Change with energy of source geometry as seen in hadron interferometry

Abstract

The variation of radii, lifetimes, correlation lengths and the chaoticity parameter of particle sources with the collision energy $\sqrt{s}$ is studied by analysing and comparing two-particle Bose-Einstein correlation data obtained by the NA22 Collaboration at $\sqrt{s}=22\ GeV$ and by the UA1-Minimum-Bias Collaboration at $\sqrt{s}=630\ GeV$. The UA1-data are found to be inconsistent with a static source, whereas both the data at $\sqrt{s}=22\ GeV$ and at $630\ GeV$ can be described in an expanding source model. In the latter model, the $s$-dependence of the data implies an increase of the transverse radius with $s$ and a decrease of the correlation lengths in longitudinal and in transverse direction. The chaoticity parameter increases or remains approximately constant as a function of the CM energy.