Stacked tungsten–carbon targets

Targets of intermixed tungsten (W) and carbon (C) were required, with a consistent composition throughout the target. Each target had a useful diameter of 5 mm and an areal density of 255 mg/cm2, with approximately 180 mg/cm2 of W and 75 mg/cm2 of C. Each target was built as a stack of 150 composite foils in an aluminum holder; each composite foil consisted of a C foil having nominal thickness 2.5 μm, overcoated with an evaporated W layer having thickness 600 nm. Methods were developed to produce a large number of similar foils while avoiding overheating of the evaporator. Procedures were developed for stacking the resulting foils.