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Publications

Search Publications by Thomas R. Gentile

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Displaying 1 - 25 of 101

Demonstration of focusing Wolter mirrors for neutron phase and magnetic imaging

April 21, 2021
Author(s)
Daniel S. Hussey, Han Wen, Huarui Wu, Thomas R. Gentile, Wangchun Chen, David L. Jacobson, Jacob LaManna, B. Khaykovich
Image-forming focusing mirrors were employed to demonstrate two different modalities of neutron imaging, phase imaging with a far-field interferometer, and magnetic-field imaging through the manipulation of the neutron beam polarization. For the phase

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

Optimizing Magnetically Shielded Solenoids for Large Volume 3 He Neutron Spin Filters

October 2, 2020
Author(s)
Wangchun Chen, Md. Hassan, Ross Erwin, Shannon M. Watson, Thomas R. Gentile, G. L. Jones
An important consideration when designing a magnetostatic cavity for various applications is to maximize the ratio of the volume of field homogeneity to the overall size of the cavity. We report a design of a magnetically shielded solenoid that

Electric-field imaging using polarized neutrons

September 10, 2020
Author(s)
Y.- Y. Jau, Daniel S. Hussey, Thomas R. Gentile, Wangchun Chen
We experimentally demonstrate that electrically neutral particles, neutrons, can be used to directly visualize the electrostatic field inside a target volume that can be physically isolated or occupied. Electric field images are obtained using a spin

Sensitive neutron transverse polarization analysis using a 3He spin filter

July 7, 2020
Author(s)
Y.- Y. Jau, Wangchun Chen, Thomas R. Gentile, Daniel S. Hussey
We report an experimental implementation for neutron transverse polarization analysis that is able to detect a small angular change (10^-3 rad) of neutron spin orientation and works for both monochromatic and polychromatic neutron beams. Our approach

Study of the neutron spin-orbit interaction in silicon

September 30, 2019
Author(s)
Thomas R. Gentile, Michael G. Huber, Muhammad D. Arif, Daniel S. Hussey, David L. Jacobson, Donald D. Koetke, Murray Peshkin, Thomas Dombeck, Paul Nord, Dimitry A. Pushin, Robert Smither
The neutron spin-orbit interaction, which results from the interaction of a moving neutron's magnetic dipole moment (MDM) with the atomic electric elds, induces a small rotation of the neutron's spin in one Bragg re ection. In our experiment neutrons

Optically Polarized He3

December 1, 2017
Author(s)
Thomas R. Gentile, P.J. Nacher, B Saam, T G. Walker
This article reviews the physics and technology of producing large quantities fo highly spin- polarized, or hyderpolarized, He3 nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping, and surveys applications of polarized He3

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

Higgs Amplitude Mode in a Two-Dimensional Quantum Antiferromagnet near the Quantum Critical Point0

July 4, 2017
Author(s)
Tao Hong, Masashige Matsumoto, Yiming Qiu, Wangchun Chen, Thomas R. Gentile, Shannon M. Watson, Firas F. Awwadi, Mark M. Turnbull, Sachith E. Dissanayake, Harish Agrawal, Rasmus Toft-Petersen, Bastian Klemke, Kris Coester, Kai P. Schmidt, David A Tennant
Spontaneous symmetry-breaking quantum phase transitions play an essential role in current condensed matter physics1-3. The collective excitations in the broken-symmetry phase near the quantum critical point can be characterized by fluctuations of phase and

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

Spin-Analyzed SANS for Soft Matter Applications

June 20, 2017
Author(s)
WangChun Chen, John Barker, Ronald L. Jones, Kathryn Krycka, Shannon Watson, Cedric Victor Lucien Gagnon, T. Perevozchivoka, Paul Butler, Thomas R. Gentile
The small angle neutron scattering (SANS) of nearly Q-independent nuclear spin-incoherent scattering from hydrogen present in most soft matter and biology samples may raise an issue in structure determination in certain soft matter applications. This is

Recent Advancements of Wide-Angle Polarization Analysis with 3 He neutron Spin Filters

October 10, 2016
Author(s)
WangChun Chen, Thomas R. Gentile, Qiang NMN Ye, A. Kirchhoff, Shannon Watson, Jose A. Rodriguez, Yiming Qiu, Collin L. Broholm
Wide-angle polarization analysis with polarized 3He based neutron spin filters (NSFs) has recently been employed on the Multi-Axis Crystal Spectrometer (MACS) at the National Institute of Standards and Technology Center for Neutron Research (NCNR). Over

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

A New Cold Neutron Imaging Instrument at NIST

July 6, 2015
Author(s)
Daniel S. Hussey, Christoph W. Brocker, David L. Jacobson, Thomas R. Gentile, Wangchun Chen, Elias M. Baltic, DV Baxter, J. Doskow, Muhammad D. Arif
The NIST neutron imaging program will build a new imaging instrument in the NCNR guide hall at the end of the neutron guide NG-6, beginning operation in summer of 2014. The NG-6 guide has a spectrum that is strongly peaked at a neutron wavelength of 5 Å

Nonproportionality in the scintillation light yield of bismuth germanate

November 11, 2014
Author(s)
Thomas R. Gentile, M J. Bales, H Breuer, T E. Chupp, Kevin J. Coakley, R L. Cooper, Jeffrey S. Nico, B. O'Neill
We present measurements of nonproportionality in the scintillation light yield of bismuth germanate (BGO) for gamma-rays with energies between 6 keV and 662 keV. The scintillation light was read out by avalanche photodiodes (APDs) with both the BGO

3 He Spin Filter Based Polarized Neutron Capability at the NIST Center for Neutron Research

July 24, 2014
Author(s)
WangChun Chen, Thomas R. Gentile, Ross W. Erwin, Shannon Watson, Qiang NMN Ye, Kathryn L. Krycka, Brian B. Maranville
A 3He neutron spin filter (NSF) program for polarized neutron scattering was launched in 2006 as part of the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) Expansion Initiative. The goal of the project was to

On the limits of spin-exchange optical pumping of 3He

July 2, 2014
Author(s)
Thomas R. Gentile, T G. Walker, E Babcock, Qiang NMN Ye, Wangchun Chen
Using diode bar lasers spectrally narrowed with chirped volume holographic gratings (VHGs), we have obtained an improvement in the 3He polarization achievable by spin-exchange optical pumping (SEOP). As compared to our past results with lasers narrowed

Neutron Interferometric Measurement of the Scattering Length Difference Between the Triplet and Singlet States of N-3 He.

June 4, 2014
Author(s)
Michael G. Huber, Muhammad D. Arif, Wei-Chen N. Chen, Thomas R. Gentile, Daniel S. Hussey, T C. Black, Dimitry A. Pushin, F. E. Wiefeldt, C.B Shahi, L Yang
We report a new determination of the n-Helium-3 scattering length difference Δ b = (−5.411 ± 0.031 (statistical) ± 0.039 (systematic) ) fm between the triplet and singlet states using a neutron interferometer. This revises our previous result Δ b = (−5.610

Polarized 3HE Spin Filters for Neutron Science

February 12, 2014
Author(s)
Thomas R. Gentile, Wei-Chen N. Chen
The large spin dependence of the absorption cross section for neutrons by 3He gas provides a method to polarize neutron beams. For certain applications, such polarized 3He-based neutron "spin filters" have advantages over conventional neutron optical

Wide Angle Polarization Analysis with Neutron Spin Filters

April 29, 2013
Author(s)
Qiang NMN Ye, Thomas R. Gentile, Jeffrey R. Anderson, Collin L. Broholm, WangChun Chen, Z DeLand, Ross W. Erwin, C. B. Fu, John E. Fuller III, Aaron V. Kirchhoff, J. A. Rodriguez-Rivera, V. Thampy, T G. Walker, Shannon Watson
We report substantial improvements in a compact wide angle neutron spin filter system that was recently employed on the Multi-Axis Crystal Spectrometer at the Center for Neutron Research at the U.S. National Institute of Standards and Technology. The

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

In-situ Polarized 3He system for the Magnetism Reflectometer at the Spallation Neutron Source

July 2, 2012
Author(s)
Thomas R. Gentile, X Tong, C Y. Jiang, V Lauter, H. Ambaye, D. Brown, L Crow, R J. Goyette, W-T Lee, A. Parizzi
We report on the in-situ polarized 3He neutron polarization analyzer developed for the time-of-flight Magnetism Reflectometer (MAGICS) at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). Using the spin exchange optical pumping

Response of large area avalanche photodiodes to low energy X-rays

April 30, 2012
Author(s)
Thomas R. Gentile, Uwe Arp, M J. Bales, R Farrell
For an experiment to study neutron radiative beta-decay, we operated large area avalanche photodiodes (APDs) at liquid nitrogen temperature to detect X-rays with energies between 0.2 keV and 15 keV. Whereas there are numerous reports of X-ray spectrometry