Observation of Ballistic Rotons in Liquid 4He
The excitations produced when a pulsed 4He atomic beam strikes the surface of liquid 4He held near T ~ OK have been measured as a function of direction in the liquid and time elapsed since the beam was generated. Comparison of the data with a theory which assumes that a single atom is converted into a single excitation indicates that the observed signals are due to ballistic phonons and rotons, although the experimental velocity and angular distributions of the excitations are displaced from the theoretical ones. The direction of the displacements suggests that multiple ripplon production occurs as an atom approaches the liquid surface, as predicted by Echenique and Pendry.
KeywordsAngular Distribution Transverse Momentum Atomic Beam Single Atom Maxwellian Velocity Distribution
Unable to display preview. Download preview PDF.
- (4).A more complete description of our work has been submitted to the Physical Review.Google Scholar
- (7).S. Balibar, Doctoral Dissertation, University of Paris (Laboratoire de Physique de l’Ecole Normale Supérieure) 1976.Google Scholar
- (8).J. R. Eckardt, D. O. Edwards, F. M. Gasparini and S. Y. Shen, Proc. of 13th Intern. Conf. on Low Temp. Physics, ed. Timmerhaus, O’Sullivan and Hammel, (Plenum Press, New York, 1974), p. 518.Google Scholar