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

Charge Coupled Devices, an arrangement of a few 100 000 photo-electric cell s on a plane, allow the spatially and temporally resolved detection of sing le swift heavy ions and delta-electrons emitted by projectile-target-intera ctions from a target foil mounted at a distance of 500 mu m above the micro chip. This detector system is read out by standard TV technique and the sig nal is digitized for further processing by image analysis. The delta-electr ons can be observed as a halo around the hit of the ion on the correspondin g TV frame. The appearance of these halos is determined by the ion paramete rs velocity and effective charge. Vice versa the delta-electron halos provi de information on the projectile within the bounds of the delta-electron st atistics. This effect has been described in detail by an appropriate nuclea r track structure model, which comprises production, transport and detectio n of delta-electrons as independent processes. First model calculations hav e been confirmed by experimental data. (C) 1998 Elsevier Science B.V. All r ights reserved.