  An important phenomenon limiting the sensitivity of bolometric detectors for
future space missions is the interaction with cosmic rays. We tested the
sensitivity of Cold Electron Bolometers (CEBs) to ionizing radiation using
gamma-rays from a radioactive source and X-rays from a X-ray tube. We describe
the test setup and the results. As expected, due to the effective thermal
insulation of the sensing element and its negligible volume, we find that CEBs
are largely immune to this problem.
