A perforator for perforating a subsurface formation surrounding a well bore to ensure perforation of channels in a cement sheath surrounding a casing pipe cemented in said well bore comprising a series of stacked plates, each plate containing spaced apart co-planar, pie-shaped linear charges and a co-planar, pie-shaped non-charged spacer arranged between each of said linear charges. There are preferably four linear charges and four non-charged spacers forming each plate. The linear charges on each plate are spaced angularly from the linear charges on each other plate so that the linear charges are aimed at different angular portions of the bore hole.