John L. (Iain) Campbell
University Professor Emeritus
Telephone: 519-824-4120 x52325
Office: MacN 326
Lab: MacN 012 Lab Extension: 58397
Degrees & awards
- BSc in Physics, University of Glasgow, 1963
- PhD in Physics, University of Glasgow, 1967
- DSc, University of Glasgow, 1982
- DTech (honorary degree) University of Lund, Sweden, 1997
- Queen’s Golden Jubilee Medal, 2003
- University of Guelph Medal of Merit 2010
Atomic inner-shell processes; X-ray spectroscopy; applications of ion beams from accelerators; development of proton-induced X-ray emission (PIXE) and PIXE software for elemental analysis and imaging; development of fundamental parameters approach for in situ X-ray emission analysis of Martian rocks and soils for elements and water.
I have spent one-year leaves at the Max Plank Institüt fur Kernphysik in Germany and at the UK Atomic Energy Authority’s Harwell Laboratory. Shorter research assignments abroad were at the University of the Witwatersrand in S. Africa and the French Bureau de Récherches Géologiques et Minières. I have presented two-day training schools on the use of our PIXE software package at the Louvre Museum in Paris, the University of Florence, the Max Planck Institüt in Heidelberg, and the University of Madrid. I am a regular speaker at international conferences on applications of accelerators in pure and applied physics: the proceedings of two such recent conferences were dedicated to me in recognition of my contributions. I am a member of the X-ray Fundamental Parameters Initiative launched recently by the French and German National Standards labs and the European X-ray Spectrometry Association.
Major Research Achievements
Two examples are noted:
- The computer software package GUPIX developed by my group on the basis of our experience in PIXE and its underlying physics has been supplied to over 150 ion beam analysis laboratories in 33 countries. This fundamental parameters approach to PIXE analysis has become the most widely adopted PIXE software. A recent Google search showed 12700 hits. Our three successive GUPIX publications have attracted 846 citations in ISI.
- In 2008, we reported the first quantitative in situ determination of water by an instrument on the Martian surface. A new approach to the photon scatter peaks in the spectra from the alpha-particle X-ray spectrometer on the Spirit rover measured water contents of up to 15% in the bright high-sulphur Paso Robles soils in the Columbia hills.
Present Research Activities
- Fundamental research focuses on creation and de-excitation of core vacancies in atoms, using particle and photon beams, radionuclides and X-ray spectroscopy. Interests include natural widths of core levels, X-ray transition rates, satellites, fluorescence and Coster-Kronig probabilities. In future, some of this work will reflect my responsibilities within the X-ray Fundamental Parameters Initiative. Our X-ray spectroscopy work is supported by continuing studies of the properties and response of Si(Li) and SDD X-ray spectrometers.
- Applied research is partly based on the Guelph Micro-PIXE Facility, which provides elemental analysis and imaging on a wide variety of sample types. Plans are being made to convert this facility for support of the Martian project described below, for example in the microbeam analysis of Martian meteorites and of terrestrial rocks that emulate Martian ones. In addition, we continue to develop our GUPIX software which is a powerful tool used worldwide to fit PIXE spectra and derive element concentrations.
- In situ analysis of the Martian surface is a new venture, arising from collaboration with Prof. Ralf Gellert. We have accomplished a major extension of GUPIX to process the rock and soil spectra created on Mars by the Alpha-Particle X-Ray Spectrometers (APXS) carried by NASA’s Mars Exploration Rovers. The new version GUAPX is being refined to handle the APXS data from the upcoming Mars Science Laboratory mission: Prof. Gellert is the lead scientist for both the MER APXS and the MSL APXS, the latter having been designed by him at Guelph. GUAPX will provide accurate elemental concentrations in the Martian samples. Extensive work has been completed using the MER calibration data from geochemical reference standards to test GUAPX and to refine our new calibration method. This approach is currently being used to calibrate the MSL APXS. During this work, we have developed the new method mentioned above, which employs the photon scatter peaks in the APXS spectra to deduce the presence of elements whose atomic number is too low for them to be detected via their X-rays. This enabled us to make the quantitative in situ determinations of bound water content in the Paso Robles soils at Gusev crater. Considerable effort is now being devoted to refining this technique, and we have now suggested two further approaches that might provide independent means for in situ water measurement.
See Campbell website: http://pixe.physics.uoguelph.ca/