In this presentation we wish to give a brief overview of the applicability of so-called cosmic rays as a passive source for both 3D or 4D bulk-density mapping of the subsurface. Naturally occurring cosmic radiation is a well-known, penetrating nuclear probe that, analogously to X-rays, can be used to infer a density map of the subsurface by using suitably designed and well positioned nuclear detectors. In most practical scenarios, however, one must deal with the fact that this flux, while free, is not constant in time nor in space, and that the measured data-sets are typically incomplete, i.e. they cannot be easily inverted to provide a voxel by voxel density map. This has typically limited the application space to the detection of gross features, such as large voids in ancient pyramids. Nonetheless, when more properly viewed as an aid to benchmark geological models or to monitor dynamic density or saturation changes in the underground, cosmic-ray density measurements appear to be well suited for a number of practical applications in mining, civil engineering as well as oil production. Historically, another practical obstacle has to do with a lack of detector configurations suitable for borehole deployment, however we will show that some are indeed possible at a relatively low cost by integrating off-the-shelf components. The necessary trade-offs between detector and installation costs, observation time and spatial/temporal resolution will be highlighted and results from a few exemplary test-case studies will be presented.
Dr. Botto is a senior applied physicist and established leader in the development of hard technology platforms, with significant experience in multidisciplinary corporate and academic R&D. Dr. Botto received his PhD in 1999 from the Vrije Universiteit in Amsterdam, The Netherlands, for research in fundamental electro-nuclear physics conducted at the Dutch National Institute for Nuclear and Particle Physics (NIKHEF). He then continued his academic research at the MIT/Bates accelerator facility focusing on the determination of the apparent shape and charge distribution of protons and neutrons in light nuclei. In 2005, Dr. Botto joined Schlumberger, the recognized world leader for technology services in the Oil & Gas industry as a research scientist. There he led the development of several advanced electromagnetic and nuclear sensing technologies, including: i) the development of an ultra-compact electron Linac (linear accelerator) for X-ray generation downhole; ii) the first-ever field-tested borehole tool for subsurface density mapping with cosmic-rays; iii) a robust, high-accuracy microwave sensor for custody transfer metering. While at SLB, Dr. Botto also led several sponsored research collaborations with Harvard and MIT on topics such as photonics, nanofabrication and high-temperature power electronics. Since 2018, Dr. Botto has been retained as a consultant and R&D expert by companies in the US, Europe and South America on a variety of topics in the oil & gas and mining sectors, as well as medical devices and nuclear fusion.