Supersonic Fe beam source for chromatic aberration-free laser focusing of atoms R. C. M. Bosch, H. C. W. Beijerinck, P. van der Straten and K. A. H. van Leeuwen Eur. Phys. J. AP, 18 3 (2002) 221-227 Published online: 06 June 2002 DOI: 10.1051/epjap:2002042