BULLCAm

One possible approach involves the irradiation of the detectors with the gamma rays produced by the radioactive decay of an Americium 241 source. Upon its decay, it produces a low-penetrating \(\alpha\) particle and an X-ray photon with a typical energy of 59.5 keV. While the penetration of the \(\alpha\) particles is extremely small, hence are stopped by just a small layer of material between the source and the detector, the X-rays penetrate deeply into the silicon irradiating even the inner-most dice of the detector stack. The energy thus deposited is fixed and can be used to calibrate the response of the BULLKID-DM KIDs to a high level of precision. The development of a cryogenic system that allows for the precise control of the radioactive source is currently under development.