section_path: Neutron temperature/Ultracold neutrons
section_name: Ultracold neutrons
paragraph_text: Ultracold neutrons
  
  Ultracold neutrons are produced by inelastic scattering of cold neutrons in substances with a low neutron absorption cross section at a temperature of a few kelvins, such as solid deuterium or superfluid helium. An alternative production method is the mechanical deceleration of cold neutrons exploiting the Doppler shift.