Bulletin of the American Physical Society
2021 Fall Meeting of the APS Division of Nuclear Physics
Volume 66, Number 8
Monday–Thursday, October 11–14, 2021; Virtual; Eastern Daylight Time
Session PL: BSM Searches in Fundamental Symmetries IX: Beta Decays |
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Chair: Francisco Gonzalez, ORNL Room: Georgian |
Thursday, October 14, 2021 9:30AM - 9:42AM |
PL.00001: An Introduction to the $^6$He-CRES Experiment William Byron
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Thursday, October 14, 2021 9:42AM - 9:54AM |
PL.00002: Recent improvements to the $^6$He-CRES apparatus, data acquisition system, and analysis methods Brent M Graner Despite the many operational challenges imposed by the COVID-19 pandemic, the $^6$He-CRES collaboration has recently made substantial improvements in experimental methods used to detect and analyze CRES signals. This talk will present a brief overview of the apparatus upgrades and improvements made to the data acquisition and analysis software in the past year. |
Thursday, October 14, 2021 9:54AM - 10:06AM |
PL.00003: Report of First Data from the $^6$He-CRES Experiment and Future Outlook Heather S Harrington The $^6$He-CRES collaboration is working on applying the Cyclotron Radiation Emission Spectroscopy technique to determine beta spectra up to several MeV. This year we demonstrated measurements with a bandwidth approximately 4 times that shown previously by Project8, improving our ability to quickly obtain the statistical power needed for a high-precision full-spectrum measurement. This talk will present our first CRES data taken by digitizing sub-femtowatt microwave signals from the cyclotron radiation of betas in a magnetic field, as well as initial track reconstruction and analysis. |
Thursday, October 14, 2021 10:06AM - 10:18AM |
PL.00004: E$\times$B trap emptying design and simulations for the $^6$He-CRES Robert Taylor, Alexander Allen, Dustin Combs The $^6$He-CRES experiment measures the cyclotron radiation of magnetically trapped beta decay electrons to precisely determine the Fierz interference parameter b. Background and scattering effects can be better understood by emptying the trap of electrons. Currently the trap can be emptied by turning off the trapping magnetic field. However, turning the trapping field off and on can be slow and create inconsistent temperatures and field strengths. Alternatively, to achieve rapid emptying times without disturbing the trapping field, the trap can be emptied using a charged electrode. A charged electrode creates an electric field perpendicular to the magnetic field, causing electrons to drift out of the trap by E$\times$B drift. The addition of an electrode in the RF guide wall can impact RF transmission, lowering the measurements signal to noise ratio. We use the HFSS (High Frequency Signal Simulation) package to obtain RF signal properties of our electrode design and Kassiopeia to evaluate the impact on trapped electron trajectories. We will present the results of these simulations and how the current electrode is designed to meet our criteria. |
Thursday, October 14, 2021 10:18AM - 10:30AM |
PL.00005: Comparing precise and accurate theoretical predictions for 6He and 23Ne beta decay observables with novel precision experiments Ayala Glick-Magid, Doron Gazit, Yonatan Mishnayot, Guy Ron, Christian Forssen, Daniel Gazda, Peter H Gysbers, Javier Menendez, Petr Navratil, Hitesh V Rahangdale, Ben Ohayon, Sergey Vaintraub, Tsviki Hirsh, Leonid Waisman, Boaz Kaizer, Aaron Gallant, Nickolas Scielzo, Jason T Harke Multiple high precision β-decay measurements are being carried out these days on various nuclei, in search of beyond the standard model signatures. Among these nuclei are 6He and isotopes of Neon. |
Thursday, October 14, 2021 10:30AM - 10:42AM |
PL.00006: Searching for Tensor Currents in the Weak Interaction in the β-decay of 8Li and 8B Aaron Gallant, Mary Burkey, Nicholas D Scielzo, Guy Savard, Jason A Clark, Barbara S Wang, Maxime Brodeur, Fritz Buchinger, Daniel P Burdette, Dmitry Gorelov, Tsviki Hirsh, Kay Kolos, Kristina D Launey, Kyle G Leach, Bernhard Maass, Scott T Marley, Peter Mueller, Rodney Orford, Dwaipayan Ray, Grigor H Sargsyan, Ralph E Segel, Kevin Siegl, Kumar S Sharma, Louis Varriano The weak interaction of the Standard Model is well-described by a vector-axial vector, or ‘V-A’, structure, which reproduces both maximal parity violation and left-handed neutrinos in beta-decay. However, there is no first-principles reason that other the interactions, such as scalar (S) or tensor (T), may not be present. To search for possible tensor contributions to the weak interaction we measure the beta-neutrino correlation coefficient aβν in the Gamow-Teller beta-decays of 8Li and 8B. The A = 8 decays are ideal to probe aβν due to the large Q-value and delayed alpha emission from the excited state 8Be. These measurements are performed with the Beta decay Paul Trap (BPT) at Argonne National Lab. The BPT is surrounded on 4 sides with double-sided silicon strip detectors backed by plastic scintillator detectors, which allow the kinematics of decay products from the trapped mass-8 ions to be over-constrained. In this presentation we will present the high precision results form 8Li and the first results from the decay of 8B. |
Thursday, October 14, 2021 10:42AM - 10:54AM |
PL.00007: UCNA+: An improved measurement of the beta assymetry parameter with ultracold neutrons. Robert W Pattie Beta-decay angular correlation coefficients can be written in terms of λ, the ratio of the axial-vector and vector coupling constants. Combining measurements of the neutron lifetime and the correlation coefficients allows for precision tests of the standard model and a complementary cross-check of Superallowed Fermi decays. The UCNA experiment at the Los Alamos ultracold neutron source measured the beta-asymmetry coefficient A to a precision of 0.55% using a 2x2π magnetic spectrometer. It was limited by electron scattering systematics due to inactive material and low UCN density. UCNA+ will replace the multiwire proportional count and plastic scintillator detection system with a 16 sided plastic scintillator with edge coupled SiPM readout to minimize scattering systematics and take advantage of upgrades to LANL UCN source to increase the UCN density by a factor roughly 6. We will present details of detector upgrades and the path towards a 0.2% determination of A. |
Thursday, October 14, 2021 10:54AM - 11:06AM |
PL.00008: Precision pulse shape modeling for the Nab experiment Leendert Hayen The Nab experiment at the Spallation Neutron Source aims to measure the electron-antineutrino correlation and Fierz interference term following neutron beta decay at the few $10^{-3}$ level, thereby probing exotic electroweak scalar and tensor currents at the TeV scale and providing crucial input for top-row CKM unitarity tests. Detection of protons and electrons is performed using large diameter, highly segmented silicon detectors at either side of the decay volume inside a magnetic spectrometer, and excellent reconstruction of both energy and timing is paramount. Per-segment determinations of both quantities depend on parameters which are either theoretically or empirically difficult to quantify, such as local impurity and trapping center concentrations, charge collection efficiency near the surface, plasma column dynamics and segment-to-segment insulation technology. We will report on a novel, consistent simulation and modeling effort for realistic pulse shape generation in silicon following low energy particle interaction, and discuss related systematic effects in the Nab experiment. |
Thursday, October 14, 2021 11:06AM - 11:18AM |
PL.00009: Measuring the Unmeasured: Detecting the $^{40}$K Electron Capture Directly to the $^{40}$Ar Ground State with the KDK Experiment Bertis C Rasco $^{40}$K is a ubiquitous background for many low-energy physics experiments and for many low-energy exotic physics searches. But $^{40}$K has positive uses too, it forms the basis of K-Ar geochronological dating techniques and it allows study of a third-forbidden unique $\beta$-decay. The precision of $^{40}$K $\beta$-decay information is an important uncertainty in low energy exotic physics searches and is one of the limits on the K-Ar geochronology dating technique accuracy and precison. The $^{40}$K $\beta$-decay information uncertainty is dominated by one branch of the \textsuperscript{40}K decay that has never been experimentally measured, the electron capture decay directly to the ground state of $^{40}$Ar. This unknown decay path impacts the estimated amount of $^{40}$K based on the number of measured 1461 keV $\gamma$ rays at the few percent level and it affects the K-Ar geochronology dating technique at the same level. With data taken at Oak Ridge National Laboratory, this small decay branch was measured by the KDK (potassium decay) collaboration by integrating an X-ray detector into the Modular Total Absorption Spectrometer (MTAS). We report details of the technique used to measure this decay branch, the expected sensitivity, and the status of the analysis [1]. |
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