SIMS–AMS depth profiles for NASA Genesis samples: Preliminary measurements

A wide variety of elements present in solar wind were collected during a 2-year space flight by the NASA Genesis Discovery mission. The high-value Genesis samples are presently analyzed by a few groups using SIMS and other techniques. For some of the more challenging measurements a combined SIMS–AMS facility may provide the advantages of accelerator mass spectrometry (AMS) to SIMS analysis, including molecular fragmentation and low-background detection. Initial results from simulating standards are presented here, demonstrating the capability of the system for this kind of surface analysis. Measurements were performed on internally produced standards consisting of Si wafers implanted with 1014 atoms/cm2 doses of Mg, Ti, Fe, Ni, Cu, and Zn. At the ion source stage, crater-edge effects were filtered by position gating, while at the spectrograph focal plane, possible interferences were rejected by coincidence position-energy detection. Thus, SIMS-like depth profiles were obtained and will be used for estimating system-specific relative sensitivity factors.