  We have determined the mass profiles of dark halos in 83 objects observed by
ASCA. The point spread function of X-ray telescope was deconvoled by the
Richardson-Lucy algorithm and the temperature profiles were calculated to
obtain the mass profiles. The derived mass profiles are consistent with the NFW
model in 0.01-1.0 r_virial. We found a good correlation between the scale
radius r_s and the characteristic mass density \delta_c, which indicates the
self-similarity of dark halos. The spectrum index of primordial density
fluctuation, P(k) \propto k^n, was determined from the slope of r_s - delta_c
relation. For M_200=10^12-10^15 M_solar, our analysis gives n=-1.2 +/- 0.3 with
a confidence level of 90%. The mass density of dark halos is a good indicator
of the mean mass density of the universe at the time when the halos were
assembled, z=z_f. Assuming delta_c \propto (1+z_f)^3, we have determined the
epoch when each dark halo was assembled. Our analysis indicates that the field
elliptical galaxies and groups of galaxies formed approximately at 1+z_f ~ 15
and at 1+z_f ~ 7-10 respectively.
