Preparation of carbon micro-ribbon targets and open-edged stripper foils for the IUCF cooler ring

Abstract

The use of 5–15 μg/cm 2 films of vacuum-evaporated carbon as targets and stripper foils in the IUCF cooler ring requires compliance with the characteristics of the ring. One way to circumvent the upper limit in target thickness of 10 15 nuclei/cm 2 (less than 100 ng/cm 2) for stationary targets is to move a somewhat thicker ribbon quickly through the beam. Our current methods for fabricating, handling, and mounting carbon micro-ribbons are described. Stripping-injection of 90 MeV H 2 + beam from the cyclotron into the cooler is accomplished using 5–15 μg/cm 2 stationary carbon foils. The requirement that these foils be mounted on a “C”-shaped frame with an open side of 31 mm, proved surprisingly easy to fulfill. A technique will be described for producing single-layer stripper foils which have a relatively straight edge that is unsupported across one side.