C. G. Davis
A5073774676- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Nuclear physics research studies
- Full-Duplex Wireless Communications
- Radar Systems and Signal Processing
- Direction-of-Arrival Estimation Techniques
- Optical Wireless Communication Technologies
- Image and Signal Denoising Methods
- Speech and Audio Processing
- Advanced Adaptive Filtering Techniques
- Digital Filter Design and Implementation
- Radio Wave Propagation Studies
- Noncommutative and Quantum Gravity Theories
- Energy Harvesting in Wireless Networks
- Radio Astronomy Observations and Technology
- Radiative Heat Transfer Studies
- Advanced Wireless Communication Technologies
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Structural Health Monitoring Techniques
University of Maryland, College Park
2011-2022
United States Naval Research Laboratory
2017-2019
We report on a search for neutrinoless double-beta decay of $^{136}$Xe with EXO-200. No signal is observed an exposure 32.5 kg-yr, background ~1.5 x 10^{-3} /(kg yr keV) in the $\pm 1\sigma$ region interest. This sets lower limit half-life $T_{1/2}^{0\nu\beta\beta}$($^{136}$Xe) > 1.6 10$^{25}$ (90% CL), corresponding to effective Majorana masses less than 140-380 meV, depending matrix element calculation.
We report the observation of two-neutrino double-beta decay in Xe-136 with T_1/2 = 2.11 +- 0.04 (stat.) 0.21 (sys.) x 10^21 yr. This second order process, predicted by Standard Model, has been observed for several nuclei but not Xe-136. The rate provides new input to matrix element calculations and search more interesting neutrino-less decay, most sensitive probe existence Majorana particles measurement neutrino mass scale.
We report on an improved measurement of the $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ half-life ${}^{136}$Xe performed by EXO-200. The use a large and homogeneous time-projection chamber allows for precise estimate fiducial mass used measurement, resulting in small systematic uncertainty. also discuss detail data-analysis methods double-$\ensuremath{\beta}$ decay searches with EXO-200, while emphasizing those directly related to present measurement. is found be...
EXO-200 is an experiment designed to search for double beta decay of $^{136}$Xe with a single-phase, liquid xenon detector. It uses active mass 110 kg enriched 80.6% in the isotope 136 ultra-low background time projection chamber capable simultaneous detection ionization and scintillation. This paper describes detector particular attention most innovative aspects design that revolve around reduction backgrounds, efficient use expensive isotopically xenon, optimization energy resolution...
A search for Lorentz- and $CPT$-violating signals in the double beta decay spectrum of $^{136}\mathrm{Xe}$ has been performed using an exposure $100\text{ }\text{ }\mathrm{kg}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{yr}$ with EXO-200 detector. No significant evidence spectral modification due to isotropic Lorentz-violation was found, a two-sided limit $\ensuremath{-}2.65\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{...
EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless double-beta decay of $^{136}$Xe. Here we report on various Majoron-emitting modes based 100 kg$\cdot$yr exposure A lower limit $T^{^{136}Xe}_{1/2} >1.2 \cdot 10^{24}$ yr at 90% C.L. the half-life spectral index = 1 Majoron was obtained, corresponding constraint Majoron-neutrino coupling constant $|< g^{M}_{ee} >|<$ (0.8-1.7)$\cdot$10$^{-5}$.
Alpha decays in the EXO-200 detector are used to measure fraction of charged $^{218}\text{Po}$ and $^{214}\text{Bi}$ daughters created from $\ensuremath{\alpha}$ $\ensuremath{\beta}$ decays, respectively. $^{222}\text{Rn} \ensuremath{\alpha}$ liquid xenon (LXe) found produce $^{218}\text{Po}^{+}$ ions $50.3\ifmmode\pm\else\textpm\fi{}3.0%$ time, while remainder atoms neutral. The $^{214}\text{Bi}^{+}$ $^{214}\text{Pb} \ensuremath{\beta}$ LXe is be $76.4\ifmmode\pm\else\textpm\fi{}5.7%$,...
The search for neutrinoless double-beta decay (0νββ) requires extremely low background and a good understanding of their sources influence on the rate in region parameter space relevant to 0νββ signal. We report studies various β γ backgrounds liquid-xenon-based EXO-2000νββ experiment. With this work we try better understand location strength specific compare conclusions radioassay results taken before during detector construction. Finally, discuss implications these EXO-200 as well...
We describe a system to transport and identify barium ions produced in liquid xenon, as part of R&D towards the second phase double beta decay experiment, nEXO. The goal is Ba ion resulting from an extremely rare nuclear isotope 136Xe, hence providing confirmation occurrence decay. This achieved through Resonance Ionization Spectroscopy (RIS). In test setup described here, can be xenon or vacuum collected on clean substrate. substrate then removed analysis chamber under vacuum, where...
The EXO-200 experiment searched for neutrinoless double-beta decay of $^{136}$Xe with a single-phase liquid xenon detector. It used an active mass 110 kg 80.6%-enriched in ultra-low background time projection chamber ionization and scintillation detection readout. This paper describes the design performance various support systems necessary detector operation, including cryogenics, handling, controls. Novel features system were driven by need to protect thin-walled containing xenon, achieve...
The energy resolution of the EXO-200 detector is limited by electronics noise in measurement scintillation response. Here we present a new technique to extract optimal measurements for signals split across multiple channels presence correlated noise. implementation these techniques improves at neutrinoless double beta decay Q-value from [1.9641 ± 0.0039]% [1.5820 0.0044]%.
In this paper we present two novel approaches to unambiguously estimate the direction of arrival (DOA) an RF source by array receive antennas whose positions can take-on any arbitrary geometry. The first approach employs a simple constrained integer optimization, while second deep learning. both impact imperfect calibration on performance DOA estimation is quantified. We demonstrate in Monte Carlo simulations that are capable achieving super-resolution under conditions. It was found...
Full duplex communication systems promise to double the available spectrum by enabling simultaneous transmit and receive capabilities. Receiver linearity its effective isolation from transmitter must be extremely large allow detection of any desired signals in presence self-interference within receiver bandwidth. Echoes environment may introduce additional distortion that further hinder detection. These challenges are multiplied if full capability is achieved over wide bandwidths. This paper...
Products of time-series signals have found wide-spread application in many fields signal processing. For example, they are often used modeling and compensating distortions generated by analog mixed-signal components. Without excess bandwidth, the products will produce aliased artifacts that do not represent physical phenomenology components being modeled. To ameliorate effects these potentially unwanted, distortion products, we compare two multidimensional filters: first is a simple...