Laboratory Background The National Ion Microprobe Facility is collection of faculty, students, and researchers engaged in various geo- and cosmochemical fields of study. The group is headed by Professors Kevin McKeegan, Mark Harrison, and Mary Reid of UCLA's Department of Earth and Space Sciences (ESS) and Institute of Geophysics and Planetary Physics (IGPP). The principal resource of the W.M. Keck Foundation Center for Isotope Geochemistry is a CAMECA ims 1270 high resolution, high sensitivity ion microprobe. The Division of Earth Sciences of the National Science Foundation provides a portion of the support for the Keck Center to enable us to host external users from the geological and related communities. We seek to provide the user with a world-class instrument that is developed to support applications that both take advantage of its unique capabilities and are at the forefront of scientific investigations. 
 
For Further Information Please Contact:
Kevin McKeegan kdm@ess.ucla.edu (310) 825-3580
Marty Grove marty@argon.ucla.edu (310) 825-7975
Mary Reid reid@zephyr.ess.ucla.edu (310) 825-1756
Chris Coath coath@argon.ucla.edu (310) 825-2719
IonProbe lab   (310) 825-4328

 Instrument Description The UCLA Cameca ims 1270 is a new generation, high-resolution / high-sensitivity ion microprobe (or Secondary Ion Mass Spectrometer: SIMS) designed specifically for microscale isotopic and elemental analysis of complex minerals. It is an extremely versatile tool, capable of analyzing either conducting or insulating samples for elements ranging from H through U. For the following discussion consult the plan view of the Cameca ims 1270. The instrument is equipped with both Cs+ and duoplasmatron (16O-) primary ion sources which can be focussed to produce ion beams as small as 1 mm diameter, although ~10 mm sputter craters are more typical for isotopic analyses. A large-radius triple-focusing mass spectrometer maintains high transmission even at the high mass resolving power (MRP ~ 6,000) required for Pb isotopic analysis of zircon. As with other Cameca ims instruments, the 1270 also functions as an ion microscope by direct ion imaging of the sample (with ~0.5 mmlateral resolution), enabling precise location of small inclusions for isotopic analysis (e.g., microfossils). A normal incidence electron flood gun provides charge compensation which enables analysis of electonegative elements (e.g, carbon and oxygen isotopic ratios) in thin-sectioned samples of (electrically insulating) rocks. Isotope ratios are measured either by rapid field switching with a laminated magnet, or by simultaneous multiple collection of up to 5 ion beams. The forward geometry design of the mass spectrometer enables energy filtering as well as multiple isotope collection. The multiple collection may be achieved with either Faraday cup detectors, or with discrete dynode electron multipliers for ion counting applications. Low (2000), moderate (4000), or high (6000) mass resolution modes are available in multicollection, whereas continously variable MRP (~1000 to ~15000) may be achieved with the off-axis monocollector. Isotopic precision achieved is typically in the range of 1 permil but is highly sample and element dependent: see specific application notes.