Bulletin of the American Physical Society
Fall 2022 Meeting of the APS Division of Nuclear Physics
Volume 67, Number 17
Thursday–Sunday, October 27–30, 2022; Time Zone: Central Daylight Time, USA; New Orleans, Louisiana
Session JD: Mini-Symposium: The Physics of Double Beta Decay - Detector Development II |
Hide Abstracts |
Chair: Leslie Rogers, Argonne National Laboratory Room: Hyatt Regency Hotel Celestin B |
Saturday, October 29, 2022 8:30AM - 8:42AM |
JD.00001: New Results from the Majorana Demonstrator's Search for Neutrinoless Double-β Decay Nicholas W Ruof The Majorana Demonstrator is a low background experiment searching for neutrinoless double-β decay in 76Ge and is located at the 4,850 ft level at the Sanford Underground Research Facility in Lead, SD. Since the previous 2019 data release, the Majorana Demonstrator has acquired more exposure, upgraded electronic cables and connectors, improved its analysis routines, and successfully operated four ICPC detectors. In March 2021, operation of the enriched detectors concluded to deploy them in the next phase of germanium experiments, LEGEND-200. The Majorana Demonstrator continues to run with a single module of natural abundance BEGe detectors for background studies and other physics searches. This talk will present results from the Majorana Demonstrator which has achieved a half-life sensitivity of 8.1 × 1025 yrs, a background index of 15.7 cts / (FWHM t yr), and a world leading energy resolution of 2.5 keV at the 2039 keV Qββ with a full enriched exposure of 64.5 kg yrs. |
Saturday, October 29, 2022 8:42AM - 8:54AM |
JD.00002: Modeling Backgrounds in the MAJORANA DEMONSTRATOR Anna L Reine The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay experiment containing ~30kg of p-type point contact germanium detectors enriched to 88% in 76Ge and ~14kg of natural germanium detectors. The detectors are divided between two cryostats and surrounded by a graded passive shield. The DEMONSTRATOR achieved one of the lowest background rates in the region of the 0?????? Q-value, ~16 cnts/(FWHM t y). Nevertheless this background rate exceeds the projected background rate of 2.9 cnts/(FWHM t y). This discrepancy arises from an excess of events from the 232Th decay chain and is non-uniformly distributed between the two modules. Background model fits aim to understand this deviation from assay-based projections, potentially determine the source location(s) of observed backgrounds, and allow a precision measurement of the two-neutrino double-beta decay half-life. Fits indicate the origin of the 232Th excess is not from a near-detector component, which informed design decisions for the next-generation LEGEND experiment. Recent findings have narrowed the suspected locations for the excess activity, motivating a final simulation and in-situ assay campaign to complete the background model. |
Saturday, October 29, 2022 8:54AM - 9:06AM |
JD.00003: Investigation of neutron-induced backgrounds in 76Ge for 0νββ decay searches Mary F Kidd, Sean W Finch, Werner Tornow Neutrinoless double-beta (0νββ) decay is one of the slowest proposed nuclear decay rates. An extensive knowledge of potential background events is necessary for interpreting results from 0νββ searches. Even deep underground, neutron-induced reactions can occur in all components of detectors searching for rare events. The double-beta decay candidate 76Ge (Qββ=2039.1 keV) has a nuclear level at 3951.9 keV that has been reported to emit a 2040.7 keV gamma ray, but which was not observed in follow-up studies. At Triangle Universities Nuclear Laboratory (TUNL), we can study this potential background by exciting an enriched 76Ge target with neutrons and observing the emitted gamma rays from the inelastic neutron scattering in situ. We studied this interaction in 76Ge by searching for the coincident emission of gamma rays from the deexciatation of the 3951.9 keV level. We will report our initial results from n,n'γ on 76Ge. |
Saturday, October 29, 2022 9:06AM - 9:18AM |
JD.00004: Poly(ethylene 2,6-naphthalate) as a structural active material for the 0νββ experiment, LEGEND Brennan T Hackett 0νββ is the most sensitive experimental test to determine the Majorana nature of the neutrino. The LEGEND experiment is an international effort to measure 0νββ decay using 76Ge as both the target isotope and the detecting material. LEGEND is currently constructing its 200-kg phase and preparing a 1000-kg phase, which have background goals of 0.6 and 0.025 counts/ton/year/FWHM, respectively. One method to improve the background identification in LEGEND is to use active structural materials like Poly(ethylene-2,6-naphthalate)-PEN. PEN is of interest because of its robust structural characteristics, scintillation properties in the blue regime and its wavelength shifting abilities for VUV light. 76Ge detectors, installed with PEN holders, were tested in the LEGEND R&D effort, the post GERDA test (PGT). The PGT included approximately 18 kg of 76Ge crystals, with 40% of the detectors being mounted with PEN holders. Limits on the background contribution from 232Th contamination in the PEN holders as well as predict the improved veto efficiency with the active PEN material versus the passive silicon material was measured. The results of this study will be presented. |
Saturday, October 29, 2022 9:18AM - 9:30AM |
JD.00005: Evaluation of Bremsstrahlung Models for nEXO Simulations Brady Eckert The nEXO experiment will search for neutrinoless double beta decay (0νββ) in 136Xe, improving on the success of EXO-200. Double β-decays are primarily single-site events in liquid xenon detectors, but as βs deposit energy, they sometimes emit a photon due to bremsstrahlung radiation, making these events multi-site. More energetic electrons, like those expected from 0νββ, are more likely to produce bremsstrahlung. Multi-site events are mostly background, but a neural network-based discriminator identifies signal-like multi-site events with bremsstrahlung, increasing the detection efficiency of 0νββ events by about 10%. Signal-like multi-site events can be used to first verify the bremsstrahlung model and later verify the 2νββ energy spectrum. Both EXO-200 and nEXO use Geant4-based simulations, but they differ in the low-energy electromagnetic model they use. This study simulates β-decay and double β-decay events for both experiments to determine if the different models produce measurable differences in bremsstrahlung events. We aim to benchmark these models using EXO-200 data and to evaluate the impact of the model on nEXO sensitivity. |
Saturday, October 29, 2022 9:30AM - 9:42AM |
JD.00006: Mitigating Muon Backgrounds for CUORE and CUPID Iris D Ponce CUORE is a tonne-scale bolometric experiment in search of neutrinoless double-beta decay (0??????) of Tellurium. CUPID, the CUORE Upgrade with Particle IDentification, will use scintillating bolometers. While CUORE will place an upper limit on the effective Majorana mass ($m_{/beta/beta}$) in the range 40-100 meV, CUPID will fully probe the inverted neutrino mass ordering and improve sensitivity to $m_{/beta/beta}$ by a factor of five compared to CUORE to 12 - 20 meV. To reach this sensitivity, CUPID aims to decrease their experimental backgrounds by a factor of 100 compared to CUORE. In order to reduce the cosmogenic backgrounds in the region of interest, CUPID will implement a muon veto system consisting of scintillator panels and read out with SiPMs. In this talk, I will discuss the design and construction of the active muon veto system for CUORE and CUPID. |
Saturday, October 29, 2022 9:42AM - 9:54AM |
JD.00007: TES Based Light Detectors using an IrPt bi-layer transition edge sensor for CUPID and beyond Bradford C Welliver CUPID is a proposed upgrade to the tonne-scale neutrinoless double beta decay experiment, CUORE. CUORE is currently operating at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. Degraded α's are the primary background in CUORE, and CUPID aims to improve this background by over a factor of 100 via a two channel energy collection approach using scintillation light and heat. This will allow for event by event discrimination of α and β/γ interactions. In order to meet the timing and energy resolution requirements of CUPID or beyond, large area light detectors which use low-Tc transition edge sensors (TES) deposited on Si wafers are a promising technology. We will present the current state of R&D performed at UC Berkeley, in collaboration with LBNL and ANL, to develop light detectors using an IrPt bilayer TES with Au pads to enhance thermal conductivity to the Si wafer. We report on the preliminary measures of timing and energy resolution, and possible differences in response due to position. Additionally we will discuss ongoing plans to explore multiplexed readout and other improvements. |
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. |
© 2025 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