  We report initial research to develop a compact and practical primary
thermometer based on Doppler broadening thermometry (DBT). The DBT sensor uses
an intrinsic property of thermalized atoms, namely, the Doppler width of a
spectral line characteristic of the atoms being probed. The DBT sensor, being
founded on a primary thermometry approach, requires no calibration or
reference, and so in principle could achieve reliable long-term in-situ
thermodynamic temperature measurement. Here we describe our approach and report
on initial proof-of-concept investigations with alkali metal vapour cells. Our
focus is to develop long-term stable thermometers based on DBT that can be used
to reliably measure temperatures for long periods and in environments where
sensor retrieval for re-calibration is impractical such as in nuclear waste
storage facilities.
