The UGRA spectrometer for the measurement of the electric polarizability of the neutron

The new neutron spectrometer UGRA has been put into operation on the 250 m long time-of-flight path of the IBR-30 booster in Dubna. It has been constructed for the determination of the electric polarizability of the neutron which will be derived from the precise measurement of the angular dependence of neutron scattering on heavy nuclei at energies ∼0.5–60 keV. The spectrometer is situated in a vacuum chamber of ∼3 m lateral dimensions, capable of holding up to 3 scattering samples and 163He-detectors (of ∼7 l volume each) in shielding tanks on a rotary platform. Some characteristics of the instrument are reported.