way that shows the relative importance of various spatial regions for producing electrons that contribute to that deposition. The radiation field from an intense reusable source of flash x-rays that delivers a measured peak dose and dose rate of 370+60 krad (CaF,) and (3.5k0.7) X lOI3 rad (CaF,)/s over a useful area of 80 cm2 is characterized. CaF,:Mn TLDs (thermoluminescent dosimeters), which are used to measure the dose field, are shown to be dose-rate independent within k 15% up to this level. Energy deposition in the CaF, TLD chip was analyzed according to the origin of the electrons responsible for that deposition with a new computational tool.