Physics Commons^™

Electron-Positron Annihilation Lifetime Spectroscopy Of Mgo And Aluminum-Doped Mgo, Elise Liebow

Honors Theses

Radiation is a form of energy that can damage materials at an atomic level. This has implications for the mobility of radioactive waste through containment materials. We are characterizing atomic defects in materials by using Electron-Positron Annihilation Lifetime Spectroscopy (EPALS). When an electron and positron come into contact with each other, they annihilate and release two antiparallel 511-keV gamma rays. In a pristine crystalline sample, positrons can easily annihilate with electrons, but in a sample with vacancies/defects in the crystal structure, positrons take longer to annihilate. Therefore, the more vacancies in a sample, the longer the average lifetime of a …

Nuclear-Targeted Gold Nanoparticles Enhance The Effects Of Radiation Therapy With And Without Liposomal Delivery, Maureen Aliru

Dissertations & Theses (Open Access)

Less that 10% of pancreatic cancer patients are eligible for curative resection, and clinical trials evaluating chemoradiation in locally advanced patients with unresectable disease have been largely disappointing. New and creative therapeutic approaches are needed to address the unment need for treatment options. The objective of this thesis is to advance radiosensitization of treatment-resistant densely desmoplastic pancreatic cancer using nanoparticles to surmount biological barriers to effective particle distribution for DNA-targeting.

Clinical translation of radiosensitizing nanoparticles has stalled owing to technical challenges. Current strategies to use AuNPs for radiosensitization require large quantities of gold, kilovoltage x-rays, immediate irradiation after intravenous administration, …

Master Integrals For Double Real Radiation Emission In Heavy-To-Light Quark Decay, Roberto Bonciani, Alessandro Broggio, Leandro Cieri, Andrea Ferroglia

Publications and Research

We evaluate analytically the master integrals for double real radiation emission in the b → uW* decay, where b and u are a massive and massless quark, respectively, while W* is an off-shell charged weak boson. Since the W boson can subsequently decay in a lepton anti-neutrino pair, the results of the present paper constitute a further step toward a fully analytic computation of differential distributions for the semileptonic decay of a b quark at NNLO in QCD. The latter partonic process plays a crucial role in the study of inclusive semileptonic charmless decays of B mesons. Our …

Angular Distribution Of Single-Photon Superradiance In A Dilute And Cold Atomic Ensemble, A. S. Kuraptsev, I. M. Sokolov, M. D. Havey

Physics Faculty Publications

On the basis of a quantum microscopic approach we study the dynamics of the afterglow of a dilute Gaussian atomic ensemble excited by pulsed radiation. Taking into account the vector nature of the electromagnetic field we analyze in detail the angular and polarization distribution of single-photon superradiance of such an ensemble. The dependence of the angular distribution of superradiance on the length of the pulse and its carrier frequency as well as on the size and the shape of the atomic clouds is studied. We show that there is substantial dependence of the superradiant emission on the polarization and the …

Progress Towards Terahertz Acoustic Phonon Generation In Doping Superlattices, Thomas E. Wilson

Thomas E. Wilson

Progress is described in experiments to generate coherent terahertz acoustic phonons in silicon doping superlattices by the resonant absorption of nanosecond-pulsed far-infrared laser radiation. Future experiments are proposed that would use the superlattice as a transducer in a terahertz cryogenic acoustic reflection microscope with sub-nanometer resolution.

Radiation Therapy Medical Physics Review – Delivery, Interactions, Safety, Feasibility, And Head To Head Comparisons Of The Leading Radiation Therapy Techniques, Cielle Collins

Honors Theses and Capstones

Radiation therapy uses high energy radiation to kill cancer cells. Radiation therapy for cancer treatment can take the form of photon therapy (using x-rays and gamma rays), or charged particle therapy including proton therapy and electron therapy. Within these categories, numerous methods of delivery have been developed. For example, a certain type of radiation can be administered by a machine outside of the body, called external-beam radiation therapy, or by a “seed” placed inside of the body near cancer cells, called internal radiation therapy or brachytherapy. Approximately half of all cancer patients receive radiation therapy, and the form of radiation …

Radiation-Induced Radicals In Polyurea-Crosslinked Silica Aerogel, Benjamin Michael Walters

Masters Theses

Free radicals are atoms or molecules with an odd number of electrons in an outer shell. Since electrons typically occur in pairs, this leaves one electron that is unpaired. In seek of another electron to pair with, free radicals react with and steal electrons from neighboring molecules, which then become free radicals themselves. This can start a chain reaction, cascading into large scale damage.

Ionizing radiation can tear through molecules, just as bullets can tear through things that we see. If free radicals can be detected, and seen to increase in a material upon radiation exposure, this can indicate molecular …

In Memoriam: Robert Katz (1917–2011), M. P. R. Waligorski, Francis A. Cucinotta

Robert Katz Publications

Bob Katz will be well remembered for his enthusiasm and strong personality. In a scientific dispute, few indeed could match his wit or his sense of humor or survive the cutting logic of his arguments. To those who had appreciation for his science and his personality, he was truly a great scientist and a master teacher. There are many people around the world who will remember Bob Katz for what he offered them and for the way he showed them what truth in science is.

The Katz Model, developed at that time for solid-state detectors and for cell cultures, relates …

Progress Towards Terahertz Acoustic Phonon Generation In Doping Superlattices, Thomas E. Wilson

Physics Faculty Research

Progress is described in experiments to generate coherent terahertz acoustic phonons in silicon doping superlattices by the resonant absorption of nanosecond-pulsed far-infrared laser radiation. Future experiments are proposed that would use the superlattice as a transducer in a terahertz cryogenic acoustic reflection microscope with sub-nanometer resolution.

A Rapidly-Converging Alternative To Source Iteration For Solving The Discrete Ordinates Radiation Transport Equations In Slab Geometry, Nicholas J. Wager

Theses and Dissertations

I present a numerical technique to solve the time independent Boltzmann Transport Equation for the transport of neutrons and photons. The technique efficiently solves the discrete ordinates equations with a new iteration scheme. I call this new scheme the angle space distribution iteration method because it combines a non-linear, high angular-resolution flux approximation within individual spatial cells with a coarse angular-resolution flux approximation that couples all cells in a spatial mesh. This shown to be an efficient alternative to source iteration. The new method is implemented using the step characteristic and exponential characteristic spatial quadrature schemes. The latter was introduced …