After obtaining his Ph.D. in high energy particle physics (measuring W bosons with the Ddetector at Fermilab) from Instituto Balseiro in Argentina, he was a fellow of the Istituto Nazionale di Fisica Nucleare in Italy, and a postdoctoral research associate at the University of New Mexico. He was also Assistant Professor at the University of Utah before joining the CSU faculty in 2008. He has been working on ultra-high energy cosmic rays as a member of the Pierre Auger Collaboration for more than 10 years. In 2009 he also joined the High Altitude Water Cherenkov Col- laboration. His research interests are in high energy particle astrophysics, including the origin of cosmic rays, acceleration mechanisms, particle physics at energies above terrestrial accelerators, gamma-ray astronomy and the structure of the Galaxy, and the nature and properties of dark matter.