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Search Publications by James A. Fedchak

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Displaying 1 - 25 of 36

NIST on a Chip: Photonic and Quantum-Based Sensors for Measurements of Pressure, Vacuum, Temperature and Beyond!

April 29, 2021
Jay Hendricks, Zeeshan Ahmed, Daniel Barker, Stephen Eckel, James Fedchak, Nikolai Klimov, Julia Scherschligt
At the core of the NIST on a Chip (NoAC) program is the idea that measurement technology can be developed to enable metrology to be done "outside the National Metrology Institute" by virtue of deployed and often miniaturized standards (that can also serve

Outgassing rate comparison of seven geometrically similar vacuum chambers of different materials and heat treatments

April 23, 2021
James Fedchak, Julia Scherschligt, Sefer Avdiaj, Daniel Barker, Stephen Eckel, Ben Bowers, Scott O'Connell, Perry Henderson
We have measured the water and hydrogen outgassing rates of seven vacuum chambers of identical geometry but constructed of different materials and heat treatments. Chambers of five different materials were tested: 304L, 316L, and 316LN stainless steels

Note: A Bitter-type electromagnet for complex atomic trapping and manipulation

February 12, 2021
Jacob L. Siegel, Daniel Barker, James Fedchak, Julia Scherschligt, Stephen Eckel
We create a pair of symmetric Bitter-type electromagnet assemblies capable of producing multiple field configurations including uniform magnetic fields, spherical quadruple traps, or Ioffe-Pritchard magnetic bottles. Unlike other designs, our coil allows

Note: A Radio Frequency Voltage-Controlled Current Source for Quantum Spin Manipulation

October 19, 2020
Daniel S. Barker, Alessandro Restelli, James A. Fedchak, Julia K. Scherschligt, Stephen P. Eckel
We present a design for a wide-bandwidth, voltage-controlled current source that is easily integrated with radiofrequency magnetic field coils. Our design uses current feedback to compensate for the frequency-dependent impedance of a radiofrequency antenna

A wide-bandwidth, high-power radio-frequency driver for acousto-optic and electro-optic devices

August 6, 2019
Daniel S. Barker, Neal C. Pisenti, Alessandro Restelli, Julia K. Scherschligt, James A. Fedchak, Gretchen K. Campbell, Stephen P. Eckel
We present a design for a general-purpose radio-frequency amplifier circuit that is suitable for driving acousto-optic and electro-optic devices. Our design uses telecom amplifiers to achieve power output > 1 W over a 10 MHz to 1.1 GHz frequency range, and

Nuclear-Spin Dependent Parity Violation in Optically Trapped Polyatomic Molecules

July 3, 2019
Eric B. Norrgard, Daniel S. Barker, Stephen P. Eckel, James A. Fedchak, Nikolai N. Klimov, Julia K. Scherschligt
We investigate using optically trapped linear polyatomic molecules as probes of nuclear spin- dependent parity violation. The presence of closely spaced, opposite-parity $\ell$-doublets is a general feature of such molecules, allowing parity-violation

A single-beam slower and magneto-optical trap using a nanofabricated grating

June 11, 2019
Daniel S. Barker, Eric B. Norrgard, Nikolai N. Klimov, James A. Fedchak, Julia K. Scherschligt, Stephen P. Eckel
We demonstrate a compact (0.25 L) system for laser cooling and trapping atoms from a heated dispenser source. Our system uses a nano-fabricated diffraction grating to generate a magneto- optical trap (MOT) using a single input laser beam. An aperture in

Light-induced atomic desorption of lithium

October 8, 2018
Daniel S. Barker, Eric B. Norrgard, Julia K. Scherschligt, James A. Fedchak, Stephen P. Eckel
We demonstrate loading of a Li magneto-optical trap using light-induced atomic desorption. The magneto-optical trap confines up to approximately 10000 lithium atoms with loading rates up to 4000 atoms/s. We study the Li desorption rate as a function of the

Challenges to miniaturizing cold atom technology for deployable vacuum metrology

September 14, 2018
Stephen P. Eckel, Daniel S. Barker, James A. Fedchak, Nikolai N. Klimov, Eric B. Norrgard, Julia K. Scherschligt, Constantinos Makrides, Eite Tiesinga
Cold atoms are excellent metrological tools; they currently realize SI time and, soon, SI pressure in the ultra-high (UHV) and extreme high vacuum (XHV) regimes. The development of primary, vacuum metrology based on cold atoms currently falls under the

Quantum-based vacuum metrology at NIST

June 20, 2018
Julia K. Scherschligt, James A. Fedchak, Zeeshan Ahmed, Daniel S. Barker, Kevin O. Douglass, Stephen P. Eckel, Edward T. Hanson, Jay H. Hendricks, Thomas P. Purdy, Jacob E. Ricker, Robinjeet Singh
The measurement science in realizing and disseminating the SI unit for pressure, the pascal (Pa), has been the subject of much interest at NIST. Modern optical-based techniques for pascal metrology have been investigated, including multi-photon ionization

Recent Developments in Surface Science and Engineering, Thin Films, Nanoscience, Biomaterials, Plasma Science, and Vacuum Technology

May 31, 2018
Miran Mozetic, Alenka Vesel, Gregor Primc, J. Bauer, A. Eder, G. H. S. Schmid, David Ruzic, Zeeshan Ahmed, Daniel S. Barker, Kevin O. Douglass, Stephen P. Eckel, James A. Fedchak, Jay H. Hendricks, Nikolai N. Klimov, Jacob E. Ricker, Julia K. Scherschligt, Jack A. Stone Jr., Gregory F. Strouse, I. Capan, M Buljan, S. Milosevic, C Teichert, S R. Cohen, A G. Silva, M Lehocky, P Humpolicek, C Rodriguez, J Hernandez-Montelongo, E Punzon-Quijorna, D Mercier, M Manso-Silvan, G Ceccone, A Galtayries, K Stana-Kleinschek, I Petrov, J E. Greene, J Avila, C Y. Chen, B Caja, H Yi, A Boury, S Lorcy, M C. Asensio, T Gans, D O?Connell, F Reniers, A Vincze, M Anderle
Nanometer-sized structures, surfaces and sub-surface phenomena have played an enormous role in science and technological applications and represent a driving-force of current interdisciplinary science. Recent developments include the atomic-scale

A 3D-printed alkali metal dispenser

May 1, 2018
Eric B. Norrgard, Daniel S. Barker, James A. Fedchak, Nikolai N. Klimov, Julia K. Scherschligt, Stephen P. Eckel
We demonstrate and characterize a source of Li atoms made from direct metal laser sintered Ti. The source's outgassing rate is measured to be $5 \,(2)\cdot 10^{-7}$\,$\rm{Pa}~ \rm{L}~ \rm{s}^{-1}$ at the temperature which optimizes the number of atoms

Recommended practice for calibrating vacuum gauges of the ionization type

April 27, 2018
James A. Fedchak, Patrick J. Abbott, Jay H. Hendricks, Paul C. Arnold, Neil T. Peacock
This document represents a recommended practice for the calibration of ionization gauges using the comparison method. In this method, ionization gauges are compared to a working standard that has an SI traceable calibration. The ionization gauge is either

3D printed ABS-MOF composite materials and their gas storage properties

March 19, 2018
Michael Bible, Makfir Sefa, Julia K. Scherschligt, Zeeshan Ahmed, James A. Fedchak, Hartings Mathew
Metal organic framework materials (MOFs) have been primarily recognized for their ability to promote selective storage of gas molecules. In their as-synthesized (powdered) form, MOFs are not easily processed for use in end-devices where their properties

Vacuum Furnace for Degassing Stainless-Steel Vacuum Components

March 1, 2018
James A. Fedchak, Julia K. Scherschligt, Daniel S. Barker, Stephen P. Eckel, Alex P. Farrell, Makfir Sefa
Ultra-high vacuum systems must often be constructed of materials with ultra-low outgassing rates to achieve pressure of 10-6 Pa and below. In such a case, any component placed into the ultra-high vacuum system must also be constructed of materials with

Development of a new UHV/XHV pressure standard (Cold Atom Vacuum Standard)

November 10, 2017
Julia K. Scherschligt, James A. Fedchak, Daniel S. Barker, Stephen P. Eckel, Nikolai N. Klimov, Constantinos Makrides, Eite Tiesinga
The National Institute of Standards and Technology has recently begun a program to develop a primary pressure standard that is based on ultra-cold atoms, covering a pressure range of 1 × 10-6 Pa to 1 × 10-10 Pa and possibly lower. These pressures

Perspectives for a new realization of the pascal by optical methods

October 24, 2017
Jay H. Hendricks, Karl Jousten, Jack A. Stone Jr., Patrick F. Egan, Tom Rubin, Christof Gaiser, Rene Schodel, James A. Fedchak, Jacob E. Ricker, Jens Fluegge, Stephen P. Eckel, Julia K. Scherschligt, Daniel S. Barker, Kevin O. Douglass, Gregory F. Strouse, Uwe Sterr, Waldimir Sabuga
Since the beginning of measurement of pressure in the 17th century, the unit of pressure has been defined by the relationship of force per unit area. The present state of optical technology now offers the possibility of using a thermodynamic definition

Toward 3D printed hydrogen storage materials made with ABS-MOF composites

September 26, 2017
Megan C. Kreider, Zeeshan Ahmed, Makfir Sefa, James A. Fedchak, Julia K. Scherschligt, Michael Bible, Nikolai N. Klimov, Bharath Natarajan, Hartings Mathew
The push to advance efficient, renewable, and clean energy sources has brought with it an effort to generate materials that are capable of storing hydrogen. Metal-organic framework materials (MOFs) have been the focus of many such studies as they are

Impact of Varying Vacuum Levels on Self-Heating in Photonic Thermometers

July 1, 2017
Zeeshan Ahmed, Nikolai N. Klimov, James R. Hands, James A. Fedchak
Here we examine the impact of vacuum levels on self-heating in photonic crystal cavity thermometers. Our results suggest that background gas pressure has a negligible impact on self- heating correction to the temperature-wavelength calibration.

Final report on the key comparison, CCM.PK15 in the pressure rangefrom 1.0 x 10-4 Pa to 1.0 Pa

January 30, 2017
Christian Wuethrich, Hitoshi Akimichi, Mercede Bergoglio, James A. Fedchak, Karl Jousten, Sueng Soo Hong, Jorge T. Guzman
The comparison CCM.M.P-K14 is a key comparison in pressure involving six laboratories in three regional metrological organizations (RMO). The measurand of the comparison is the accommodation coefficient of two spinning rotating gauge characterized in

Gas Uptake of 3-D Printed Acrylonitrile Butadiene Styrene (ABS) Using a Vacuum Apparatus Designed for Absorption and Desorption Studies

October 25, 2016
Makfir Sefa, Zeeshan Ahmed, James A. Fedchak, Nikolai N. Klimov, Julia K. Scherschligt
We describe a vacuum apparatus for determining the outgassing rate into vacuum, the diffusion coefficient, and the amount of gas absorbed for various materials. The diffusion coefficient is determined from a model applied to time-dependent desorption data

How to Build a Vacuum Spring-Transport Package for Spinning Rotor Gauges

April 7, 2016
James A. Fedchak, Julia K. Scherschligt, Makfir Sefa
The spinning rotor gauge (SRG) is a high-vacuum gauge often used to as a secondary or transfer standard for vacuum pressures in the range of 1.0 × 10-4 Pa to 1.0 Pa. In this application, the gauges are frequently transported to laboratories for calibration