Author: Richard Jones

Department, alumni celebrate career of Prof. Doug Hamilton

Friday afternoon on April 20, 2018 the UConn Physics Department held a colloquium in honor of Professor Douglas Hamilton on the occasion of his retirement from active service on the faculty. The colloquium was MC’ed by Prof. Jason Hancock, who surveyed the highlights of a career spanning four decades marked by notable accomplishments in research, teaching, and service. Several of Doug’s former students also presented tributes to their mentor, some in person, and some by video or written message, expressing their gratitude for what they learned from him, both by instruction and example. At the end of the hour, Doug presented some final comments, which were followed by a standing ovation in recognition of Doug’s many contributions to our field, our department, and the University. Doug, you will be missed!

-Richard Jones

Hands-on teaching of introductory physics gains momentum

Students in PHYS 1601Q, taught by Professor Jason Hancock, work during a lab that observes how an external mass can affect oscillation by producing torque. They use a device called an ioLab to record data, and use the data in a program called Mathematica for analysis. The lab was in the Edward V. Gant science complex on April 20, 2018. (Garrett Spahn/UConn Photo)

 

A recently renovated physics classroom in the Edward V. Gant Science Complex was built to pilot a new approach to physics education, integrating lecture with lab rather than the classical approach of separating these components.

Students and instructors apply concepts with hands-on activities throughout the lecture, practice new tools, and problem solve as a group. The space is equipped with whiteboards on every wall, and computers and projectors for each station. Though built for entry-level courses such as Physics 1601 and 1602, the end goal is to convert larger classes into this format as well, including entry-level engineering and biology classes, for a more interactive learning experience.

– Garrett Spahn ’18 (CLAS) & Elaina Hancock

In memoriam, George H. Rawitscher (1928-2018)

It is with great sorrow that we report the passing of our long-time colleague and friend, George Rawitscher on March 10, 2018, after a brief illness and just having passed his 90th birthday, which was celebrated with a cake at a meeting of the UConn Physics Department. George was born in 1928 in Germany, where his fa-ther was a distinguished Professor of Botany at The University of Freiburg. In 1934 his father, Felix Rawitscher who was Jewish, brought his family which in-cluded George’s mother, Charlotte Oberlander, his sister Erika, and George from Germany to Brazil to escape the Nazis. In Brazil, Felix established and chaired the Botany Department, which still bears his name, at the University of Sao Paulo.

George grew up in Sao Paulo, where he learned fluent Portuguese. From an early age he knew he wanted to be a physicist, and taught himself quantum mechanics from a book during high school. He graduated in physics and mathematics from the University of Sao Paulo in 1949, and he served as an Instructor at the Brazilian Center for Physical Research in Rio de Janiero for two years, receiving a Brazilian National Research Council Fellowship. While he was in the Center for Physical Research at Rio, he worked under Richard Feynman who was a visiting professor at the same institute. He told his grandson Nicholas that Feynman had made a big mark on his life, inspiring his approach to physics, and observing that he had the potential to become a “real” physicist, which he remained until the end of his life.

Following his time in Rio, George went to Stanford University as a graduate student in theoretical nuclear physics and mathematics. He received his Ph.D. in 1956, for a study of Fierz-Pauli spin 3/2 particles and the anomalous magnetic moment of the muon under Profs. Leonard Schiff and D.R. Yennie. His first paper had to do with the effect of the finite size of the nucleus on muon pair production by gamma rays.

While at Stanford, George met and later married Mary Adams, a fellow Stanford student, and they proudly raised two sons, Peter and Henry. Mary, a biochemist, died in 1980. In his later years, George was again happily married to Joyce Rawitscher in 2009, who passed away in 2016. Following his graduate work, George became an Instructor at the Physics Nuclear Structure Center (University of Rochester) for two years and then joined the Physics Department at Yale as Instructor, doing research in collaboration with Prof. Gregory Breit. He remained at Yale as Assistant Prof. of Physics until 1964. He joined the Physics Department at the University of Connecticut in Storrs as an Associate Professor and then became Professor of Physics from 1972. He retired in 2009 but remained at UConn as an emeritus Research Professor until days before his death, continuing to do active research in nuclear physics, computational physics and ultracold atomic collision physics until his final days.

Prof. Rawitscher received several prestigious academic honors including one of the early Research Fellowship awards from the Alexander von Humboldt Foundation (Germany) in 1964 and became a Fellow of the American Physical Society, nomi-nated by the Division of Nuclear Physics in 2016. During his tenure at the University of Connecticut, he took academic leaves at the Max Planck Institut fur Kernphysik in Heidelberg (1964-1966), the Laboratory for Nuclear Science at MIT (1972), as guest professor at the University of Surrey, England 1973, the University of Maryland (1987-1988) and served on the Board of Directors of Bates Users Theory Group at MIT (1982-1985) and the Executive Committee of the American Physical Society topical group on Few Body Systems and Multi-Particle Dynamics (1993-1995). He gave a number of invited presentations in nuclear theory at conferences, published approximately 88 refereed papers and numerous conference proceedings. His principal research interests involved scattering problems using non-local opti-cal models of nuclear processes, coupled-channel reaction mechanisms for nuclear break-up such as the (e,e’p) reaction, and virtual nuclear excitations. Recently he emphasized development of numerical methods such as Galerkin and spectral expansions for solving integral equations. He has applied some of these techniques to studies of ultracold atomic collisions as well as nuclear reactions. His most recent refereed papers (2015-2017) concerned “Revival of the Phase-Amplitude description of a Quantum-Mechanical wave function.”

Professor Rawitscher was an engaged and untiring participant both in his Department and in the general community up to the last moments of his life. He promoted public awareness and activism on ameliorating the effects of global climate change and he and his wife Joyce have been active in the peace movement. He was a member of the Storrs, CT Quaker Meeting. He was also active in community service in the Storrs area, for example serving on the Town of Mansfield Sustainability Committee. Recently he has been working on a nearly-finished book summarizing his lifelong expertise in numerical computational physics, under contract with Springer, with two younger colleagues from Brazil. George was a dedicated and effective undergraduate teacher and empathetic mentor to a large number of graduate students, colleagues and collaborators. George was a central member of the department for more than 50 years, and has earned a special place in our hearts forever. His inspiring presence and example will be very much missed at the University, amongst his family, friends and the community, and it was a great loss to see him go.

UConn Prof. Kate Whitaker interviewed by Gizmodo

Gizmodo has recently launched a new series of articles to explore how the best images in science were created and why.  In a recent article in this series by Ryan F. Mandelbaum entitled, “The Making of ‘Pillars of Creation,’ One of the Most Amazing Images of Our Universe”, the author presents a classic set of images taken with the Hubble Space Telescope showing a zoomed-in view of the Eagle Nebula. The article explains some of the details about the instrument that took these images, and how a color image is obtained by combining black-and-white photographs taken at a number of different wavelengths. In the article, UConn astronomer Prof. Kate Whitaker explains why an advanced space-based instrument like the HST is required to obtain awesome views like this of our cosmic neighborhood.

21st Annual Katzenstein Distinguished Lecture

Monday, March 26, 2018

The 21st Annual Katzenstein Distinguished Lecture was hosted by the UConn Physics Department, featuring Dr. Takaaki Kajita, 2015 Nobel Prize Winner from the University of Tokyo, speaking on “Oscillating Neutrinos.”  After the lecture,  a banquet with the speaker was held for members and guests of the department. We enjoyed welcoming alumni and visitors to the department for this special occasion, made possible by a generous gift from UConn Physics alumnus Henry Katzenstein and his family.

Video recording of the lecture

Katzenstein lecture 2018

Physics students boost interdisciplinary research in materials

Krishna (left) and Lukasz (right) posing in front of their EAM-2018 award winning posters.

By Amanda Olavarria

The Electronic and Advanced Materials Conference (EAM) is geared towards engineers, technologists, researchers and students with an interest in science, engineering and the applications of electroceramic materials. Several MSE students and faculty attended this year’s EAM Conference held in Orlando, FL.

MSE Associate Professor and Director for Undergraduate Studies, Serge Nakhmanson, co-organized a symposium at this event entitled “Mesoscale Phenomena in Ceramic Materials.” Four UConn students including Tulsi Patel, Krishna Chaitanya Pitike, Lukasz Kuna and Hope Whitlock showcased their research.

In addition to the oral presentations, two UConn students claimed 2nd and 3rd place in the American Ceramics Society (ACerS) Electronics Division “Best Student Poster Presentation” awards. Lukasz Kuna received 3rd place for his poster entitled, “Mesoscale Simulations of the Influence of Elastic Strains on the Optical Properties of Semiconducting Core-Shell Nanowires.” Krishna Chaitayna Pitike won 2nd place for his poster, “Shape and Size Dependent Phase Transformations and Field-induced Behavior in Ferroelectric Nanoparticles.”

In response to the latter award Serge Nakhmanson said, “This remarkable work involves contributions from five UConn students (including Physics undergraduate Hope Whitelock) and an exchange student from China visiting my group. It started as a team project in the “Phase Transformations in Solids” graduate class (MSE 5305). Since the original results appeared to be significant, we decided to continue this project beyond the end of the semester to generate a publication for a peer-review scientific journal. This is now being finalized for submission. It is relatively rare to see classroom projects successfully transition into publication quality research, but this one is being well received by the community.” Department Head Bryan Huey adds, “Devising a class project that can be guided through to a publication is a testament to Professor Nakhmanson’s commitment to teaching and the hard work he inspires with these bright students.”

EAM, jointly arranged by the Electronics Division and Basic Science Division of the ACerS, focuses on the properties and processing of ceramic and electroceramic materials and their applications in electronic, electro/mechanical, dielectric, magnetic, and optical components and devices and systems.

Categories: awards, conferences, news, research, students

Published: February 16, 2018

Prof. C. Trallero awarded multiple research grants

Anna Zarra Aldrich, Office of the Vice President for Research
(Photo: Trallero Lab/Kansas State Photo)

University of Connecticut physics professor Carlos Trallero has been granted $1.06 million from the Department of Defense, the U.S. Air Force and the Air Force Office of Scientific Research to study recollision physics at the nanoscale to help develop ultrafast electronics.

This research will enhance the knowledge base of electron recollision dynamics at the nanoscale, which can be used to develop ultrafast light-driven electronics. These applications may be made possible by cultivating an improved understanding of the interactions and knowledge of the time scales of light-induced electronic motion including collective plasmonic excitations.

Trallero and co-PIs from Kansas State University will study the response of individual gas-phase nanoparticles to intense femtosecond (10-15 seconds) laser fields using high-harmonics spectroscopy, momentum-resolved photoelectron imaging and corresponding theoretical modeling.

Earlier research on photoelectron emission from dielectric and metal nanoparticles has demonstrated that nanoparticles may be a promising system for exploiting the effects of laser-induced electron recollision due to the interplay between the laser field and the near-field of the particle.

By extending these studies to longer wavelengths (400 to 9000 nanometers) and complementing them with high-harmonic generation from nanoparticles and nanoparticle aggregates, Trallero and his team will help build a better knowledge base of electron recollision dynamics at the nanoscale.

“We predict that through this study, we will identify behaviors on the nanoscale that will differ significantly from those that have been studied at the atomic level,” said Trallero.

The UConn-led team will work on the possibilities of controlling the nanoparticle response, especially plasmonic excitations, by applying synthesized two-color fields. They will also explore harmonic generation from tailor-made nanoparticles as a potential source of intense, short-pulsed XUV light.

By generating harmonics from fractal aggregates and supper-lattices of nanoparticles, Trallero will gather information on the transition from localized molecule-like to de-localized solid-like electron-field interactions. The team also plans to study plasmonic excitations in laser pump, X-ray probe experiments using time-resolved soft X-ray scattering.

In collaboration with ultrafast physics faculty, Professors George Gibson and Nora Berrah, Trallero has started planning and building an “Ultrafast Center,” with ties to industry for research that includes an interdisciplinary group of faculty from the department of physics, the Institute of Materials Science,  and the Schools of Engineering and Pharmacy. These faculty are specialized in optics, atomic and molecular physics, condensed matter, material science and engineering.

Carlos Trallero, who received his PhD in physics from Stony Brook University in 2007, joined UConn in 2017. His research focuses on attosecond science, strong field molecular spectroscopy, cohere control, higher-order harmonic generation, non-Gaussian optics, strong field science at long wavelengths and ultrafast optics.

This research is funding under DOD project number FA9550-17-1-0369.

One Giant Leap in Mapping the Universe

An artist’s rendering of hot material falling into a supermassive black hole, creating what is called the accretion disk, shown in orange. Reverberation mapping measures the time it takes light to travel between two areas of the accretion disk. The ‘light echo’ enables direct measurement of the mass of the black hole. This reverberation mapping project is the first project to weigh many black holes at once. (Image by Nahks Tr’Ehnl, Penn State University)

 – Elaina Hancock – UConn Communications

Surveying millions of astronomical objects, such as supermassive black holes, is a huge and time-consuming undertaking. An international team of researchers, including UConn assistant professor and astronomer Jonathan Trump and graduate student Yasuman Homayouni, have been successful in improving and speeding up this complex task of surveying and mapping our skies, in a study published in the Astrophysical Journal.

“In one sentence, it’s a new, industrial-scale way to weigh large numbers of supermassive black holes,” says Trump.

The effort is part of the Sloan Digital Sky Survey, one of the most successful survey projects in the history of astronomy, which has produced the largest and most detailed three-dimensional maps of the Universe to date. Just like early map makers trying to better understand the planet we live on, modern mapping of galaxies, quasars, and supermassive black holes – the largest type of black hole, found in the center of almost all currently known massive galaxies – gives researchers insight into these phenomena and the Universe we live in. The Sloan Digital Sky Survey is creating as detailed a map as possible of a portion of our sky, and has already collected data on more than three million astronomical objects.

Trump and his colleagues are working toward this goal using a method called reverberation mapping on an especially large sample of distant galaxies with supermassive black holes. The technique measures the mass of the black holes by using light echoes of gas orbiting the black holes, far outside the ‘event horizon’ within which nothing can escape falling into the black hole. With this data, he says, black holes can be described very easily.

“Mass is fundamental,” Trump says. “Once you know the mass, you can calculate almost everything there is to know about a black hole.”

It is this ability to understand so much about black holes from knowing just their mass that makes them good mapping targets. Black holes are more than just rips in space and time, and more than vacuum cleaners sucking up everything that gets too close to their event horizons, Trump explains. There are tight connections between black holes and the galaxies they exist in, so knowing the mass of a black hole allows researchers to unlock more information about the galaxy itself. For example, as black hole mass increases, the galaxy’s mass also increases in lockstep. There is also evidence that black holes act as stabilizing forces within their galaxies, and if a black hole happens to be located close to a supernova, the black hole can act to disperse the heavy elements that are created only in these exploding stars throughout the galaxy.

But there is more to learn. “We know black holes are important and they matter for the rest of the Universe, but we still don’t know exactly why,” says Trump. “They are such strange beasts in our reality.”

Speeding up the Mapping Technique

One drawback of reverberation mapping is that it requires multiple observations, over extended periods of time. With so many astronomical objects to observe and only so much equipment capable of taking such detailed measurements, large-scale mapping of this kind has not previously been possible.

“This technique is hard to do,” says Trump. “You need a lot of very well calibrated observations.”

In addition to the sheer number of objects observed for this project, the light signals observed were at times very faint because their sources of emission are at such great distances.

However, this project’s sizable dataset has increased the sample of black holes with reliably known masses by two-thirds in the past year alone – by 44 quasars to be exact. These data are quickly building on decades of existing work that had around 60 well mapped, representing only the last few percent of the history of the Universe.

The reverberation mapping data have reached deeper, around six or seven billion light years away, looking at more distant black holes. And the future of the project will go even farther, Trump says, which will translate to going even farther back in the history of the Universe.

He draws an analogy to periods in a human life to explain the distances in space and time: “We published data on 44 well-characterized black holes at about the middle age of the Universe. We hope to get to 100 [black holes] at around a quarter of the Universe’s age, so equivalent to around its early adolescence or maybe even childhood. A lot of changes happen in adolescence and childhood for us, and the Universe went through a lot of changes at that age too.”

Read more in the Sloan Digital Sky Survey press release here.

This research was supported by funding from the National Science Foundation grant AST-1517113, and Trump’s research group has additional support from the National Aeronautics and Space Administration, NASA HST-GO-15260.

LQCD workshop to take place in Storrs

Muon g-2 Theory Initiative Hadronic Light-by-Light working group workshop

Workshop participants will discuss recent progress and plans to determine the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment, which is expected to contribute the largest uncertainty in the Standard Model prediction. The goal of the workshop is to estimate current and expected systematic errors from lattice QCD, dispersive methods, and models  and create a plan to address them in time for new experiments at Fermilab and J-PARC. For more information, please visit the workshop web site.

Starts 12 Mar 2018, 09:00
Ends 14 Mar 2018, 17:00
UConn Physics Department
Room P-121
2152 Hillside Road, Storrs, CT 06269-3046, USA

Ultracold group achieves new milestone in quantum control


 – Colin Poitras – UConn Communications

Scientists from three major research universities successfully manipulated the outcome of a chemical reaction and, in doing so, created a rare molecular ion.

Through a process known as “controlling chemistry,” the researchers bonded an oxygen atom to two different metal atoms, creating the barium-oxygen-calcium molecular ion or BaOCa The same process could lead to the creation of other exotic new materials and the design of novel chemical compounds, according to the team from the University of Connecticut, University of California-Los Angeles, and University of Missouri, whose work appeared in the Sept. 29 online issue of Science.

“It’s doing chemistry with the tools of physics,” says Robin Côté, UConn physics professor and associate dean for physical sciences who co-authored the study. Côté is a leading theorist in the field of ultracold molecular ion reactions.

“Usually in chemistry you can’t see molecules react,” says Côté. “You do experiments and you get a reaction with a range of products, which can be analyzed with mass spectrometry and other tools. What our team did allowed us to image ions directly to get a much clearer picture of what is happening within the chemical reaction itself. We were able to prepare a system in an ultracold environment that was very pristine and that allowed us to see exactly how the molecules and atoms were behaving.”

<a href="https://www.youtube.com/watch?v=2IkerjKjzFM"><em>Watch an animation of barium ions inside a Paul Trap</em></a><em>.</em>
Watch an animation of barium ions inside a Paul Trap.

Previous work had observed hypermetallic alkaline earth oxides consisting of an oxygen atom sandwiched between two identical alkaline earth atoms, such as barium or calcium.

But for the first time in this study, researchers observed compounds consisting of an oxygen atom bonded to two different metal atoms. Such compounds are believed to have unique properties resulting from the broken symmetry.

It’s nice to see that a phenomenon you envisioned at one time as too difficult to do, is indeed possible.— Robin Côté

The researchers used a host of equipment to accomplish the breakthrough – quantum chemistry computations, lasers, a hybrid ultracold atom-ion trap, and something called a “radially-coupled time-of-fight mass spectrometer.”

By trapping atoms and ions in an ultracold hybrid magneto-optical trap and then cooling them down to a temperature one one-thousandth degree above absolute zero, the scientists were able to observe a reaction between atoms and molecules that hadn’t been seen before.

See a real time image of crystal ions.

They used lasers to manipulate calcium atoms into a specific quantum state, which allowed the chemical reaction to proceed and the new molecules to form when they normally shouldn’t. To confirm their results, the researchers released the ions and molecules from their ultracold suspension, where they would then “fly” into the mass spectrometer to be analyzed and measured further.

The process could serve as a platform for gaining greater insight into chemical reaction dynamics. Armed with such knowledge, chemists and physicists could engineer specific chemical reactions and synthesize new products currently unavailable to us, such as more advanced chemical sensors, quantum computer processors, and medications with fewer side effects.

Joining Côté on the project were UConn research professor John Montgomery Jr., an expert in computational quantum chemistry, and postdoctoral researcher Ionel Simbotin. UCLA physics professor Eric Hudson, an expert in hybrid atom-ion trapping, served as the project’s principal investigator; and UCLA graduate students Prateek Puri (lead author) and Michael Mills, together with postdoctoral researcher Christian Schneider, performed the measurements. University of Missouri chemistry professor Arthur Suits rounded out the team.

Côté was the first to propose studying ultracold atom-ion systems in 2000, shortly after arriving at UConn. And, UConn physics professor emeritus Winthrop Smith, in 2001, was the first to propose using a hybrid ultracold ion-atom trap to conduct the observations in order to learn more about the fundamental processes of chemical reactions.

Experimental and theoretical physicists and chemists have been working in the field ever since. Lately, new advances in technology, such as the hybrid trap used in this study, are providing scientists the tools they need to progress.

To some extent, the study confirmed Côté’s and Smith’s proposal that hybrid atom-ion traps could be valuable tools for exploring the fundamental dynamics underlying chemical reactions.

“It’s nice to see that a phenomenon you envisioned at one time as too difficult to do, is indeed possible,” says Côté. “We did calculations showing this behavior should take place, and it is great to see that now confirmed in the lab.”

In the current study, the researchers spent more than 18 months trying to figure out what was driving the chemical reaction creating the new molecule. They analyzed experimental data, performed quantum chemistry calculations, and tested various theories in the lab. In many ways, it was like solving a mystery. The scientists knew the molecule could be formed because their UCLA peers had seen them in the hybrid ion trap. The challenge was trying to explain how it was happening.

The team ultimately determined the precise mechanisms that allowed the mixed hypermetallic earth oxide to form, which involved the amount of energy expended in the reaction and a certain spin of electrons.

“Most chemical reactions take place in the ground state, which is to say, a system’s lowest-energy state,” says Montgomery. “The use of quantum chemical calculations enabled us to understand that this particular reaction could only take place on the excited triplet state, which is a higher-energy state. This was then verified by experiments.”

That kind of precise knowledge of what exactly is occurring during a chemical reaction goes to the very core of controlling chemistry.

“When something reacts in chemistry, you can compute the outcome or products, but you can rarely control the process,” says Côté. “But if you are able to know exactly what is happening in that reaction, what components are rotating, what is spinning, what’s vibrating with this energy or that energy, and if you’re able to control those quantities, then it is feasible to design a reaction or a device to ensure a particular outcome most of the time.”

The research was funded by the National Science Foundation (PHY-1205311, PHY-1415560, and DGE-1650604) and Army Research Office (W911NF-15-1-0121, W911NF-14-1-0378, and W911NF-13-1-0213).

UConn is one of seven universities working in this area under a multimillion-dollar research grant awarded by the Department of Defense. The MURI award, which stands for Multidisciplinary University Research Initiative, also includes researchers from the physics departments at UCLA, Northwestern, and Temple, and from the chemistry departments at Georgia Tech, Emory, and Missouri.