Tapered scintillator crystal modules and methods of using the same

A particle detection device comprising:

• an array of optical sensors arranged in a 2-dimensional array, where there is a first gap between adjacent optical sensors, each optical sensor corresponding to a pixel and has an active area;
• a plurality of scintillator modules, where at least one scintillator module corresponds with an optical sensor in the array of optical sensor, respectively, each scintillator module has a first end in contact with its corresponding optical sensor and a second end, where there is a second gap between adjacent scintillator modules, the second gap being a minimum gap between the adjacent scintillator modules, and where scintillator modules adjacent a boundary of the active area of a corresponding optical sensor have a tapered portion at the first end such that a first cross sectional area at the first end overlaps the active area as viewed along a direction of a longitudinal axis, where the first cross sectional area is orthogonal to the longitudinal axis,
• a segmented light guide in contact with the second end of each scintillator module;
• and
• wherein the second gap is smaller than the first gap.