You searched on: Author: Thomas Gentile
Displaying records 1 to 10 of 86 records.
Resort by: Date / Title
1. ^u3^He Spin Filter Based Polarized Neutron Capability at the NIST Center for Neutron Research
Wangchun Chen, Thomas R Gentile, Ross W. Erwin, Shannon Watson, Qiang NMN Ye, Kathryn Krycka, Brian B. Maranville
A ^u3^He 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 wa ...
2. Spin-exchange optical pumping of He3 with VHG-narrowed diode bar laser
Thomas R Gentile, Wei-Chen N. Chen, T G Walker, E Babcock, Qiang NMN Ye
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 narro ...
3. Neutron Interferometric Measusrement of the Scattering Length Difference Between the Triplet and Singlet States of N-3 He.
Michael G Huber, Muhammad 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 Delta b = (−5.411 ± 0.031 (statistical) ± 0.039 (systematic) ) fm between the triplet and singlet states using a neutron interferometer. This revises our previous res ...
4. Polarized 3HE Spin Filters for Neutron Science
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 optica ...
5. Comment on "Enhanced polarization and mechanisms in optically pumped hyperpolarized ^u3^He in the presence of ^u4^He"
Thomas R Gentile, M E Hayden, P.J. Nacher, A K. Petukhov, B Saam, T G Walker
H.H. Chen et al  claim that adding 4He to spin-exchange optical pumping (SEOP) cells confines
3He atoms to a diffusion-limited region, which effectively reduces the wall relaxation factor X.
Here X is a phenomenological parameter used to charact ...
6. Wide Angle Polarization Analysis with Neutron Spin Filters
Qiang NMN Ye, Thomas R Gentile, Jeffrey R. Anderson, Collin Leslie 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 ...
7. A gamma and X-ray dector for cryogenic, high magnetic field applications
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, Brian O'Neill, K. Pulliam, Alan K 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 wa ...
8. In-situ Polarized 3He system for the Magnetism Reflectometer at the Spallation Neutron Source
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
9. Response of large area avalanche photodiodes to low energy X-rays
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 spect ...
10. Comment on "Pressure dependence of wall relaxation in polarized He3 gaseous cells"
Thomas R Gentile, B Saam
W. Zheng et al. [Phys. Rev. A 83, 061401(R) (2011)] measure under certain conditions a linear
pressure dependence of the wall-induced nuclear relaxation rate of 3He in glass cells typically used
to generate and/or store hyperpolarized 3He. Their in ...