Abstract :
A formula is given that permits the calculation of both neutron reflectivity and attenuation of Iron Oxide (FeO) single–crystals as a function of wavelength at both room and LN temperatures. A computer program FeO written in FORTRAN-77, has been developed to carry out the required calculations. The monochromatic and filtering characteristics of FeO single-crystals are detailed in terms of crystal cutting plane, mosaic spread, thickness and reactor moderating temperature within the wavelength band from 0.001nm up to 1.4nm. Calculation shows that, 10mm thick FeO single-crystal cut along its (200) plane having 0.4^0 FWHM on mosaic spread are the optimum parameters when, it used as a monochromator from a thermal reactor flux at neutron wavelengths shorter than 0.15nm. While, from a cold reactor flux, it is also appreciated as a neutron monochromator, free from higher order contaminations at wavelengths from 0.3 nm up to 0.42 nm. Calculation also shows that 50 mm thick FeO-single crystal cut along its (200) plane, with 0.01^0 FWHM on mosaic spread, is a good thermal neutron filter, with high effect-to-noise ratio.
