Department of Physics

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Colloquia & Seminars, Fall 2013

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2013 Lecture Series on the Nobel Prizes

The Western Illinois University Department of Physics Lecture Series on the Nobel Prizes
The Higgs Boson and the Material World

Speaker: Dr. James Rabchuk

Date: Friday, December 6, 2013
Time: 4 pm
Room: 205 Currens Hall

Lecture presented in celebration of the 2013 Nobel Prize in Physics, awarded to Francois Englert and Peter Higgs "for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider"

Abstract
The 2013 Nobel Prize in Physics was awarded to two researchers, Francois Englert and Peter Higgs, for their theoretical work describing the nature of the Higgs mechanism for explaining the masses of the fundamental particles in our universe, as well as the prediction of the so-called Higgs boson, the particle associated with the Higgs field. Their predictions were validated by the recent discovery of the Higgs particle at the Large Hadron Collider (LHC) at CERN in Switzerland. This discovery confirms and completes what is known as the Standard Model, which embodies our present understanding of the nature of our universe. In this talk, I will summarize what we do understand about the fundamental building blocks of our universe, and why their interactions with the Higgs field are so important.

About the speaker:
Professor Dr. James Rabchuk is a physics professor from the Department of Physics, Western Illinois University.

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Illuminating the Properties of Dark Matter: X-ray and Phase Space Density Constraints

Speaker: Dr. Casey Watson
Date: Tuesday, November 19, 2013
Time: 4 pm
Room: 205 Currens Hall

Abstract
After reviewing the basics of sterile neutrino production and their interactions with Standard Model particles, I will provide an overview of X-ray constraints on the mass and mixing of this excellent dark matter particle candidate. I will then turn to more general phase space density arguments, and describe how they can be used constrain the mass of the dark matter particle in the context of Milky Way dwarf satellite galaxies. The data for the study on dwarf satellite galaxies was drawn from research conducted by Matt Walker, currently Assistant Professor at Carnegie Mellon University and a graduate in physics/philosophy at WIU (1999)

About the speaker:
Casey completed his PhD and a brief postdoctoral appointment at The Ohio State University in 2006, and joined the faculty at Millikin University as an Assistant Professor in the Department of Physics and Astronomy in the fall of the same year. He was promoted to Associate Professor in 2012. Casey enjoys working on many aspects of cosmology and astrophysics including the multi-wavelength (optical, IR, X-ray) evolution of galaxies, AGN and the Star Formation Rate, dark matter, dark energy, gravitational lensing, and stellar evolution. Most recently, he has focused exclusively on dark matter research, which has generated many student presentations at regional and national meetings, a publication with a Millikin student (Nick Polley; 2012), and two back-to-back invitations to deliver one hour lectures on his work in Paris, France (June, 2012; July 2013).

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Exploring the Mysteries of the Quark-Gluon Plasma and the Birth of the Universe

Speaker: Dr. John Hill
Date: Friday, November 15, 2013
Time: 4 pm
Room: 205 Currens Hall

Abstract
It is postulated that a microsecond after the birth of the universe in the “Big Bang” matter existed in a deconfined state of quarks and gluons called the quark-gluon plasma (QGP). A strongly coupled version of the QGP (sQGP) has been created at the Relativistic Heavy Ion Collider (RHIC) using collisions of 100 GeV/A Au nuclei. After an introduction to the concept of the QGP I will discuss how it is produced at RHIC and studied with the PHENIX detector. I will first concentrate on the evidence that it is actually the QGP followed by data showing it to flow like a liquid rather than a hot gas. Then I will present measurements of the temperature of the plasma. In addition I will compare PHENIX results with recent data from the heavy ion program at the LHC. If time is left I will discuss future projects planned by our group at Iowa State for PHENIX.

About the speaker:
Prof. John Hill received his PhD in nuclear physics from Purdue University. After a postdoc at the University of Michigan and an assistant professorship at Texas A&M University he moved to the Physics Department of Iowa State University. He is a Fellow of the American Physical Society and is the P.I. for the Experimental Nuclear Physics Program at Iowa State that is supported by the U.S. Department of Energy. His early work was in low energy nuclear physics on the decay of neutron-rich nuclei. His program evolved to the present that involves the study of the interaction of relativistic heavy ions to produce hot dense nuclear matter.

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Superconductivity and Magnetism:enemies turned allies

Speaker:Dr. Ashwani Kumar
Date: October 11, 2013,
Time: 4 pm
Room: 205 Currens Hall

Transition to superconducting state in thin film of amorphous lead (a-Pb)

Dr. Kumar

Abstract
When some materials are cooled below a certain temperature, called the critical temperature (TC), they completely lose their electrical resistance and expel weak magnetic fields applied to them. These materials are called superconductors and this phenomenon is called superconductivity. Magnetic fields have long been known to suppress superconductivity through two main effects: first, by raising the kinetic energy of the superconducting electrons (i.e., orbital de-pairing) and second, by aligning the electron spins (i.e., spin paramagnetic effect). However, we have observed pronounced enhancement in superconductivity upon application of a parallel magnetic field in two different two-dimensional (2D) superconducting systems: ultrathin homogeneously disordered amorphous Pb films and the 2D electron gas at the interface of LaAlO3 and SrTiO3 [Nature Phys. v7, pp.895 (2011)]. The focus of this presentation will be on amorphous lead (a-Pb) films where the TC enhancement as large as 13.5% in as high as 8T parallel field has been observed. Interestingly and contrary to recent predictions, the presence of paramagnetic impurities in the films diminished the field enhancement of superconductivity.

About the speaker:
Dr. Ashwani Kumar presently works as an assistant professor in the Department of Physics, Monmouth College. He received his M.Sc (with Honors) from Panjab University (India) in 1999 and his Ph.D. from Florida State University in 2009. His research interest is in quantum phase transitions (QPT) and superconductivity in geometrically constrained systems.

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