature Tc (above 6Tc) and densities over double the critical density were observed. Some explained this by extrapolating Widom lines (thermodynamic continuation of vapour pressure curve) from the critical point (CP) and others with newly proposed Frenkel line. The Frenkel line is unrelated to the CP, Widom lines and vapour pressure curve. It should follow P,T path beginning in subcritical region at significantly higher density than the CP and following a roughly isochoric path into the supercritical region. Here we propose to obtain key data missing in this puzzle: A single study along P,T path encountering Widom lines then, at higher density, the Frenkel line. This will enable us to distinguish the effects of these different transitions.