Events at Physics
Events on Friday, April 20th, 2012
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:00 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Le Zhang (email@example.com)
- Host: Peter Timbie
- Special Physics History Lecture
- Matter waves in Paris: the de Broglie you don't know
- Time: 12:05 pm
- Place: 2241 Chamberlin Hall
- Speaker: Bruce R. Wheaton, Technology & Physical Science History Associates, Berkeley, CA
- Abstract: IT IS WELL KNOWN that Louis de Broglie received the 1929 Nobel Prize for his audacious proposal six years earlier that atoms possess a wave component. Less well known is his motivation and justification for this concept. It occurred within the context of the first industrial electronics research laboratory in France, where numerous aspirants learned new techniques to be applied in French industries for process management, product sampling, lubrication studies, and a panoply of new control mechanisms. This Laboratoire francaise des rayons x was created after WWI in the fashionable 8th arrondissement of Paris by Louis' elder brother Maurice. Of distinctly noble status and possessing immense wealth, Maurice did this strictly as amateur and utilized his noblesse to form the necessary partnerships with recalcitrant French industrialists. But in the process, which led among many things to the first electron microscope intended for study of industrial procedure, Maurice and his student Alexandre Dauvillier rediscovered an enigma in the behavior of x-rays. When x-rays strike matter they release electrons whose velocities can easily be measured. The problem they found was that these velocities were virtually equal to the velocities of the cathode beam that produced the x-rays. As W. H. Bragg put it "it is as if a log falls in the sea, and the waves that result concentrate themselves on another log a thousand miles away sufficient to propel that log up into the air." To answer this conundrum, "little Louis" appealed to Einstein's theory of relativity and came up with his pilot wave hypothesis of matter in 1923. That it happened in the physics backwater of France owes much to the pragmatic atmosphere in his brother's lab where he could find nobody to test it because they were too busy trying to invent television.
- Host: Sam Hokin
- Physics Department Colloquium
- The Neutrino at Eighty - A remarkable journey and a feisty future
- Time: 3:30 pm
- Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
- Speaker: John Wilkerson, University of North Carolina
- Abstract: Eighty years ago the neutrino was postulated by Pauli to explain the puzzling observations of nuclear beta decay. At the time many thought neutrinos would never be observed, but a quarter century later Reines and Cowan successfully detected their elusive signal. Following their discovery, a broad set of experiments were undertaken that culminated in the past decade with a remarkable transformation of our understanding of neutrino properties and the revelation that the standard model of particle interactions is incomplete. We have found that neutrinos morph from one species to another as they journey through matter and space. And based on these observations we know that neutrinos are not massless particles, but have tiny masses, being at least 250,000 times lighter than electrons. Even with such diminutive masses, neutrinos influence the largest scales of the cosmos. Today much remains unknown about neutrino properties. What do neutrinos "weigh?" -- Why are their masses so light compared to other particles? Are neutrinos and anti-neutrinos indistinguishable from one another (Majorana particles), indicating lepton number violation? A number of next-generation experiments aim to address these questions, but the reticent nature of neutrinos presents daunting challenges for experimentalists. The talk will focus on how nuclear beta decay and double beta decay serve as sensitive probes of neutrino properties.
- Host: Heeger