The detector's ability to distinguish between X-rays with very similar energies should be especially useful to the semiconductor industry for chemical analysis of microscopic circuit features or contaminants. Many types of high-resolution microscopes routinely used in the industry and throughout science produce detailed chemical maps by scanning a surface with electrons and then analyzing the X-rays emitted, which are characteristic of specific elements.
The NIST device, an improved version of its previous microcalorimeter X-ray detector, uses a quantum-level, transition edge sensor (TES). NIST has led development of these sensors for several years. A TES works by measuring the current across a thin metal film that is held just at the knife-edge transition temperature between a superconducting state and normal conductance. A single X-ray photon striking the detector raises the temperature enough to alter the current proportional to the energy of the photon.