An arrangement for detecting energy particle impingement includes a support frame and a multi-tube detector pack. Each pack includes multiple detector tubes. Each tube contains at least one sensitive material. Each tube is elongate along a respective axis. The tubes extend parallel with the respective axes being co-planar. Each pack includes mounting tabs located at each axial end. The tabs provide support for the tubes within the pack. At least one of the tabs has at least one securing portion and at least one adjusting portion. Each pack includes at least one operable securing member extending from the respective securing portion to the frame. Operation of the securing member secures the pack to the support frame. Each pack includes at least one operable adjusting member extending from the respective adjusting portion to the frame. Operation of the adjusting member changes an orientation of the pack.