U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Physical Measurement Laboratory /Sensor Science Division

Thermodynamic Metrology Group

The Thermodynamic Metrology Group realizes, maintains, and disseminates the national measurement standards for temperature, humidity, pressure, vacuum, and leaks.

The group mission is to advance the state of the art in measurement of thermodynamic quantities. We have active efforts in optics, nano-photonics, and quantum-based metrology along with traditional precision measurements to advance U.S. industry. We collaborate nationally and internationally, and engage in metrology education and outreach.

News and Updates

empty petri dish

Tracking Lab-Grown Tissue With Light

Someday, doctors would like to grow limbs and other body tissue for soldiers who have lost arms in battle, children who need a new heart or liver, and many

Projects and Programs

Thermometry

The NIST Thermodynamic Metrology Group maintains and develops national standards of temperature (in the range 0.65 K to 1235 K), and supports calibration of all

Pressure

The NIST Thermodynamic Metrology Group (TMG) provides critical research into pressure measurement capabilities improving uncertainties in user facilities and
Photonic thermometer packages

Photonic Thermometry

Resistance thermometry, a time-tested method for taking temperature measurement, relies on taking accurate temperature-dependent resistance measurement of a

Publications

On-chip Silicon Photonics Radiation Sensors

Author(s)
Nikolai N. Klimov, Zeeshan Ahmed, Lonnie T. Cumberland, Ileana M. Pazos, Ronald E. Tosh, Ryan P. Fitzgerald
We have examined the impact of cobalt-60-ray radiation up to 1 megagray (MGy) absorbed dose on silicon photonic devices. We do not find any systematic impact

A photonic pH sensor based on photothermal spectroscopy

Author(s)
Zeeshan Ahmed, Nathan J. Castro, Matthew R. Hartings
Although the determination of pH is a standard laboratory measurement, new techniques capable of measuring pH are being developed to facilitate modern

Tools and Instruments

PG

Piston gauges and pressure transducers

Piston gauges are used to calibrate customer piston gauges and pressure sensing devices. Piston gauges are calibrated via a direct comparison to another piston
3m UIM w/ Jay Hedricks

Low Pressure Gauges

NIST has developed best-in-the-world primary standard pressure measurement capabilities for pressures spanning the range of 0.01 Pa to 360 kPa through the

Vacuum Gauges

Most calibrations of vacuum gauges are based on a known gas flow rate that is generated by one of two flow meters that operate at constant pressure. The "piston

Leak Artifacts

Leak artifacts are calibrated in the range 1 x 10-6 to 1 x 10-13 mol/s (2 x 10-2 to 2 x 10-9 std. cm3/s at 0 °C). The calibration can be performed directly

Awards

View All Awards

Highlights

Related Links

Contacts

Group Leader

Office Manager