International Collaboration in Physics Research: A Summer at CERN

During the summer of 2014, after my junior year as a physics major at the University of New Hampshire, I took part in a nine-week Research Experience for Undergraduates sponsored by the University of Michigan and the National Science Foundation. During the program, I lived and worked at the European Organization for Nuclear Research (CERN) just outside of Geneva,Switzerland. CERN is home to the largest particle collider in the world, the Large Hadron Collider (LHC), and is the world’s leading particle physics laboratory. As a summer student, I attended daily lectures on particle physics from leading experts in the field, carried out research under the supervision of a staff scientist, and networked with students and scientists from around the world. This experience has informed both my professional goals and my view of myself as a student in a global community. I was amazed by the collaboration between individuals who were from diverse countries and cultures and spoke different languages, but were able to set aside their differences to pursue a common goal

The Toric Approach to F-theory Model Building

We describe the theoretical motivation for F-theory as a non-perturbative generalization of string theory. The four complex-dimensional compactification spaces of F-theory, called elliptically-fibered Calabi-Yau manifolds, consist of the six compact dimensions of string theory, plus a two-dimensional fiber that describes the string coupling field as a function of position on the string theory manifold. The methods of toric geometry are developed and applied to construct examples of elliptically-fibered Calabi-Yau manifolds. We analyze in detail models in which the fiber is free of singularities as a test bed for a more general analysis

A first look at the MadGraph 5 and Pythia 8 simulation tools

My project was part of the Future Circular Collider (FCC) design study . The goal of the study is to evaluate the feasibility of constructing the next generation 100 km collider facility with nominal beam energy of 100 TeV. As part of this evaluation, the study aims to determine hardware and software requirements, detectors, and costs for the project. There are three branches of this study (FCC-hh, FCC-eh, and FCC-ee) which focus on different collider facilities that would be housed in the same 100 km tunnel. The FCC-hh is the 100 TeV hadron collider that will define the infrastructure requirements for the project. The FCC-ee is an e+e- collider that would be a first step in the construction of the FCC-hh, and the FCC-eh is an intermediate lepton-hadron collider that is being considered [1]. My project focused on physics of particular interest to the FCC-hh study

New models of sympatric speciation through sexual selection in animals

The theory of sympatric speciation has gained support through both empirical evidence and theoretical analysis. Sexual selection has been empirically linked to sympatric speciation, and many models of sympatric speciation are based on non-random mating. This thesis presents an analysis of the model of sympatric speciation through sexual selection presented by Turner and Burrows (1995) in order to make predictions for the experimental analysis of modes of speciation.The introduction of a mutation in female preference does not guarantee the formation of sympatrically co-existent sibling species, but is dependent on a form of runaway process. Reduction in the genetic variation in male trait, either through fixation or through too few loci, is an obstacle to the formation of sympatric species. Increasing the strength of female preference or the effort females are prepared to make increases the strength of sexual selection and increases the likelihood of sympatric speciation. Population size affects the probability of sympatric speciation either through the excessive fixation of male trait loci in small populations, or through reducing the changes of individuals carrying mutations in female preference genes meeting and mating in larger populations.The Turner and Burrows (1995) model was found to be robust under a variety of genetic assumptions. A variation of the model, using dominance in male trait alleles and removing stabilising selection on male phenotype was less affected by fixation at the male courtship trait loci. Spatial distributions affected the probability of sympatric speciation when the dispersal of offspring is limited, creating localised concentrations of female preference types and the preferred male trait.Breeding experiments may be used to indicate whether this mode of speciation has operated in a particular instance.Fast, sympatric speciation was found to be more likely in clades with small population sizes, where females choose from a large number of males, if a moderate number of loci code for male courtship traits, and in taxa with a life history matching K-selected species rather than r-selected species.</p

Enhancement of proton acceleration from focusing targets

Particle acceleration from laser-plasma interactions has been a vibrant area of research since the discovery of electron and proton beams emitted from high intensity laser-plasma interactions in the 1980s. Since then, a large body of work has developed in pursuit of understanding and controlling the mechanisms that generate these particle beams, as well as the beams themselves. In particular, proton beams have a rich set of applications in the fields of medicine, fusion energy, and fundamental physics that motivates their study. In this thesis, we first discuss the laser technology that has enabled this research. We follow this with detailed information on the design and development of a 100 TW power upgrade to the graduate student-run GHOST laser system for the purposes of conducting repetition-rated laser-plasma experiments. We then outline the physics that drives particle acceleration during the interactions of high intensity lasers and solid targets with a particular focus on target normal sheath acceleration, the most widely studied laser-plasma particle acceleration mechanism. Finally, we describe experiments conducted on the Texas Petawatt Laser system to test an approach to enhance the yield, peak energy, and beam characteristics of proton beams generated by laser-plasma interactions with the use of focusing targets.Physic

Love Me A Little Little

https://digitalcommons.library.umaine.edu/mmb-vp-copyright/6908/thumbnail.jp

Plasma emission characteristics in laser-induced breakdown spectroscopy of silicon with mid-infrared, multi-millijoule, nanosecond laser pulses from a Ho:YLF excitation source

We characterized the plasma emission produced by the interaction of multi-millijoule, 40 ns duration, mid-infrared laser pulses with a silicon surface. The laser pulses were produced by a Q-switched Ho:YLF master oscillator power amplifier system. Using spectral measurements and a framing camera, we observed a spatial separation of the plasma plume, increased emission signal with low white-light generation, and a drop in the time- and space-averaged apparent plasma density with increasing pump energy. Our results can be explained by continuous heating of the plasma by the pump pulse due to the more efficient inverse bremsstrahlung absorption at longer wavelengths. (C) 2019 Optical Society of America1

SUMMARY

Markov chain Monte Carlo-based approaches for inference in computationally intensive inverse problem