An ion implantation system and method, providing cooling of dopant gas in the dopant gas feed line, to combat heating and decomposition of the dopant gas by arc chamber heat generation, e. The magnetic tape comprises a flexible support, a magnetic layer provided on one side of said flexible support and a backcoat layer provided on the reverse side of said flexible support. The image data obtained are stored in or deleted from a memory. The nested magnets are rotated along the vault. The present invention further relates to processes for their preparation, to pharmaceutical compositions comprising them, and to methods of using them.