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Particle Physics and Astro-Cosmology Seminar

Spring 2017

The seminars are held in Nielsen Room 512 from 3:35 until 4:35 PM.

Date Speaker Title

January 18

Sowjanya Gollapinni

Calibrating LArTPC detectors — Part I
[Slides]

January 25

Yuri Kamyshkov

Decoherence in Two-Level Quantum Systems
[Slides]

February 1

Tom Handler

The Relationship between Science and Public Policy
[Slides]

February 8

Eric Lentz

A Three-Dimensional View of Core-Collapse Supernovae

February 15

Yuri Efremenko

CEvNS, Can We See Them Soon?
[Slides]

February 22

Stefan Spanier

CP Violation in B Meson Decays
[Slides]

March 1

Andrew Steiner

Disentangling Dense Matter From Accreting Neutron Stars
[Slides]

March 8

James Matta
Josh Barrow

James Matta's Talk Title: The PROSPECT Project and the Effects of Reactor Backgrounds
Josh Barrow's Talk Title: Characteristic Signal of Neutron-Antineutron Oscillation
in Argon Nuclei at DUNE

Josh Barrow's Slides

March 15

No Seminar: Spring Break

NA

March 22

Eirik Endeve

Computational Method for Neutrino Transport in Core-Collapse Supernovae
[Slides]

March 29

Konstantin Yakunin

Gravitational Signals from Core Collapse Supernova
[Slides]

April 5

Matthew Frost
Biswas Sharma

Matthew Frost Talk Title: Development of a New Search for Neutron/Anti-neutron Oscillation at the European Spallation Source [Slides]
Biswas Sharma Talk Title: Survey of the Performance of Scintillation Materials at Low Temperatures [Slides]

April 12

Nadia Fomin

Short-range NN interactions: Experimental Past and Future
[Slides]

April 19

Chloe Keeling and
Michael Sandoval

Chloe Keeling's title: Determining the Origin of the Monoceros Tidal Stream [Slides]
Michael Sandoval's title: Ultra Diffuse Galaxies: VCC1287 and Dragonfly 44 [Slides]

April 26

Charles Hughes

Constraining the Mass of Neutrinos from Recent Cosmological Observations


Abstracts
January 18

Sowjanya Gollapinni

Calibrating LArTPC Detectors — Part I

Due to their exceptional calorimetric and position resolution capabilities, Liquid Argon Time Projection Chambers (LArTPCs) are currently the favored technology for a number of current and upcoming neutrino oscillation experiments including the Deep Underground Neutrino Experiment. A precise and unbiased LArTPC detector calibration is crucial for all of these experiments to achieve the intended physics goals. A variety of topics related to LArTPC calibration such as electron lifetime, space charge effects, electron diffusion and recombination are discussed highlighting some recent results from MicroBooNE.

February 1

Thomas Handler

The Relationship between Science and Public Policy

The United States faces many issues that involve science. Issues ranging from climate change to nano-technology, from human genomics to modified food crops. What is the role that science plays in determining what the public policy for these issues should be? How as scientists should we respond to requests for advice?

February 8

Eric Lentz

A Three-Dimensional View of Core-Collapse Supernovae

Driving an explosion from the collapsed core of a massive star is an inherently non-symmetric process. I will explore the nature of the neutrino-driven supernova mechanism and the nature of the explosion and its ejecta from recent 3D supernova models computed with the Chimera supernova code.

February 8

Yuri Efremenko

CEvNS, Can We See Them Soon?

CEvNS stands for the Coherent Elastic Neutrino Nucleus Scattering. This kind of neutrino interaction was predicted more than forty years ago, but never detected. Presently there is a race which experiment will be the first to detect CEvNS. I will review the present experimental activities, and outline how detailed study of this interaction can be used as a probe of a physics beyond the Standard Model of Electro-weak Interactions.

February 22

Stefan Spanier

CP Violation in B Meson Decays

The violation of charge conjugation C and parity P combined can be studied to very high precision in B-meson decays. The standard model of particle physics includes CP violation. The magnitude within the standard model though is too small to support cosmic models of the matter anti-matter asymmetry in the universe. Observation of deviations from predicted CP violation with B-meson decays is a pathway to indirectly probe physics models beyond the standard model that might include stronger CP violation. Such measurements with B-mesons will be discussed.

March 1

Andrew Steiner

Disentangling Dense Matter From Accreting Neutron Stars

One of the holy grails of dense QCD is to determine the relevant degrees of freedom for cold (temperatures less than tens of MeV) and dense (densities higher than nuclear saturation but lower than those where QCD perturbation theory is applicable) matter. Although we cannot yet answer this question, in this talk I will report on results in the direction of an answer. We analyze the thermal emission of accreting neutron stars assuming that dense matter contains no exotic matter (no strange quarks or pion condensates). In spite of our large parameter space (14 parameters) we find it difficult to explain 2 data points without significant amount of fine-tuning. The natural way out of this quandary is to conclude that our assumption was false and that neutron stars must contain exotic matter.

March 8

James Matta

PROSPECT and the Effects of Reactor Backgrounds

The PROSPECT experiment is designed to probe short-baseline neutrino oscillations and precisely measure the 235U reactor antineutrino spectrum using a segmented antineutrino detector containing 4.6T of 6Li-loaded liquid scintillator at distances of 7-12 meters from the High Flux Isotope Reactor (HFIR) core. While HFIR is an ideal location for this experiment, there are a few challenges to overcome in regards to the background radiation field the detector will be immersed in. Since there is very little overburden to shield cosmogenic backgrounds and since the reactor itself (and its associated beamlines) is a significant source of radiation a meticulous spatial and temporal characterization of the background radiation field is necessary. In this talk the PROSPECT experiment will be discussed and ongoing efforts and results in the background characterization will be presented.

March 8

Josh Barrow

Characteristic Signal of Neutron-Antineutron Oscillation
in Argon Nuclei at DUNE

Babu et al. have recently proposed a model of post-sphaleron baryogenesis following the electroweak phase transition. Their theory naturally gives rise to a plausible baryon abundance and a ΔB=2 six-quark operator which allows for the generation of nbar from n. Using n bound in Ar, DUNE currently plans to include n-nbar events in their nucleon decay searches. Using GENIE, modeling and analysis is underway on intranuclear interactions mimicking n-nbar annihilation in Ar nuclei. Eliminating atmospheric ν background from such events will be a challenge for liquid Ar TPCs at DUNE, so simulation work must be considered for ν interactions in Ar nuclei, which produce similar signals to n-nbar annihilation. Key to understanding possible experimental signals will be the integration of these two for a proper robust analysis, which will determine the viability of any detection of this process above background levels.

March 22

Eirik Endeve

Computational Method for Neutrino Transport in Core-Collapse Supernovae

The majority of the gravitational energy released during the collapse of the stellar core in a core-collapse supernova (CCSN) is radiated away in the form of neutrinos. As such, neutrinos play a fundamental role in shaping the CCSN explosion dynamics. Since neutrinos are weakly coupled to the stellar fluid in the region where critical four-momentum and lepton exchange occurs, a non-equilibrium description based on the Boltzmann transport equation is warranted. This again makes CCSN models extremely compute intensive. We will discuss some considerations and approaches to solving the Boltzmann transport equation on a computer.

March 29

Konstantin Yakunin

Gravitational waves from Core Collapse Supernova

Recent direct detections of gravitational signals from coalescence of binary black holes opened a new window on the Universe. Gravitational waves (GW) carry out unique information about physical processes taking place in the dense matter. Core-collapse supernovae (CCSN) are among the most interesting object to explore with the help of gravitational signals. In this talk I will review the ensemble of anticipated GW emission processes in stellar core collapse and postbounce CCSN evolution. I will also present new results on the GW emission from 3D supernova models and discuss a feedback between CCSN simulations and methods used in signal searches in the LIGO pipelines.

April 5

Matthew Frost

Development of a New Search for Neutron/Anti-neutron Oscillation at the European Spallation Source

There has yet to be any evidence of Baryon Number Violation (BNV) in any particle physics experiment or astronomical observation. Yet, there are anomalies at the non-perturbative level in the Standard Model that allow for BNV, and cosmological baryogenesis models require BNV as an explanation for the imbalance of matter and anti-matter in the universe, one of the three Sakharov conditions. This, along with the quantum mechanical two-level system phenomenology (presented previously during this seminar series), suggest that a free neutron oscillation would be an ideal candidate for experimental BNV observation. The current lower limit on the free neutron oscillation time has been determined to be 8.7 x 107 seconds (nearly three years) from a pioneering experiment performed at Institute Laue-Langevin (ILL) at Grenoble in 1991. There has been no attempt since then to try and observe BNV in the oscillation of a free neutron. Modern advances in thermal and cold neutron transport technology, as well as new facilities that produce high-intensity sources of cold neutrons allow for the possibility of an experiment that would provide three orders of magnitude better sensitivity than at ILL. The European Spallation Source currently under construction in Lund, Sweden will be the latest in a series of world-class, high-flux cold neutron sources that could be used for such a search. Simulations describing the proposed experiment geometry as well as novel methods for improved sensitivity will be presented.

Biswas Sharma

Survey of the Performance of Scintillation Materials at Low Temperatures

An increasing number of applications of scintillators at low temperatures, particularly in cryogenic experiments searching for rare events, has motivated the investigation of scintillation properties of materials over a wide temperature range. Studies of temperature dependence of decay times and the light yield give an opportunity to gain insight into the features of the scintillation process in the material and to identify possible routes for improvements. This talk presents a summary of the findings of researchers around the world in the past few years regarding the temperature dependence of the performance of several organic and inorganic scintillators.

April 12

Nadia Fomin

Short-range NN interactions: Experimental Past and Future

High momentum components of the nuclear wave-function are believed to arise as a result of short-range NN correlations in the ground state. The 6 GeV era at Jefferson Lab has yielded a wealth of information about these high momentum nucleons across many nuclei, and revealed a tantalizing connection to the EMC effect, possibly linking very different kinematic regimes. Existing measurements will be reviewed and future measurement plans will be discussed.

April 19

Chloe Keeling

Determining the Origin of the Monoceros Tidal Stream

The Monoceros Tidal Stream is a galactic feature of the Milky Way with uncertain origin. Understanding the origin of the Monoceros Tidal Stream can help us understand how the Milky Way evolved over time. Three possible explanations for this feature will be briefly discussed: 1. tidal streaming, 2. flared thick disk, and 3. disrupted thick/thin disk. Each of possible explanation can give us insight into the structure and evolution of our Galaxy.

Michael Sandoval

Highlighting Ultra Diffuse Galaxies: VCC1287 and Dragonfly 44

Recently a population of large, very low surface brightness, spheroidal galaxies was identified in the Coma cluster. The apparent survival of these Ultra Diffuse Galaxies (UDGs) in a rich cluster suggests that they have very high masses. A key to understanding their origins comes from their total masses, but their low surface brightnesses generally prohibit dynamical studies. Here I will discuss the first reports of such first measurements for UDGs VCC 1287 and Dragonfly 44, based on their globular cluster system dynamics and size. The results add to other recent evidence that many UDGs are "failed" galaxies, with the sizes, dark matter content, and globular cluster systems of much more luminous objects. The enclosed dark matter mass for Dragonfly 44 suggests a total mass of ~10^12 M_sun, similar to the mass of the Milky Way. The existence of nearly-dark objects with this mass is unexpected, as galaxy formation is thought to be maximally-efficient in this regime.

April 26

Charles Hughes

Constraining the Mass of Neutrinos from Recent Cosmological Observations

Measuring the mass of the three known neutrino flavors is an ongoing problem in modern-day experimental physics research. Cosmological observations can provide constraints on the neutrino mass spectrum possibilities. Observations of the Cosmic Microwave Background (CMB), Large Scale Structure (LSS), Baryon Acoustic Oscillations (BAO), and Hubble Parameter can provide an upper limit on the sum of the neutrino flavor masses. An upper of 0.126 eV range can be reached at 95 % CL by analyzing the recent 2015 Planck Satellite CMB temperature data, measurements of the Hubble parameter measurements from Hubble Space Telescope, and BAO measurements from Sloan Digital Sky Survey and 6 degree Field Galaxy Survey using the Lambda Mixed Dark Matter model.


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