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View Paper |
Session Topic: 2E, Time & Frequency |
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Paper Title: An Overview of Primary Frequency Standards at NIST |
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Date & Time: MONDAY, August 5, 2002 |
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2:30pm - 4:00pm
PARALLEL SESSIONS - SESSION 2 |
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Speaker: Steven R. Jefferts
NIST |
Email: jefferts@boulder.nist.gov |
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The National Institute for Standards and Technology (NIST, formerly NBS) has been building the nations primary frequency standards based on the ground-state hyperfine transition in cesium-133 for more than 40 years. The newest generation of frequency standard, NIST-F1, is fundamentally different from its predecessors NBS-1 through NIST-7. NIST-F1 relies on laser cooling of atoms and a vertical interrogation scheme that allows interaction times of about 1 second as opposed to 10 ms in the old thermal beam geometry. The increased observation time results in an unprecedented relative frequency accuracy of 10-15. If NIST-F1 were to operate continuously for 30 million years it would neither lose nor gain 1 second. The talk will outline the physics and engineering which underlies all cesium based atomic clocks. The concepts that apply specifically to NIST-F1 will be discussed in more detail. A somewhat detailed discussion of the sources of error in NIST-F1 will be included. |
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