The properties of electron cooled heavy ion beams in the ESR storage r
ing are dominated by heating due to intrabeam scattering. For low inte
nsity ion beams a sudden reduction of the longitudinal ion beam temper
ature has been detected by Schottky noise analysis. This can be interp
reted as the disappearance of intrabeam scattering heating which could
allow a longitudinal ordering of the ion beam.