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Maynard S. Dewey (Fed)

Professional Interest: 

A major thrust of Dr. Maynard S Dewey’s research is focused on precise measurements of decay parameters in neutron beta decay in order to probe the Standard Model (e.g. the neutron lifetime and the correlation between the outgoing electron and electron-antineutrino momenta). This includes precise measurements of thermal and cold neutron fluences in order to reduce the uncertainty in beam-type measurements of the neutron lifetime, to measure important neutron capture cross sections (e.g. boron and lithium), and to re-calibrate the national neutron source NBS-1 which underpins our neutron source and detector calibration services.  A second thrust is precise measurements of neutron source intensities using the manganese bath method in order to reduce the uncertainty of neutron source calibrations for industry and government.

Dr. Dewey has been a member of the Neutron Physics group since 1990, after working in precise gamma-ray spectroscopy in the Quantum Metrology Group/Division for his first three years at NIST. Before coming to NIST in late 1987, he was a postdoctoral fellow at Princeton University where he continued his Ph.D. thesis work on a precise measurement of the Lamb shift in hydrogen-like 4He.  He received his Ph.D. in Physics from Princeton University in 1984 with a thesis in atomic physics under Prof. Robert Dunford entitled “A Precise Measurement of the 2S-2P Lamb Shift in Hydrogen-like Helium” and his B.S. in Physics from the State University of New York at Stony Brook in 1978. 

Dr. Dewey was awarded a NIST Bronze Medal in 2020; he was elected to Fellowship in the American Physical Society in 2017 through the Topical Group on Precision Measurements and Fundamental Constants; and he is an author on about 60 peer-reviewed publications.


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 Pieter 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 Polarimetry Using a Polarized 3He Cell for the aCORN Experiment

Benjamin C. Schafer, W A. Byron, Wangchun Chen, B Collett, Maynard S. Dewey, Thomas R. Gentile, Md. T. Hassan, Gordon L. Jones, Alexander Komives, Fred E. Wietfeldt
The neutron polarization of the NG-C beamline at the NIST Center for Neutron Research was measured as part of the aCORN neutron beta decay experiment. Neutron

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

Precision measurement of the radiative beta decay of the free neutron

Christopher D. Bass, Maynard S. Dewey, Thomas R. Gentile, Hans Pieter Mumm, Alan Keith Thompson, M J. Bales, R. Alarcon, E J. Beise, H Breuer, Jim Byrne, T E. Chupp, Kevin Coakley, R L. Cooper, B. O'Neill, F E. Wietfeldt
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 October 9, 2019, Updated December 8, 2022