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A new facility is constructed for measurements of neutron‐induced fission cross sections in the 20–180 MeV energy region versus the np scattering cross section, which is adopted as the primary neutron standard. The advantage of the experiment compared to earlier studies is that the fission‐fragment detection and the neutron‐flux measurement via np scattering are performed simultaneously and at the same position in the beam, and, therefore, many sources of systematic errors cancel out. Further reduction of systematic errors is achieved due to “embedded” determination of effective solid angle of particle detectors using α‐particles from the radioactive decay of the target nuclei. The performance of the facility is illustrated by first data obtained for angular distributions of fission fragments in the 238U(n,f) reaction.

A new quasi‐monoenergetic neutron beam facility has been constructed at the The Svedberg Laboratory (TSL) in Uppsala, Sweden. Key features include an energy range of 20 to 175 MeV, high fluxes, and the possibility of large‐area fields. Besides cross‐section measurements, the new facility has been designed specifically to provide optimal conditions for testing of single‐event effects in electronics and for dosimetry development. First results of the beam characterization measurements performed in early 2004 are reported.