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Search Publications

NIST Authors in Bold

Displaying 18101 - 18125 of 74178

Multiscale Correlative Measurements of Nanoparticles in Cells

August 26, 2014
Author(s)
Aric W. Sanders, Kavita M. Jeerage, Cindi Schwartz, Alexandra E. Curtin, Ann C. Chiaramonti Debay
Nanoparticles are emerging as invaluable tools in disease diagnosis, disease treatment and imaging contrast enhancement agents. The interactions of nanoparticles with host organisms are complex and affect biological systems over length scales that vary

Absolute pulse energy measurements of soft x-rays at the Linac Coherent Light Source

August 25, 2014
Author(s)
Uwe Arp, Alexander Sorokin, Ulf Jastrow, Pavle Jurani?, Svea Kreis, Mathias Richter, Yiping Feng, Dennis Nordlund, Kai Tiedtke, Philip Heimann, Bob Nagler, Hae Ja Lee, Stephanie Mack, Marco Cammarata, Oleg Krupin, Marc Messerschmidt, Michael Holmes , Michael Rowen, William Schlotter, Stefan Moeller, Joshua Turner
This paper reports novel measurements of x-ray optical radiation on an absolute scale from a recently developed source of radiation generated in the soft x-ray regime of a free electron laser. We give a brief description of the physics behind the

Milligram Mass Metrology Using Electrostatics

August 25, 2014
Author(s)
Gordon A. Shaw, John A. Kramar
— Although mass has historically been defined using an artifact standard, other means of realization are possible. One alternative approach employs a precision electromechanical balance, using the SI electrical units to derive a force used to measure the

Pseudomagnetic Fields in a Locally Strained Graphene Drumhead

August 25, 2014
Author(s)
Shuze Zhu, Yinjun Huang, Nikolai Klimov, David B. Newell, Nikolai Zhitenev, Joseph A. Stroscio, Santiago D. Solares Rivera, Teng Li
Recent experiments reveal that a scanning tunneling microscopy (STM) probe tip can generate a highly localized strain field in a graphene drumhead, which in turn leads to pseudomagnetic fields in the graphene that can spatially confine graphene charge

A 100 Tohm Guarded Hamon Transfer Standard

August 24, 2014
Author(s)
Dean G. Jarrett, Edward O'Brien, Marlin E. Kraft
Guarded Hamon transfer standards are used at NIST for scaling to high resistance levels. An improved design for a guarded Hamon transfer standard in the range from 1 TΩ to 100 TΩ is described. Measurements taken to select the primary and guard resistor

AC Waveform Source Referenced to a Programmable Josephson Voltage Standard

August 24, 2014
Author(s)
Alain Rufenacht, Charles J. Burroughs, Bryan C. Waltrip, Stephane P. Solve, Paul D. Dresselhaus, Samuel P. Benz
We are integrating an AC waveform source into our Programmable Josephson Voltage Standard system (PJVS). The objective is to provide a convenient, highly automated quantum-referenced source for ac voltage metrology that does not require the use of a

Accurate High-Ohmic Resistance Measurement Techniques up to 1 Pohm

August 24, 2014
Author(s)
Dean G. Jarrett, Gert Rietveld, Beat Jeckelmann
An overview is presented on precision high-ohmic resistance measurements for values of 100 Mohmand above. The two main measurement techniques in this resistance range are discussed, the current integration technique and the adapted Wheatstone bridge. The

Alignment and testing of the NIST Calculable Capacitor

August 24, 2014
Author(s)
Yicheng Wang, Felipe Guzman, Corey A. Stambaugh, Radek Smid, Hugo Zuniga Calvo, Andrew D. Koffman, Jon R. Pratt, John R. Lawall
This paper reports progress on the NIST effort to develop a new calculable capacitor, focusing on improvement of the guard electrode motion control as well as issues associated with the overall electrode alignment. Design of a multi-wavelength Fabry-Perot

Construction and Performance of the NIST-4 Magnet System

August 24, 2014
Author(s)
Frank C. Seifert, Alireza R. Panna, Leon S. Chao, Yusi A. Cao, Darine El Haddad, Shisong Li, Stephan Schlamminger, Jon R. Pratt, Heeju Choi, Lori Haley
A watt balance is a promising instrument to realize the unit of mass at the kilogram level. The magnet system is one of the key elements of such an instrument. For the new watt balance currently under construction at the National Institute of Standards and

Heterodyne interferometer with subnanometer accuracy

August 24, 2014
Author(s)
Darine El Haddad, Frank C. Seifert, Stephan Schlamminger, Leon S. Chao, David B. Newell, Jon R. Pratt
This paper gives a brief description of the laser interferometer system designed for the next generation watt balance experiment aimed to realize the unit of mass by direct link to Planck constant at the National Institute of Standards and Technology. The

Measurement of the Boltzmann Constant with Noise Thermometry at NIM

August 24, 2014
Author(s)
Jifeng Qu, Kunli Zhou, Horst Rogalla, Samuel Benz, Yunfeng Fu
Since 2010 we have been developing a quantum-voltage-calibrated Johnson noise thermometer at NIM to measure the Boltzmann constant k. With recent improvements in grounding and shielding of the electronics, and matching of the noise sources and transmission

Photonic-assisted Endoscopic Analysis of Guided W-band Pulses

August 24, 2014
Author(s)
Jeffrey A. Jargon, DongJoon Lee, JaeYong Kwon
We present a photonic-assisted time-domain measurement technique for exploring millimeter-wave propagation through a W-band waveguide. The electric fields, guided inside a rectangular waveguide, are sampled using a sub-millimeter-scale electro-optic probe

Relative Humidity Effects on Rectangular Waveguide Thermistor Sensors

August 24, 2014
Author(s)
Thomas P. Crowley
A correlation between the relative humidity nd the effective efficiency of several rectangular waveguide thermistor sensors has been observed. The difference between effective efficiency measurements made at 10 % and 30 % relative humidity can be 10 times

Systematic Error Resolved in NIST Johnson Noise Thermometer

August 24, 2014
Author(s)
Alessio Pollarolo, Weston L. Tew, Horst Rogalla, Samuel P. Benz
In the Johnson Noise Thermometry approach, Boltzmann’s constant k is obtained as the ratio of the noise power measured across a sense resistor at the triple point of water and the noise power measured for a synthesized reference waveform. The reference

The Design of the NEW NIST-4 Watt Balance

August 24, 2014
Author(s)
Leon S. Chao, Stephan Schlamminger, Frank C. Seifert, Yusi A. Cao, Darine El Haddad, David B. Newell, Jon R. Pratt
The design of the new permanent-magnet driven watt balance and novel mechanical features will demonstrate the high-precision capabilities of a large complex mass measurement system with expected overall uncertainties on the order of 3 parts in 10^8.

The Measurement of the Local Acceleration of Gravity for the NIST4 Watt Balance

August 24, 2014
Author(s)
David B. Newell, Jacques Liard, Leon S. Chao, Yusi A. Cao, Frank C. Seifert, Darine El Haddad, Jon R. Pratt, Stephan Schlamminger
A new watt balance is being constructed at NIST in preparation for the redefinition of the International System of Units and the realization of mass through an exact value of the Planck constant. We describe the procedures used and give results for the
Displaying 18101 - 18125 of 74178