When I first came to Wooster, I had no clue what discipline I would explore, and didn’t even take my first physics class until the second semester of my freshman year; now, I’m coming up on the end of my second month conducting research at Michigan State’s National Superconducting Cyclotron Laboratory (NSCL), one of the nation’s top nuclear science research labs. Not only has it been a wonderful period of growth for me as a physicist, it’s also the first experience I’ve had living alone in a new place for any significant length of time. It’s been a long, rewarding journey, and I continue to learn new things and expand my horizons nearly every day.
During my time here, it has been my privilege to work with Dr. Fritsch and the rest of the AT-TPC detector group. The “AT-TPC” stands for ”Active Target Time Projection Chamber,” which means that it’s filled with a gas that both reacts with the beam of particles shot into the detector, and also serves as a medium to track the reaction.
The Prototype AT-TPC (at the top middle of photo) in its natural habitat
My first week or so at the lab, I spent most of my time reading papers on the AT-TPC and other detectors, catching up so I could better understand the work I would be doing. Since then, most of my time here has been spent in the lab, working with another undergrad researcher from France to perform tests on the smaller Prototype AT-TPC (PAT-TPC), as shown above. Though I had high expectations coming in, I’ve actually been surprised by how much time I’ve spent in the lab, hands-on with the equipment. Last week, we packed up the prototype and sent it to the nuclear physics lab at Notre Dame, where we’ll be conducting an experiment next week. Even in the last few days of my research position, I’ll be going new places and experiencing new things.
In a famous Star Trek misquotation, Mr. Spock says to Captain Kirk, “It’s life, Jim, but not as we know it”. Well, yesterday the New Horizons spacecraft returned its first closeup of Pluto, and it’s geology, but not as we know it.
Pluto’s Tombaugh Regio (left) with 2-mile high distinctly non-terrestrial water-ice mountains (right).
The Tombaugh region of Pluto contains a craterless expanse dotted with two-mile high mountains. The nitrogen, methane, and carbon monoxide ices that cover much of Pluto’s surface are not strong enough to support such tall mountains, but water ice at Pluto’s frigid temperatures is, and it is water ice that must form the bedrock or “bed-ice” of these mountains.
What generates the heat that continues to erase Pluto’s craters against planetary bombardment? It can’t be tidal forces, like those that generate Io’s volcanoes at Jupiter, because nearby Charon is too small and in tidal equilibrium with Pluto. Possibilities include Pluto’s heat of formation, from a big “splat” that formed Charon and its smaller moons, or radioactivity from the uranium and thorium in the silicates in its interior, which must be present to account for Pluto’s relatively high density. A more provocative proposal is a global interior liquid water ocean that is gradually freezing and whose latent heat drives geysers or cryovolcanism while dredging up nitrogen and methane to replenish Pluto’s tenuous atmosphere, which is rapidly escaping to space. Stay tuned!
Where do I begin? Experimental physics research has definitely been one of the longest love affairs that I have had, and this is only the beginning. This summer, I was given the opportunity to be a research assistant at CERN, Switzerland, and what an experience it has been so far!
At CERN, I am a part of the AEgIS (The Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy) collaboration of 70 scientists. The main goal of AEgIS is to measure the fall of antihydrogen in the gravitational field of the Earth, which is a direct test of Einstein’s weak equivalence principle. This is the first measurement to test the gravitational interaction between matter and antimatter. I work at the Antimatter Factory (yes!), and currently we are in the middle of “beam time” where we trap and cool the antiprotons that were produced earlier this year.
Popi in the AntiMatter Factory
Last week I met Jack Steinberger, who won the Nobel prize for the muon neutrino, for coffee. He so casually spoke about his advisor Enrico Fermi, and Einstein, who apparently was a very good friend of his! And I just looked at him, amused.
For the past month I have been living, breathing and eating physics, in a good way. The collaboration meetings, encounters with experienced and famous scientists, dinner and lunch with friends from all over the world, lectures, workshops and meetings (all of which take place in either German, French or Italian by the way and none of which I understand!) have moulded and made my summer an experience that I never expected. I have learned so much more than just physics.
Overall, this summer has been an eye-opener for me. I have learned so much about the diverse people and cultures around me, the work and life balance, and most importantly about myself. Over the next month, I look forward to traveling, exploring the European culture, and working closely with the AEgIS collaboration in order to take forward their mission.
Summer Lovin’ – Falling in Love with Experimental Physics
I remember the first hour of my research experience very clearly. I had always been horrible at keeping a good lab notebook and now I had been given an extremely fancy lab notebook with my name in silver and “Lehman Research Group” engraved in bold letters on the cover. I was so intimidated by this book that when I opened it to take notes on our readings, I wrote as neatly and as tiny as I could. That only lasted for a page though, because as soon as Dr. Lehman came in she told me that it would be best with my handwriting to write big and with lots of space. She reminded us to write everything we thought – questions, ideas, anything relevant to the experiment – and not to limit our writing and ourselves. With this advice, my writings in my notebook became more spontaneous and I had more fun recording my thoughts. As time passed, I began to feel more and more comfortable writing my thoughts down and expressing my ideas. That notebook became a home to my work, so that as I watched the pages fill I became prouder of and more confident with my ideas.
This lab notebook is the embodiment of my experience this summer. I was so intimidated at the start – I was afraid to ask questions, speak my mind, and be anything but perfect. As the weeks flew by, I became more comfortable, started being more inquisitive, and learned that being imperfect is what makes me a good Physicist. Being willing to make mistakes is what leads to important questions and discoveries.
Not only have I grown as a Physicist, but I’ve also grown as a person. The group of Physics researchers was very small this summer (just two students and two professors!) so it felt like a very friendly environment. I learned how to better collaborate with colleagues and how to be a more open-minded world citizen.
I wouldn’t trade this experience for the world. The group this summer was amazing to work with. I never loved Physics more than I have now. Physics is not just an exciting area of study; it helps you feel like a part of something bigger than yourself.
Next week the New Horizons spacecraft falls through (or “flies by”) the Pluto-Charon binary system. This week New Horizons photos reveal dramatic differences between Pluto and Charon, despite their presumed common origin in an interplanetary collision. (By the way, some astronomers — and apparently the New Horizons science team — pronounce “Charon” more like “Charlene”, the name of the wife of Charon’s discoverer, and less like “Karen”).
So close, yet so different: beige Pluto (left) and gray Charon (right) orbit the common center of mass between them forming a double planet. UPDATED 2015 July 17; click image for a larger version.
We already know spectroscopically that water H2O, methane CH4, nitrogen N2, and carbon monoxide CO ices cover Pluto’s surface (and form its tenuous and dynamic atmosphere). Ultraviolet or UV radiation probably converts nitrogen and methane into reddish, organic tholins CxHyNz. But what causes the patterns of bright ices and dark orangish tholins? By contrast, Charon’s darker surface appears to contain water crystals and ammonia hydrates (NH3)2H2O. Like Triton, the largest moon of Neptune, both Pluto and Charon may have active geysers, which may contribute to the distribution of their surface materials. Stay tuned!
My first internship at Wooster has been a highly rewarding experience. Justine and I had the privilege to work with Dr. Lehman and Dr. Jacobs on a Wooster project that has been ongoing for over two decades – The Bead Pile Experiment.
The essence of the project is the creation of a pile, using small metal beads that come from shotgun shells (yeah! pretty neat!). As additional beads are added, the pile topples. The avalanche characteristics are demonstrated when a critical point is reached or surpassed, changing in order to return to a stable point.
The bead pile models critical systems – a few examples are avalanches, forest fires, stock markets (to a certain extent), and even dynamical synapses in neural networks! By studying the pile, the conclusions will be used to discern complex critical systems in the real world.
When we commenced work, I didn’t completely understand what we were attempting to do. The thought of dropping one bead at a time to watch a pile build up and avalanche, wasn’t exactly exciting to me. Being a first year student, I was also a little anxious about being able to grasp the complexities, and make a significant contribution.
After the final Examinations, Dr. Lehman briefed us in the intricacies of the project, allowing us to gain a better understanding of the work we would be doing. It was in the third week that I truly began understanding the specifics of our model, after Dr. Jacobs went over the theory of the Bead Pile Project with us, and even gave us a few classes on Criticality!
During the course of the summer, we did a few more runs, but spent more time analyzing past data. Our focus was to recognize how changing the height the beads fall from and the stickiness of the beads changes the probability of getting avalanches of specific sizes.
With Dr. Jacobs and Dr. Lehman’s help, we installed and programmed a high-speed camera to record videos of large avalanches. This enhanced our ability to analyze the variation of trends in the graphs of the large and small avalanches. The camera is mounted above the pile (next to the bead dropper) in order to be able to see the whole pile.
A massive avalanche on the beadpile, viewed from above using the newly installed high speed camera. The perspective is slightly distorted because of the fish-eye lens and because the camera is not directly above the center of the pile. The pile center is slightly to the left of the visual center of the circle; you can tell because that’s the point the beads move away from.
We were also very keen to study how the time between certain size avalanches changed as we varied the drop height and stickiness of the beads. We also wanted to set up particle tracking with the camera to trace the path of a bead in an avalanche. However, we didn’t have enough time to do this.
In conclusion, I believe that I have gained a lot of knowledge this summer, and have thoroughly enjoyed my time working on The Bead Pile Experiment. While we learned a lot, and increased our understanding through our analysis, there is much left to be done. But isn’t that what science is all about?
We held the 12th annual picnic and pie festival at my house just over a week ago. (The tradition started the summer after my first year at the College, when one of the summer research students explained that, while she liked to bake pies, she didn’t really like to eat pies. Dr. Lindner explained that he was the ideal complement — he liked to eat pies, but not to bake pies! The pie festival was born!)
The pie festival is wonderful especially because of the participation of the students. Many start the summer daunted by the prospect of producing a pie, but by the time the pie festival rolls around, they rise to the challenge! The rule of the pie party is that everyone brings a pie. (Families are allowed to bring one pie for the family, and Dr. Lindner has a pass.) I think our all time largest pie party had 15 pies for 17 people!
This year we had 10 pies for 12 adults (and 4 young kids). Delicious! Pies included lemon meringue, peach, apple, pina colada, chocolate pecan, gooseberry, and one of the richest pies I’ve ever tasted – dark chocolate caramel Oreo! At least three people managed to take at least a thin slice of all the pies (and also eat part of each slice!)!
I was a little worried about the weather earlier in the day — it rained most of the morning, but cleared up so that we could eat outside by 5 pm. The weather did put a damper on our traditional games of badminton and croquet, but we played games inside instead.
One of the Wooster summer traditions is the BWISER science camp for 7th and 8th grade girls. The physics department has been responsible for an evening of demos for the campers since before I came to the College in 2003, and I’ve taken over responsibility for running our highly-choreographed rotation of nearly 100 girls through seven different demos over the course of two hours. It’s quite an event!
Usually we have at least six summer research students on campus who are the ones actually presenting the demos to the campers. This year, although we have a lot of students doing research for the summer, only two are on campus! So, I had to put out a plea for volunteers and was so impressed with the awesome response from students who were near enough to Wooster to help.
Popi and Carlos at the Sound demo
For one hour, the BWISER girls cycle through five shorter demos of about 12 minutes each — these are Sound, Polarization, Total Internal Reflection, Holography and Spectral Lines. For the other hour, the girls spend a half an hour building squeeze rockets and half an hour contemplating the vastness of the universe and communication at the speed of light watching Powers of 10 and the opening sequence to Contact.
Building squeeze rockets is best with lots of stickers and glitter tape.
The squeeze rockets have turned out to be a great alternative to the Moon Cratering experiment that we used to do. Moon Cratering was a lot of fun, but quite a mess, since it involved dropping different mass balls from different heights into a vat of flour with a fine coating of either tempera paint or cocoa powder. Squeeze rockets has pretty much all the fun of Moon Craters plus glitter tape, and none of the mess.
For the last two or three years, I’ve also been doing a session for the BWISER Alumnae camp (for 8th graders coming back a second time to camp). This year I had the alumnae for longer than previously, so I decided to do sessions on Light as a Wave, and Light as a Particle. I’ve been doing optics and imaging for the camp already, so the Light as a Wave stuff mostly came from that, but the new Light as a Particle activities were a lot of fun! The sun print paper in particular was really popular, with some very creative arrangements of leaves and flowers to make some beautiful prints. I only have pictures here of the prints as they are being developed in the sun; after this step you develop the paper in water and the colors invert so that the paper turns dark blue wherever it was exposed to the sun and white wherever there was shadow.
In addition to the BWISER outreach events, I also did a one-day special session for the West Holmes Summer Science Sessions. Last year was the first year I did this program — I was worried that I didn’t have enough cool stuff and the night before the program, I built the GIANT kaleidoscope, which is now one of my favorite demos! All it takes are three full-length mirrors (like you would hang on a door) and a serious amount of duct tape. What you get is awesome, especially when there are small children around to make crazy faces.
Kaleidoscope crazy faceKaleidoscopic shirt and shorts
The kaleidoscope was a hit again at the Summer Science Session, as were the Light as a Particle activities. Besides the sun paper, I also talk about ultraviolet light, including why it’s more dangerous than visible light, since one photon has more energy and so can be more damaging. And, we got some “secret message” pens that write with ink only visible under UV light. Turns out, the pens can write not only on paper but also on skin. I’m sure you can see where this is headed.
UV temporary tattoos
Sooner or later, it had to happen — the combination of the kaleidoscope and the UV pens.
In the interest of safety, I’ll just add that the students had previously tested this pair of sunglasses and found that they did in fact block UV. Generally you should avoid shining a UV flashlight into someone’s eyes.
Overall, these different outreach programs reached around 120 kids this summer! Hopefully they all still remember my main take-home message: Physics is Awesome!
I’ve started following various science sites on Twitter as a way to keep up on the latest research, and last week an interesting article popped up on Phys.org with the title “Functioning brain follows famous sand pile model”. Since my current research on avalanches on the beadpile is a essentially an experimental investigation of criticality and the sand pile model, I clicked on the link, interested to see how it connected to the brain.
The article was about an article just published in Nature Physics on June 22, looking at the electrical activity (visual avalanches) in the brain and comparing to the sand pile model, but it got really interesting in about the fourth paragraph when I discovered that the first author on the paper was Woodrow Shew, Wooster physics alum from 1998! What a great way to bump into an alumnus! Woodrow is now an assistant professor at the University of Arkansas, and clearly is doing some cool work.
The work of Newton and Laplace suggested to many that the solar system was like a giant clockwork, which was illustrated by beautiful mechanical models called orreries. The controversial Molchanov hypothesis avers that every oscillatory system evolves to a resonance governed by a family of integers, like the 3/2 resonance between the orbits of Pluto and Neptune, or the 2/1 resonance between Jupiter’s giant natural satellites Ganymede and Europa, and Europa and Io. (Europa orbits Jupiter once when Io orbits twice.) Yet my research this sabbatical suggests that the irrational golden ratio describes some variable stars. Indeed, overlapping resonances may account for evidence of chaos in the solar system.
Saturn and two of its natural satellites, giant Titan and tiny Hyperion (left), and the Pluto-Charon binary system and one of its small satellites Nix. Hyperion and Nix appear to tumble chaotically in their orbits. The systems are drawn to different scales.
In the Saturn system, the 3/4 orbital resonance between tiny, irregularly-shaped Hyperion and planet-sized Titan causes Hyperion to tumble chaotically in its orbit. If you lived on Hyperion, the sun would appear to rise and set at irregular times. Last week, researchers announced that something similar occurs in the Pluto-Charon binary system. Using archival Hubble space telescope data ahead of the New Horizon’s July flyby, Mark Showalter and Doug Hamilton argued that the tiny moons are in orbital resonance but light curves of Nix and Hydra are not sinusoidal, suggesting chaotic tumbling. Nix’s small size implies an irregular shape. (We should know for sure next month.) Just as the dynamic gravity of Saturn and Titan chaotically tumble irregular Hyperion, the dynamic gravity of Pluto and Charon chaotically tumble irregular Nix. If you lived on Nix, the sun might one day rise in the east and set in the north.
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Thanks, Mark! I enjoy reading your posts as well.
Nice post, John! Thanks for writing these. I always enjoy them.
Thanks, Mark! I enjoy reading your posts as well.