  Recent research suggests that the supercritical state consists of liquidlike
and gaslike states where particle dynamics and key system properties are
qualitatively different. We report experimental evidence of the structural
crossover in supercritical neon at pressure and temperature conditions
significantly exceeding the critical point values: 250$\,P_c$ and 6.6$\,T_c$.
The experimental results show a crossover of the medium-range order structure
evidenced by the change of the structure factor with pressure. We also observe
the crossover of the short-range order structure indicated by changes in the
coordination number. The relative width of the crossover is fairly narrow and
is smaller than 10-12 \% in pressure and temperature. By comparing our
experimental results with molecular dynamics simulations, we suggest that the
observed crossover can be attributed to the Frenkel line and discuss the
relationship between the structural crossover and qualitative changes of
dynamical and thermodynamic properties of supercritical matter.
