Intrabeam scattering and the coasting beam in the HERA proton ring

Undesired coasting beam of protons has been detected in the HERA proton ring in high energy storage operation. This mainly disturbs the operation of the HERA-B experiment, and can have some impact on H1 and ZEUS where it generates background spikes (depending also on the collimator settings). In this work we present a collection of data and facts, to be taken as starting point for further theoretical and experimental studies. We propose Intra Beam Scattering as a possible physical mechanism for creating the coasting beam and discuss the implications of this longitudinal dynamics model on observables such as the bunch length, energy spread, dc current and reaction rate at the HERA-B wires. The results seem to be in qualitative agreement with the measurements.