A detector includes a photosensitive array including at least one photosensitive surface. The first semiconductor package includes a first package substrate, first and second memory chips spaced apart from each other on the first package substrate in a first direction, third and fourth memory chips on the first and second memory chips, respectively, and first and second jumper chips on the first and second memory chips, respectively. The pivot axis of each control arm and the connection of that control arm to the spindle define a control arm plane; the control arm planes intersect to define a control line that intersects a vertical plane containing said longitudinal axis.