  The radiation hardness of the AToM chips of the BaBar Silicon Vertex Tracker
has been investigated by means of irradiations with photons from a 60Co source
and 0.9 GeV electrons. The increase in noise and the decrease in gain of the
amplifier have been measured as a function of the applied capacitive load and
the absorbed dose. Different beam intensities have been used to study the
effect of different dose rates to the AToM radiation damage. The chip digital
functionalities have been tested up to a dose of 5.5 Mrads for the 60Co photons
and 9 Mrads for the 0.9 GeV electrons. In addition a pedestal shift for the
irradiated channels has been observed in the test with electrons but is not
present in the irradiation with photons. This effect reproduces qualitatively
the behavior observed since 2002 in the front-end electronics of the installed
BaBar Silicon Vertex Tracker. After some investigation of the chip layout, this
peculiar behavior could be associated to radiation damage in a well-identified
component of the AToM. The results of the radiation tests are presented and
used to extrapolate the performance and lifetime of the installed detector in
the next few years.
