Boston University Physics News Archive: 2008
Glasses do not flow, while superfluids flow without resistance. A phase of matter that is both glassy and superfluid sounds like an oxymoron.
In a recent paper, Professor Claudio Chamon and his collaborators have shown that interacting bosons can form a superglass at a very low temperature and high density. This phase of matter is the amorphous counterpart to supersolids, which may have been observed in He4 experiments. Superglassy phases may also appear in mixtures of cold atoms trapped by lasers in frustrated lattices.
This year’s Pumpkin Drop went off with a smash, as in previous years. Please take a look at the following documentation of the event:
- Photos of this year’s event
- YouTube video, created by Richard Laskey
- Article in the Boston Herald, with a video
You may also be interested in past pumpkin drop goodies:
Danièle and Jean-Marie Haboury, French friends of Professor Ken Lane, atop the Great Wall. Danièle and Jean-Marie were part of a group of 104 cyclists who, starting on March 16, biked 12,000 km from Paris to Beijing, arriving on August 3 for the opening of the Olympics. Read about it at parispekinavelo.com. To see more pictures and read the blogs from the trip, go to the Velo Club d’Annecy website.
BU’s Daily Free Press of September 16 ran a story on the LHC. Professors Steve Ahlen, Ken Lane and Jim Shank and graduate students Jeremy Love and Nigel Nation discuss the LHC’s particle physics potential, its capacity to search for dark matter, and what it means to society in general. The LHC is bound to discover the mechanism underlying electroweak symmetry breaking. Several scenarios for this phenomenon have a particle which will serve as the elusive dark matter, and these particles may be produced and detected at the LHC. Many indirect spin-offs have been spawned by high-energy research — the World Wide Web to name one outstanding example — and the LHC era is likely to see more such boons to society. But one thing the LHC will not do, they stress, is produce a mini-black hole that grow to eat Geneva, Switzerland and the rest of the world.
The article may be read at the Free Press website.
After over 15 years of planning and construction, the first proton beam circulated on September 10 in the Large Hadron Collider at the CERN laboratory in Geneva, Switzerland. The LHC is the highest-energy particle collider in the world with a beam energy of up to 7 TeV and allow physicists to study the fundamental particles and forces that make up our universe at energy scales that have never before been accessible. Several faculty members in the BU Physics Department are involved with the LHC physics program and the ATLAS and CMS experiments: Steve Ahlen, Tulika Bose, John Butler, Ulrich Heintz, Jim Rohlf, Larry Sulak.
- BU Today article
- Boston Globe article, All eyes on collider as it comes to life, featuring Steve Ahlen.
- Live webcast of first beam
- CERN’s first beam page
- CERN’s first beam wiki page
- LHC fact sheets
- The ATLAS experiment
- The CMS experiment
- CERN press release
- BU ATLAS
- BU CMS
From John Butler: “The LHC started beam operations today and it took less than an hour, in careful steps, to get the beam completely around the entire machine for the first time. It went incredibly smoothly given the enormous complexity of the machine. The project director quipped that the beam was then traveling at 27 km/h. At a certain time, they stopped the beam in a block just upstream of the ATLAS detector and the debris from that was observed in ATLAS. Congratulations to all involved in getting to this moment.”
Says Michael Litos, BU Physics graduate student: The first beam injection of the LHC is scheduled to happen at 9:30 CET (that’s 3:30 EDT—yikes!) on September 10th. You can watch a live webcast of the event here: http://webcast.cern.ch/. Can you believe it is finally going to happen? Of course at this stage it’s more about ceremony and technical experimental procedure than anything else. Yet you must admit, it’s pretty exciting stuff, even if you’re not a particle physicist. Huzzah for the next giant leap forward in our understanding of the Universe (or lack thereof)!
Heavy fermions are materials which, at low temperatures, behave like metals with unusually high specific heat and magnetic susceptibility coefficients. These materials can be modeled as a lattice of magnetic impurities embedded in a metallic host. The magnetic interaction between the impurities and the conduction electrons gives rise to new collective entities, called quasi-particles, which behave as very massive electrons.
It is known that an applied magnetic field will eventually destroy the heavy fermion state, however the exact mechanism for this has been debated. In a recent paper published in Physical Review B, graduate student Silvia Viola Kusminskiy and collaborators have proposed a model for the evolution of the Fermi surface of heavy fermion materials in the presence of a magnetic field. Opposite to what is generally argued, they find that the Fermi surface fully polarizes well before the heavy fermion state is destroyed. This manifests itself as a crossover to a phase that they call the “locked state,” which can be confused with the collapse of the heavy fermion state.
Kusminskiy et al. claim that this model can explain the metamagnetic behavior of the heavy fermion compound YbRh2Si2 that has previously been attributed to the aforementioned collapse. Recent experimental results have provided strong evidence for this prediction. You can read more about those results here.
Weighing in at 6 lbs 11oz at a height of 18in, Phebe Kou Wonmein Wenzler came into the world on May 31st at 5:08am. Congratulations to father Josef-Stefan Wenzler and mother Enia!
In thermodynamics, it is generally believed that a system will behave adiabatically – that is, no heat will be produced – if the parameters of the system are changed sufficiently slowly. This is often justified using the adiabatic theorem of quantum mechanics, which states that the transitions between different energy levels in a quantum system are suppressed if the system changes sufficiently slowly. Though these two ideas have long been connected, their exact relationship has remained elusive.
In a recent paper published in Nature Physics, Professor Anatoli Polkovnikov and his colleague have elucidated this relationship. They have identified three response regimes for slowly changing thermodynamic systems, and as a result, have shown that adiabaticity can break down for low-dimensional, gapless systems.
Women in Physics is proving the power of the personal narrative. Through a series of biographical seminars held this spring, WIP has made good on its promise to showcase the accomplishments of female scientists and educate the physics community on relevant issues. The talks are by women about women – yet have attracted and engaged both men and women. And in an environment where only 8 percent of faculty and 13 percent of graduate students are female, that means WIP has turned up the volume on a voice that has been relatively quiet.
Read the full story here.
As a delectable means to celebrate the end of the semester, students in Professor So-Young Pi’s Electromagnetic Field and Waves course brought in a special-edition cake, adorned with Maxwell’s Equations.
The creation, designed by Rosie’s Bakery, was filled with strawberries and cream. Professor Pi said she found it delicious.
What do air particles and voters have in common? According to Professor Sid Redner, they’re a lot more alike than you’d think.
As a statistical physicist, Redner applies the same physical principles used to study interacting particles to social situations, and in turn hopes to model large-scale social phenomena, such as voting behavior. “The human world provides such a rich laboratory that I can see statistical physics almost everywhere that I look.”
You can read more about Professor Redner’s research in his recent interview with physicsworld.com.
The last big piece of the ATLAS experiment at the Large Hadron Collider near Geneva, Switzerland was recently installed. Most of the detectors on the “A Side Small Wheel” were built by the Boston Muon Consortium under the direction of BU personnel. The BU contingent of ATLAS includes Steve Ahlen, John Butler, Rob Harrington, Eric Hazen, Ulrich Heintz, Marta Lewandowska, Jeremy Love, Nigel Nation, Jim Shank, Scott Whitaker, Saul Youssef, and Zhen Yan. See this Boston.com article for more.
Professor Richard Averitt has received a DARPA Young Faculty Award for his proposal “Metamaterial Enhanced MEMS for Terahertz Technology”. The Young Faculty Award program is designed to seek out ideas from non-tenured faculty with an emphasis on ideas that are innovative, speculative, and high-risk. DARPA’s Microsystems Technology Office sponsors the program. Read more about this award here.
“The United States is losing its competitive edge in science and engineering, one bored kid at a time.”
A recent article in BU Today describes this dilemma, and the ways in which several BU professors are trying to change this. They are developing hands-on programs that will help elementary school teachers more effectively approach math and science in the classroom.
In PY103, “Cinema Physica,” Hollywood is a teaching tool. Professor Andy Cohen points to action films to demonstrate the possibilities of physics, while bringing the excitement of science to students outside the field.
“When you do an experiment, you don’t know what the answer is going to be,” he says. “And because we don’t know whether the movies actually obey the laws of physics, they are our experiments. They are our laboratories.”
To find out more, and catch a video that takes you inside the classroom, click here.
GIMS awarded travel grants of up to $800 each to students as the first author of contributed papers in sessions sponsored by GIMS at the March Meeting. Applicants were chosen on the basis of the quality of their work as evidenced by the abstract of the paper, a letter of support from their thesis advisor and the travel distances.
BU’s Scientific Instrument Facility (SIF), a 10,500-square-foot shop in the basement of the Physics Research Building, can build it all.
The Machine Shop opened its doors to the BU community in 1987, using its state-of-the-art equipment to fill a wide variety of requests. Its small staff develops intricate machinery for Physics, the School of Management and beyond. One example? A soap canister that plays music every time the dispenser is pumped.
To find out more about SIF, check out this article from BU Today.
Professor Michael El-Batanouny has been selected as a 2008-2009 Jefferson Science Fellow at the U.S. State Department.
This select fellowship program was established in 2003 as an initiative of the Science and Technology Adviser to the Secretary of State to expand on scientific expertise within the Department.
Fellows work full-time for one year in the State Department or the U.S. Agency for International Development, after which they remain available to the Department as consultants as they return to their academic careers. The program is centered on the notion that “science and technology make fundamental contributions to the security, economic, health, and cultural foundations of modern societies, and are integral to the development and implementation of foreign policy.”
To learn more, click here.
Professor Sid Redner was recently named an Outstanding Referee of the American Physical Society. The APS award program is in its first year, aiming to applaud the efforts of a small number of their 42,000 referees annually.
The editors of the APS journals are honoring Redner and others whose “reports and advice have helped to advance and diffuse the knowledge of physics, while creating a resource that is invaluable to authors, researchers, students, and readers.”
At 10:00 AM Feb 25th 2008, Viviana Foster Rappoccio came into the world. Congratulations to father Salvatore Rappoccio, a former undergraduate student, and mother Roberta, one of our previous undergraduate coordinators!
His name is Oliver and he was born Friday, January 25th weighing 8 lbs 8 oz. Father Jon sends his best to everyone in the department!
We’re happy to announce that our son David was born on Monday, January 7th. Ariel and Davey are both doing well. Please enjoy the attached pictures.
Arthur and Ariel
For the past several years, the one-atom-thick carbon material known as graphene has intrigued physicists. Its size, strength and conductivity make it a possible semiconductor alternative to silicon in modern technology.
An important property of a semiconductor is its energy gap, which can turn electrical currents on and off when receiving external voltage. Were this gap “tuneable,” the resulting semiconductor could bring with it new electronic devices.
Professor Antonio Castro Neto, as part of an international team, has created the first semiconductor with “tuneability.” In other words, the energy gap between the valence and conduction bands of the semiconductor’s graphene bilayer can be altered with external voltage. This development has possible applications in a variety of fields including laser technology.
Physicsworld.com recently published an article on Castro Neto’s research. To read it, click here.
If you do not have an IOP account, you can view the article here.
Professor Gene Stanley reviewed “Random Processes in Physics and Finance” (M. Lax, W. Cai, M. Xu) in Physics Today:
“The term ‘econophysics’ was introduced just 14 years ago, but the tradition of physicists being fascinated by random processes in finance has a history much older than that. In fact, both Nicolaus Copernicus and Isaac Newton invested considerable intellectual energy in attempting to understand the economic problems of their day.”
To read the full review, click here.
Professor Kevin Smith has been named a 2007 fellow of the American Vacuum Society. The honor recognizes members who have made scientific and technical contributions to areas of interest to AVS.
The citation read: “For pioneering studies of the band structure of complex materials using angle-resolved photoemission spectroscopy and high resolution x-ray emission and absorption spectroscopies.”
To read more about AVS awards, click here.
Meenakshi Narain, an adjunct associate professor, was elected as an American Physical Society fellow in the division of particles and fields last week. Professor Narain was chosen for her work in the measurement of the properties of the top quark.
“We congratulate her,” said Dmitri Denisov, DZero co-spokesman. “We feel that this is also a success story for DZero, for the Tevatron and for Fermilab.”
About her work, Narain said, “It is nice to finish something I started a decade and a half ago, and to continue with that knowledge at the LHC.”
To read more about the honor, click here.
The BU Research Internship Program in Science and Engineering, co-founded by Professor Emeritus George Zimmerman, has a 30-year history of immersing high school students in the world of scientific research.
Featured in the BU Metropolitan College winter newsletter, the program enlists faculty mentors to help students explore their scientific interests and prepare for the rigor of college-level research.
“Our students find out that science is a relatively disorganized search for truth,” Zimmerman said. “Very often you don’t discover what you set out to discover.”
To read more about the program, including how a high school junior built a CAT-scanning robot out of Legos, click here.
The search for signatures of magnetic monopoles in the cosmos has been a subject of intense work within the Physics community. Claudio Castelnovo, a recent BU Physics graduate and now a postdoc at Oxford, has proposed an alternative strategy to finding magnetic monopoles
in nature: They can be realized not as elementary but rather as emergent particles, i.e., as manifestations of the correlations present in a strongly interacting many-body system.