The superconducting camera, SCAM, is an ultra-fast photon-counting camera, developed by the ESA. It is cooled to just 0.3 K (three-tenths of a degree above absolute zero). This enables its sensitive electronic detectors, known as superconducting tunnel detectors, to register almost every photon of light that falls into it.
The number of free primary electrons generated per photon event is proportional to the photon energy and amounts to ~18000 per electronvolt, and therefore if the device is operated in single-photon count mode the energy of each captured photon can be calculated in the visible-light range, where photons have energies of a few electron-volts, each generating >20000 electrons. In a normal CCD only one primary electron is generated per photon, except for very energetic photons, like X-Rays, where a normal CCD can operate in a similar way to a SCAM.