  Detectors proposed for the International Linear Collider (ILC) incorporate a
tungsten sampling calorimeter (`BeamCal') intended to reconstruct showers of
electrons, positrons and photons that emerge from the interaction point of the
collider with angles between 5 and 50 milliradians. For the innermost radius of
this calorimeter, radiation doses at shower max are expected to reach 100 Mrad
per year, primarily due to minimum-ionizing electrons and positrons that arise
in the induced electromagnetic showers of e$^+$e$^-$ `beamstrahlung' pairs
produced in the ILC beam-beam interaction. However, radiation damage to
calorimeter sensors may be dominated by hadrons induced by nuclear interactions
of shower photons, which are much more likely to contribute to the non-ionizing
energy loss that has been observed to damage sensors exposed to hadronic
radiation. We report here on prior highlights and recent results of SLAC
Experiment T-506, for which several different types of semiconductor sensors
were exposed to doses of radiation induced by showering electrons of energy
3.5-13.3 GeV. By embedding the sensor under irradiation within a tungsten
radiator, the exposure incorporated hadronic species that would potentially
contribute to the degradation of a sensor mounted in a precision sampling
calorimeter. Depending on sensor technology, significant post-irradiation
charge collection was observed for doses of several hundred Mrad.
