Amelia Henkel, graduating Double Major in Physics and Human Rights, and President of the Undergraduate Women in Physics Club, speaks on the CLAS website about her passion for physics and human rights, and how she mastered challenges in her remarkably interdisciplinary curriculum. “We really need to interact with other disciplines,” says Amelia, “because that’s when physics has the opportunity to make a real impact on the rest of the world.” Her broad research interests range from A to W: from Astronomy to Women’s, Gender, and Sexuality Studies. “Respecting and promoting human rights is a prerequisite to realizing our full potential as human beings,” says Amelia. Physics as a discipline has made progress to become more inclusive, but many groups remain minorities including women. In daily college life in physics departments female students still face “microaggressions and discriminatory practices” which are often unintended and unconscious but nonetheless damaging and frustrating. As the President of the Undergraduate Women in Physics Club, Amelia helped to organize “events that promote community cohesion and inform the students about the nature of some of the barriers that exist in physics and in STEM, while talking about how we can overcome them.” The recent department-wide event Women in Physics Colloquium organized by Amelia was thought provoking and well-received. The percentage of women earning a Bacheleor’s Degree in Physics from UConn, though slowly increasing and compatible with the national average of about 20% published by APS, is far away from where we wish to be. But the efforts of students like Amelia contribute to improving the situation. Many thanks to Amelia whose commitment helps to make our department better.
Read more about Amelia on the CLAS website. A short summary of her story is in UConn Today.
Step into a fall 2018 class section of PHYS 1602: Fundamentals of Physics II, and you’ll find a scene that’s far from the large introductory science lectures common on most college campuses.
Anna Regan ’21 (CLAS) utilizes a whiteboard to try out
solutions during her group’s problem-solving tutorial.
(Bri Diaz/UConn Photo)
To start, the class of 30 students sits at several triangular workspaces, which today are covered with wires, coils, magnets, and power supplies that the students are using to demonstrate electromagnetic induction. At the start of class, the instructors provided a short lecture before the students set off on their own problem-solving tutorials.
Now, the instructors move from group to group, stopping to answer questions, as students shuttle back and forth to the whiteboards that line the classroom walls.
It’s a scene that’s about to become common in UConn physics courses, thanks to renovations to the Edward V. Gant Science Complex, according to Barrett Wells, professor and head of the Department of Physics.
“We’re rebuilding our classes from the ground up,” he says. “It’s the basis for what we’re going to spread across most of our introductory courses.”
The curricular redesign, says Wells, will replace the typical large-lecture format with smaller classes, utilizing five new studio-style physics learning laboratories to be added to the Gant Science Complex in 2019. These changes will promote active learning, collaborative problem solving, and faculty-student interaction, he says.
“This is a trend we’re seeing in our discipline,” Wells says. “Restricting class size to promote students actively participating during class has been documented to help them achieve and learn more across the board.”
Lecture Meets Lab
Traditional science courses, including those in physics, typically consist of three weekly lectures that hold 100 to 200 students, with once-per-week lab sections where students practice the concepts they learn in lecture.
But this setup poses challenges for professors and teaching assistants to cover the material at the same rate, often causing lecture and lab sections to fall out of synchrony, says Diego Valente, assistant professor in residence of physics and instructor of Fundamentals of Physics II.
In addition, many physics concepts are difficult to teach within the logistical setup of a lecture, and the instructors may have a difficult time knowing whether students comprehend the material, says Valente.
To combat these issues, the Department of Physics piloted redesigned versions of Fundamentals of Physics I and II, the introductory sequence for physics majors, in the spring and fall of 2018, respectively.
Course instructor and Ph.D. student Lukasz Kuna ’14
(CLAS), ’17 MS assists a group that includes Ian Segal-
Gould ’21 (CLAS), far right. (Bri Diaz/UConn Photo)
The new courses, which will use the physics learning laboratories, merge the lecture and lab sections into three 2-hour class periods per week that hold up to 54 students. Classes are led by the same professor and graduate students.
“[The studio classrooms] allow instructors to interact with students more frequently and discuss concepts with them in depth,” says Valente. “Previously, hands-on group work was limited to lab courses. Now, every single day in class there’s some kind of group activity where students solve problems.”
Lukasz Kuna ’14 (CLAS), ’17 MS, a physics Ph.D. student and teaching assistant for Fundamentals of Physics II, agrees.
“We can present a topic that’s somewhat difficult to understand, and then attack it from all angles,” he says. “It certainly should be the way physics is taught, because it prepares you for more difficult problem solving.”
A Learning Community
The studio learning model also increases the amount of time students spend working collaboratively, says Valente.
Ian Segal-Gould ’21 (CLAS), a physics and mathematics major enrolled in Fundamentals of Physics II, says that the class fosters the collaborative problem-solving that is expected of professional physicists.
“In lecture-based courses, people look at the professor,” he says. “They’re not talking to each other, they’re not solving the problem—they’re looking at somebody else solve the problem. In the real world, physicists work together, so I think the interactive component to this course is on the right track.”
Physics major Megan Sturm ’21 (CLAS) says that working in small groups helps build camaraderie and exposes her to new ideas.
“I know at least half of the class, and it’s way easier to learn that way,” she says. “Someone else will ask a question or say something during the lab that I wouldn’t have even thought about.”
Sturm also says that she enjoys the frequency of interaction with the instructors, noting that Valente circulates through the class, asks students specific questions, and engages in hands-on work with them.
Physics major Megan Sturm ’21 (CLAS) says that working
in small groups helps build camaraderie and exposes her to
new ideas. (Bri Diaz/UConn Photo)
“He’s way more approachable, so when I’m having trouble with things, I don’t have a problem going to office hours,” she says.
Kuna, who has taught for three years in the Department, says that the faculty-student interaction helps him better gauge how students are learning the material.
“Traditionally, if you’re teaching in a large lecture, you somewhat lose the students when they go to lab,” he says. “Here, you get to see where your class stands.”
With a target completion date for phase one renovations set for fall of 2019, the Department is gearing up to redesign other introductory courses, including Physics for Engineers and Physics with Calculus, a general education sequence taken by many pre-med students.
“This is important because we offer courses to majors across the University, and we’re teaching more students each year,” Wells says.
“Our goal is to develop not just comprehension of physical concepts, but also transferable skills–things like communication through group work and computer programming, which students can use in their professional lives,” adds Valente.
He says that these investments in teaching and infrastructure give UConn an advantage in addressing instructional issues common at institutions across the United States.
“This is a really large-scale venture we are doing, something a lot of comparable institutions aren’t able to do,” Valente says. “It shows that UConn is making a big commitment to physics education.”
By: Bri Diaz, College of Liberal Arts and Sciences
This article was originally published in the UConn CLAS Newswletter, November 28 issue
Connor Occhialini – Finalist 2018 LeRoy Apker Undergraduate Achievements Award
by Jason Hancock
One of our star undergraduates, Connor Occhialini, has won national recognition as a finalist in the 2018 LeRoy Apker Undergraduate Achievements Award competition for his research in the UConn Physics department. The honor and distinction is awarded not only for the excellent research achievements of the student, but also for the department that provides the supportive environment and opportunities for students to excel in research. Connor is in fact the second Apker finalist in three years’ time (Michael Cantara was a 2016 Apker finalist). Connor graduated with a BS in Physics from UConn in May 2018 and stayed on as a researcher during summer 2018. During his time here, he developed theoretical models, helped build a pump-probe laser system, and carried out advanced analysis of X-ray scattering data which revealed a new context for an unusual phenomenon – negative thermal expansion. With these outstanding achievements, the department presented Connor’s nomination to the 2018 LeRoy Apker award committee of the American Physical Society. Connor was selected to be one of only four Apker finalists from all PhD-granting institutions in the US. With this prestigious honor, the department receives a plaque and a $1000 award to support undergraduate research. Connor is now a PhD student in the Physics Department at MIT.
Physics major Brenna Robertson has been selected as the recipient of the 2018 Mark Miller Undergraduate Research Award. Brenna’s proposal, which focuses on modeling supermassive black hole spin using spectral emission diagrams, was selected from among a strong pool of applicants. Brenna Robertson is working with Prof. Jonathan Trump.
The Mark Miller Award is a stipend to allow a student to remain in Storrs over the Summer session to work on a research project with a faculty member of the Physics Department. It was created through a donation made by Mark E. Miller, a UConn physics major alum.
Sam was awarded an Undergraduate Research Fellowship to perform research at UConn this summer working with Prof. Kate Whitaker. The title of his research project is “Examining High Redshift Rotation Curve Outside the Local Universe”.
Josh was awarded the Undergraduate Scholarship by the NASA Connecticut Space Grant Consortium, and will be performing astrophysics research this summer at UConn working with Prof. Cara Battersby.
The U.S. Centers for Disease Control lists radon as a primary cause of lung cancer, second only to smoking. The Environmental Protection Agency estimates that 20,000 deaths each year from lung cancer in the U.S. are the result of exposure to radon in the living environment. It is believed that as many as 1 in 15 homes in the continental United States have radon levels that require some form of mitigation. In spite of this, very few homes are equipped with continuous radon monitoring devices and most radiation monitoring facilities only provide feedback on time scales of weeks or even months.
The technology used in standard residential radon monitoring has not changed significantly over the past 50 years. On the other hand, development of fast detectors for particle physics experiments at large international laboratories such as the Large Hadron Collider over the past two decades has opened up new technologies for radiation detection that may result in a significant improvement in the efficiency and response time for radon detection.
UConn undergraduate Mira Varma, pictured above, is holding a part of what she hopes to assemble into a hand-held radon detector capable of detecting changes in radon concentration on the time scale of an hour, close to the time scale of the natural variation in a residential environment, rather than days or weeks. Mira is carrying out this development under the direction of UConn Physics Prof. Richard Jones.
Whoever said rules were made to be broken wasn’t a physicist. When something doesn’t act the way you think it should, either the rules are wrong, or there’s new physics to be discovered. Which is exactly what UConn’s Connor Occhialini ’18 (CLAS), an honors student majoring in physics and math, found when he began researching scandium fluoride.
Scandium fluoride is a transparent crystal with a cubic shape, a byproduct of mining. It’s not used commercially and it wouldn’t be particularly interesting to anyone except for one odd thing: it shrinks as it warms.
Most materials swell as they heat up. Really simple materials like hydrogen gas swell because the heat makes their atoms zoom around faster, bumping into each other more, so the same number of hydrogen atoms need more space. More complicated materials also swell, which is why your wooden front door tends to stick in the summertime. But solids like wood can’t swell as much as a gas because their atoms are tightly linked together into long, interlocked molecules, so they just jiggle around, swelling the door a little bit.
Scandium fluoride must be doing something else, reasoned Occhialini. His advisor for his honors physics project, Jason Hancock, had been working with scandium fluoride, and asked Occhialini to study a model of the crystal’s dynamics. Scandium fluoride has a pretty simple structure: it’s a solid crystal, with each scandium atom surrounded by six fluorines to make stacks of octahedra (eight-sided diamonds). The researchers hoped the simple structure might be easy to understand. Understanding scandium fluoride’s strange ‘negative thermal expansion’, as physicists call the heat-related shrinkage, might yield more general insight into other, more complex materials that do the same thing.
Occhialini’s first step was to simplify the problem. So instead of a three-dimensional crystal, he decided to think about it as a two-dimensional sheet that looks like this:
Each black diamond represents a molecule of scandium fluoride. The scandium atoms (blue dots) are at the center of each diamond, and a fluorine atom is at each corner.
Most of the time, bonds between atoms are flexible. So in a normal crystalline solid – calcium fluoride, for example – the fluorines and calcium atoms would all be able to wiggle around independently when the material warmed up. As they wiggled, they’d take up a little more space, and the solid would swell. Normal solid behavior.
But Occhialini wondered if maybe that wasn’t what was happening in scandium fluoride. Maybe in this model, he should assume the bonds connecting each fluorine to its scandium were stiff? So stiff the fluorine-scandium bonds don’t move at all, so the diamonds are like solid blocks. The only places the structure would be able to flex when it warmed up would be at the fluorine atoms, which would act like tiny little joints. As the crystal heated up, the little scandium fluoride blocks would tilt around the fluorines at the corners. That’s what you see happening in the picture. You’ll notice that when the diamonds tilt, the whole structure gets smaller. It actually tightens up. The blue outline shows the structure at its coldest, perfectly ordered state, with no molecular motion. When the diamonds tilt, they take up a smaller total volume than the blue outline delineates. This is negative thermal expansion.
Occhialini figured out that you can describe this shrinkage mathematically, using just the angle of the molecules’ tilt. He called the angle Θ (theta). When the scandium fluoride blocks tilt by an angle Θ, the distance between the center of each block shortens by a factor of cosine Θ, and the crystal’s total volume shrinks.
To calculate that shrinkage (or, in a normal material, expansion) in detail, Occhialini added a third term to the classic equation that describes the energy of a vibrating crystal. The first two terms in the standard equation describe the potential energy a crystal has from the bending at each molecular junction, plus the kinetic energy of rotation of each molecule. Occhialini’s equation also describes the translational kinetic energy of the molecules–not just from rotating around, but also moving toward and away from their original positions as they rotate. The further they are from the center of mass of the crystal, the more they move. Look back at Figure 1 and notice the dot in the middle; that’s the center of mass. The diamonds in the middle barely move in relation to it, while the diamonds at the edges move a lot. Now imagine how much of a difference there would be if the crystal had millions of molecules instead of just 25. And now you understand how important that third term could be to the energy of the crystal.
Now, molecules being molecules, they don’t just shrink and stay there. They’re moving constantly, and the warmer they get, the more they move. Part of Occhialini’s insight is that, on average, the molecular structure gets bendier the warmer it gets. So the molecules tilt more and spend more time at bigger values of Θ, closer to 45 degrees. After Occhialini thought it over for a while together with Hancock and physics Ph.D. students Sahan Handunkanda and Erin Curry, they realized there was a geometric shape that had the same mathematical description. It’s Archimedes’ spiral pendulum, and it looks like this:
Each turning of the spiral is exactly the same distance from the last. That spacing – the distance between turns – is controlled by Θ. Imagine a line that stretches from the center of the sphere to a point on the spiral. The angle between that line and the pole of the sphere is Θ. You see the little ball traveling along the spiral? That’s the end of the imaginary line. As Θ gets bigger, the ball moves towards the equator.Imagine that the ball represents the instantaneous state of the scandium fluoride crystal – the physicists calculated the statistical average of what every molecule in the crystal is doing. You’ll notice the ball spends more time near the equator of the spiral sphere, that is, it tends to hang out where Θ is large. If the temperature of the crystal drops and the molecules wiggle less, Θ gets smaller, the more time the ball spends near the pole of the sphere and the less the crystal shrinks.
So not only can a really weird phenomenon of a crystal that shrinks as it warms be explained by just assuming the molecules are rigid, but it can be illustrated with a classical geometric shape!
Occhialini was just a freshman when Hancock introduced him to the scandium fluoride puzzle. He had to learn the math as he went, but after about two semesters of working on it he’d figured out the equation that described what was going on. Now in his senior year, he says his research experiences in Hancock’s lab have been integral to his experience as an undergraduate.
The equation works beautifully and explains certain aspects of Hancock’s experimental x-ray measurements as well.
“I learned a lot more doing research than any course could have given me,” Occhialini says.
And now you, dear reader, have learned a little bit, too.
Spring 2017 the UConn chapter of the Sigma Pi Sigma Honor Society inducted 11 new members: Filip Bergabo, Vincent Flynn, Kevin Grassie, Daniel Kovner, Jack Lichtman, Paul Molinaro, Connor Occhialini, Brian Roy, Andrew Sampino, Theodore Sauyet, and Hope Whitelock. The academic scholarship of this group is truly outstanding, and probably unprecedented in the chapter’s history. Congratulations to all! In addition Bergabo and Whitelock are both doing REU’s this summer, Occhialini and Flynn are double Physics and Math majors, and both Roy and Sauyet were the 2015 recipients of the department’s Mark Miller award for undergraduate research while Vincent Flynn is the 2016 recipient of the department’s Mark Miller award for undergraduate research. The induction ceremony and banquet again took place in the Morosko Student Lounge of the Pharmacy Building. Barry Wells, the new SPS club advisor, masterfully mastered the ceremonies. Micki Bellamy (newly appointed Undergrad Physics Major Advisor!) worked tirelessly behind the scenes to make the days’
Jason Hancock, Assistant Professor in Physics, with graduate students, Erin Curry and Sahan Handunkanda, have been investigating a substance that shrinks when it warms.
Most materials swell when they warm, and shrink when they cool. But UConn physicist Jason Hancock has been investigating a substance that responds in reverse: it shrinks when it warms.
Although thermal expansion, and the cracking and warping that often result, are an everyday occurrence – in buildings, bridges, electronics, and almost anything else exposed to wide temperature swings – physicists have trouble explaining why solids behave that way.
Research by Hancock and his colleagues into scandium trifluoride, a material that has negative thermal expansion, recently published in Physical Review B, may lead to a better understanding of why materials change volume with temperature at all, with potential applications such as more durable electronics. For the complete article in UConn Today that explains their findings, see “Caution: Shrinks When Warm” .