Session E03: Combined Physics Topics

Integrating Computation and Experimentation in the Advanced Physics Undergraduate Curriculum

The University of Mount Union recently restructured its undergraduate physics curriculum to increase training in computational techniques at the intermediate and advanced levels.  The upper-level course Data Acquisition and Analysis builds on intermediate computational and experimental coursework and challenges students to independently shepherd experiments from conception to completion.  After providing a broad overview of course structure and learning objectives, the presentation will summarize three course projects, including (1) automated video motion tracking, (2) audio capture and signal separation, and (3) verification of “double slit” interference with sound. Assignment files will be made available to interested instructors upon request.   

An ab-initio study of ternary oxide phases of MgSnO3 as an application in solar cells

MgSnO₃ in Ilmenite, Perovskite and LiNbO₃ type crystal structures have been studied by first-principles methods using density functional theory (DFT) and beyond. We found that MgSnO₃ in LiNbO₃ type is both mechanically and dynamically stable, whereas Ilmenite and Perovskite crystal structures are mechanically stable but dynamically unstable. Vibrational stability in MgSnO₃ requires some distortion in octahedra caused due to the bonding strength between the atom pairs Sn-O in LiNbO₃ type crystal structure. Similarly, Ilmenite and Perovskite crystal structures need a higher number of Mg-Sn and (Mg-Mg, Sn-Sn, O-O and Mg-O) bonds respectively for stability. Ilmenite and LiNbO₃ type crystal structures can be deployed as window layers showing a large bandgap of 5.22 eV and 3.88 eV respectively, together with a lower absorption coefficient and reflectivity. Likewise, Perovskite crystal structure with a bandgap of 2.55 eV can be utilized as an absorber layer that absorbs green light of solar irradiation in tandem solar cells. Perovskite crystal structure has the lowest charge carrier effective masses among all the structures in MgSnO₃. LiNbO₃ type crystal structure has a high hardness of 56.5 GPa. It should be assessed experimentally in applications requiring super-hard materials.   

Using group theory to understand B meson decays

The up, down, and strange quarks can be thought of as elements of an SU(3) group due to the similarity in their masses. We utilize this fact to investigate the properties of the bottom quark in charmless B meson decays. Our focus is on final states consisting of three pseudoscalar mesons. Using SU(3) representations for the quarks, we demonstrate how to construct the three-body final states. We show that there are 120 fully-symmetric and 56 fully-antisymmetric final states under the interchange of any two final-state mesons. We calculate the three-body decay amplitude in terms of parameters of the Standard Model (SM). We present relations between SU(3) matrix elements and establish a way to determine a key parameter in the SM, the weak phase γ. Our work seeks to create new methods for measuring γ, thereby improving its precision and accuracy.   

Deblurring a decay energy spectrum from a nuclear reaction

In nuclear reaction experiments, the measured decay energy spectra can give insights about the shell spectroscopy of the systems. However, it is challenging to extract the underlying physics from the measurements due to detector resolution and acceptance effects. We introduce a deblurring method, novel for nuclear physics application, that utilizes the Richardson-Lucy algorithm that has proven to be successful in optics. We demonstrate that the technique could help recover the physics from highly degraded nuclear decay energy spectrum measurements. The method does not require any prior knowledge about the resonance states in the observed spectrum, and it circumvents the singularity issue by iteratively adjusting a positive definite distribution.  The only inputs are the observed energy spectrum and the detector's response matrix also referred to as the Transfer Matrix (TM). We tested the method’s performance on a simulated spectrum generated using the in-house simulation package for the MoNA-LISA-Sweeper setup and the associated TM. Finally, the approach is applied to the energy spectrum of the ²⁶O system decaying into  ²⁴O + n +n, from an experiment conducted at NSCL by the MoNA Collaboration. We demonstrate its successful performance in restoring the resonance states in the decaying systems from decay energy measurement.   

Elastic scattering observables using realistic NN-interactions for Carbon 12

The study of atomic nuclei depends on nuclear reactions to extract both reaction- and structure-related observables. With the development of new realistic nucleon-nucleon interactions, derived from chiral effective field theory, used in an ab initio no-core shell model (NCSM) we can calculate one-body nuclear densities and scattering observables of carbon isotopes. For the elastic scattering of protons and neutrons from nuclei, a microscopic optical potential is derived with the Watson expansion of the multiple scattering series. This spectator expansion allows for the use of the same nucleon-nucleon (NN) interaction when calculating the one-body densities, which must be folded with the NN scattering amplitudes. We present the dependence of scattering observables in the 65-100 MeV range for Carbon 12 on the NN interaction.   

Towards Unreasonable Effectiveness in Five Dimensions

We discuss four-derivative corrections to pure $\mathcal{N}=2$, $D=5$ gauged supergravity, up to field redefinitions. In particular, the possible four-derivative corrections can be parametrized on-shell by a basis of five terms. We have found that, up to factors of the two-derivative action, supersymmetry picks out a unique set of coefficients for these terms, ie, there is a unique five-dimensional superinvariant at the four-derivative level.   

Review of quantum tunneling mechanism

A quantum mechanical wave upon interaction with a potential barrier experiences change of momentum. In this process there's increase in momentum on the negative side (reflected wave) from zero, and equivalent increase in the incident momentum up to the height of the barrier. At this stage the reflected wave separates from the incident wave, and the corresponding remainder is transmitted through the barrier.