HEW simulations and quantification of the microroughness requirements for X-ray telescopes by means of numerical and analytical methods

摘要

Future X-ray telescopes like SIMBOL-X will operate in a wide band of theX-ray spectrum (from 0.1 to 80 keV); these telescopes will extend the opticalperformances of the existing soft X-ray telescopes to the hard X-ray band, andin particular they will be characterized by a angular resolution (convenientlyexpressed in terms of HEW, Half-Energy- Width) less than 20 arcsec. However, itis well known that the microroughness of the reflecting surfaces of the opticscauses the scattering of X-rays. As a consequence, the imaging quality can beseverely degraded. Moreover, the X-ray scattering can be the dominant problemin hard X-rays because its relevance is an increasing function of the photonenergy. In this work we consistently apply a numerical method and an analyticalone to evaluate the X-ray scattering impact on the HEW of an X-ray optic, as afunction of the photon energy: both methods can also include the effects offigure errors in determining the final HEW. A comparison of the resultsobtained with the two methods for the particular case of the SIMBOL-X X-raytelescope will be presented.