The differential cross sections and vector analyzing powers for nd elastic scattering at E n = 248 MeV were measured for 10 •-180 • in the center-of-mass (c.m.) system. To cover the wide angular range, the experiments were performed separately by using two different setups for forward and backward angles. The data are compared with theoretical results based on Faddeev calculations with realistic nucleon-nucleon (NN) forces such as AV18, CD Bonn, and Nijmegen I and II, and their combinations with the three-nucleon forces (3NFs), such as Tucson-Melbourne 99 (TM99), Urbana IX, and the coupled-channel potential with-isobar excitation. Large discrepancies are found between the experimental cross sections and theory with only 2N forces for θ c.m. > 90 •. The inclusion of 3NFs brings the theoretical cross sections closer to the data but only partially explains this discrepancy. For the analyzing power, no significant improvement is found when 3NFs are included. Relativistic corrections are shown to be small for both the cross sections and the analyzing powers at this energy. For the cross sections, these effects are mostly seen in the very backward angles. Compared with the pd cross section data, quite significant differences are observed at all scattering angles that cannot be explained only by the Coulomb interaction, which is usually significant at small angles.

Abstract. Three neutron-deuteron scattering experiments at 95 MeV have been performed recently at The Svedberg Laboratory in Uppsala. Subsets of the results of these experiments have been reported in two short articles, showing clear evidence for three-nucleon force effects. In this paper, we present further discussion of the results. We obtained excellent precision in the angular range of the nd cross section minimum. The data are in good agreement with Faddeev calculations using modern NN potentials and including 3N forces from a 2π-exchange model, while the calculations without 3N forces fail to describe the data. CHPT calculations at next-to-next-to-leading order represent an improvement compared to calculations with NN forces only, but still underestimate the data in the minimum region. In addition to neutron-deuteron scattering data, neutron-proton and 12 C(n,n) elastic scattering data have been measured for normalization purposes, and 16 O(n,n) data have been obtained for the first time at this energy. It was possible to extract 12 C(n,n') and 16 O(n,n') inelastic scattering cross sections to excited states below 12 MeV excitation energy. These data are shown to have a significant impact on the determination of nuclear recoil kerma coefficients.

Sweden and Finland are preparing for final deposition of spent nuclear power fuel. The adopted method is to encapsulate spent nuclear fuel in copper canisters filled with iron before deposition in a deep bedrock repository. The canisters will have a diameter of about one metre, which makes examination of the content in sealed canisters virtually impossible with any known technique today. Two methods for tomography of sealed canisters have been studied, high-energy neutron tomography and cosmic-ray muon tomography. Monte Carlo simulations using MCNPX have shown that it would indeed be possible to produce images of good resolution of thick massive objects, like these canisters, using high-energy neutrons. The cost for installing such a method would, however, be very high. GEANT simulations, supported by experimental tests, indicate that tomography using the natural flux of cosmic-ray muons results in images of lower quality, but to a much more modest cost, acceptable to the application. Figure 1: Canisters for spent BWR nuclear fuel. The canister consists of a cylindrical copper shell with a pressure-bearing insert of nodular iron. The outer diameter is 1.05 m and the length 4.83 m [1].

Abstract. Three neutron-deuteron scattering experiments at 95 MeV have been performed recently at The Svedberg Laboratory in Uppsala. Subsets of the results of these experiments have been reported in two short articles, showing clear evidence for three-nucleon force effects. In this paper, we present further discussion of the results. We obtained excellent precision in the angular range of the nd cross section minimum. The data are in good agreement with Faddeev calculations using modern NN potentials and including 3N forces from a 2π-exchange model, while the calculations without 3N forces fail to describe the data. CHPT calculations at next-to-next-to-leading order represent an improvement compared to calculations with NN forces only, but still underestimate the data in the minimum region. In addition to neutron-deuteron scattering data, neutron-proton and 12 C(n,n) elastic scattering data have been measured for normalization purposes, and 16 O(n,n) data have been obtained for the first time at this energy. It was possible to extract 12 C(n,n') and 16 O(n,n') inelastic scattering cross sections to excited states below 12 MeV excitation energy. These data are shown to have a significant impact on the determination of nuclear recoil kerma coefficients.

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