2009/07/31 by Christian Stock, C. Stock, R. A. Cowley +3 · 2 citations
Physics and Astronomy · #Atomic physics #Cross section (physics) #Hydrogen #Hydrogen atom #Inelastic scattering #Momentum (technical analysis) #Neutron #Neutron scattering #Nuclear Physics and Applications #Nuclear physics #Optics #Physics #Quantum mechanics #Quantum, superfluid, helium dynamics #Scattering #Scattering length #Spectrometer #X-ray Spectroscopy and Fluorescence Analysis #cond-mat.mtrl-sci #cond-mat.stat-mech
paper · pdf · doi:10.1103/physrevb.81.024303
published as Phys. Rev. B 81, 024303 (2010) · 16 pages, 19 figures, submitted to Physical Review B, new discussion on resolution
arxiv created 2009/08/19 · openalex publication_date 2010/01/12 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Deep inelastic neutron-scattering experiments using indirect time-of-flight spectrometers have reported a smaller cross section for the hydrogen atom than expected from conventional scattering theory. Typically, at large momentum transfers, a deficit of 20--40 % in the neutron-scattering intensity has been measured and several theories have been developed to explain these results. We present a different approach to this problem by investigating the hydrogen cross section in polyethylene using the direct geometry time-of-flight spectrometer MARI with the incident energy fixed at a series of values ranging from Ei=0.5 to 100 eV. These measurements span a much broader range in momentum than previous studies and with varying energy resolutions. We observe no momentum dependence to the cross section with an error of 4% and through a comparison with the scattering from metal foil standards measure the absolute bound cross section of the hydrogen atom to be \ensuremathσ(H)=80\ifmmode±\else\textpm\fi4 b. These results are in agreement with conventional scattering theory but contrast with theories invoking quantum entanglement and neutron experiments supporting them.