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

Research Interests:

My research interests have centered around studies fundamental physics using neutrons and the field of neutron detection and dosimetry. In particular, I have been involved in experiments to measure the neutron lifetime, the time-reversal violating D coefficient, and radiative neutron decay. I am also interested in hadronic parity violation and am a collaborator in an experiment to measure the spin rotation of polarized neutrons in a liquid helium target. I have a continued interest in neutrino physics and have been a collaborator in the SAGE solar neutrino experiment since 1991. I work in the field of neutron standards and dosimetry and help to maintain neutron fields with thermal and fast neutrons at NIST. I collaborate in efforts to improve the detection and spectroscopy of fast neutrons.


  • Fellow of the American Physical Society and American Association for the Advancement of Science
  • University of Maryland Visiting Research Scientist
  • Member American Physical Society (Division of Nuclear Physics, Topical Group on Precision Measurements and Fundamental Constants, and Topical Group on Few-Body Systems)
  • Member American Association for the Advancement of Science (2002-present)
  • Member Council on Ionizing Radiation Measurements and Standards (CIRMS)


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

aCORN: an experiment to measure the electron-antineutrino correlation coefficient in free neutron decay

Maynard S. Dewey, Fred B. Bateman, Wangchun Chen, Thomas R. Gentile, Md. T. Hassan, Michael P. Mendenhall, Jeffrey S. Nico, Brian Collett, Jim Byrne, William Byron, Guillaume Darius, Christina DeAngelis, Gordon L. Jones, Alexander Komives, Alexander Laptev, George Noid, Hyeonseo Park, Ed Stephenson, I Stern, K Stockton, Bob Trull, Fred Wietfeldt, B G. Yerozolimsky
We describe an apparatus used to measure the electron-neutrino angular correlation coefficient, a, in free neutron decay. The apparatus employs a novel

A Backscatter-Suppressed Beta Spectrometer

Maynard S. Dewey, Taufique Hassan, Fred B. Bateman, Brian Collett, Guillaume Darius, Christina DeAngelis, Gordon L. Jones, Alexander Komives, Alexander Laptev, Michael Mendenhall, Jeffrey S. Nico, George Noid, Ed Stephenson, Fred Wietfeldt, Isaac Stern, Bob Trull
Backscatter of electrons from a beta spectrometer, with incomplete energy deposition, can lead to undesirable effects in many types of experiments. We present

Precision measurement of the radiative beta decay of the free neutron

Jeffrey S. Nico, Kevin J. Coakley, Maynard S. Dewey, Thomas R. Gentile, Hans P. Mumm, Alan Keith Thompson, M J. Bales, R. Alarcon, C. D. Bass, E J. Beise, H Breuer, Jim Byrne, R L. Cooper, B. O'Neill, F E. Wietfeldt, T E. Chupp
The theory of quantum electrodynamics predicts that a continuous spectrum of photons is emitted in the beta decay of the free neutron in addition to a proton
Created July 30, 2019