Charles is a senior researcher at Nikhef, the national institute for subatomic physics in the Netherlands. He received his PhD in physics in 1992 for his work in the L3 experiment at the LEP collider in CERN. Afterwards, he took up a post-doctoral fellowship at the University of Michigan in preparation of the superconducting supercollider. In 1994 Charles started working at the University of Minnesota, measuring the anomalous magnetic moment of the muon at the AGS in Brookhaven. After returning to the Netherlands in 1998, he worked on L3+Cosmics, and briefly on ATLAS. Since 2005 he works in the Pierre Auger Experiment, where he contributed in the development of using radio waves to measure properties of cosmic ray induced air showers.
In 2001, Charles started an outreach project in Nijmegen in which local schools participate in the measurement of cosmic rays. This experiment has evolved in HiSPARC that has received the ALTRAN award for innovation in 2004. Charles received the EPS HEPP outreach prize in 2007 for founding this experiment in which around 100 high schools, some outside the Netherlands, participate. Within the Auger experiment, Charles is one of the coordinators of the outreach task.
Charles was nominated as the Netherlands' representative to IPPOG in March 2016.