Roton-Roton Scattering

  • A. F. G. Wyatt
  • A. C. Forbes
Part of the NATO ASI Series book series (NSSB, volume 257)


The combination of quantum evaporation (QE) and time of flight measurements enables roton-roton scattering to be studied as a function of wavevector.1 Hitherto scattering has been has been seen with thermal populations2 which confines the wavevector to values very near that of the roton minimum\(q=1.924{{A}^{-{{1}^{3}}}}\), and averages over all angles between the two scattering rotons. Preliminary results using QE indicate a strong wavevector dependence of the scattering cross-sectionl.1


Probe Beam Probe Pulse Interaction Point Probe Flux Finite Pulse 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    A C Forbes and A F G Wyatt Phys. Rev. Letts. 64 1393 (1990).ADSCrossRefGoogle Scholar
  2. 2.
    See for example F Mezei Phys. Rev. Letts. 44 1601 (1980) and the references therein.ADSCrossRefGoogle Scholar
  3. 3.
    The one exception is reference 2 where the neutron line width was not found to be significantly different to that at the roton minimum.Google Scholar
  4. 4.
    F R Hope, M J Baird and A F G Wyatt Phys. Rev. Letts. 52 1528–31 (1984)ADSCrossRefGoogle Scholar
  5. 5.
    M Brown and A F G Wyatt J.Phys, Condens. Matter 2 (1990) 5025–46.ADSCrossRefGoogle Scholar
  6. 6.
    This was inadvertently quoted as 1.95A−1 in reference 1.Google Scholar
  7. 7.
    A C Forbes and A F G Wyatt, “Phonons 89”, S Hunklinger, W Ludwig and G Weiss, eds., World Scientific, Singapore (1990) p1047.Google Scholar
  8. 8.
    A C Forbes and A F G Wyatt. Proc LT19.Google Scholar
  9. 9.
    See for example A D B Woods and R A Cowley. Reports in progress in Physics 36 1135–1231 (1973) and references therein.Google Scholar
  10. 10.
    M Brown priv. comm.Google Scholar
  11. 11.
    Equation 5 only applies for QE at normal incidence. Finite collimation and a non normal angle of incidence will give a significantly different signal shape.Google Scholar

Copyright information

© Plenum Press, New York 1991

Authors and Affiliations

  • A. F. G. Wyatt
    • 1
  • A. C. Forbes
    • 1
  1. 1.Department of PhysicsUniversity of ExeterExeterUK

Personalised recommendations