An investment group headed by American Magnetics...

An investment group headed by American Magnetics Corp. of Sherman Oaks said it is negotiating an all-cash deal to buy Damon Corp., a Needham Heights, Mass., laboratory chain. The group, Nomad Partners, had earlier launched a $201-million, $24-a-share bid that was spurned by Damon. The two sides said there is no guarantee they will reach an agreement. Nomad is headed by American Magnetics Chairman Robert L. Rosen, formerly a top executive with Texas takeover specialist Charles E. Hurwitz.