Abstract
Two different formulas relating the index of refraction of gases for atom waves to the scattering amplitude have been published. We show here that these two formulas are not consistent with the definition of the total scattering cross section while the formula developed by one of us [C. Champenois, Ph.D. thesis, Université P. Sabatier, 1999 (unpublished)] is in agreement with this standard knowledge. We discuss this result, in particular in the neutron case for which such an index was first introduced. We finally evaluate the index of refraction as a function of well-known quantities and we discuss the order of magnitude of the ratio of , where is the gas density.
- Received 8 November 2007
DOI:https://doi.org/10.1103/PhysRevA.77.013621
©2008 American Physical Society