Pulsed-neutron monochromator

A pulsed-neutron monochromator for use in time-of-flight spectrometry, comprising:

• a row of elongated single crystals disposed for axial transversal by a neutron beam, each of said crystals being characterized by a peak reflectivity exceeding about 75% and each being oriented to reflect incident neutrons onto a common target, said crystals respectively defining neutron-scattering angles with said beam which increase progressively throughout said row whereby the energies of neutrons reflected from said crystals increases successively from said first crystal to said last crystal, each crystal carrying longitudinal-wave-damping means at one end thereof,
• electrically driven transducers coupled to the other end of each of said crystals to selectively vibrate each of said crystals in response to an electrical signal, and
• means for sequentially vibrating said crystals in descending order with respect to the size of their scattering angles whereby nuetrons reflected from said crystals and elastically scattered from said common target arrive simultaneously at a plurality of neutron detectors deployed in an array at equal distances from said target said crystals being vibrated at a frequency which exceeds their natural frequency and differs from harmonics thereof.

A method for generating monochromatic neutron pulses, comprising:

• providing a row of elongated, nearly perfect single crystals disposed for axial transversal by a neutron beam, said crystals being oriented to reflect incident neutrons onto a common target, said crystals respectively defining nuetron-scattering angles with said beam which increase progressively throughout said row whereby the energies of neutrons reflected from said crystals increases successively beginning with the first crystal in said row which is intersected by said neutron beam, and
• sequentially and non-resonantly vibrating said crystals in descending order with respect to the magnitudes of said scattering angles in a time sequence whereby neutrons reflected from said crystals reach said common target simultaneously, said crystals being vibrated at a frequency which exceeds their natural frequency and differs from harmonics thereof.