Publications & Talks

2020
Taylor Contreras. 10/30/2020. “Recent Results from NEXT-NEW.” 2020 Fall Meeting of the APS Division of Nuclear Physics.Abstract
It is currently unknown if neutrinos are Majorana particles, a property that would transform our understanding of the nature and mass of neutrinos. The NEXT experiment is searching for Majorana neutrinos through neutrinoless double beta decay in a high pressure gaseous xenon time projection chamber. The NEXT collaboration has shown through a phased approach that this technology can achieve excellent energy resolution and great tracking capabilities. Here we present the latest results of the current detector, NEXT-NEW, including the energy resolution measurements, the power of the topological reconstruction, and the latest measurement of the two-neutrino double beta decays.
2018
Taylor Contreras. 4/16/2018. “Clustering Algorithm Performance Studies for the ATLAS Trigger System at the HL-LHC.” APS April Meeting 4/16/2018. Abstract

The Large Hadron Collider (LHC) at CERN is a particle accelerator providing massive amounts of data which can reveal new physics about fundamental particles and forces. An upgrade to the LHC that will increase the luminosity will be enacted in 2026, called the High-Luminosity LHC (HL-LHC) to run with pp collisions at sqrt(s)= 14 TeV with the ATLAS detector. The higher luminosity will increase the rate of proton-proton interactions in detectors like ATLAS, thus these detectors must increase the speed of sorting through data. This sorting is performed by the ATLAS Trigger System, which decides whether an interaction is interesting enough to keep within about ten microseconds. Our group is studying the efficiency of different algorithms that cluster energy for implementation on a Field Programable Gate Array (FPGA) in the Global Trigger. These algorithms cluster energetic cells in multiple layers of the detector to reconstruct particle showers. We have implemented the algorithms used on the FPGA in python in order to validate the performance of the FPGA, analyze the background rejection and trigger efficiency of the clustering algorithms, and compare these quantities between different algorithms.

2017
Charity Woodrum, Inger Jorgensen, Scott Fisher, Lindsey Oberhelman, and Taylor Contreras. 8/20/2017. “The Evolution of Bulge-Dominated Field Galaxies from z~1 to the Present.” The Astrophysical Journal, 847, 1. Publisher's VersionAbstract
We analyze the stellar populations and evolutionary history of bulge-dominated field galaxies at redshifts $0.3\lt z\lt 1.2$ as part of the Gemini/Hubble Space Telescope (HST) Galaxy Cluster Project (GCP). High signal-to-noise optical spectroscopy from the Gemini Observatory and imaging from the HST are used to analyze a total of 43 galaxies, focusing on the 30 passive galaxies in the sample. Using the size–mass and velocity dispersion–mass relations for the passive field galaxies we find no significant evolution of sizes or velocity dispersions at a given dynamical mass between $z\ \approx \ 1$ and the present. We establish the Fundamental Plane and study mass-to-light (M/L) ratios. The M/L versus dynamical mass relation shows that the passive field galaxies follow a relation with a steeper slope than the local comparison sample, consistent with cluster galaxies in the GCP at z = 0.86. This steeper slope indicates that the formation redshift is mass dependent, in agreement with "downsizing," meaning that the low-mass galaxies formed their stars more recently while the high-mass galaxies formed theirs at higher redshift. The zero-point differences of the scaling relations for the M/L ratios imply a formation redshift of ${z}_{\mathrm{form}}={1.35}_{-0.07}^{+0.10}$ for the passive field galaxies. This is consistent with the $({\rm{H}}{\delta }_{{\rm{A}}}+{\rm{H}}{\gamma }_{{\rm{A}}})^{\prime} $ line index which implies a formation redshift of ${z}_{\mathrm{form}}={1.40}_{-0.18}^{+0.60}$.