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Search Publications by: Maynard S. Dewey (Fed)

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Displaying 1 - 25 of 81

Progress on the BL2 beam measurement of the neutron lifetime

April 17, 2021
Author(s)
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 tests of the Standard Model, and predictions of light element abundances in Big Bang

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

November 16, 2020
Author(s)
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 transmission through a polarized 3He spin filter cell was recorded while adiabatic fast passage

Precision determination of absolute neutron flux

June 8, 2018
Author(s)
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 counter. The method requires only the counting of measured rates and is independent of neutron

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

August 1, 2017
Author(s)
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 measurement technique in which the angular correlation is converted into a proton time-of-flight

Precision measurement of the radiative beta decay of the free neutron

June 30, 2017
Author(s)
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, an electron, and an antineutrino. We report the first precision test of the shape of the photon

A Backscatter-Suppressed Beta Spectrometer

June 16, 2017
Author(s)
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 and discuss the design and operation of a backscatter-suppressed beta spectrometer that was

Precision measurement of the radiative beta decay of the free neutron

June 14, 2016
Author(s)
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, an electron, and an antineutrino. We report the first precision test of the shape of the photon

Survival analysis approach to account for non-exponential decay rate effects in lifetime experiments

January 13, 2016
Author(s)
Kevin J. Coakley, Maynard S. Dewey, Michael G. Huber, Hans P. Mumm, Alan Keith Thompson, Andrew T. Yue, C. R. Huffer, P. R. Huffman, C. M. O'Shaughnessy, K. W. Schelhammer, D. E. Marley
In experiments that measure the lifetime of trapped particles, in addition to loss mechanisms with exponential survival probability functions, particles can be lost by mechanisms with non-exponential survival probability functions. Failure to account for

International Key Comparison of Neutron Fluence Measurements in Monoenergetic Neutron Fields – CCRI(III)-K11

November 3, 2014
Author(s)
Maynard S. Dewey, V. Gressier, A. C. Bonaldi, David M. Gilliam, H. Harano, A. Masuda, T Matsumoto, N. Moiseev, Jeffrey S. Nico, R. Notle, S. Oberstedt, N. J. Roberts, S. Rottger, D. J. Thomas
To ensure the validity of their national standards, National Metrology Institutes, NMIs, participate regularly in international comparisons. In the area of neutron metrology, Section III of the Consultative Committee for Ionizing Radiation is in charge of

Improved Determination of the Neutron Lifetime

December 2, 2013
Author(s)
Jeffrey S. Nico, A. T. Yue, Maynard S. Dewey, David M. Gilliam, G L. Greene, A. Laptev, William M. Snow, F. E. Wiefeldt
The most precise determination of the neutron lifetime using the beam method was completed in 2005 and reported a result of tau_n = (886.3 ± 1.2 [stat] ± 3.2 [sys]) s. The dominant uncertainties were attributed to the absolute determination of the fluence

A gamma and X-ray dector for cryogenic, high magnetic field applications

July 13, 2012
Author(s)
Thomas R. Gentile, R L. Cooper, R. Alarcon, M J. Bales, E J. Beise, H Breuer, J. Byrne, T E. Chupp, Kevin J. Coakley, Maynard S. Dewey, Changbo Fu, Hans P. Mumm, Jeffrey S. Nico, B. O'Neill, K. Pulliam, Alan Keith Thompson, F E. Wietfeldt
As part of an experiment to measure the spectrum of photons emitted in beta-decay of the free neu- tron, we developed and operated a detector consisting of 12 bismuth germanate (BGO) crystals coupled to avalanche photodiodes (APDs). The detector was

An experiment for the precision measurement of the radiative decay mode of the neutron

October 5, 2009
Author(s)
R Cooper, Christopher D. Bass, E Beise, H Breuer, Jim Byrne, T E. Chupp, Kevin Coakley, Maynard S. Dewey, B Fisher, Changbo Fu, Thomas R. Gentile, M. McGonagle, Hans Pieter Mumm, Jeffrey S. Nico, Alan Keith Thompson, F E. Wietfeldt
The neutron typically beta decays into a proton, electron, and antineutrino. In some decays, it can be accompanied by a high energy photon. We recently performed the rst observation of the radiative beta decay branch for the free neutron with photons of

Prospects for a New Cold Neutron Beam Measurement of the Neutron Lifetime

October 5, 2009
Author(s)
Maynard S. Dewey, Kevin J. Coakley, David M. Gilliam, G. Greene, A. Laptev, Jeffrey S. Nico, William M. Snow, F. E. Wiefeldt, A. Yue
In the most accurate cold neutron beam determination of the neutron lifetime based on the absolute counting of decay protons, the largest uncertainty was attributed to the absolute determination of the capture flux of the cold neutron beam. Currently an

Measuring 6LI(N,T) and 10B(N,A) Cross Sections Using the NIST Alpha-Gamma Device

April 15, 2009
Author(s)
Maynard S. Dewey, David M. Gilliam, Jeffrey S. Nico, G.L. Green, A. Laptev, A. Yue
The 6LI(N,T) and 10B(N,A) cross sections are important neutron cross section standards. Precise knowledge of these cross sections is essential because they are often used as reference standards for obtaining the neutron fluence in investigations of the

Radiative Beta Decay of the Free Neutron

February 2, 2009
Author(s)
R L. Cooper, T E. Chupp, Maynard S. Dewey, Thomas R. Gentile, Hans Pieter Mumm, Jeffrey S. Nico, Alan Keith Thompson, B M. Fisher, I Kremsky, F E. Wietfeldt, E J. Beise, H Breuer, K G. Kiriluk, J Bryne, Kevin Coakley, Changbo Fu
The theory of quantum electrodynamics predicts that the beta decay of the neutron into a proton, electron, and antineutrino is accompanied by a continuous spectrum of emitted photons described as inner bremsstrahlung. While this phenomenon has been

Accurate Determination of High Energy Gamma-Ray Standards

October 16, 2008
Author(s)
Ernest G. Kessler Jr., Maynard S. Dewey, R Deslattes, Albert Henins, H G. Borner, M Jentschel, H Lehmann
The extension of accurate crystal diffraction spectroscopy to the 2 to 6 MeV region is described. Gamma-ray standards with a relative uncertainty of (2 to 5)x10 -7 are obtained by measuring the small diffraction angles (a few tenths of a degree) through

Particle and Photon Detection for a Neutron Radiative Decay Experiment

April 11, 2007
Author(s)
Thomas R. Gentile, Maynard S. Dewey, Hans P. Mumm, Jeffrey S. Nico, Alan K. Thompson, T E. Chupp, R Cooper, B M. Fisher, I Kremsky, F E. Wietfeldt, K G. Kiriluk, E Beise
We present the particle and photon detection methods employed in a program to observe neutron radiative beta-decay. The experiment is located at the NG-6 beam line at the National Institute of Standards and Technology Center for Neutron Research. Electrons

Observation of the Radiative Decay Mode of the Free Neutron

December 29, 2006
Author(s)
Jeffrey S. Nico, Maynard S. Dewey, Thomas R. Gentile, Hans P. Mumm, Alan K. Thompson, B Fisher, I Kremsky, Fred E. Wietfeldt, T E. Chupp, R Cooper, E Beise, K G. Kiriluk, J Byrne, Kevin J. Coakley
The theory of quantum electrodynamics predicts that beta decay of the neutron into a proton, electron, and antineutrino should be accompanied by a continuous spectrum of soft photons. While this inner bremsstrahlung branch has been previously measured in

Radiative Decay Mode of the Free Neutron

January 1, 2006
Author(s)
Jeffrey S. Nico, Maynard S. Dewey, Thomas R. Gentile, Hans P. Mumm, Alan K. Thompson, B M. Fisher, I Kremsky, Fred E. Wietfeldt, T E. Chupp, R L. Cooper, E J. Beise, K G. Kiriluk, J Byrne, K Coakley

A direct test of E=mc 2

January 1, 2005
Author(s)
S T. Rainville, E G. Meyers, J M. Brown, Maynard S. Dewey, Kessler, G E, R Deslattes, H G. Borner, M Jentschel, P Mutti, D E. Pritchard