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Larry T. Hudson

Since 1990, Larry Hudson has worked as a physicist at the National Institute of Standards and Technology (NIST). Dr. Hudson’s career began as a flight controller for the U.S. Space Shuttle Orbital Flight Test Program before attending graduate school at Vanderbilt University with NASA support to work on radiation interactions with surfaces in the space environment. Later at NIST, this theme continued with work on the pre- or post-flight calibrations of five x-ray astronomy platforms for NASA.

At NIST Hudson leads a program that produces custom-designed calibrated curved-crystal spectrometers that are fielded to help characterize the performance and spectra from exotic x-ray sources including the electron beam ion trap, the electron cyclotron resonance ion source, advanced medical radiography sources, laser-produced plasmas, terawatt pulsed accelerators, ultrafast Petawatt lasers, and inverse-Compton backscatter sources. This and related work has produced over 100 archival publications and is rooted in a culture of instrument making and an infrastructure of fundamental precision metrology efforts, including absolute x-ray wavelength determination (at the femtometer level) in support of high-accuracy transfer standards needed in fundamental and applied spectroscopy experiments around the world.

After the deliberate contamination of the U.S. mail with anthrax, Hudson assisted in design and coordination of experiments for the White House Task Force on Mail Irradiation resulting in the development of the protocol still in use to sanitize government mail with industrial x-ray sources. With sponsorship of the U.S. Department of Homeland Security, Hudson currently serves as the NIST project leader for the development of national and international measurement standards needed to test and evaluate the technical performance and radiation safety of the nation’s x-ray and gamma-ray security screening systems in all venues in which they are deployed. This is accomplished through a corpus of new documentary standards, test methods, test artifacts, dosimetry protocols and technical guidance documents, supported by NIST measurement science and computational modeling. This work fills well-documented gaps in transportation and commercial security that have been highlighted in Executive and Legislative requirements for 100 % screening of baggage, cargo, and airline passengers.



Radiation Physics Division
Dosimetry Group

Employment History:

NIST, 1990 - present


Ph.D., Physics, Vanderbilt University, 1989

M.S., Physics, Vanderbilt University, 1986

B.S., Physics and Math, Mississippi College, 1983


Phone: 301-975-2537
Fax: 301-869-7682