the NIST mission. This imbalance in the ratio is influenced by the current structure of the overhead for permanent and associate staff.

Examples of the division’s high-impact accomplishments include the aluminum ion “logic clock” (best in the world for precision), the femtosecond laser frequency combs enabling the world’s most precise intercomparisons, with a wide range of other applications in diverse fields such as astronomy and biological/chemical detection, remote time and frequency calibrations (best-in-the-world accuracy and usability), phase-noise metrology, NIST network time services, and chip-scale atomic clocks and sensors.

An important area of concern is related to the declining and inadequate funding supplied to division core services, such as network time services, radio stations, time and frequency calibrations, and maintaining the operation of the F-1 time standard.


Following is the panel’s assessment of the overall quality of the Time and Frequency Division (including opportunities for improvement) in terms of the three criteria as requested by the NIST Director (see Chapter 1).

Assessment Relative to Technical Merit

The technical quality of the work of this division is among the best in the world. The Time and Frequency Division is indeed an important national asset and fills a major need. The staff is first-rate, and its accomplishments, as measured by the academic standards of publications, conferences, and professional recognition, are first-rate. Some important highlights of the division’s accomplishments include the following:

  • Realization of the SI Second:

    • Primary frequency standards: best-in-the-world accuracy with the atomic standard F-1 (3 × 1016 frequency uncertainty reported to BIPM [the International Bureau of Weights and Measures]).

    • The upcoming cryogenic F-2 primary standard, which will improve the above accuracy by the factor three (to 10−16 uncertainty).

    • One of two best timescales in the world in terms of accuracy and stability.

  • Measurement Services:

    • Remote time and frequency calibrations: best-in-the-world accuracy and usability.

    • Phase-noise metrology: unique capabilities, best-in-the-world metrology.

    • NIST network time services: the world’s most heavily used Web clock (more than 3 billion hits per day).

    • NIST radio stations: best-in-the-world accuracy, stability; heavily used.

    • Global time service: low cost, ubiquitous 10 ns uncertainty service. The division has a new Web-based capability to track timescales across many laboratories in several countries around the world.

    • Time Measurement and Analysis Service: real time, 15 ns uncertainty; expanded to the Sistema Interamericano de Metrologia (SIM) Time Network.

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