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Search Publications by: Thomas R. Gentile (Assoc)

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Displaying 26 - 50 of 101

Friedel-like Oscillations from Interstitial Iron in Superconducting Fe 1+y Te 0.62 Se 0.38

March 7, 2012
Author(s)
V. Thampy, J. Kang, Jose Rodriguez Rivera, W. Bao, A. T. Savici, J. Hu, T. J. Liu, B. Qian, D. Fobes, Z. Q. Mao, C. B. Fu, Wangchun Chen, Q. Ye, Ross Erwin, Thomas R. Gentile, Z. Tesanovic, Collin L. Broholm
Using polarized and unpolarized neutron scattering we show that interstital Fe in superconducting Fe 1=y Te 1-x Se x induces a magnetic Friedel-like oscillation that idffracts at Q = (1⁄20) and involves greater than}50 neighboring Fe sites. The

Magnetic field effects on large area avalanche photodiodes at cryogenic temperatures

August 30, 2011
Author(s)
Thomas R. Gentile, C. D. Bass, Jeffrey S. Nico, H Breuer, R Farrell
We present results for detection of X-rays by large area avalanche photodiodes (APDs) in strong magnetic fields and at cryogenic temperatures. Whereas at room temperature we observe essentially no effects on the response, at cryogenic temperature we

Polarized He-3 cell development and application at NIST

June 14, 2011
Author(s)
Thomas R. Gentile, WangChun Chen, Changbo Fu, Shannon Watson, Gordon L. Jones, J. W. McIver, D. R. Rich
Over a period of well over a decade, a large number and variety of polarized 3He cells for neutron applications have been developed and tested at the U.S. National Institute of Standards and Technology (NIST). These cells have primarily been employed for

Neutron Charged Radius and the Neutron Electric Form Factor

May 2, 2011
Author(s)
Thomas R. Gentile, C.B. Crawford
For nearly forty years, the Galster parametrization has successfully fit existing data for the neutron electric form factor, GEn,vs. the square of the four-momentum transfer, Q^2. Typically this parametrization is constrained to be consistent with

A Measurement of the Parity Violating Gamma-ray Asymmetry in the Capture of Polarized Cold Neutrons on Protons

January 31, 2011
Author(s)
Thomas R. Gentile, M T. Gericke, R. Alarcon, S. Balascuta, L. Barron, C S. Blessinger, J D. Bowman, R D. Carlini, W.C. Chen, T E. Chupp, C. Crawford, S. Covrig, M Dabaghyan, N. Formin, S J. Freedman, R C. Gillis, G L. Greene, F W. Hersman, T. Ino, Gordon L. Jones, B Lauss, M Leuschner, W R. Lozowski, R Mahurin, Y Masuda, J Mei, G S. Mitchell, S Muto, H Nann, S A. Page, S I. Penttila, W D. Ramsay, A. Salas-Bacci, S Santra, Katelynn A. Sharma, P.-N. Seo, E I. Sharapov, T B. Smith, William M. Snow, W S. Wilburn, V Yuan
The NPDGamma collaboration reports results from the first phase of a measurement of the parity violating up-down asymmetry A_gamma with respect to the neutron spin direction of gamma-rays emitted in the reaction n + p -> d + gamma using the capture of

In-situ Polarized He3-Based Neutron Polarization Analyzer for SNS Magnetism Reflectometer

January 31, 2011
Author(s)
W-T Lee, X Tong, J. Pierce, M. Fleenor, A. Ismaili, JL Robertson, Wangchun Chen, Thomas R. Gentile, A. Hailemariam, R J. Goyette, A. Parizzi, V Lauter, F. Klose, H. Kaiser, C. Lavelle, DV Baxter, G L. Jones, J. Wexler, L. McCollum
We report here the construction and neutron transmission test results of an in-situ polarized 3He-based neutron polarization analyzer system for the Magnetism Reflectometer at the Spallation Neutron Source, Oak Ridge National Laboratory. The analyzer uses

A Wide Angle Neutron Spin Filter System Using Polarized 3He

October 16, 2010
Author(s)
Changbo Fu, Thomas R. Gentile, Wangchun Chen, Ross Erwin, Shannon M. Watson, Collin L. Broholm, Jose Rodriguez Rivera, Julia Scherschligt, G L. Jones
Polarized 3He neutron spin filters can operate over a wide neutron energy range and provide a large angular acceptance. A compact 3He neutron spin filter system has been developed for the Multi Axis Crystal Spectrometer at the NIST Center for Neutron

Internal quantum efficiency modeling of silicon photodiodes

April 1, 2010
Author(s)
Thomas R. Gentile, Steven W. Brown, Keith R. Lykke, Ping-Shine Shaw, John T. Woodward IV
Results are presented for modeling of the internal quantum efficiency (IQE) of silicon photodiodes in the 400 nm to 900 nm wavelength range. The IQE data are based on measurements of the external quantum efficiencies of three transmission trap detectors

Effects of High Flux Neutron Beams on He-3 cells Polarized In-situ with Spin-exchange Optical Pumping

December 30, 2009
Author(s)
E Babcock, Stephen Boag, Maria Becker, W.C. Chen, T E. Chupp, Thomas R. Gentile, G L. Jones, A K. Petukhov, Torsten Soldner, T G. Walker
Polarized 3He produced by spin-exchange optical pumping (SEOP) has potential as a neutron spin filter for polarization and polarization analysis in many neutron scattering and neutron particle physics applications. The advantage of the SEOP method is its

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

Effects of high intensity neutron flux on in-situ spin-exchange optical pumping of He-3

September 17, 2009
Author(s)
Thomas R. Gentile, E Babcock, Stephen Boag, C. Becham, T E. Chupp, Gordon L. Jones, A K. Petukhov, T G. Walker
Prior studies revealed neutron beam-induced alkali-metal spin relaxation in 3He cells polarized in-situ by spin-exchange optical pumping. These effects are minor for neutron beams of low to moderate intensity, but become important at the highest neutron

Coupled magnetic and ferroelectric hysteresis in multiferroic Ni ^ d3 ^ V ^ d2 ^ O ^ d8 ^

August 18, 2009
Author(s)
I. Cabrera, M. Kenzelmann, Wangchun Chen, Ross Erwin, Thomas R. Gentile, Juscelino Leao, Jeffrey W. Lynn, N. Rogado, R. J. Cava, C. Broholm, G. Lawes, Ying Chen
Electric control of spin chirality in a magnetically frustrated multiferroic is demonstrated through polarized magnetic neutron diffraction. Cooling to the cycloidal multiferroic phase of Ni ^ d3 ^ V ^ d2 ^ O ^ d8 ^ in an electric field causes 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

Spin-exchange Optical Pumping of 3He with Rb/K Mixtures and Pure K

December 31, 2007
Author(s)
Wangchun Chen, Thomas R. Gentile, S E. Babcock, T G. Walker
We have studied the efficiency of spin-exchange optical pumping (SEOP) in cells that contain either pure rubidium, mixtures of rubidium and potassium, or pure potassium. Optical pumping was performed with spectrally narrowed diode array lasers operating at

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

A Large Area Polarized 3He Neutron Spin Filter

January 1, 2007
Author(s)
T E. Chupp, K A. Coulterpark, M Kandes, Katelynn A. Sharma, T B. Smith, G Jones, W C. Chen, Thomas R. Gentile, D R. Rich, B Lauss, M T. Gericke, R C. Gillis, S A. Page, J D. Bowman, S I. Penttila, W S. Wilburn, M Dabaghyan, F W. Hersman, M Mason

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