[en] A method is described for producing megavolt neutron beams with a relative energy spread of ∼ 5 x 10^-4, based on the use of an electrostatic accelerator and a gas target with no foil, making it possible to carry out continuous, controlled production of the working substance. In the target differential pumping of the vapor of the working substance is effected by freezing out in liquid-nitrogen condensers. A method has been developed for using beams of neutrons from the ¹²C(d,n) reaction to measure the total cross sections for the interaction of neutrons with nuclei and the differential cross sections for elastic scattering