Properties of 23Na implanted targets

Ten types of 23Na implanted targets have been fabricated for the purposes of investigating the effects of proton beam bombardment on the implanted sodium distribution. Targets were implanted at energies of ENa = 10–30 keV using copper, tantalum, and nickel as host materials. Thin layers (100–200 Å) of chromium and gold were also evaporated over some of the targets to provide a protective layer for the implanted sodium. The 23Na(p, γ) resonance at a lab proton energy of Ep = 309 keV was used to determine the implanted distribution. Successive resonance profile measurements are presented for each implanted target, and the concurrent loss of 23Na resulting from beam bombardment is reported. The calculated temperature rise of the targets indicates that beam heating has a negligible effect on the implanted sodium distribution, and that the principal mechanism for 23Na loss during beam bombardment is sputtering.