U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Metrology

Search Publications

Search Title, Abstract, Conference, Citation, Keyword or Author
  • Published Date
Displaying 201 - 225 of 5208

Measurement of Transient Environmental Effects in GPS-Disciplined Clocks

January 23, 2023
Author(s)
Andrew Novick, Michael A. Lombardi, Demetrios Matsakis, John Clark
GPS-disciplined clocks (GPSDCs) are designed to optimize the accuracy and stability of their pulse-per-second (PPS) and frequency outputs by steering an internal oscillator to the timing solution from a GPS receiver based on the received satellite signals

What does the pixel measure?

January 11, 2023
Author(s)
David W. Flater
The pixel is often used as a unit of measurement in information technology. Unfortunately, there is not a simple, consistently-applicable answer to what it is a measure of. This report analyzes the pixel unit through the lens of metrology and shows how one

Dealing with counts and other quantal quantities in quantity calculus

January 1, 2023
Author(s)
David W. Flater
Continuity is usually assumed as a defining feature of measured quantities. This premise is false for counted quantities, amount of substance, electric charge, and others that are constrained to exist in integral multiples of a quantum. A software

Isotope Dilution Mass Spectrometry as an Independent Assessment for Mass Measurements of Milligram Quantities of Aqueous Solution

January 1, 2023
Author(s)
Richard Essex, Jacqueline L. Mann, Denis E. Bergeron, Ryan P. Fitzgerald, Svetlana Nour, Gordon A. Shaw, R. Michael Verkouteren
Isotope dilution mass spectrometry was used to independently assess the accuracy of mass measurement methods developed to quantitatively dispense milligram quantities of aqueous solution. Solutions of isotopically enriched 158Gd and enriched 155Gd were

Precise Quantum Measurement of Vacuum with Cold Atoms

December 20, 2022
Author(s)
Daniel Barker, Bishnu Acharya, James A. Fedchak, Nikolai Klimov, Eric Norrgard, Julia Scherschligt, Eite Tiesinga, Stephen Eckel
We describe the cold-atom vacuum standards (CAVS) under development at the National Institute of Standards and Technology. The CAVS measures pressure in the ultra-high and extreme-high vacuum regimes by measuring the loss rate of sub-millikelvin sensor

Crystallization Kinetics in an Immiscible Polyolefin Blend

December 12, 2022
Author(s)
Derek Huang, Anthony Kotula, Chad R. Snyder, Kalman Migler
Motivated by the problem of brittle mechanical behavior in recycled blends of high density polyethylene (HDPE) and isotactic polypropylene (iPP), we employ optical microscopy, rheo-Raman, and differential scanning calorimetry (DSC) to measure the

Determination of the Gravitational Constant Using a BIPM Balance

December 12, 2022
Author(s)
Stephan Schlamminger, Leon Chao, Vincent Lee, David B. Newell, Clive Speake
With the torsion balance developed at the Bureau International des Poids et Mesures (BIPM), the Newtonian constant of gravitation, $G$, can be measured with two methods. In the Cavendish method, the external gravitational torque is obtained from the

Development of an Improved Standard Reference Material for Folate Vitamers in Human Serum

December 12, 2022
Author(s)
Johanna Camara, Jeanita Pritchett, Yasmine Daniels, Mary Bedner, Michael Nelson, Mark Lowenthal, Zia Fazili, Christine Pfeiffer, Karen W. Phinney, Katherine E. Sharpless, Lane C. Sander, Katrice Lippa, James H. Yen, Adam Kuszak, Stephen Wise
The US National Institute of Standards and Technology (NIST) developed a Standard Reference Material® (SRM®) 3949 Folate Vitamers in Frozen Human Serum to replace SRM 1955 Homocysteine and Folate in Human Serum. The presence of increased endogenous levels

Gas Flow Standards and Their Uncertainty

December 12, 2022
Author(s)
John D. Wright, Aaron Johnson, Michael R. Moldover, Shin-ichi Nakao
We review diverse types of gas flow standards that are used to calibrate other gas flow meters. For each type of standard, we describe the principles of its operation and at least one hardware example. We identify the practical limits of the example's

Cannabis Laboratory Quality Assurance Program: Exercise 2 Moisture Final Report

November 29, 2022
Author(s)
Chuck Barber, Colleen E. Bryan Sallee, Carolyn Burdette, Shaun Kotoski, Melissa M. Phillips, Walter Brent Wilson, Laura Wood
In 2020, NIST launched Cannabis Laboratory Quality Assurance Program (CannaQAP) to improve the comparability of the analytical measurements of cannabis and cannabis-derived products in forensic and cannabis (hemp and marijuana) testing laboratories

DIMENSIONAL METROLOGY IN DETERMINATION OF G WITH BIPM'S TORSION BALANCE

November 7, 2022
Author(s)
Vincent Lee, Stephan Schlamminger, Leon Chao, David B. Newell, Jon Pratt, Craig Shakarji, Clive Speake
This paper discusses the dimensional metrology challenges encountered while performing G measurements using the BIPM torsion balance and our solutions.