Elemental analysis in medical physics and astro-geology

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The central theme of the proposed research program is the application of radiation physics to elemental analysis in medical physics and astro-geology.  The program consists of three major initiatives:1) Measuring Bound Water in Martian Soil SamplesThe alpha-particle x-ray spectrometers (APXS) carried on the Mars Exploration Rovers during NASA's 2004/2006 mission have provided elemental analysis of a large number of Martian rock and soil samples.  There are some suggestions that these samples contain salts left behind after the evaporation of large bodies of water, and an advanced version of APXS will be deployed in 2009/2010 to further investigate this hypothesis.  This research project will investigate the sensitivity of indirect detection of light elements in Martian samples based on the observed scatter features present in the APXS spectra.2)Measuring Silver with X-ray FluorescenceOccupational exposure to silver can occur in many settings.  Furthermore, there has been a re-emergence of the medicinal use of silver compounds, promoted in alternative medicine. Such exposure can lead to adverse biological effects such as argyria, a permanent skin discoloration. This work will investigate the application of a non-invasive in vivo technique to detect silver in the skin of individuals who are at risk of developing argyria, with the aim of providing a means of intervening before the onset of this irreversible skin condition.3) Measuring Nitrogen with Gamma-ray Resonance AbsorptionThe ability to measure nitrogen is a direct means of assessing protein status in many nutritional disorders. The goal of this research is to investigate an alternative approach to the current method, which is problematic.  This new measurement technique has the potential to improve substantially the uniformity and dose of the current method, and would facilitate clinical studies in a number of medical and health-related fields, e.g. nutritional sciences, pediatrics, gerontology, kinesiology and rehabilitation sciences.