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Abstract

Thanks to its extremely fine sampling size, Secondary Ion Mass Spectrometry (SIMS) is one of the most powerful methods available to the analytical geochemist. State-of-the-art SIMS instrumentation can determine precise isotope ratios at the < 200 pg scale and can provide high quality U-Pb data from e.g., zircons at total sampling masses under 5 ng. In late 2013 the Helmholtz Zentrum Potsdam completed installation of a Cameca 1280-HR instrument, which is to operate as an open user facility. This instrument is to server the global user community by providing access to top-quality SIMS infrastructure in as simple and uncomplicated means as possible. The Potsdam 1280-HR instrument is equipped with a five trolley multi-collection ion detection system that enables isotope ratio determinations (e.g., δ11B, δ18O, δ34S) with repeatabilities at or below ± 0.2 ‰ (1sd) on major elements. We can equip the multi-collector with both electron multipliers or Faraday cups, and the system is flexible permitting both types of two ion detection methods to be combined, as is best optimize for a given application. During a typical 24 hour operating cycles between 250 and 35 analyses can be produced. Other applications such as U-Pb geochronology, depth profiling and the quantification of volatile element cycles will also be major research themes in the Potsdam facility. We also have a major focus on the precaution of a new suite of reference materials for calibrating both SIMS and other microanalytical methods, and here we benefit from a large consortium of interested universities and research facilities within the Berlin/Potsdam region. Along side our SIMS tool we are also supported by an extensive range of peripheral instrumentation. This includes a fully motorized optical microscope for sample documentation, a white light optical profilometer for determining crater dimensions at the sub-micron scale and a polychromatic cathode luminescence chamber. Additionally, the GFZ can provide access to a complete sample preparation facility along with other large instruments such as a field emission (FE) scanning electron microscope for backscattered electron and monochromatic CL imaging, a FE electron microprobe for major element determinations, a dual-beam FIB instrument and a Raman spectrometer. During the planning of the Potsdam SIMS facility detailed consideration was given to the design of our laboratory space. Our 1280-HR is housed in a room which has 2 autonomous air handling systems. Temperature within the majority of the room is dynamically controlled to maintain an air temperature stability within a 0.5 C° range, regardless of variations in heat load into the laboratory. Air supply is provided from below floor level and the heat is extracted at ceiling level. The air in the room is completely exchanged every 2 minutes with relative humidity maintained at below 72 % relative. In order to further assure the maximum stability of the instrument there is a second, independent air supply operating at a constant temperature and flow rate which delivers air to the main electronics rack from beneath floor level. The electronics rack has its own heat extraction hood to extract the thermal output immediately from the laboratory. The Cameca 1280-HR can operate autonomously for up to 45 minutes using an uninterruptable power supply, which also acts as a line conditioner. In order to fully minimize disturbances to laboratory environment the actual machine operation is conducted from an adjoining office. All superfluous heat sources, such as a vacuum-capable drying oven and sample coater, have been removed to a dedicated sample preparation room, which also adjoins the SIMS laboratory. We have already completed a number of projects, and here we will show some of the performance capabilities of our instrument.