Ion-implanted S targets for astrophysics studies

The fabrication of isotopically pure 10.4 μg/cm² targets of ³²S by the implantation of 60-100 keV negative ions into a 61 μg/cm² pure ¹²C thin foil is described. The process has been accomplished in rather shorter times than has been achieved previously by implanting the as-prepared carbon foil while still mounted on the underlying glass slide, thereby allowing for the use of much larger beam current intensities. The target has been assayed for absolute composition as a function of depth using Rutherford backscattering spectrometry and excellent agreement between the measured and nominal ³²S fluences was observed. The implanted targets exhibit excellent stability with regard to subsequent 34.5 MeV proton beam irradiation.