As a research assistant in the physics department at UCONN, I assisted in the alignment, maintenance, and principles of operation of the various apparatuses and measurement techniques used within cold atomic, molecular, and optical (AMO) experimental physics research. This included optical components, laser alignment, laser locking, saturation absorption spectroscopy, and electrodynamic ion trapping. Some specific experiments ran included measuring the fraction of a trapped, sodium atom-cloud (fe) pumped into an optically excited state using laser beams as well as measuring the temperature of a trapped, neutral atom-cloud via spatio-temporal fluorescence imaging.
Highlights
Synopsis or brief article reporting on research or teaching highlights taking place within the department.
Detection of recent seismic events in Storrs
Attached is our record for the Mw 6.9 earthquake associated with eruptions of the Kilauea volcano on the big island of Hawaii. The large waves arriving after 2300 GMT are surface waves (elastic energy that exponentially decays with depth away from the surface) traveling from the earthquake to us. The beating pattern is characteristic of surface waves interfering from slightly different multi paths as they are refracted by the sharp transition in elastic structure between the ocean and continent.
The amplitude of strain associated with the waves is on the order of 10**-12 (peak particle velocity divided by propagation velocity). For comparison, the strain associated with gravity waves recorded by LIGO is on the order of 10**-21.
The newly upgraded CEBAF Accelerator opens door to strong force studies
The Science
Scientists have been rigorously commissioning the experimental equipment to prepare for a new era of nuclear physics experiments. This equipment is at the newly upgraded Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab in Newport News, Virginia. These activities have already led to the first scientific result. This research demonstrates the feasibility of detecting a potential new form of matter.
The Impact
The result demonstrates the feasibility of detecting hybrid mesons. These mesons are particles that are built of the same stuff as ordinary protons and neutrons: quarks bound together by the “glue” of the strong force. But unlike ordinary mesons, the glue in hybrid mesons behaves differently. The research provides a window into how mesons and other particles that are smaller than atoms are built by the strong force. The study also offers insights into “quark confinement” — why no quark has ever been found alone.
Summary
The first experimental result has been published from the newly upgraded Continuous Electron Beam Accelerator Facility (CEBAF). The 12-GeV CEBAF Upgrade is a $338 million, multi-year project to triple CEBAF’s original operational energy for investigating the quark structure of the atom’s nucleus. The upgrade is scheduled for completion in the fall of 2017. This first result demonstrates the feasibility of detecting a potential new form of matter. It comes from the Gluonic Excitations Experiment, which is staged in the new Experimental Hall D that was built as part of the upgrade. GlueX collaborators are working to produce new particles, called hybrid mesons, which are particles in which both the quarks and the strong-force gluons have a role in the structure. Producing and studying the spectrum of these particles will provide nuclear physicists a window to “quark confinement” — why no quark has ever been found alone. Data were collected over a two-week period following equipment commissioning in the spring of 2016. The experiment produced two ordinary mesons called the neutral pion and the eta, and the production mechanisms of these two particles were carefully studied. The data provided powerful new information on meson production mechanisms, ruling out several, and the data also showed that the GlueX experiment can produce timely results.
Contact
Richard Jones
Group Leader, University of Connecticut
richard.t.jones@uconn.edu
Funding
This material is based upon work supported by the U.S. National Science Foundation under grant 1508238.
Publications
H. Al Ghoul, et al. (GlueX Collaboration), “Measurement of the beam asymmetry Σ for π0 and η photoproduction on the proton at Eγ = 9 GeV” Physical Review C 95, 042201 (2017). [DOI: 10.1103/PhysRevC.95.042201]
Related Links
Symmetry magazine article: Exploring the universal glue
Jefferson Lab news release: Jefferson Lab accelerator delivers its first 12 GeV electrons
Jefferson Lab news release: Jefferson Lab accelerator upgrade completed: Initial operations set to begin while experimental equipment upgrades continue
This article first appeared under Science Highlights on the Dept. of Energy web site, October 6, 2017.
UConn astronomers on the American eclipse
A Total Eclipse of the Heart (of America)
– Elaina Hancock – UConn Communications
A spectacular and likely unforgettable show will take place in the sky Aug. 21.
“Have you ever seen a total solar eclipse?” asks Cynthia Peterson, professor emerita of physics. “It’s a really, really exciting event!”
The reason she and so many others are excited for this event has a lot to do with its rarity. The last time a total solar eclipse was visible from the mainland United States was 38 years ago, in February 1979.
Very specific conditions have to be met to create an eclipse that can be viewed from Earth. The Earth and the moon must align perfectly with the sun as they speed through space, an amazing coincidence. To fully understand how this happens, Peterson says, it’s helpful to know some basic astronomy.
Conditions for a Total Solar Eclipse
The Earth moves in space around the sun, completing a full orbit once every 365.25 days, she explains. As the Earth and other members of our solar system travel around the sun, they continue in essentially the same plane, on a path called the ecliptic. Some celestial bodies, such as our moon, deviate from the ecliptic slightly.
The orbit of the moon is inclined on the ecliptic plane at an inclination of 5 degrees. As the moon deviates 5 degrees above or below the ecliptic plane, it will cross the plane at points called nodes.
“That is the first essential piece of the eclipse puzzle,” says Peterson. “The moon must be at a node for an eclipse to occur. Otherwise, the moon will not align and no eclipse will be seen from Earth.”
The moon’s position in the lunar cycle is another vital eclipse component. As the Earth travels in its orbit, the moon tags along, keeping its gaze locked on Earth, always facing from the same side as it completes its own orbit around Earth once every 29.5 days. Over the course of a month, the moon’s appearance changes, from crescent to full to crescent again and finally to what appears to be its absence, when it’s called a new moon. A new moon is the other requirement for a solar eclipse.
“The basic rule for a solar eclipse is to have a new moon at a node,” Peterson points out.
But during an eclipse, how can our moon, which is relatively small, appear almost as big as the sun, which is pretty gigantic?
Peterson explains, “The sun is 400 times bigger than the moon and the sun is also 400 times farther away from the moon, so the moon appears to fit exactly during an eclipse, when they are both the same angular size.”
Holding up her fist, she demonstrates: “Find a large object ahead of you and pretend it is the sun and your fist is the moon. If you hold up your fist and look with one eye, you can’t see the object/sun.”
These are the conditions for a total solar eclipse like the one coming up. “Solar eclipses happen when the new moon obstructs the sun and the moon’s shadow falls on the earth, creating a total solar eclipse.” Peterson moves her fist slightly away from herself until the edges of the object can be seen around it. “Or, when the moon covers the Sun’s center and creates a ‘ring of fire’ around the moon, it’s what’s called an annular eclipse.”
It’s those bits of the sun peeking out from behind the moon – in both partial and total eclipses – that everyone needs to be careful of. It’s extremely important to view the eclipse safely, Peterson stresses. “The problem with the eclipse is that every time it happens, some people are blinded [from looking at it unprotected]. The shadow goes whipping by at 1,000 miles per hour, and you never want to stare at the sun, even a sliver of it.”
So be prepared, and ensure you wear proper solar eclipse eye protection. Regular sunglasses will not help. Solar eclipse glasses can be used, welder’s goggles, or telescopes with proper lenses. Be sure the eye protection you choose is certified by the International Organization for Standardization (ISO). Other popular viewing methods are DIY viewing boxes like these.
Peterson, like many others who wish to get the full eclipse experience, will be traveling to an area directly in the path of the eclipse’s shadow. These areas are called totality. The Aug. 21 eclipse will cover an expansive area of totality that will include 14 states and 14 major U.S. cities, stretching from Lincoln Beach, Oregon to Charleston, South Carolina. For a map of the path of totality, go to the NASA website. Connecticut is unfortunately hours of travel from the nearest totality. Peterson will go as far as Nebraska for the experience.
“You’ll only see a partial eclipse here in Connecticut,” she says. “It will get a little darker, like a cloud covering part of the sun, and then brighten up again.”
She encourages those who can to try to travel to a viewing point for the total eclipse, where they may see “amazing phenomena” like the diamond ring, shadowbands, crescent-shaped solar images under trees (instead of the usual ‘coins’ which are pinhole images of the sun), and extremely sharp shadows in the final minute before totality, due to the very narrow sun at that time. “These phenomena can only be seen in totality,” she says.
The next chance to see a total solar eclipse will be in 2024, when its shadow will be cast closer to Connecticut. It will start in the U.S. in Texas, then make its way north, through northern Vermont and New Hampshire.
“That’s less than seven years from now,” Peterson points out, “but that’s the end of eclipses crossing the U.S. until the 2050s.”
For those on campus next week, you aren’t out of luck. For this eclipse there will be a viewing party on Horsebarn Hill behind the Dairy Bar, from 1 to 4 p.m., hosted by the Department of Physics. “We’ll have solar telescopes, a pinhole camera activity, and will do some short mini-lectures on astronomy at UConn and about how eclipses work,” says Assistant Professor of Physics Jonathan Trump, one of the faculty members who will lead the viewing party.
Peterson, longtime astronomer and scientist, says witnessing an eclipse – especially a total eclipse – can be extremely emotional. She suggests reading Annie Dillard’s essay about solar eclipses, where the author compares the contrast between viewing a partial eclipse and viewing a total eclipse to the difference between flying in an airplane versus falling out of the airplane. “Those are very different experiences.”
But wherever you are on the afternoon of Aug. 21, Peterson says, stop and enjoy the show: “Good luck and clear skies!”
The eclipse will be live-streamed by NASA, and can also be viewed on PBS’ NOVA at 9 p.m. on Aug. 21.
Copied from the original UConn Today article
GlueX experiment publishes first scientific results following accelerator upgrade
Scientists are one step closer to understanding the strong force that binds quarks together forever. Researchers working with the Continuous Electron Beam Accelerator Facility (CEBAF) at the U.S. Department of Energy’s Jefferson National Accelerator Facility (J-Lab) have published their first scientific results since the accelerator energy was increased from six billion electron volts (GeV) to 12 GeV. The upgrade was commissioned to enable the next generation of physics experiments that will allow scientists to see smaller bits of matter than have ever been seen before. The first publication from the upgraded CEBAF was published by the Gluonic Excitation Project (GlueX) in the April issue of Physical Review C, available online through the APS web site.
University of Connecticut Associate Professor of Physics Richard Jones and students have played a leading role in the GlueX experiment since its inception in a series of scientific workshops nearly 20 years ago. The goal of GlueX is to discover whether or not a new class of subatomic particle known as “hybrid mesons” actually exists, and if they do, to measure their masses and other properties. While their existence is widely accepted on the basis of general theoretical arguments, definitive experimental evidence is still lacking. If they exist, hybrid mesons should be much more massive than ordinary mesons, so they should decay into ordinary mesons before they can travel any further than a few femtometers from where they were formed. Hence, the GlueX experiment is equipped with a multi-particle tracking spectrometer with nearly full angular coverage and sensitivity to both charged particles and neutrals.
In this new paper, the GlueX team describes how they produced two ordinary mesons, the neutral pion and eta. While creating these two particles is fairly simple for an accelerator of the CEBAF’s magnitude, what was interesting to the researchers is that they were able to show that the linear polarization of the accelerator’s photon beam can provide enough information about how the meson was formed. They can use that information to narrow down theories about how the mesons were produced. The research team plans to continue to analyze the data the accelerator has produced since it was commissioned a year ago, and they will begin to collect new data this fall.
-based on a news article by Jocelyn Duffy
“Caution: Shrinks When Warm”
– Kim Krieger – UConn Communications
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” .
Physicists Solve Low-Temperature Magnetic Mystery
– Tim Miller
Researchers have made an experimental breakthrough in explaining a rare property of an exotic magnetic material, potentially opening a path to a host of new technologies. From information storage to magnetic refrigeration, many of tomorrow’s most promising innovations rely on sophisticated magnetic materials, and this discovery opens the door to harnessing the physics that governs those materials.
The work, led by University of Connecticut professor Jason Hancock, and Ignace Jarrige of the Brookhaven National Laboratory, marks a major advance in the search for practical materials that will enable several types of next-generation technology. A paper describing the team’s results is published this week in the journal Physical Review Letters.
The full text of this article can be found on the UConn Today website at “Physicists Solve Low-Temperature Magnetic Mystery”.