Physics Commons^™

Improved Contacts And Device Performance In Mos2 Transistors Using 2d Semiconductor Interlayers, Kraig Andrews

Wayne State University Dissertations

The rapid growth of modern electronics industry over the past half-century has been sustained by the continued miniaturization of silicon-based electronics. However, as fundamental limits approach, there is a need to search for viable alternative materials for next-generation electronics in the post-silicon era. Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDs) have attracted much attention due to their atomic thickness, absence of dangling bonds and moderately high carrier mobility. However, achieving low-resistance contacts has been major impediment in developing high-performance field-effect transistors (FETs) based on 2D semiconductors. A substantial Schottky barrier (SB) is often present at the metal/2D-semicondcutor interface, …

Reflection And Reverberation In Neutron Star Low-Mass X-Ray Binaries, Benjamin Coughenour

Wayne State University Dissertations

Neutron star low-mass X-ray binaries (NS LMXBs) are systems which consist of a NS and a low-mass companion star. They are naturally variable on a variety of timescales, and are even classified by their X-ray spectral variability on the timescales of hours to days. The most luminous NS LMXB sources are known as ‘Z’ sources, because they trace out a characteristic ‘Z’ shape when plotted on a color-color or hardness-intensity diagram. The physical mechanisms causing this variability are not well understood. To try to address this, we model spectra taken from different positions on a hardness-intensity diagram of two Z …

Effective Field Theory And Machine Learning Approaches To Controlling Nonperturbative Uncertainties In Flavor Physics, Ayesh Gunawardana

Wayne State University Dissertations

The radiative decay $\bar{B}\to X_s\gamma$ and semileptonic heavy meson decay $D\to \pi l \nu$ are important flavor physics probes of new physics. However, these decays are plagued with nonperturbative uncertainties that are needed to be controlled to obtain a theoretically clean description. In this dissertation, we provide effective field theory and machine learning approaches to controlling these uncertainties.\par

In $\bar B\to X_s\gamma$, the largest uncertainty on the total rate and the CP asymmetry arises from resolved photon contributions. These appear first at order $1/m_b$ and are related to operators other than $Q_{7\gamma}$ in the effective weak Hamiltonian. One of the …

Exploring Jet Transport Coefficients In The Quark-Gluon Plasma, Amit Kumar

Wayne State University Dissertations

The modifications of hard jets play an essential role as multi-scale probes of the properties of the Quark-Gluon Plasma (QGP) produced in high-energy heavy-ion collisions. In this thesis, we explore the interplay between the soft and hard scales involved in the modification of jet partons as they propagate through the QGP. First, we focus on a regime where the exchanged momenta between the hard parton and the medium are at a high enough scale that QCD perturbation theory can be applied. Based on the assumption that the multiple scatterings inside the plasma are incoherent in the high-energy and high-virtuality phase …

Data Analysis Of Large Angle Beamstrahlung Monitor, Samuel Doeg Izaguirre Gamez

Wayne State University Dissertations

The first experimental evidence of large angle beamstrahlung at SuperKEKB is discussed in this Thesis. Beamstrahlung is the tn radiation emitted by particles belonging to one beam when they are accelerated transversely by the electro-magnetic field of the other beam. The properties of the radiation are related to the beam interaction topologyand can be used to optimize the beam-beam collision. This, in turn, makes the machine’s luminosity, and therefore the number of produced events, higher. A device entirely built at WSU, the Large Angle Beamstrahlung Monitor, or LABM, has been deployed in the SuperKEKB accelerator since 2015. A five Institutions …

Incorporating Cardiac Substructures Into Radiation Therapy For Improved Cardiac Sparing, Eric Daniel Morris

Wayne State University Dissertations

Growing evidence suggests that radiation therapy (RT) doses to the heart and cardiac substructures (CS) are strongly linked to cardiac toxicities, though only the heart is considered clinically. This work aimed to utilize the superior soft-tissue contrast of magnetic resonance (MR) to segment CS, quantify uncertainties in their position, assess their effect on treatment planning and an MR-guided environment.

Automatic substructure segmentation of 12 CS was completed using a novel hybrid MR/computed tomography (CT) atlas method and was improved upon using a 3-dimensional neural network (U-Net) from deep learning. Intra-fraction motion due to respiration was then quantified. The inter-fraction setup …