A particle beam detector system can comprise a particle beam generator, a particle beam fluence and position detector array based on Micromegas technology, and data readout electronics coupled to the position detector array. The particle beam fluence and position detector array can comprise a sealed, gas-filled, ionizing radiation detector chamber. A printed circuit board (PCB) can be disposed within the ionizing radiation detector chamber, the PCB comprising a multi-layer array arrangement of interconnected conductive sensor pads comprising three planar coordinate grids, X, Y, and ST (stereo) situated on separate layers of the PCB. The multi-layer array arrangement of interconnected conductive sensor pads can comprise a first footprint. A dielectric lattice structure can be disposed over the PCB and the multi-layer array arrangement of sensors. A conductive mesh structure can comprise a second footprint disposed over the dielectric lattice structure and extending over an entire area of the first footprint.