Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session DJ: Mini-symposium on Physics of Ultracold Neutron Sources IMini-Symposium
|
Hide Abstracts |
Chair: Ruediger Picker, TRIUMF Room: Junior Ballroom A |
Friday, October 14, 2016 10:30AM - 11:06AM |
DJ.00001: Ultracold Neutron Sources Invited Speaker: Jeffery Martin The free neutron is an excellent laboratory for searches for physics beyond the standard model. Ultracold neutrons (UCN) are free neutrons that can be confined to material, magnetic, and gravitational traps. UCN are compelling for experiments requiring long observation times, high polarization, or low energies. The challenge of experiments has been to create enough UCN to reach the statistical precision required. Production techniques involving neutron interactions with condensed matter systems have resulted in some successes, and new UCN sources are being pursued worldwide to exploit higher UCN densities offered by these techniques. I will review the physics of how the UCN sources work, along with the present status of the world's efforts. [Preview Abstract] |
Friday, October 14, 2016 11:06AM - 11:18AM |
DJ.00002: Determining Absolute Polarization of Ultracold Neutrons in the UCNA Experiment Eric Dees The UCNA experiment uses the decay of trapped ultracold neutrons (UCN) to measure the angular correlation A between the emitted electron's momentum and the direction of the neutron's spin. For a precision measurement of A, a similarly precise determination of the equilibrium neutron polarization \textbf{\textless P\textgreater }is required. By utilizing UCN, transport through a large (7T) B field provides \textasciitilde 100{\%} polarization, and a spin flipper allows state selection during loading phases. This spin flipper also measures the equilibrium polarization of the UCN population present in the spectrometer, after each hour-long beta-counting cycle. By including a neutron reflecting shutter the leading uncertainty in polarimetry measurements prior to 2011, resulting from the residual background population, was reduced to near zero. However, this modification also introduces new systematic corrections, requiring new run types to quantify. Among these corrections are effects from the spin flipper efficiency, spectral velocity conditioning, and depolarization feeding. We will review the analytic underpinning for these contributions, discuss additional measurements required to quantify these parameters, and present a Monte-Carlo analysis to determine the corrected depolarized fraction, and associated uncertainty. [Preview Abstract] |
Friday, October 14, 2016 11:18AM - 11:30AM |
DJ.00003: Cryogenic testing of the PULSTAR UCN Source Christian White, Ayman Hawari, Paul Huffman, Ekaterina Korobkina, Kent Leung, Graham Medlin, Bernard Wehring, Albert Young An ultracold neutron (UCN) source is being constructed at the NC State University 1 MW PULSTAR reactor facility. UCN will be utilized for multiple experiments, including an investigation of systematic effects relevant to the Spallation Neutron Source (SNS)-based neutron electric dipole moment (nEDM) experiment. The UCN source consist of 1 L of solid deuterium that will reside in the thermal column of the reactor, surrounded by heavy water and methane moderators. Construction of the source is complete and cryogenic testing is in progress to fully characterize growth of the solid deuterium crystal under various pressures and heat loads. Results of this testing program will be presented. [Preview Abstract] |
Friday, October 14, 2016 11:30AM - 11:42AM |
DJ.00004: The Ultra-Cold Neutron Facility at TRIUMF Lawrence Lee Construction of an Ultra-Cold Neutron (UCN) facility is nearing completion in the TRIUMF Meson Hall. The new 500 MeV proton beamline (BL1U) and neutron spallation target, which feeds the superthermal UCN source, was completed in Spring 2016 and is presently transitioning over to the commissioning phase. As well, the front end of the UCN source was installed and will also be undergoing commissioning tests. Installation of the full UCN source is scheduled for completion in late 2016 or early 2017, with UCN production planned for Spring 2017. A first experiment searching for the neutron electric dipole moment (nEDM) is also currently under development. The design and construction highlights, as well future plans for the UCN facility, will be presented. [Preview Abstract] |
Friday, October 14, 2016 11:42AM - 11:54AM |
DJ.00005: Commissioning of the upgraded ultracold neutron source at Los Alamos Neutron Science Center Robert Pattie The spallation-driven solid-deuterium ultracold neutron (UCN) source at Los Alamos Neutron Science Center (LANSCE) has provided a facility for precision measurements of fundamental symmetries via the decay observables from neutron beta decay for nearly a decade. In preparation for a new room temperature neutron electric dipole moment (nEDM) experiment and to increase the statistical sensitivity of all experiments using the source an effort to upgrade the existing source has been carried out during 2016. This upgrade includes installing a redesigned cold neutron moderator and with optimized UCN converter geometries, improved coupling and nickel-phosphorus coating of the UCN transport system through the biological shielding, optimization of beam timing structure, and increase of the proton beam current. We will present the result of the commissioning run of the new source. [Preview Abstract] |
Friday, October 14, 2016 11:54AM - 12:06PM |
DJ.00006: Measurement of cold neutron spectrum by multi-foil activation method Tatsuya Kikawa In 2016, we will start commissioning the ultracold neutron (UCN) source at TRIUMF: the proton beamline including the spallation target, as well as the cold neutron moderators will be tested. In order to gain a better understanding of the UCN production, a measurement of the cold neutron flux in the UCN source is needed. However, a measurement with the time-of-flight (TOF) method is not adaptable to our geometry. Thus, we are planning to measure the cold neutron spectrum using multiple neutron activation foils with unfolding technique. We will place special foils in the (empty) UCN production volume to measure the neutron spectrum; their activities will be measured by Ge detectors after the activation. The neutron spectrum is reconstructed from the measured activities by an unfolding analysis. This technique has been conventionally used for the measurement of the fast neutron spectrum. In this presentation, we will explain the application of this technique to the measurement of cold neutron spectrum and the status of preparations for the measurement at TRIUMF. [Preview Abstract] |
Friday, October 14, 2016 12:06PM - 12:18PM |
DJ.00007: Degaussing and NMR Coil R{\&}D for the nEDM Experiment at TRIUMF Russell Mammei The TRIUMF nEDM experiment aims to constrain the neutron's electric dipole moment by and order magnitude over the current sensitivity. The experiment employs a magnetically shielded Ramsey Resonance based EDM apparatus employing ultracold neutrons from a spallation based isopure Helium-II UCN source, currently under construction at TRIUMF. In this design, inhomogeneities (gradients) and lack of stability of the applied magnetic fields are expected to be one of the leading sources of systematic errors in the measurement. This presentation will discuss recent R{\&}D efforts toward the development of a magnetic shield degaussing/idealization apparatus, magnetic field generation inside shielded volumes with a focus on employing self-shielded coil geometries, and precision magnetometry. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700