Detection of δ-electron events in charge coupled devices: a fingerprint of single swift heavy ions

Abstract Charge Coupled Devices, an arrangement of a few 100 000 photo-electric cells on a plane, allow the spatially and temporally resolved detection of single swift heavy ions and δ -electrons emitted by projectile-target-interactions from a target foil mounted at a distance of 500 μm above the microchip. This detector system is read out by standard TV technique and the signal is digitized for further processing by image analysis. The δ -electrons can be observed as a halo around the hit of the ion on the corresponding TV frame. The appearance of these halos is determined by the ion parameters velocity and effective charge. Vice versa the δ -electron halos provide information on the projectile within the bounds of the δ -electron statistics. This effect has been described in detail by an appropriate nuclear track structure model, which comprises production, transport and detection of δ -electrons as independent processes. First model calculations have been confirmed by experimental data.