The addition of an ionized radiation sensor had been on his creator’s “not necessary but nice to have” list.  It would allow the X9 coursers to track trails of entities – biological or synthetic – that had been exposed to radiation in much the same manner as a dog’s olfactory sense.  At 21:09.128 this sensor was bombarded with gamma particles.  At 21:09.134 the concussive blast of the mini-nuke detonation echoed through the streets of Concord…