Session MA: Award Session

DNP Mentoring Award Talk: A Collective Solution to an Individual Particle Problem

As the exciting opportunities FRIB offers to better understand nuclear structure farther from stability approach, it becomes more important to strengthen the foundations of our current understanding at higher spin and neutron excess. One of these foundations has been the configuration-interaction models of sd-shell nuclei based on effective interactions (USD, USDA, USDB) fitted to a wide range of nuclear states. Perhaps one of its greatest successes has been the failure to describe the binding energies of low Z - high N nuclei like 31Na. This island of inversion has been investigated with precursors to FRIB and is generally understood as involving excitations into the fp-shell which are not included in the USD family of interactions. The higher spins accessible with heavy-ion reactions and the large high-resolution gamma detector arrays both call for a more comprehensive theoretical treatment of cross-shell excitations and provide the data to tackle it. An experimental-theoretical collaboration of FSU researchers from graduate students to professors has determined such a more comprehensive cross-shell effective interaction based on nuclei from 13C to 51Ti. Examples of comparisons with experimental energy levels, spectroscopic factors, lifetimes, shell migration, isobaric analog states, and island of inversion effects will be presented.   

Stuart Jay Freedman Award Talk: From Electrons to Neutrinos: Nuclear Effects in Oscillation Measurements

Precision accelerator-based neutrino oscillation measurements relay on precise and accurate modeling of the interaction of neutrinos with atomic nuclei. At the moment, our insufficient understanding of such interactions is a dominant systematic in extraction of neutrino oscillation parameters and can stand as a significant challenge for achieving the goals of next-generation neutrino oscillation experiments such as DUNE and T2-HyperK. \\ \\ Following the spirit of Stuart Freedman’s own research, this talk will focus on the synergy between nuclear and particle physics in searching for a deeper understanding of our universe. Specifically, I will present new results from novel experimental constrains on neutrino-nucleus interactions, from synergic measurements of wide phase-space neutrino and electron exclusive scattering reactions using the MicroBooNe (Fermilab) and CLAS (JLab) detectors. I will also show how such data allow addressing outstanding issues in neutrino physics such as the accuracy of incident neutrino energy reconstruction for oscillation analyses, and constraints on searches for physics beyond the standard model.   

Dissertation Award in Nuclear Physics Talk: The Hunt for Astrophysical Neutrinos

Astrophysical neutrinos are excellent probes of neutrino properties, the solar core, and high-energy cosmic accelerators. But their detection suffers from high backgrounds and from uncertainties in how we reconstruct and interpret events. For example, solar neutrino signals in Super-Kamiokande are overwhelmed by beta-decay backgrounds initiated by cosmic-ray muons. Meanwhile, the detection of high-energy astrophysical neutrinos in IceCube opened new ground for studying cosmic accelerators, but IceCube cannot effectively distinguish $\nu$$\tau$ from $\nu$$e$, as both generate similar-looking events. Using understanding of the common shower physics underlying both problems, I will show new methods to reject spallation backgrounds in Super-Kamiokande, applicable to their solar neutrino analysis, and to improve the measurement of flavors of astrophysical neutrinos in IceCube.   

Dissertation Award in Nuclear Physics Talk: Global polarization of Lambda hyperons in Au+Au Collisions at RHIC

Non-central heavy-ion collisions have large ($\sim 10^{5} \hbar$) angular momentum which may be transferred, in part, to the quark-gluon plasma (QGP) through shear forces that generate a vortical substructure in the hydrodynamic flow field. The vortical nature of the system can polarize emitted hadrons along the direction of system angular momentum. $\Lambda$ and $\overline{\Lambda}$ hyperons, which reveal their polarization through decay topology, should be polarized similarly. These same collisions are also characterized by dynamic magnetic fields with magnitude as large as $10^{14}$ Tesla. A splitting between $\Lambda$ and $\overline{\Lambda}$ polarization may signal a magnetic coupling and provide a quantitative estimate of the field strength at freeze out. Details of the magnetic field and its evolution are of particular interest to other novel phenomena in heavy-ion collision physics. \\ \\ The STAR Collaboration made the first non-trivial observation of global hyperon polarization in non-central Au+Au collisions in the RHIC Beam Energy Scan. A magnetic splitting is hinted at, but the improved statistics and resolution achievable with future runs are required to make a definitive measurement of the magnetic field. Using a simple magneto-hydro equilibrium framework for interpreting the data allows for the direct extraction of the physical parameters relevant to this measurement, the vorticity and magnetic field. The extracted vorticity in this system is found to be considerably larger than any previously measured value, lending a new superlative to the QGP: ``the most vortical fluid’'.