Interaction of stored, cooled proton beams with fiber targets

The use of thin fibers as internal targets for nuclear physics experiments in storage rings is discussed. We have measured the lifetime and the energy spread of stored, electron-cooled beams in the presence of an internal carbon fiber target. Measurements have been carried out in the Indiana Cooler with proton beams between 100 MeV and 300 MeV. The effect of the inhomogeneous fiber target on the beam is the same as that of a homogeneous gas target of equivalent thickness within the accuracy of the measurement. The measurements are compared with a Monte Carlo simulation of the stored beam. It is demonstrated that charging of the fiber target can significantly affect the lifetime and energy spread of the stored beam.