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Search Publications by: Thomas R. Gentile (Assoc)

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Displaying 26 - 50 of 202

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