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Physics

Nuclear physics

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Displaying 51 - 75 of 136

Determination of the isotopic change in nuclear charge radius from extreme-ultraviolet spectroscopy of highly charged ions of Xe

June 16, 2020
Author(s)
Yuri Ralchenko, Roshani Silwal, A. Lapierre, John Gillaspy, Joan M. Dreiling, S A. Blundell, Dipti Goyal, A. Borovik, Jr., G Gwinner, A.C.C. Villari, Endre Takacs
The electron beam ion trap (EBIT) at the National Institute of Standards and Technology was employed to measure the isotopic shift of the Na-like D 3s 2S1=2 3p 2P1=2;3=2, Mg-like 3s2 1S0 3s3p 1P1, Mg-like 3s2 1S0 3s3p 3P1, Al-like 3s23p 2P1=2 3s23p 2P3=2

Non-fuel Antineutrino Contributions in the High Flux Isotope Reactor

May 14, 2020
Author(s)
PROSPECT COLLABORATION, Jerome LaRosa, Hans Pieter Mumm, Svetlana Nour, Mark Tyra, Denis E. Bergeron
Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties starting to surpass those from theory, it is important to carefully consider all sources of e in making theoretical predictions

Accurate Integral Counting Using Multi-channel Analyzers

May 1, 2020
Author(s)
Ryan P. Fitzgerald, Lynne E. King
Many techniques in radionuclide metrology rely on accurate measurement of the total count rate, that is integral counting, from a detector. In modern experiments, this can be achieved by integrating the total number of counts in an energy spectrum produced

228Th breakthrough in 224Ra samples: what can we know and when can we know it?

April 6, 2020
Author(s)
Denis E. Bergeron, Ryan P. Fitzgerald, Leticia S. Pibida
Recent renewed interest in radium-224 (224Ra) as a radiotherapeutic agent prompted the development of a primary standard for activity at the National Institute of Standards and Technology (NIST). The 224Ra decay chain includes the emission four alpha

Optimum lithium loading of a liquid scintillator for neutron and neutrino detection

February 11, 2020
Author(s)
Hans Pieter Mumm, Denis E. Bergeron, Mark Tyra, Jerome LaRosa, Svetlana Nour, T.J. Langford, Dimitry A. Pushin
Neutral particle detection in high-background environments is greatly aided by the ability to easily load 6Li into liquid scintillators. We describe a readily available and inexpensive liquid scintillation cocktail stably loaded with up to 1 % Li by mass

A Precision Measurement of the Neutron Scattering Length of4He Using Neutron Interferometry

January 7, 2020
Author(s)
Robert W. Haun, Fred Wietfeldt, Muhammad D. Arif, Michael G. Huber, T C. Black, Ben Heacock, Dmitry Pushin, Chandra B. Shahi
We report a 0.08% measurement of the bound neutron scattering length of 4He using neutron interferometry. The result is b=(3.0982 ± 0.0021[stat] ± 0.0014[syst]) fm. The corresponding free atomic scattering length is a=(2.4746 ± 0.0017[stat] ± 0.0011[syst])

Primary standardization of Ra-224 activity by liquid scintillation counting

October 11, 2019
Author(s)
Denis E. Bergeron, Jeffrey T. Cessna, Ryan P. Fitzgerald, Brian E. Zimmerman, Lizbeth Laureano-Perez, Ronald Colle, Leticia S. Pibida, Elisa Napoli
A standard for 224Ra activity has been developed, based on triple-to-double coincidence ratio (TDCR) liquid scintillation (LS) counting. The standard was confirmed by efficiency tracing and 4παβ(LS)-γ(NaI(Tl)) anticoincidence counting, as well as by 4πγ

Study of the neutron spin-orbit interaction in silicon

September 29, 2019
Author(s)
Thomas R. Gentile, Michael G. Huber, Muhammad D. Arif, Daniel Hussey, David 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 fields, induces a small rotation of the neutron's spin in one Bragg reflection. In our experiment neutrons

Measurement of the 10B(?,n0)13N cross section at E? ? 3.6 MeV and its application as a diagnostic at the National Ignition Facilit

September 3, 2019
Author(s)
Q Liu, M Febbraro, R.J. deBoer, A Boeltzig, Y Chen, C Cerjan, M Couder, B Frentz, G Gilardy, J. Gorres, E. A. Henry, E. Lamere, K. T. Macon, K. Manukyan, L. Morales, P. D. O'Malley, S Pain, W. A. Peters, D. Schneider, C. Seymour, R. Toomey, B. Vande Kolk, Jamie Weaver, M. Wiescher
The National Ignition Facility provides the opportunity to study nuclear reactions under controlled conditions at high temperatures and pressures at a level never before achieved. However, the time scale of the DT implosion is only a few nanoseconds

Standardization of I-124 by three liquid scintillation-based methods

August 9, 2019
Author(s)
Denis E. Bergeron, Leticia S. Pibida, Brian E. Zimmerman, Jeffrey T. Cessna, Ryan P. Fitzgerald
A solution of 124I was standardized for activity by 4πβ(LS)-γ(NaI) live-timed anticoincidence (LTAC) counting, with confirmatory measurements by triple-to-double coincidence ratio (TDCR) and CIEMAT-NIST efficiency tracing (CNET) liquid scintillation

Ampoules for Radioactivity Standard Reference Materials

August 6, 2019
Author(s)
Ronald Colle
Standard-sized ampoules for radioactive solution standards have been employed by the National Institute of Standards and Technology (NIST) for nearly the past 70 years. This note briefly summarizes the origins and history of the five different batches of

Experimental Upper Bound and Theoretical Expectations for Parity-Violating Neutron Spin Rotation in He-4

July 16, 2019
Author(s)
Jeffrey S. Nico, Hans P. Mumm, H E. Swanson, C. D. Bass, T. D. Bass, J M. Dawkins, J C. Horton, D Luo, William M. Snow, S. C. Walbridge, B. E. Crawford, K. F. Gan, A M. Micherdzinska, C. R. Huffer, D M. Markoff, Murad Sarsour, E I. Sharapov, V Zhumabekova, Blayne R. Heckel
Neutron spin rotation is expected from quark-quark weak interactions in the Standard Model, which induce weak interactions among nucleons that violate parity. We present the results from an experiment searching for the effect of parity violation via the

Nuclear-Spin Dependent Parity Violation in Optically Trapped Polyatomic Molecules

July 3, 2019
Author(s)
Eric B. Norrgard, Daniel S. Barker, Stephen P. Eckel, James A. Fedchak, Nikolai N. Klimov, Julia K. Scherschligt
We investigate using optically trapped linear polyatomic molecules as probes of nuclear spin- dependent parity violation. The presence of closely spaced, opposite-parity $\ell$-doublets is a general feature of such molecules, allowing parity-violation

Measurement of the Antineutrino Spectrum from 235U Fission at HFIR with PROSPECT

June 28, 2019
Author(s)
Hans Pieter Mumm, Denis E. Bergeron, Mark Tyra, Svetlana Nour, Jerome LaRosa
This Letter reports the first measurement of the 235U e energy spectrum by PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, operating 7.9 m from the 85MWth highly-enriched uranium (HEU) High Flux Isotope Reactor. With a surface-based

The PROSPECT Reactor Neutrino Experiment

April 1, 2019
Author(s)
Hans Pieter Mumm, Denis E. Bergeron, Mark Tyra, Jerome LaRosa, Svetlana Nour
The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, is designed to make both a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and to probe eV-scale sterile neutrinos by searching for neutrino

Lithium-loaded Liquid Scintillator Production for the PROSPECT experiment

March 26, 2019
Author(s)
Hans Pieter Mumm, Denis E. Bergeron, Mark Tyra, Svetlana Nour, Jerome LaRosa
This work reports the production and characterization of lithium-loaded liquid scintillators (LiLS) for the Precision Reactor Oscillation and Spectrum Experiment (PROSPECT). Fifty-nine 90 L batches of LiLS (6Li mass fraction 0.082%0.001%) were produced

Observation of antineutrinos from 235U fission by the PROSPECT experiment at HFIR

December 19, 2018
Author(s)
Mark A. Tyra, Denis E. Bergeron, Jerome J. LaRosa, Hans P. Mumm, Svetlana Nour
This letter reports the first observation of antineutrinos from the fission products of highly enriched 235U at the High Flux Isotope Reactor. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, consists of a segmented 4 ton 6Li-doped

Methods for preparation and detection of neutron spin-orbit states

October 10, 2018
Author(s)
Michael G. Huber, D. Sarenac, J. Nsofini, I. Hincks, David Cory, Muhammad D. Arif, Charles W. Clark, D. A. Pushin
The generation and control of neutron orbital angular momentum (OAM) states and spin correlated OAM (spin-orbit) states provides a powerful probe of materials with unique penetrating abilities and magnetic sensitivity. We describe techniques to prepare and

PRIMARY STANDARDIZATION OF THE MASSIC ACTIVITY OF A PROTACTINIUM-233 SOLUTION

August 23, 2018
Author(s)
Ryan P. Fitzgerald, Leticia S. Pibida
Protactinium-233 (233Pa) is used as a tracer for radiochemical analysis and is of particular interest as an isotope dilution mass spectrometry (IDMS) spike for 231Pa/235U radio- chronometry. To this end, we present massic activity determinations by two

New determination of the 229Th half-life

July 23, 2018
Author(s)
Richard Essex, Jacqueline L. Mann, Ronald Colle, Lizbeth Laureano-Perez, Megan E. Bennett, Heather Dion, Ryan P. Fitzgerald, Amy M. Gaffney, Amelie Hubert, Robert E. Steiner, Ross W. Williams, Alkiviadis Gourgiotis, William S. Kinman
A new determination of the 229Th half-life was made based on measurements of the 229Th massic activity of a high-purity solution for which the 229Th molality had previously been measured. The 229Th massic activity was measured by direct comparison with SRM

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

Standardization of 64Cu activity

May 25, 2018
Author(s)
Denis E. Bergeron, Jeffrey T. Cessna, Ryan P. Fitzgerald, Leticia S. Pibida, Brian E. Zimmerman
The complex decay scheme that makes 64Cu promising as both an imaging and therapeutic agent in medicine also makes the absolute measurement of its activity challenging. The National Institute of Standards and Technology (NIST) has completed a primary
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