Penning collisions of laser-cooled metastable helium atoms F. Pereira Dos Santos, F. Perales, J. Léonard, A. Sinatra, Junmin Wang, F. Saverio Pavone, E. Rasel, C. S. Unnikrishnan and M. Leduc Eur. Phys. J. D, 14 1 (2001) 15-22 Published online: 15 April 2001 DOI: 10.1007/s100530170228