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June 2, 2005

  In This Issue:
bullet NIST Photon Detectors Have Record Efficiency

Shadow Technique Improves Measurement of Micro Holes

bullet New Authentication Code Urged for Digital Data
bullet Software Addresses Terrorist Building Threats
  Quick Links:
bullet NIST June Workshop Focuses on BFRs in Environment
bullet Meeting Slated to Discuss Structural Steel and Fire
bullet 2004 Baldrige Winners' Applications Available
bullet NIST Withdraws Outdated Data Encryption Standard

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NIST Photon Detectors Have Record Efficiency

The four yellow squares in the center of this micrograph are NIST single photon detectors.

The four yellow squares in the center of this micrograph are NIST single photon detectors. The top two detectors are 25 by 25 micrometers. The bottom two detectors are 50 by 50 micrometers. The detectors operate with a record 88 percent efficiency.

Credit: NIST
Click here for a high resolution version of this photo.

Sensors that detect and count single photons, the smallest quantities of light, with 88 percent efficiency have been demonstrated by physicists at the National Institute of Standard and Technology (NIST). This record efficiency is an important step toward making reliable single photon detectors for use in practical quantum cryptography systems, the most secure method known for ensuring the privacy of a communications channel.

Described in the June issue of Physical Review A, Rapid Communications,* the NIST detectors are composed of a small square of tungsten film, 25 by 25 micrometers and 20 nanometers thick, chilled to about 110 milliKelvin, the transition temperature between normal conductivity and superconductivity. When a fiber-optic line delivers a photon to the tungsten film, the temperature rises and results in an increase in electrical resistance. The change in temperature is proportional to the photon energy, allowing the sensor to determine the number of photons in a pulse of monochromatic light.

This type of detector typically has limited efficiency because some photons are reflected from the front surface and others are transmitted all the way through the tungsten. NIST scientists more than quadrupled the detection efficiency over the past two years by depositing the tungsten over a metallic mirror and topping it with an anti-reflective coating, to enable absorption of more light in the tungsten layer.

The NIST sensors operate at the wavelength of near-infrared light used for fiber-optic communications and produce negligible false (or dark) counts. Simulations indicate it should be possible to increase the efficiency well above 99 percent at any wavelength in the ultraviolet to near-infrared frequency range, by building an optical structure with more layers and finer control over layer thickness, according to the paper.

Quantum communications and cryptography systems use the quantum properties of photons to represent 1s and 0s. The NIST sensors could be used as receivers for quantum communications systems, calibration tools for single photon sources, and evaluation tools for testing system security. They also could be used to study the performance of ultralow light optical systems and to test the principles of quantum physics. The work is supported by the Director of Central Intelligence postdoctoral program and the Advanced Research and Development Activity.

*D. Rosenberg, A.E. Lita, Aaron J. Miller, and S.W. Nam. 2005. Noise-free, high-efficiency, photon-number-resolving detectors. Physical Review A, Rapid Communications. June.

Media Contact:
Laura Ost,, (301) 975-3392



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Shadow Technique Improves Measurement of Micro Holes

NIST researchers and collaborators have developed a new method for measuring the interior dimensions of small holes with an uncertainty of only 35 nanometers.

NIST researchers and collaborators have developed a new method for measuring the interior dimensions of small holes with an uncertainty of only 35 nanometers. Here, a glass probe is inserted into an optical "ferrule," a device for connecting optical fibers used in communications systems.

NIST Photo

Click here for a high resolution version of this image.

Sometimes seeing a shadow can be as good or better than seeing the real thing. A new measurement method* developed by researchers working at the National Institute of Standards and Technology (NIST) is a case in point. The method uses the shadow cast by a small glass probe to infer the dimensions of tiny, microscale holes or other micrometer-sized components. The technique may provide an improved quality control method for measuring the interior dimensions of fuel nozzles, fiber optic connectors, biomedical stents, ink jet cartridges and other precision-engineered products.

Designed to be implemented with the type of coordinate measuring machine (CMM) routinely used in precision manufacturing settings, the method uses a flexible glass fiber with a microsphere attached on one end. The glass probe is attached to the CMM's positioning system, inserted into the part to be measured, and systematically touched to the part's interior walls in multiple locations. A light-emitting diode is used to illuminate the glass fiber. While the microsphere inside the part is not visible, the shadow of the attached fiber—with a bright band of light at its center—shows the amount of deflection in the probe each time the part's interior is touched. A camera records the shadow positions. Based on prior calibration of the force required to bend the probe a specific distance, the part's dimensions can be determined with an uncertainty of about 35 nanometers (nm). The method can be used for holes as small as 100 micrometers in diameter.

"Our probe has a much smaller measurement uncertainty than other available methods and it is very cost effective to make," says Bala Muralikrishnan, a NIST guest researcher from the University of North Carolina at Charlotte.

The thin, glass fiber is about 20 millimeters long and 50 micrometers in diameter, making it especially useful for measuring relatively deep holes not easily measured with other methods. Replacement probes cost about $100 compared to about $1,000 for those manufactured using silicon micromachining techniques.

*B. Muralikrishnan, J.A. Stone and J. R. Stoup. Measuring internal geometry of fiber ferrules. Presented at the SME MicroManufacturing Conference, Minneapolis, Minn., May 4-5, 2005.

Media Contact:
Gail Porter,, (301) 975-3392


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New Authentication Code Urged for Digital Data

The National Institute of Standards and Technology (NIST) is recommending a new algorithm for authenticating digital data for federal agencies. Called CMAC (cipher-based message authentication code), the algorithm can authenticate the source of digital data, such as messages sent over the Internet, and thus provide assurance that the data have not been modified either intentionally or accidentally.

The main component of CMAC is a block cipher. Within encryption algorithms, block ciphers are used to scramble the data after they are broken down into blocks. In CMAC, the block cipher creates a digital tag that authorized parties can use to verify that the received message has not been altered.

Other authentication mechanisms, such as the hash function message authentication code (HMAC) and digital signatures, have long been available. CMAC is a new option, intended especially for devices in which a block cipher is more readily available than the components of these other mechanisms.

CMAC was submitted to NIST as part of an ongoing public effort to develop and update block cipher-based algorithms, called modes of operation. A team of Japanese scientists, Tetsu Iwata and Kaoru Kurosawa of Ibaraki University, developed CMAC based on an earlier proposal by a team of American scientists, John Black of the University of Nevada, Reno, and Philip Rogaway of the University of California at Davis.

Recommendation for Block Cipher Modes of Operation: The CMAC Mode for Authentication (NIST Special Publication 800-38B) is available at It is the third of a series of publications recommending modes of operation to provide confidentiality or authentication for digital data. For more information, see

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



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Software Addresses Terrorist Building Threats

National Institute of Standards and Technology (NIST) economists have released risk assessment software that building owners and managers can use to identify and guard against terrorist threats to their facilities.

The software, developed by NIST's Office of Applied Economics (OAE) as part of NIST's commitment to homeland security, is the finished version of a beta program released last year for limited testing.

The "Cost Effectiveness Tool for Capital Asset Protection" (CET), Version 1.0, employs a three-step process for developing a risk mitigation plan. Its essential components are risk assessment, identification of potential mitigation strategies and economic evaluation. CET first allows users to look at possible damage scenarios. Users then can explore strategies to reduce facility vulnerability. Choices include engineering alternatives (such as sensors to detect airborne contaminants); management practices (such as evacuation drills or increased security) and financial mechanisms (such as tax-write offs for capital improvements). Finally,CET users can evaluate the actual life-cycle costs (planning, installation and maintenance) of the various mitigation strategies. The combination of strategies that reflects the lowest life-cycle cost is designated the cost-effective risk mitigation plan.

The software is available for free download at Users are invited to send comments about Version 1.0 to Robert Chapman at Suggestions will be used to improve CET 2.0 expected to be released in 2006.

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



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Quick Links

NIST June Workshop Focuses on BFRs in Environment

The National Institute of Standards and Technology (NIST) will host the Seventh Annual Workshop on Brominated Flame Retardants (BFRs) in the Environment on June 13 and 14 , 2005, at the NIST laboratories in Gaithersburg, Md. For years, BFRs have been added to consumer products ranging from carpets and cushions to computers and appliances because they can reduce flame sprawl and provide more time for people to escape.

Fires claim about 3,600 lives annually in the United States and cause an additional $10 billion in direct property loss. However, concerns have grown over the possible toxic effects of these compounds as they leach out into the environment. Some types of BFRs have been implicated in developmental, reproductive, neurotoxic and thyroid effects in rats, mice and fish and may be carcinogenic. Recently, the European Union issued a directive prohibiting use of two specific types of BFRs, referred to as pentaBDE and octaBDE, in consumer products.

The June workshop will include presentations on current work in human exposure to BFRs, their use in consumer products, improved analytical methods, toxicology and their presence in the environment. Dr. Andreas Sjöjin of the Centers for Disease Control and Dr. Robert Letcher of the National Wildlife Research Center will give keynote addresses.

Reporters interested in covering this meeting should contact Michael Baum,, (301) 975-2763.



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Meeting Slated to Discuss Structural Steel and Fire

The World Trade Center (WTC) terrorist attacks on Sept. 11, 2001, showed the critical importance of fire resistant materials for structural steel. To accelerate technological advances in this area, the National Institute of Standards and Technology (NIST) will host a meeting to evaluate industry interest in the creation of a NIST/industry consortium on the materials science of fire resistive materials for structural steel. The meeting will be July 14, 8 a.m. to 5 p.m., at NIST's Gaithersburg, Md., campus.

The meeting will explore possible goals and the initial scope of work for the consortium. Expected goals include the development of measurement methods for the thermal and adhesive properties of fire-resistive materials, tools for the characterization of their three-dimensional microstructure and linkages between microstructure and performance properties.

S. Shyam Sunder, lead investigator of NIST's building and fire safety investigation of the WTC collapses, will report on insights learned relevant to fire-resistive materials for structural steel. Attendees also will review NIST efforts to accurately predict performance of fire-resistant materials with laboratory measurements. A tour of NIST laboratory facilities is planned.

Preregistration for the free meeting is required. For further information, see or contact Dale Bentz at (301) 975-5865 or at Reporters interested in attending should contact John Blair, (301) 975-4261 or at




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2004 Baldrige Winners' Applications Available

While the overall frozen baked goods industry has remained relatively flat, sales for The Bama Companies have increased 72 percent; total revenue has grown from $123 million in 1999 to $211 million in 2004. Small manufacturer Texas Nameplate Company used innovative processes and new technology to decrease cycle time by 50 percent and increase profits by 40 percent. For the past several years, Kenneth W. Monfort College of Business has scored in the top 1 percent for overall student satisfaction and has been above the 90th percentile nationally for academic rigor. Over the past five years, Robert Wood Johnson University Hospital Hamilton has steadily improved its market share, especially in the areas of cardiology and oncology. The hospital's retention rate for nurses is at 99 percent.

To learn more about the outstanding results and innovative practices that earned these four organizations the 2004 Malcolm Baldrige National Quality Award, see their recently released award application summaries at

The Baldrige Award recognizes organizations in manufacturing, small business, service, education and health care for their performance excellence and quality achievements. For more information, see



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NIST Withdraws Outdated Data Encryption Standard

Secretary of Commerce Carlos Gutierrez recently approved the withdrawal of the Data Encryption Standard (Federal Information Processing Standard 46-3) and two related standards that provide for the implementation and operation of the DES. Adopted in 1977 for federal agencies to use in protecting sensitive, unclassified information, the DES is being withdrawn because it no longer provides the security that is needed to protect federal government information.

Federal agencies are encouraged to use the Advanced Encryption Standard, a faster and stronger algorithm approved as FIPS 197 in 2001. For more information, see


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Editor: Gail Porter

Date created:6/1/05
Date updated:6/2/05