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Since 1991 I am a Professor at the Physics Institute of the National Autonomous University of Mexico, UNAM. In 1974 I was awarded a BSc in Physics from Universidad de Chile and a PhD in Physics from the University of Wisconsin, Madison, USA in 1979. I did postdoctoral stays at Institut des Sciences Nucléaires, ISN, Grenoble, France, and Universidad de Chile in Santiago, was visitor at the Lawrence Berkeley Laboratory and the Cyclotron Institute in College Station, Texas, and have spent sabbatical years at ISN, France, and Universidad Complutense de Madrid, Spain. |
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My early research interests were in the field of heavy-ion physics where I studied the effective interaction between atomic nuclei deduced from measurements of heavy-ion elastic scattering. The first experimental data I worked on (taken during scientific visits to Lawrence Berkeley Laboratory and ISN) showed hints of refractive effects in the angular distributions for relatively light heavy-nuclei, in particular the systems 12C-12C and 12C-16O at energies per nucleon near 20-38 MeV. The analysis of these and other data showed that the interpretation could be the presence of -predicted but yet unobserved for heavy-ions-- nuclear rainbows in the angular distribution. The observation of nuclear rainbows is consequence of weak absorption in the complex interaction, thus their presence permitted a complete and consistent determination of the nuclear potential properties for these not-so-heavy systems. Required properties of the potential, such as the fulfillment of dispersion relations between the real and the imaginary parts, were also confirmed. These analyses promoted a series of careful measurements as well as theoretical studies of nuclear properties.
My PhD thesis at UW was a nuclear physics measurement of interest to radiotherapy, thus I was familiar with the fields of dosimetry and medical physics. In 1995 I proposed to use low-energy accelerators available at UNAM to do experimental research in the properties of solid dosemeters (used to measure radiation dose to individuals, radiation workers and environment). The interest were the processes induced by densely ionizing particles. I created a group to study the thermoluminescent response of materials exposed to low-energy ion beams. Little was known experimentally about the response of these materials to ion tracks where ionizations would be closely localized spatially. We characterized two main types of response to radiation, visible at different heating temperatures. The same material, understood as a single detector, could give information not only of the amount of deposited energy (dose) but also of the spatial ionization characteristics of the irradiation beam (linear energy transfer). Our work with collaborators and students has addressed the measurement and interpretation of the LiF:Ti,Mg and CaF2:Tm response to ions and low-energy photons. My recent projects in medical physics are aimed at developing techniques of subtraction of radiological images to obtain information on angiogenesis, the development of new vessels around tumors. This project is pursued at the pre-clinical and clinical stage at the National Institute of Cancerology, in Mexico City.
A project with great impact was the creation in 1997 of a graduate program in medical physics. This postgraduate program has graduated near 200 medical physics specialists, thus helping to solve the need for specialized medical physicists in the country's health services. At the same time, the program has strengthened research in the field of medical physics, at UNAM and beyond, since it has promoted the direct collaboration between physicists, biologists and medical doctors. Soon after the program launching, I was a founding member of the Medical Physics Division of the Mexican Physics Society and the Mexican Federation of Organizations for Medical Physics. I have participated in national and international IAEA projects, and presently, I am a member of committees and projects oriented to strengthening the academic and professional aspects of medical physics.
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