Compact Blackbody Radiation Atomic Sensor (CoBRAS)

The NIST Fundamental Thermodynamics group is leveraging the physical properties of atoms to provide accurate metrology of radiative temperature. Atoms are quantum systems whose interactions with electromagnetic radiation have been characterized with exquisite precision and, in many cases, are amenable to ab initio calculation. Compact Blackbody Radiation Atomic Sensor (CoBRAS) uses fluorescence detection of optically excited atoms in vapor cells to determine temperature.  A CoBRAS temperature measurement is fast, with statistical uncertainty as low as 0.1% in one second. We provide an update on the temperature precision, range, and sensitivity of the CoBRAS.  We also describe a new fiberized CoBRAS sensor with a form factor similar to traditional four-wire resistance thermometers.