Harmonic-free single-crystal monochromators for neutrons and X-rays

Comparisons are made between theoretical and actual performance of some novel crystal monochromators. Both perfect and slightly imperfect silicon crystals were used. It is demonstrated that with imperfect crystals and with an intensity loss of only 50% compared with a single perfect crystal, harmonic rejection ratios in excess of 1000 to one can be obtained. Calculations show harmonic rejection ratios of greater than 10⁵ to one in perfect crystals.