Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session F16: Fundamental Symmetries |
Hide Abstracts |
Sponsoring Units: DNP GFB Chair: Ashot Gasparian, North Carolina A&T State University Room: Marquette VII - 2nd Floor |
Sunday, April 16, 2023 8:30AM - 8:42AM |
F16.00001: Improved neutron beta decay asymmetry experiment at LANL Maninder Singh Beta decay of a free neutron is the simplest form of "semi-leptonic" weak interaction and is free from nuclear structure effects. A critical measurement from the decay is the correlation (Ao) between the neutron's initial spin and emitted electron's momentum. The angular correlation coefficient, A0, determines the axial neutron charge. Neutron lifetime and axial neutron charge determined are inputs to determine the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element (Vud) and provide a means to study physics beyond the Standard Model. |
Sunday, April 16, 2023 8:42AM - 8:54AM |
F16.00002: Simulations of Electron Detection Systematic Errors for a UCNA+ Experiment Rashika Gupta Research and Development towards UCNA+, an upgrade of the UCNA experiment, is underway at the LANSCE UCN facility. The UCNA experiment extracted the beta asymmetry, A0, from polarized neutron decay. The angular correlation coefficient A0 determines, λ, the ratio of the weak axial vector and vector coupling constants, gA/gV . In practice, A0 is determined from the asymmetry in the number of counts in two detector systems, mounted at either end of a cylindrical decay cell with its symmetry axis aligned with the spectrometer magnetic field. In order to extract A0 from the measured asymmetry we have investigated the effect of electron scattering. We present results from a Monte Carlo analysis of the UCNA+ experimental setup. We have modeled various possible geometries for thin foils in the experiment, such as the thickness of the decay trap endcap foils, foils encapsulating conversion electron sources, detector dead layers, etc. The goal of the simulations of these various geometries is to define a set of dedicated measurements that can be used to tune and benchmark the Monte Carlo beta scattering corrections to the asymmetry in a full UCNA+ experiment. Results from this work will be presented. |
Sunday, April 16, 2023 8:54AM - 9:06AM |
F16.00003: Improving sensitivity of the nEDM@SNS experiment with a redesigned neutron guide Rhett A Croley
|
Sunday, April 16, 2023 9:06AM - 9:18AM |
F16.00004: Geant4 simulation studies for the spectrometer, detector, and shielding systems for the MOLLER experiment Sakib Rahman The MOLLER experiment is a flagship experiment that will take advantage of the 12 GeV upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab in Virginia, USA. MOLLER will employ parity-violating electron-electron scattering to indirectly search for Physics Beyond the Standard Model at a relatively low energy scale, complementing direct searches at high-energy colliders. An 11 GeV longitudinally polarized electron beam with rapidly flipping helicity will be scattered from a liquid Hydrogen target and the scattered electrons will be propagated through two spectrometers. The relative difference between scattering cross-sections (detector yields) in opposite helicity states will be measured over integrating windows. This difference, also known as the parity-violating asymmetry, will be used to precisely determine the weak charge of the electron to a precision of 2.4% and the electroweak mixing angle, a fundamental parameter of Standard Model. The high-precision measurements will be compared against Standard Model predictions. In this talk, we will discuss the status of Geant4 simulation studies that looked at the expected risk from radiation on the spectrometer magnets, electronics, and experimental hall site boundary as well as the main sources of background at the detectors for MOLLER. These assessements are critical to the safe operation of the experiment from the perspective of both equipment and personnel. |
Sunday, April 16, 2023 9:18AM - 9:30AM |
F16.00005: The neutron electric dipole moment experiment at Los Alamos National Laboratory Steven M Clayton The electric dipole moment of the neutron (nEDM) is exceedingly small in the standard model of particle physics. However, beyond standard model theories allow for larger values of the nEDM, possibly within the reach of upcoming experiments. This talk will present an overview and status of the nEDM experiment under development at the Los Alamos National Laboratory (LANL) ultracold neutron source and targeting a measurement uncertainty of $3 imes 10^{-27}$~$e$-cm. The experiment features a double-cell geometry, $^{199}$Hg co-magnetometry, external optical magnetometers, precision holding field and gradient coils, and a large, state-of-the-art magnetically shielded enclosure. The overall status of the experiment and some details of the apparatus will be described. |
Sunday, April 16, 2023 9:30AM - 9:42AM |
F16.00006: Nuclear Effective Theory of Muon-to-Electron Conversion Evan J Rule Limits on the charged lepton flavor violating (CLFV) process of μ→e conversion are expected to improve by four orders of magnitude due to the next generation of experiments, Mu2e at Fermilab and COMET at J-PARC. While the kinematics of the decay of a trapped muon are ideal for detecting a signal of CLFV, the intervening nuclear physics presents a significant roadblock to the interpretation of experimental results. We introduce an effective theory of μ→e conversion formulated at the nuclear scale, which factorizes the nuclear physics from the CLFV leptonic physics, sequestering the latter quantity into unknown low-energy constants (LECs) that are probed directly by experiments. Utilizing state-of-the-art shell-model calculations of nuclear response functions, we estimate the limits that can be obtained on these LECs if the next-generation experiments achieve their design sensitivity. |
Sunday, April 16, 2023 9:42AM - 9:54AM |
F16.00007: Measurements of the binding energies of ions on plastic surfaces in cryogenic liquid. Ashok Timsina, Wolfgang Korsch To improve the present limit of the neutron electric dipole moment (nEDM) from 1.8 × 10-26 e. cm to ∼ 3 × 10-28 e. cm, the nEDM@SNS experiment plans to use a cryogenic technique. In this experiment, the central part of the apparatus consists of two deuterated tetraphenyl butadiene (dTPB) coated PMMA cells, which are sandwiched between grounded and high-voltage electrodes. To achieve such precision, the externally applied electric field has to be stable at the 1% level over a measurement cycle. During this experiment, several sources of ambient ionizing radiation generate charged particles in the cryogenic liquid. These ions are adsorbed on the cell walls. Consequently, an opposing static electric field is generated which will impact the stability of the electric field. At the University of Kentucky, we have devised a compact test setup to study the behavior of ions inside cryogenic liquids using a scaled-down version of the nEDM cell and the electrodes. In our setup, ion-electron pairs are generated by ionizing the nitrogen (helium) with a 137Cs γ-source, and the electro-optic Kerr effect is utilized to understand the cell charging effects in the dummy measurement cell. We are in the process of developing a new method to measure the binding energy of the ions bonded on insulating surfaces. Determining the binding energy can potentially reduce the data-taking time of the nEDM@SNS experiment if partial field reversal is sufficient. I will present the binding energy measurements of ions on coated and uncoated PMMA surfaces in the cryogenic liquid. |
Sunday, April 16, 2023 9:54AM - 10:06AM |
F16.00008: Model-independent determination of nuclear weak form factors and implications for Vud and CKM unitarity Chien Yeah Seng We analyze the recoil corrections in superallowed beta decays of $T=1$, $J^P=0^+$ nuclei by fixing the mean square charge weak radius model-independently using the data of multiple charge radii across the nuclear isotriplet. We argue that the existing theory uncertainty in the statistical rate function $f$ might have been substantially underestimated. We discuss its possible impact on precise Vud determination and first-row CKM unitarity. |
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