First ASCA results for high-redshift Radio-Quiet Quasars
  Here we report the X-ray spectral analysis of 5 high-redshift ($z \geq 2$) radio-quiet quasars (RQQs) observed with the ASCA satellite. A simple power law with Galactic absorption model well fits the data. There is no evidence of a reflection component. The average spectral slope in the observed 0.5--10 keV energy range, $< \Gamma > = 1.68\pm{0.09}$ (dispersion $\sigma \sim 0.11$), places the high-z objects of the present sample in the lower-\Gamma tail of the RQQs spectral indices distribution. 
C. Vignali, A. Comastri, M. Cappi, G.G.C. Palumbo, M. Matsuoka