York University
Department of Physics and Astronomy
Petrie Science Building
Toronto, Ontario M3J 1P3, Canada

hessels@yorku.ca
Phone at CERN: (+41) 22 767 1758 and 7 9813

CERN Office: Building 600 R-012, phone: 767-3107
CERN Experiment Barrack:  Building 193, phone: 767-9813