SRON ' s TES Microcalorimeter

The 15-year development of the European interpretation of the Transition Edge Sensor (TES) microcalorimeter is described within this document. In essence, a TES microcalorimeter is a high-resolution cryogenic photon detector that converts temperature changes induced by incoming photons into changes in electrical resistance. Conceptually, the device consists of an absorber, a detector, heat sink, amplifier, and a current loop. When a photon strikes the absorber-detector pair, its energy is converted into heat and the temperature of the detector increases. The detector, which resides at the transition point between the superconducting and nonsuperconducting state, undergoes a significant and measurable change in its Ohmic resistance profile. As a result, the photon's energy can be measured very accurately by the change in electrical resistance of the detector. [D1] After the photon is absorbed, the resulting heat is removed from the system by a momentary reduction of the electrical power that is fed into the detector, thus returning the system to its pre-measurement state. Since the TES microcalorimeters can be produced using lithographic techniques, they can be made into imaging spectroscopic arrays, thus enabling efficient and high quality astronomical observations.