Acquisition-hungry Thermo Fisher Scientific ($TMO) is taking it down a notch in 2012. CEO Marc Casper tells Bloomberg that after making 5 acquisitions last year, it will use its cash to pay down its $7 billion in debt. Last year, Thermo Fisher made news with its $3.5 billion acquisition of Phadia and $2.1 billion purchase of Dionex. But it may be a little weary after those big buys. Although Casper's company will keep its eye open for deals, he doesn't see larger transactions happening "any time soon." Report