Fall 2017 Joint High Energy Physics and Astrophysics Seminar Schedule

Talks are on Wednesdays at 3:35pm in Nielsen 512. For updates and changes, contact Andrew W. Steiner. Graduate students signed up for credit, see instructions here.

Aug. 23Xiao Luo (Yale)Liquid Argon Time Projection Chamber for Neutrino Physics

Abstract: The Time Projection Chamber (TPC) is a widely used detector technology in particle physics. As neutrino physics enters the era of precision measurement of oscillation parameters, Liquid Argon TPC (LArTPC) is chosen as the main detector technology for the future DUNE experiment - an international mega-science project seeking answers to the fundamental questions such as CP violation, neutrino mass hierarchy, and proton decay. In this talk, I will discuss the working principle of LArTPC, as well as advantages and challenges from the experiences of several existing LArTPC experiments.

Sep. 6Wei Tang (UTK)Data Unfolding with the Wiener-SVD Method

Abstract: Data unfolding is a common analysis technique used in HEP data analysis. Inspired by the deconvolution technique in the digital signal processing, a new unfolding technique based on the SVD technique and the well-known Wiener filter is introduced. The Wiener-SVD unfolding approach achieves the unfolding by maximizing the signal to noise ratios in the effective frequency domain given expectations of signal and noise and is free from regularization parameter. Through a couple examples, the pros and cons of the Wiener-SVD approach as well as the nature of the unfolded results are discussed.

Sep. 13Sophia Han (UTK)Thermal states of transiently accreting neutron stars

Abstract: The standard picture for the composition of neutron stars assumes that they are composed of neutrons and protons, embedded in a gas of electrons and muons. Current observations of neutron star masses and radii are yet not fully convincing to rule out possibilities of exotic phases such as hyperonic or quark matter in their densest cores. In this talk, I will report on our recent efforts in discerning compositions of neutron star interiors. Confining the study within nucleons-only framework, we analyze the thermal states of accreting neutron stars in quiescence, taking into account variations in e.g. the equations of state, superfluidity gaps, and deep crustal heating. We find that the stringent limitation imposed by the hottest and coldest sources observed disfavors the scenario without exotic matter.

Sep. 20Andrew W. Steiner (UTK) Using qLMXBs to Determine the Nature of Dense Matter

In this talk, I will report on our recent work determining the mass and radius of neutron stars in globular clusters. The principal challenge which this paper tackles is how to address the potential systematic uncertainties which have plagued the analysis of observations of quiescent low-mass X-ray binary systems. Some of the systematics can be handled by properly rescaling the data, so I will outline this formalism. Then, I will apply the Bayesian inference machinery we have previously developed to obtain final results on the neutron star mass-radius curve and the equation of state of dense matter.

Sep. 27Leah Broussard (ORNL)New Search for Mirror Neutrons at HFIR

The observation of neutron oscillations into an invisible neutron state would indicate the existence of a new form of matter which could explain some or all of dark matter. Neutron oscillations are predicted by some models which contain Mirror Matter, which is an identical copy of Standard Model particles and interactions, but opposite Parity. Direct searches for neutron oscillations to mirror neutrons in a controlled magnetic field have previously been performed using ultracold neutrons in storage/disappearance measurements, with some inconclusive results for oscillation times of \( \tau\sim \) 10 s. I will describe a proposed disappearance and regeneration experiment in which the neutron oscillates to and from a mirror neutron state. An experiment performed using the existing General Purpose-Small Angle Neutron Scattering instrument at the High Flux Isotope Reactor at Oak Ridge National Laboratory could have the sensitivity to exclude up to \( \tau<\) 15 s with short beamtime and low cost.

Oct. 4
Oct. 11Yuri Kamyshkov (UTK) The Magnetic Moment of Mirror Neutrons

This is a work in progress. Together with collaborators Z. Berezhiani and L. Varriano we are studying the role of the magnetic moment in the transformations of neutrons to mirror neutrons and the possible observable effects it might create.

Oct. 18Josh BarrowStudies Toward the Search for Neutron-Antineutron Oscillation

The baryon asymmetry of the universe (BAU) remains a conundrum for the Standard Model (SM), as no SM process has been able to adequately theoretically explain the vast asymmetry between matter and antimatter we easily see across the universe. Theoretical extensions have been proposed to go beyond the Standard Model (BSM), adding higher order operators to the SM Lagrangian; these include proton decay, but the addition of many of these new operators to the SM does not explain the BAU. Post-sphaleron baryogenesis (PSB) via neutron-antineutron oscillation is the leading candidates to explain the BAU, predicting observable oscillation phenomena at high-energy scales.

A review of this physics, along with experimental techniques to search for oscillations, will be presented to the seminar. Further details will be given as to the progress toward accurate simulation of the oscillation, analysis of generated data, and observation viability within multiple future experiments.

Oct. 25Ryan Landfield (UTK)TBD
Nov. 1Zurab Berezhiani (University L'Aquila and LNGS/INFN)TBD
Nov. 8Jordi Bustamante TBD
Nov. 15Gray Yarbrough and Andrew Mogan MicroBooNE
Nov. 29Charles Hughes