Disclosed herein is a detector having a pixel in a substrate and configured to detect radiation particles incident thereon; a first guard ring in the substrate, surrounding the pixel, and comprising a first doped semiconductor region in the substrate and a first electrically conductive layer in electrical contact to the first doped semiconductor region; a second guard ring in the substrate, surrounding the first guard ring, and comprising a second doped semiconductor region in the substrate and a second electrically conductive layer in electrical contact to the second doped semiconductor region. The first electrically conductive layer overhangs the first doped semiconductor region toward an interior of the first guard ring by a greater extent than the second electrically conductive layer overhangs the second doped semiconductor region toward an interior of the second guard ring.