Valerie Hanson ’10 and Lauren Vilardo '11 Take Helium for a Spin

Valerie Hanson '10 and Lauren Vilardo '11
Valerie Hanson '10 and Lauren Vilardo '11
Physicists are often forced to work through tedious preparations only to take quick measurements and arrive at small, sometimes inconsequential conclusions. Therefore, much of modern research consists of trying to find ways to increase efficiency without sacrificing quality results. Lauren Vilardo ’11 and Valerie Hanson ’10 are developing a faster, more accurate measurement of the absolute polarization of 3Helium (3He). This summer they're collaborating with Professor of Physics Gordon Jones and Associate Professor of Physics Brian Collett to do so. 

A quantum particle has a “spin” to it which gives it an intrinsic angular momentum, unlike the ordinary angular momentum you might experience as you ride your bike in a circle. The angular momentum of a neutron experiences a torque (a force that rotates something about an axis), and in the presence of a magnetic field, that torque will make the neutron spin like a spinning top on a table. Vilardo and Hanson will look at the strong relationship between the 3He neutron spin and the polarization of 3He that results from it. 

3He has two paired protons – one spins up and one spins down – and one unpaired neutron. Hanson and Vilardo are polarizing a neutron beam by sending it through a cell of these unpaired neutrons. The unpaired neutrons pair with the beam’s neutrons that spin in the opposite directions, thereby allowing only the neutrons with the same spin state to pass through. This is called a polarized beam. 

A process known as AFP (Adiabatic Fast Passage) flips the beam 180 degrees and allows the researchers to see how severe an effect scattering of the beam might have had. But this process could lead to a loss in polarization, so Vilardo’s job is to optimize AFP through an NMR (Nuclear Magnetic Resonance) scan. If she sees a decrease in amplitude of the NMR scan, that indicates a loss in polarization due to the flip. She and Hanson want the lowest possible loss, thus, the lowest possible change in amplitude. 

In addition to this work, Hanson is optimizing the EPR (Electron paramagnetic resonance) process, which is another way to calculate the polarization of 3He from its magnetic field. If she is successful, EPR measurements should occur almost instantaneously, thus increasing both quality and efficiency. 

Last summer, Hanson worked at the Oakridge National Lab in Tennessee, where Jones frequently does research. This year, she is continuing the research she began last summer, and intends to complete it for her senior thesis. This project was specifically designed to connect her research with her thesis goals. 

"What I like about the summer research is that I got to take it wherever I wanted,” she said. “The project was specialized to fit my interests." 

Vilardo appreciates many of the learning experiences that accompany working in a professor’s lab. When Jones went to a conference in Russia, Vilardo left her equipment alone to polarize the neutrons overnight, but when she came back in the morning, she noticed that the signals she was receiving were atrocious. She was concerned that she had broken the laser, but eventually she discovered that the cause was just a short-circuiting capacitor. "A lesson in experimental physics is that things do go wrong,” she laughed. 

Hanson concurs that physics is all about trouble-shooting and painstaking work.
“While physics is challenging and often confusing,” she said, “that’s what makes the eventual outcome so rewarding." Soon she will complete Dartmouth College’s duel degree program and continue her studies in electrical engineering. 

Vilardo, however, is unsure of her plans post-Hamilton. But with a major in physics and a minor in religious studies, she has many doors open to her. She says religious studies actually pertains more to the physical world than one would think. "Physics describes how things happen but not why,” she said. “That's where religious studies might come in." To supplement her already interdisciplinary studies, she will go abroad to Italy in the spring, where she will study art history, Italian and the humanities. 

Hanson is a graduate of Smithfield High School and Vilardo graduated from Nardin Academy.
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