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Oct. 7, 2005

  In This Issue:
bullet NIST/JILA Fellow Shares Nobel Prize in Physics

Better Measurements Reveal Seasonal Changes in Sulfur

bullet NIST Method Improves Reliability of GPS Clocks
bullet Airtightness Simulations Cut Building Energy Tab
bullet Groups Join Forces for DHS Rescue Robot Standards
bullet Federal Cryptography Guide Available for Comment

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NIST/JILA Fellow Shares Nobel Prize in Physics

Nobel laureate John L. (Jan) Hall

Nobel laureate John L. (Jan) Hall

© 2005 Geoffrey Wheeler

For a high-resolution version of this photo contact

On Oct. 4, John L. (Jan) Hall of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder and Theodor W. Hänsch of the Max-Planck-Institute of Quantum Optics, Garching and Ludwig-Maximilians-Universität, Munich, Germany, were named winners of the 2005 Nobel Prize in Physics, sharing the honor with Roy J. Glauber of Harvard University.

Hall, 71, is a scientist emeritus in the NIST Quantum Physics Division and a fellow of JILA, a joint research institution of NIST and the University of Colorado in Boulder, Colo. He was one of the founding fellows of JILA (created in 1962 as the Joint Institute for Laboratory Astrophysics), and he significantly contributed to the development of the laser, first demonstrated in 1961, from a laboratory curiosity to one of the fundamental tools of modern science and a ubiquitous component of modern communications systems.

Hall is known as a preeminent laser experimentalist, concentrating on improving the precision and accuracy with which lasers can produce a specific, sharp frequency or color of light, and the stability with which they can hold that frequency. His work has been essential to the development of the laser as a precision measurement tool. In the 1960s he worked on the development of the methane-stabilized helium-neon laser, which became the cornerstone of a famous experiment at NIST to measure the speed of light at least 100 times better than any previous determination. The work ultimately led to a fundamental redefinition of the meter, the basic unit of distance measurement.

Precise control of the frequency and improved stability have enabled a broad range of laser applications in science and technology, including precision spectroscopy for physical and chemical analysis, new tests and measurements of fundamental physical laws and constants, time and length metrology, and fiber-optic communications, among others.

Hall shares the Nobel Prize with Hänsch "for their contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique.”

For further information and congratulatory quotes, see

Media Contact:
Michael Baum,, (301) 975-2763



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Better Measurements Reveal Seasonal Changes in Sulfur

aerial photo of Greenland coastline.

Aerial view of the Greenland coast.


View a high resolution version of this image.

Researchers from the University of Maryland (UMD) and the National Institute of Standards and Technology (NIST) have developed a new and improved technique for the simultaneous measurement of sulfur isotopic ratios and concentrations of atmospheric sulfate using snow samples from Greenland and Kyrgyzstan.

Sulfur plays an important role in the Earth’s climate. Sulfate particles in the atmosphere scatter and absorb sunlight, provide "seeds" for cloud formation, and affect the reflectivity and radiance of clouds, and thus the temperatures at the Earth’s surface. Atmospheric sulfate comes from natural sources, including oceans and volcanoes, but a large fraction comes from the burning of fossil fuels. Researchers can distinguish between various natural and anthropogenic sources in snow by measuring sulfur isotopes—forms of the element with different numbers of neutrons.

To study how these particulates have changed over time, scientists dig holes in snow that provide an archive of atmospheric particles deposited on the Earth’s surface. The standard analysis technique, gas-source isotope ratio mass spectroscopy (GIRMS), requires relatively large samples—up to four kilograms (about 9 pounds) of snow and ice, but the cycling of sulfur in the atmosphere is dynamic and variable, so samples this large blur seasonal changes.

To solve this problem, the UMD/NIST team developed a new analytical tool based on thermal ionization mass spectrometry (TIMS), which requires much smaller samples. The researchers used an advanced calibration technique known as double isotopic spiking to correct measurement drift and obtain isotope ratio measurements comparable to or better than GIRMS. The smaller snow samples required for TIMS make it possible to distinguish seasonal changes in sulfur particulate composition. The technique also can be used for making highly precise and accurate measurements of sulfur in low-sulfur fossil fuels, and similar applications.

The new technique was presented in a poster* at the 230th National Meeting of the American Chemical Society (2005). A description of the technique has been accepted for publication in Rapid Communications in Mass Spectrometry.

* J. Mann and W.R. Kelly. Measurement of sulfur isotopic signatures in two high elevation snow pits. American Chemical Society Annual Meeting (2005).

Media Contact:
Michael Baum,, (301) 975-2763



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NIST Method Improves Reliability of GPS Clocks

An Air Force staff sergeant operates a GPS navigation device.

A U.S. Air Force staff sergeant acquires Global Positioning System coordinates.

Photo by S. A. Cuomo/U.S. Air Force

The average user may not notice, but the Global Positioning System (GPS) is more reliable today than it was several years ago.

Widely used by the military, first responders, surveyors and even consumers, GPS is a navigation and positioning system consisting of ground-based monitors and a constellation of satellites that rely on atomic clocks. A statistical method, developed by the National Institute of Standards and Technology (NIST) and tested and implemented with the help of several collaborators, has made the job of analyzing the accuracy and reliability of these satellite-borne time signals significantly faster and easier. The method will help ensure that GPS clocks produce accurate location and distance measurements and remain closely synchronized with official world time.

The NIST method, described in a recent paper,* has been incorporated over the past few years into the GPS clock analysis software system managed by the Naval Research Laboratory (NRL). The satellite clocks—commercial devices based in part on research originally done at NIST—use the natural oscillations of rubidium atoms as "ticks," or frequency standards. The algorithm helps detect and correct GPS time and frequency anomalies. The algorithm also can be used to improve the control of other types of atomic clocks and has been incorporated into commercial software and instruments for various timing applications, according to NIST electronics engineer David Howe, lead author of the paper.

A GPS receiver pinpoints its location based on the distance to three or more GPS satellites at known locations in space. The distance is calculated from the time it takes for satellite radio signals to travel to the receiver. Thus, timing accuracy affects distance measurements. The NIST method makes a series of mathematical calculations to account for numerous measures of random "noise" fluctuations in clock operation simultaneously. This makes it easier to estimate many sources of error and identify the onset of instabilities in the clocks in minutes or hours rather than days. Adjustments then can be made promptly. The technique also could accelerate the evaluation of clocks during the process of building GPS satellites, where test time is at a premium. "Ultimately, it should improve reliability, stability and accuracy for many people who use GPS for time and navigation,"said Howe.

Co-authors of the paper include scientists from NRL, the Jet Propulsion Laboratory at the California Institute of Technology, the Observatoire de Besancon in France, and Hamilton Technical Services in South Carolina.

* D.A. Howe, R.L. Beard, C.A. Greenhall, F. Vernotte, W.J. Riley, T.K. Peppler. Enhancements to GPS operations and clock evaluations using a "total" hadamard deviation. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control. August 2005.

Media Contact:
Laura Ost,, (301) 975-4034



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Simulations Predict Savings From More Airtight Buildings

U.S. commercial building owners could save substantially on annual heating and cooling energy costs by improving airtightness of their buildings’ envelope, according to a recent National Institute of Standards and Technology (NIST) study. The research used simulation software to evaluate the energy impact of improved air barriers in three typical non-residential buildings in five cities, each in a different climate zone. The results predicted potential annual heating and cooling energy cost savings as high as 37 percent.

With baseline energy, climate and building data from each city, the researchers simulated conditions of a typical, two-story office building; a one-story retail building; and a four-story apartment building in Bismarck, N.D.; Minneapolis, Minn.; St. Louis, Mo.; Miami, Fla.; and Phoenix, Ariz. Each building was modeled with wood frame and masonry construction. Methods for increasing air tightness included building wraps or coatings for masonry blocks. The study focused on changes in energy expenditures as a result of increased airtightness, not on the methods themselves, so it does not single out a “best” airtightness method.

For the frame construction, the combined annual gas-electric cost savings of improved airtightness would be 33 percent for the hypothetical office building, 21 percent for the retail building, and 31 percent for the apartment in Bismarck. In Minneapolis, the predicted savings would be 37 percent, 26 percent and 33 percent, respectively. In St. Louis, the numbers would be 37 percent, 24 percent and 31 percent.

Improved air tightness in the warmer climates would produce smaller savings but could still be significant in the long run. In Phoenix, the estimated cost-savings are 10 percent, 16 percent and 3 percent for the office, retail and apartment, respectively; and in Miami, the estimates are 9 percent, 14 percent and 9 percent.

Predicted savings for the masonry buildings were similar to the frame construction. Although not evaluated in this report, improving building envelope airtightness also reduces the potential for problems caused by air leakage such as poor indoor air quality, thermal comfort and degradation of building materials due to moisture damage. (Like most commercial buildings, the buildings in the study used mechanical ventilation systems to maintain good indoor air quality.)

The NIST findings are expected to be useful to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), which is currently considering updating building air leakage requirements in its non-residential building energy standard 90.1.

Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use (NISTIR 7238) is available at

The research was sponsored by the U.S. Department of Energy Office of Building Technology.

Media Contact:
John Blair,, (301) 975-4261



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Groups Join Forces for DHS Rescue Robot Standards

first responders in hard hats stand on a pile of concrete rubble

First responders are briefed on a variety of urban rescue scenarios. The rubble pile was used with many different types of search and rescue robots.

Photo by Brian Antonishek /NIST

At the recommendation of the National Institute of Standards and Technology (NIST), the U.S. Department of Homeland Security (DHS) this month asked ASTM International to work with NIST and other stakeholders to develop voluntary consensus standards for urban search and rescue (US&R) robots. ASTM will disseminate the final consensus approved standards and test methods via its Committee E54 on Homeland Security Applications.

To assist this effort, NIST engineers, first responders, technology developers and robot vendors have begun to examine potential types of standards as well as tests needed to certify compliance to them. The comprehensive US&R standards drive, sponsored by DHS, is aimed at increasing federal, state and local officials' confidence in the emerging technology, spurring the purchase and deployment of the potentially life-saving devices.

Participants in a series of NIST-hosted workshops to define performance requirements identified at least 13 different robot varieties that may be applicable to search and rescue, from R2D2-type machines that search for victims within collapsed buildings to aerial ledge landers and aquatic bottom crawlers. They also counted more than 100 possible individual performance requirements in the categories of human-system interaction, logistics, operating environment, and system components (which includes chassis, communications, mobility, payload, power and sensing). Additional requirements are expected to arise during the standardization process.

The project Web site lists the robot categories and specific areas of inquiry at First responders, robot vendors and technology vendors who have suggestions for technologies to focus on or promising US&R robots to consider as well those interested in serving on the ASTM E54 standards committee, should contact Elena Messina
(301) 975-3235 or

Media Contact:
John Blair,, (301) 975-4261


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Federal Cryptography Guide Available for Comment

Today, federal agencies use computer systems and networks to store information and to interact with industry, private citizens and other governments both in this country and around the world. In this increasingly open environment of interconnected systems and networks, security is essential to ensure that information remains confidential, is not modified or destroyed, and is available when needed. To help federal agencies protect sensitive, but unclassified information, the National Institute of Standards and Technology (NIST) has updated a set of guidelines for selecting and implementing cryptographic methods.

Originally published in 1999, Guideline for Implementing Cryptography in the Federal Government (NIST Special Publication 800-21) is intended primarily for federal employees who design computer systems and procure, install and operate security products to meet specific needs. NIST is asking for comments on the publication, which is available at (.pdf; download Acrobat Reader) by Oct. 17, 2005. Send comments to, specifying "SP 800-21 Comments" in the subject field.

The draft publication is one of a series of key standards and guidelines produced by NIST’s computer security experts to help federal agencies improve their information technology security and comply with the Federal Information Security Management Act (FISMA) of 2002.

Media Contact:
Jan Kosko,, (301) 975-2767



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Editor: Gail Porter

Date created:10/7/05
Date updated: 10/7/05