Starting off as a physicist, Axel studied physics and math at Muenster, Germany. In 2000, he got a PhD position for high energy physics at Nijmegen, The Netherlands. They sent him to Fermilab at Chicago, where he worked with the D0 experiment - which also meant writing software from PCI drivers to data analysis code. During that time he got involved with ROOT, slowly converting from a user to a developer. He contributed to whatever he needed, e.g. the statistics part, the documentation engine, and porting it to cygwin. After a position with the Fermilab Computing Division in 2005 he ended up at CERN in the ROOT development team. He is now responsible for the reflection system, the interpreter CINT, and the documentation system.