Skip to main content
U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Jeffrey S. Nico (Fed)

Dr. Jeffrey Nico’s research interests have centered around studies of fundamental physics using neutrons and the field of neutron metrology and standards. He has been involved in experiments that probe the weak interaction formulation within the Standard Model through precision measurements of neutron beta decay properties. Specifically, he has used cold neutron beams to measure the neutron lifetime, the time-reversal violating D-coefficient, and radiative neutron decay. He is also interested in using neutrons to understand hadronic parity violation in few body systems. It is experimentally studied using polarized neutrons that undergo a rotation in a liquid helium target as a result of the nucleon-nucleon weak interaction. He has a longstanding interest in neutrino physics and has been a collaborator in the Russian-American Gallium Experiment (SAGE) solar neutrino experiment since 1991.

In the field of neutron standards and dosimetry, Dr. Nico maintains thermal and fast neutron fields at NIST. These fields are made available to users from academia, industry, and governmental laboratories for applications such as detector calibration, neutron transport studies, sample activation experiments, electronic damage studies, and radiation effects on biological systems. He works to ensure the reliability of methods in neutron metrology through the participation in international key comparisons of the BIPM. He is also interested in improving techniques of neutron detection and spectroscopy. The approach uses segmented spectrometers and the principle of capture-gating to suppress backgrounds. Spectrometers are used for the measurement of low levels of fast neutrons for applications including the detection of very low-activity neutron sources and the characterization of the flux and spectrum of fast neutrons at the Earth's surface and in the underground environment.

Dr. Nico is currently the leader of the Neutron Physics Group. He is a Fellow of the American Physical Society and Fellow of the American Association for the Advancement of Science. He holds a position as a Visiting Research Scientist at the University of Maryland. He has served on numerous committees, reviews, and panels for the American Physical Society, Department of Energy, and the National Science Foundation including the APS Committee on Scientific Publications, the Nuclear Science Advisory Committee, and the Physical Review C editorial board.


Progress on the BL2 beam measurement of the neutron lifetime

Shannon M. Hoogerheide, Jimmy P. Caylor, Evan R. Adamek, Eamon S. Anderson, Ripan Biswas, B. E. Crawford, Christina DeAngelis, Maynard S. Dewey, N Fomin, David M. Gilliam, Kyle Grammer, G L. Greene, Robert W. Haun, Jonathan Mulholland, Hans Mumm, Jeffrey S. Nico, William M. Snow, F E. Wietfeldt, Andrew Yue
A precise value of the neutron lifetime is important in several areas of physics, including determinations of the quark-mixing matrix element |Vud|, related

Neutron Spin Rotation Measurements

Jeffrey S. Nico, Shannon M. Hoogerheide, Hans Mumm, Murad Sarsour, J Amadio, Eamon Anderson, Libertad Barron-Palos, Bret Crawford, Chris Crawford, D. Esposito, Walter Fox, I Francis, J Fry, Chris Haddock, Adam Holley, Kirill Korsak, J Lieers, S Magers, M. Maldonado-Velazquez, D Mayorov, T Okudaira, C Paudel, S Santra, H.M. Shimizu, William M. Snow, A. Sprow, K. Steen, H E. Swanson, John Vanderwerp, P. A. Yergeau
The neutron spin rotation (NSR) collaboration used parity-violating spin rotation of transversely polarized neutrons transmitted through a 0.5 m liquid helium

Experimental Upper Bound and Theoretical Expectations for Parity-Violating Neutron Spin Rotation in He-4

Jeffrey S. Nico, Hans P. Mumm, H E. Swanson, C. D. Bass, T. D. Bass, J M. Dawkins, J C. Horton, D Luo, William M. Snow, S. C. Walbridge, B. E. Crawford, K. F. Gan, A M. Micherdzinska, C. R. Huffer, D M. Markoff, Murad Sarsour, E I. Sharapov, V Zhumabekova, Blayne R. Heckel
Neutron spin rotation is expected from quark-quark weak interactions in the Standard Model, which induce weak interactions among nucleons that violate parity

Precision determination of absolute neutron flux

Jeffrey S. Nico, Maynard S. Dewey, David M. Gilliam, Andrew T. Yue, Eamon Anderson, Geoff Greene, Alexander Laptev, William M. Snow
A technique for establishing the total neutron rate of a highly-collimated monochromatic cold neutron beam was demonstrated using the method of an alpha- gamma
Created July 30, 2019, Updated February 2, 2021