Research News
Upgrade to the Advanced Lab (PHY 243): Positon Tomography Teaching Laboratory
062508: By far, the course that our undergraduates like the most is the Advanced Lab (PHY 243), which they take in the fall of senior year. This course is a centerpiece of the curriculum leading to a BS in Physics, enabling students to perform sophisticated experiments, where they apply everything they've learned.
Thanks largely to Physics alumnus Dr. Chris Lirakis, a board member of the Donaldson Trust, the Department is adding an interdisciplinary experiment to the Advanced Lab in the emerging frontier of bio-medical physics. Because Dr. Lirakis enjoyed the Advanced Lab during his undergraduate years at the University of Rochester, he has enabled the Department to purchase a high-resolution germanium detector for use in the study of positron tomography. Future upgrades are also in the works.
The Advanced Lab has been heavily focused on optics experiments for years, having been run by quantum optics specialists Chair and Professor Nicholas Bigelow and Assistant Professor John Howell. Professor Frank Wolfs, who is in charge of our undergraduate program, has always wanted to give the Advanced Lab a medical twist because, as he says, "a lot of physics students want to do graduate work in medical applications. This is a burgeoning field." After talking with Dr. Lirakis during Meliora Weekend, Professor Wolfs devised a new experiment, one that focuses on nuclear radiation. (lhg)
Twenty Students Present Results at 2008 Rochester Symposium for Undergraduate Physics Students (RSPS)
040508: April 4, 2008 marked the day of the twenty-seventh Annual Rochester Symposium for Undergraduate Physics Students (RSPS), where twenty Physics, Astronomy, and Optics majors presented their research findings. The northeast regional RSPS conference is typically held each year during the Spring semester. This year's participants represented the University of Rochester, Houghton College, Rochester Institute of Technology, Colgate College, West Point Military Academy, Binghamton University, Siena College, and SUNY at Oswego.
Three University of Rochester undergraduates gave 15-minute presentations:
- Elizabeth Pollock, "Cosmic Ray Muon Imaging and Decay and Capture Process Detection," Advisor: Udo Schröder
- Zhengqing Qi, "Hadronic Jets and Clustering Algorithms in CMS," Advisor: Professor Regina Demina
- Jordan Webster, "Analysis of Momentum Resolution in VLE Beamlines," Advisor: Professor Regina Demina
The first twenty-four RSPS conferences were hosted from 1981 through 2005 by the University of Rochester. In 2006, the twenty-fifth RSPS conference was held at Houghton College, New York. In 2007 and 2008, the conference returned to Rochester, and in 2009, it will be hosted by the United States Military Academy at West Point, New York. (lhg)
Slowing and Stopping Images
020608: Associate Professor John Howell reported in January of 2007 that his group showed how to slow images down to "300 times lower than the speed of light" and preserve the amplitude and phase of the image. He also stated that, "we're working on systems that slow images down to 10 million times lower than the speed of light." Howell and his Quantum Optics team of Ryan Camacho, Curtis Broadbent, and Irfan Ali Khan used a technique known as slow light. When close to a narrow resonance feature, the group velocity of the light can be very slow. His team used naturally-occurring resonances in a cesium vapor to precisely slow images and delayed them for about 10 nanoseconds while retaining their properties.
Now the group (above from left to right: Ryan Camacho, Praveen VudyaSetu, and John Howell) has stopped images in a hot gas of Rubidium atoms for about 10 microseconds and is working toward a goal of a millisecond (Phys. Rev. Lett. 100, 123903). The new process changes the light field into an atomic excitation, then reads out that atomic excitation and converts it back into a light field. This differs from the method used in January of 2007, in which the light propagated slowly through a dilute vapor. In the stored light technique, the light field is interconverted into a coherence in the atoms and then read out at a later time. Remarkably, the storage process remains robust even given the diffusion of the rapidly moving atoms. (lhg)
Nobelist Steven Weinberg Praises Professor Carl Hagen and Collaborators for Higgs Boson Theory
030308: In October 2007, Nobel Prize Winner Steven Weinberg reminded a new generation of physicists about the crucial contribution regarding the Higgs boson theory made by Professor Carl Hagen of the University of Rochester and his collaborators. Weinberg's comments were part of his invited presentation at a conference celebrating the fiftieth anniversary of John Bardeen, Leon Cooper, and J. Robert Schrieffer's (BCS) theory of superconductivity.
The method suggested by Professor Hagen and others gives mass to vector bosons and is an essential ingredient in the unified electroweak theory for which Sheldon Lee Glashow, Abdus Salam, and Weinberg shared the 1979 Nobel Prize in Physics. In their acceptance speeches, they all gave equal prominence to the contributions of three independent teams who had predicted the existence of the Higgs boson, as it is now commonly called.
Three independently formulated papers describing the theoretical mechanism appeared in Volume 13 of Physical Review Letters in 1964. They were by Gerald Guralnik, Carl Hagen, and Tom Kibble; by Peter Higgs; and by Francois Englert and Robert Brout. All three papers were written from different perspectives, and each made a distinct contribution. (lhg)
Building Super-Amplifiers in Nano-Electric Systems using Strange Weak Values
020508: In a recent Physical Review Letters (PRL 100, 026804) article, Assistant Professor Andrew Jordan and third-year PhD student Nathan Williams describe how to implement one of the most bizarre predictions in quantum mechanics: a strange weak value in a nano-electric system. For a quantum system, their proposed method could provide an electrical current that exceeds the current supplied by the analogous classical system by factors of hundreds or thousands; that is, their device could boost a nano-amp to one amp or even to ten amps. This new method could also be used to determine whether an experimental system is a quantum mechanical device. (lhg)
Finally, the 'Planet' in Planetary Nebulae?
Astronomers at the University of Rochester, home to one of the world’s largest groups of planetary nebulae specialists, have announced that low-mass stars and possibly even super-Jupiter-sized planets may be responsible for creating some of the most breathtaking objects in the sky.
The news is ironic because the name "planetary" nebula has always been a misnomer. When these objects were discovered 300 years ago, astronomers couldn't tell what they were and named them for their resemblance to the planet Uranus. But as early as the mid-19th century, astronomers realized these objects are really great clouds of dust emitted by dying stars.
Now, Rochester researchers have found that planets or low-mass stars orbiting these aged stars may indeed be pivotal to the creation of the nebulae's fantastic appearance.
Embryonic Solar System Assembly Seen for the First Time
082907: Using NASA's Spitzer Space Telescope, a team of astronomers led by Professor Dan M. Watson of the University of Rochester has observed the onset of planetary-system formation, a process nobody has seen until now. The group's exciting first look at the creation of an embryonic solar system yields many new insights about the physics and chemistry of evolving astronomical objects.
Publishing their results in the August 30, 2007 issue of Nature, the researchers note that the Spitzer Space Telescope enabled them to see water, in the form of ice, "raining" from a cloud enveloping the infant star NGC 1333-IRAS 4B approximately 1,000 light years away from Earth. The ice is vaporizing as it lands supersonically on a dense, dusty disk surrounding the baby star, a long-sought phenomenon called a disk-accretion shock. In time, planets will form within the dusty disk. (lhg)
Assistant Professor Andrew Jordan Discovers How to Save Schrodinger's Cat
091707: The feature story of the May 14, 2007 issue of New Scientist features Assistant Professor Andrew Jordan's work on reversing quantum measurements, published with co-author Alexander Korotkov in Physical Review Letters 97, October 2006. Jordan defines experiments to physically undo a measurement of an unknown quantum state. In the case of Schrodinger's cat, this means that he has figured out how to monitor the state (dead or alive) of the classic "cat in a box," then undo any damage caused by the monitoring. (lhg)