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SMU physicists: CERN’s Large Hadron Collider is once again smashing protons, taking data

CERN’s Large Hadron Collider (LHC) and its experiments are back in action, now taking physics data for 2016 to get an improved understanding of fundamental physics.

Following its annual winter break, the most powerful collider in the world has been switched back on.

Geneva-based CERN’s Large Hadron Collider (LHC) — an accelerator complex and its experiments — has been fine-tuned using low-intensity beams and pilot proton collisions, and now the LHC and the experiments are ready to take an abundance of data.

The goal is to improve our understanding of fundamental physics, which ultimately in decades to come can drive innovation and inventions by researchers in other fields.

Scientists from SMU’s Department of Physics are among the several thousand physicists worldwide who contribute on the LHC research.

“All of us here hope that some of the early hints will be confirmed and an unexpected physics phenomenon will show up,” said Ryszard Stroynowski, SMU professor and a principal investigator on the LHC. “If something new does appear, we will try to contribute to the understanding of what it may be.”

SMU physicists work on the LHC’s ATLAS experiment. Run 1 of the Large Hadron Collider made headlines in 2012 when scientists observed in the data a new fundamental particle, the Higgs boson. The collider was then paused for an extensive upgrade and came back much more powerful than before. As part of Run 2, physicists on the Large Hadron Collider’s experiments are analyzing new proton collision data to unravel the structure of the Higgs.

The Higgs was the last piece of the puzzle for the Standard Model — a theory that offers the best description of the known fundamental particles and the forces that govern them. In 2016 the ATLAS and CMS collaborations of the LHC will study this boson in depth.

Over the next three to four months there is a need to verify the measurements of the Higgs properties taken in 2015 at lower energies with less data, Stroynowski said.

“We also must check all hints of possible deviations from the Standard Model seen in the earlier data — whether they were real effects or just statistical fluctuations,” he said. “In the long term, over the next one to two years, we’ll pursue studies of the Higgs decays to heavy b quarks leading to the understanding of how one Higgs particle interacts with other Higgs particles.”

In addition, the connection between the Higgs Boson and the bottom quark is an important relationship that is well-described in the Standard Model but poorly understood by experiments, said Stephen Sekula, SMU associate professor. The SMU ATLAS group will continue work started last year to study the connection, Sekula said.

“We will be focused on measuring this relationship in both Standard Model and Beyond-the-Standard Model contexts,” he said.

SMU physicists also study Higgs-boson interactions with the most massive known particle, the top-quark, said Robert Kehoe, SMU associate professor.

“This interaction is also not well-understood,” Kehoe said. “Our group continues to focus on the first direct measurement of the strength of this interaction, which may reveal whether the Higgs mechanism of the Standard Model is truly fundamental.”

All those measurements are key goals in the ATLAS Run 2 and beyond physics program, Sekula said. In addition, none of the ultimate physics goals can be achieved without faultless operation of the complex ATLAS detector, its software and data acquisition system.

“The SMU group maintains work on operations, improvements and maintenance of two components of ATLAS — the Liquid Argon Calorimeter and data acquisition trigger,” Stroynowski said.

Intensity of the beam to increase, supplying six times more proton collisions
Following a short commissioning period, the LHC operators will now increase the intensity of the beams so that the machine produces a larger number of collisions.

“The LHC is running extremely well,” said CERN Director for Accelerators and Technology, Frédérick Bordry. “We now have an ambitious goal for 2016, as we plan to deliver around six times more data than in 2015.”

The LHC’s collisions produce subatomic fireballs of energy, which morph into the fundamental building blocks of matter. The four particle detectors located on the LHC’s ring allow scientists to record and study the properties of these building blocks and look for new fundamental particles and forces.

This is the second year the LHC will run at a collision energy of 13 TeV. During the first phase of Run 2 in 2015, operators mastered steering the accelerator at this new higher energy by gradually increasing the intensity of the beams.

“The restart of the LHC always brings with it great emotion”, said Fabiola Gianotti, CERN Director General. “With the 2016 data the experiments will be able to perform improved measurements of the Higgs boson and other known particles and phenomena, and look for new physics with an increased discovery potential.”

New exploration can begin at higher energy, with much more data
Beams are made of “trains” of bunches, each containing around 100 billion protons, moving at almost the speed of light around the 27-kilometre ring of the LHC. These bunch trains circulate in opposite directions and cross each other at the center of experiments. Last year, operators increased the number of proton bunches up to 2,244 per beam, spaced at intervals of 25 nanoseconds. These enabled the ATLAS and CMS collaborations to study data from about 400 million million proton–proton collisions. In 2016 operators will increase the number of particles circulating in the machine and the squeezing of the beams in the collision regions. The LHC will generate up to 1 billion collisions per second in the experiments.

“In 2015 we opened the doors to a completely new landscape with unprecedented energy. Now we can begin to explore this landscape in depth,” said CERN Director for Research and Computing Eckhard Elsen.

Between 2010 and 2013 the LHC produced proton-proton collisions with 8 Tera-electronvolts of energy. In the spring of 2015, after a two-year shutdown, LHC operators ramped up the collision energy to 13 TeV. This increase in energy enables scientists to explore a new realm of physics that was previously inaccessible. Run II collisions also produce Higgs bosons — the groundbreaking particle discovered in LHC Run I — 25 percent faster than Run I collisions and increase the chances of finding new massive particles by more than 40 percent.

But there are still several questions that remain unanswered by the Standard Model, such as why nature prefers matter to antimatter, and what dark matter consists of, despite it potentially making up one quarter of our universe.

The huge amounts of data from the 2016 LHC run will enable physicists to challenge these and many other questions, to probe the Standard Model further and to possibly find clues about the physics that lies beyond it.

The physics run with protons will last six months. The machine will then be set up for a four-week run colliding protons with lead ions.

“We’re proud to support more than a thousand U.S. scientists and engineers who play integral parts in operating the detectors, analyzing the data, and developing tools and technologies to upgrade the LHC’s performance in this international endeavor,” said Jim Siegrist, Associate Director of Science for High Energy Physics in the U.S. Department of Energy’s Office of Science. “The LHC is the only place in the world where this kind of research can be performed, and we are a fully committed partner on the LHC experiments and the future development of the collider itself.”

The four largest LHC experimental collaborations, ALICE, ATLAS, CMS and LHCb, now start to collect and analyze the 2016 data. Their broad physics program will be complemented by the measurements of three smaller experiments — TOTEM, LHCf and MoEDAL — which focus with enhanced sensitivity on specific features of proton collisions. — SMU, CERN and Fermilab

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Nearby massive star explosion 30 million years ago equaled brightness of 100 million suns

Analysis of exploding star’s light curve and color spectrum reveal spectacular demise of one of the closest supernova to Earth in recent years; its parent star was so big it’s radius was 200 times larger than our sun

A giant star that exploded 30 million years ago in a galaxy near Earth had a radius prior to going supernova that was 200 times larger than our sun, according to astrophysicists at Southern Methodist University, Dallas.

The sudden blast hurled material outward from the star at a speed of 10,000 kilometers a second. That’s equivalent to 36 million kilometers an hour or 22.4 million miles an hour, said SMU physicist Govinda Dhungana, lead author on the new analysis.

The comprehensive analysis of the exploding star’s light curve and color spectrum have revealed new information about the existence and sudden death of supernovae in general, many aspects of which have long baffled scientists.

“There are so many characteristics we can derive from the early data,” Dhungana said. “This was a big massive star, burning tremendous fuel. When it finally reached a point its core couldn’t support the gravitational pull inward, suddenly it collapsed and then exploded.”

The massive explosion was one of the closest to Earth in recent years, visible as a point of light in the night sky starting July 24, 2013, said Robert Kehoe, SMU physics professor, who leads SMU’s astrophysics team.

The explosion, termed by astronomers Supernova 2013ej, in a galaxy near our Milky Way was equal in energy output to the simultaneous brightness of 100 million of the Earth’s suns.

The star was one of billions in the spiral galaxy M74 in the constellation Pisces.

Considered close by supernova standards, SN 2013ej was in fact so far away that light from the explosion took 30 million years to reach Earth. At that distance, even such a large explosion was only visible by telescopes.

Dhungana and colleagues were able to explore SN 2013ej via a rare collection of extensive data from seven ground-based telescopes and NASA’s Swift satellite.

The data span a time period prior to appearance of the supernova in July 2013 until more than 450 days after.

The team measured the supernova’s evolving temperature, its mass, its radius, the abundance of a variety of chemical elements in its explosion and debris and its distance from Earth. They also estimated the time of the shock breakout, the bright flash from the shockwave of the explosion.

The star’s original mass was about 15 times that of our sun, Dhungana said. Its temperature was a hot 12,000 Kelvin (approximately 22,000 degrees Fahrenheit) on the tenth day after the explosion, steadily cooling until it reached 4,500 Kelvin after 50 days. The sun’s surface is 5,800 Kelvin, while the Earth’s core is estimated to be about 6,000 Kelvin.

The new measurements are published online here in the May 2016 issue of The Astrophysical Journal, “Extensive spectroscopy and photometry of the Type IIP Supernova 2013j.”

Shedding new light on supernovae, mysterious objects of our universe
Supernovae occur throughout the universe, but they are not fully understood. Scientists don’t directly observe the explosions but instead detect changes in emerging light as material is hurled from the exploding star in the seconds and days after the blast.

Telescopes such as SMU’s robotic ROTSE-IIIb telescope at McDonald Observatory in Texas, watch our sky and pick up the light as a point of brightening light. Others, such as the Hobby Eberly telescope, also at McDonald, observe a spectrum.

SN 2013ej is M74’s third supernova in just 10 years. That is quite frequent compared to our Milky Way, which has had a scant one supernova observed over the past 400 years. NASA estimates that the M74 galaxy consists of 100 billion stars.

M74 is one of only a few dozen galaxies first cataloged by the astronomer Charles Messier in the late 1700s. It has a spiral structure — also the Milky Way’s apparent shape — indicating it is still undergoing star formation, as opposed to being an elliptical galaxy in which new stars no longer form.

It’s possible that planets were orbiting SN 2013ej’s progenitor star prior to it going supernova, in which case those objects would have been obliterated by the blast, Kehoe said.

“If you were nearby, you wouldn’t know there was a problem beforehand, because at the surface you can’t see the core heating up and collapsing,” Kehoe said. “Then suddenly it explodes — and you’re toast.”

Distances to nearby galaxies help determine cosmic distance ladder
Scientists remain unsure whether supernovae leave behind a black hole or a neutron star like a giant atomic nucleus the size of a city.

“The core collapse and how it produces the explosion is particularly tricky,” Kehoe said. “Part of what makes SN 2013ej so interesting is that astronomers are able to compare a variety of models to better understand what is happening. Using some of this information, we are also able to calculate the distance to this object. This allows us a new type of object with which to study the larger universe, and maybe someday dark energy.”

Being 30 million light years away, SN 2013ej was a relatively nearby extragalactic event, according to Jozsef Vinko, astrophysicist at Konkoly Observatory and University of Szeged in Hungary.

“Distances to nearby galaxies play a significant role in establishing the so-called cosmic distance ladder, where each rung is a galaxy at a known distance.”

Vinko provided important data from telescopes at Konkoly Observatory and Hungary’s Baja Observatory and carried out distance measurement analysis on SN 2013ej.

“Nearby supernovae are especially important,” Vinko said. “Paradoxically, we know the distances to the nearest galaxies less certainly than to the more distant ones. In this particular case we were able to combine the extensive datasets of SN 2013ej with those of another supernova, SN 2002ap, both of which occurred in M74, to suppress the uncertainty of their common distance derived from those data.”

Supernova spectrum analysis is like taking a core sample
While stars appear to be static objects that exist indefinitely, in reality they are primarily a burning ball, fueled by the fusion of elements, including hydrogen and helium into heavier elements. As they exhaust lighter elements, they must contract in the core and heat up to burn heavier elements. Over time, they fuse the various chemical elements of the periodic table, proceeding from lightest to heaviest. Initially they fuse helium into carbon, nitrogen and oxygen. Those elements then fuel the fusion of progressively heavier elements such as sulfur, argon, chlorine and potassium.

“Studying the spectrum of a supernova over time is like taking a core sample,” Kehoe said. “The calcium in our bones, for example, was cooked in a star. A star’s nuclear fusion is always forging heavier and heavier elements. At the beginning of the universe there was only hydrogen and helium. The other elements were made in stars and in supernovae. The last product to get created is iron, which is an element that is so heavy it can’t be burned as fuel.”

Dhungana’s spectrum analysis of SN 2013ej revealed many elements, including hydrogen, helium, calcium, titanium, barium, sodium and iron.

“When we have as many spectra as we have for this supernova at different times,” Kehoe added, “we are able to look deeper and deeper into the original star, sort of like an X-ray or a CAT scan.”

SN 2013ej’s short-lived existence was just tens of millions of years
Analysis of SN 2013ej’s spectrum from ultraviolet through infrared indicates light from the explosion reached Earth July 23, 2013. It was discovered July 25, 2013 by the Katzman Automatic Imaging Telescope at California’s Lick Observatory. A look back at images captured by SMU’s ROTSE-IIIb showed that SMU’s robotic telescope detected the supernova several hours earlier, Dhungana said.

“These observations were able to show a rapidly brightening supernova that started just 20 hours beforehand,” he said. “The start of the supernova, termed ‘shock breakout,’ corresponds to the moment when the internal explosion crashes through the star’s outer layers.”

Like many others, SN 2013ej was a Type II supernova. That is a massive star still undergoing nuclear fusion. Once iron is fused, the fuel runs out, causing the core to collapse. Within a quarter second the star explodes.

Supernovae have death and birth written all over them
Massive stars typically have a shorter life span than smaller ones.

“SN 2013ej probably lived tens of millions of years,” Kehoe said. “In universe time, that’s the blink of an eye. It’s not very long-lived at all compared to our sun, which will live billions of years. Even though these stars are bigger and have a lot more fuel, they burn it really fast, so they just get hotter and hotter until they just gobble up the matter and burn it.”

For most of its brief life, SN 2013ej would probably have burned hydrogen, which then fused to helium, burning for a few hundred thousand years, then perhaps carbon and oxygen for a few hundred days, calcium for a few months and silicon for several days.

“Supernovae have death and birth written all over them,” Kehoe said. “Not only do they create the elements we are made of, but the shockwave that goes out from the explosion — that’s where our solar system comes from.”

Outflowing material slams into clouds of material in interstellar space, causing it to collapse and form a solar system.

“The heavy elements made in the supernova and its parent star are those which comprise the bulk of terrestrial planets, like Earth, and are necessary for life,” Kehoe said.

Besides physicists in the SMU Department of Physics, researchers on the project also included scientists from the University of Szeged, Szeged, Hungary; the University of Texas, Austin, Texas; Konkoly Observatory, Budapest, Hungary; and the University of California, Berkeley, Calif. — Margaret Allen

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.

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SMU 2015 research efforts broadly noted in a variety of ways for world-changing impact

SMU scientists and their research have a global reach that is frequently noted, beyond peer publications and media mentions.

By Margaret Allen
SMU News & Communications

It was a good year for SMU faculty and student research efforts. Here is a small sampling of public and published acknowledgements during 2015:

Simmons, Diego Roman, SMU, education

Hot topic merits open access
Taylor & Francis, publisher of the online journal Environmental Education Research, lifted its subscription-only requirement to meet demand for an article on how climate change is taught to middle-schoolers in California.

Co-author of the research was Diego Román, assistant professor in the Department of Teaching and Learning, Annette Caldwell Simmons School of Education and Human Development.

Román’s research revealed that California textbooks are teaching sixth graders that climate change is a controversial debate stemming from differing opinions, rather than a scientific conclusion based on rigorous scientific evidence.

The article, “Textbooks of doubt: Using systemic functional analysis to explore the framing of climate change in middle-school science textbooks,” published in September. The finding generated such strong interest that Taylor & Francis opened access to the article.

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Research makes the cover of Biochemistry
Drugs important in the battle against cancer were tested in a virtual lab by SMU biology professors to see how they would behave in the human cell.

A computer-generated composite image of the simulation made the Dec. 15 cover of the journal Biochemistry.

Scientific articles about discoveries from the simulation were also published in the peer review journals Biochemistry and in Pharmacology Research & Perspectives.

The researchers tested the drugs by simulating their interaction in a computer-generated model of one of the cell’s key molecular pumps — the protein P-glycoprotein, or P-gp. Outcomes of interest were then tested in the Wise-Vogel wet lab.

The ongoing research is the work of biochemists John Wise, associate professor, and Pia Vogel, professor and director of the SMU Center for Drug Discovery, Design and Delivery in Dedman College. Assisting them were a team of SMU graduate and undergraduate students.

The researchers developed the model to overcome the problem of relying on traditional static images for the structure of P-gp. The simulation makes it possible for researchers to dock nearly any drug in the protein and see how it behaves, then test those of interest in an actual lab.

To date, the researchers have run millions of compounds through the pump and have discovered some that are promising for development into pharmaceutical drugs to battle cancer.

Click here to read more about the research.

SMU, Simpson Rowe, sexual assault, video

Strong interest in research on sexual victimization
Teen girls were less likely to report being sexually victimized after learning to assertively resist unwanted sexual overtures and after practicing resistance in a realistic virtual environment, according to three professors from the SMU Department of Psychology.

The finding was reported in Behavior Therapy. The article was one of the psychology journal’s most heavily shared and mentioned articles across social media, blogs and news outlets during 2015, the publisher announced.

The study was the work of Dedman College faculty Lorelei Simpson Rowe, associate professor and Psychology Department graduate program co-director; Ernest Jouriles, professor; and Renee McDonald, SMU associate dean for research and academic affairs.

The journal’s publisher, Elsevier, temporarily has lifted its subscription requirement on the article, “Reducing Sexual Victimization Among Adolescent Girls: A Randomized Controlled Pilot Trial of My Voice, My Choice,” and has opened it to free access for three months.

Click here to read more about the research.

Consumers assume bigger price equals better quality
Even when competing firms can credibly disclose the positive attributes of their products to buyers, they may not do so.

Instead, they find it more lucrative to “signal” quality through the prices they charge, typically working on the assumption that shoppers think a high price indicates high quality. The resulting high prices hurt buyers, and may create a case for mandatory disclosure of quality through public policy.

That was a finding of the research of Dedman College’s Santanu Roy, professor, Department of Economics. Roy’s article about the research was published in February in one of the blue-ribbon journals, and the oldest, in the field, The Economic Journal.

Published by the U.K.’s Royal Economic Society, The Economic Journal is one of the founding journals of modern economics. The journal issued a media briefing about the paper, “Competition, Disclosure and Signaling,” typically reserved for academic papers of broad public interest.

The Journal of Physical Chemistry A

Chemistry research group edits special issue
Chemistry professors Dieter Cremer and Elfi Kraka, who lead SMU’s Computational and Theoretical Chemistry Group, were guest editors of a special issue of the prestigious Journal of Physical Chemistry. The issue published in March.

The Computational and Theoretical research group, called CATCO for short, is a union of computational and theoretical chemistry scientists at SMU. Their focus is research in computational chemistry, educating and training graduate and undergraduate students, disseminating and explaining results of their research to the broader public, and programming computers for the calculation of molecules and molecular aggregates.

The special issue of Physical Chemistry included 40 contributions from participants of a four-day conference in Dallas in March 2014 that was hosted by CATCO. The 25th Austin Symposium drew 108 participants from 22 different countries who, combined, presented eight plenary talks, 60 lectures and about 40 posters.

CATCO presented its research with contributions from Cremer and Kraka, as well as Marek Freindorf, research assistant professor; Wenli Zou, visiting professor; Robert Kalescky, post-doctoral fellow; and graduate students Alan Humason, Thomas Sexton, Dani Setlawan and Vytor Oliveira.

There have been more than 75 graduate students and research associates working in the CATCO group, which originally was formed at the University of Cologne, Germany, before moving to SMU in 2009.

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Vertebrate paleontology recognized with proclamation
Dallas Mayor Mike Rawlings proclaimed Oct. 11-17, 2015 Vertebrate Paleontology week in Dallas on behalf of the Dallas City Council.

The proclamation honored the 75th Annual Meeting of the Society of Vertebrate Paleontology, which was jointly hosted by SMU’s Roy M. Huffington Department of Earth Sciences in Dedman College and the Perot Museum of Science and Nature. The conference drew to Dallas some 1,200 scientists from around the world.

Making research presentations or presenting research posters were: faculty members Bonnie Jacobs, Louis Jacobs, Michael Polcyn, Neil Tabor and Dale Winkler; adjunct research assistant professor Alisa Winkler; research staff member Kurt Ferguson; post-doctoral researchers T. Scott Myers and Lauren Michael; and graduate students Matthew Clemens, John Graf, Gary Johnson and Kate Andrzejewski.

The host committee co-chairs were Anthony Fiorillo, adjunct research professor; and Louis Jacobs, professor. Committee members included Polcyn; Christopher Strganac, graduate student; Diana Vineyard, research associate; and research professor Dale Winkler.

KERA radio reporter Kat Chow filed a report from the conference, explaining to listeners the science of vertebrate paleontology, which exposes the past, present and future of life on earth by studying fossils of animals that had backbones.

SMU earthquake scientists rock scientific journal

Modelled pressure changes caused by injection and production. (Nature Communications/SMU)
Modelled pressure changes caused by injection and production. (Nature Communications/SMU)

Findings by the SMU earthquake team reverberated across the nation with publication of their scientific article in the prestigious British interdisciplinary journal Nature, ranked as one of the world’s most cited scientific journals.

The article reported that the SMU-led seismology team found that high volumes of wastewater injection combined with saltwater extraction from natural gas wells is the most likely cause of unusually frequent earthquakes occurring in the Dallas-Fort Worth area near the small community of Azle.

The research was the work of Dedman College faculty Matthew Hornbach, associate professor of geophysics; Heather DeShon, associate professor of geophysics; Brian Stump, SMU Albritton Chair in Earth Sciences; Chris Hayward, research staff and director geophysics research program; and Beatrice Magnani, associate professor of geophysics.

The article, “Causal factors for seismicity near Azle, Texas,” published online in late April. Already the article has been downloaded nearly 6,000 times, and heavily shared on both social and conventional media. The article has achieved a ranking of 270, which puts it in the 99th percentile of 144,972 tracked articles of a similar age in all journals, and 98th percentile of 626 tracked articles of a similar age in Nature.

It has a very high impact factor for an article of its age,” said Robert Gregory, professor and chair, SMU Earth Sciences Department.

The scientific article also was entered into the record for public hearings both at the Texas Railroad Commission and the Texas House Subcommittee on Seismic Activity.

Researchers settle long-debated heritage question of “The Ancient One”

The skull of Kennewick Man and a sculpted bust by StudioEIS based on forensic facial reconstruction by sculptor Amanda Danning. (Credit: Brittany Tatchell)
The skull of Kennewick Man and a sculpted bust by StudioEIS based on forensic facial reconstruction by sculptor Amanda Danning. (Credit: Brittany Tatchell)

The research of Dedman College anthropologist and Henderson-Morrison Professor of Prehistory David Meltzer played a role in settling the long-debated and highly controversial heritage of “Kennewick Man.”

Also known as “The Ancient One,” the 8,400-year-old male skeleton discovered in Washington state has been the subject of debate for nearly two decades. Argument over his ancestry has gained him notoriety in high-profile newspaper and magazine articles, as well as making him the subject of intense scholarly study.

Officially the jurisdiction of the U.S. Army Corps of Engineers, Kennewick Man was discovered in 1996 and radiocarbon dated to 8500 years ago.

Because of his cranial shape and size he was declared not Native American but instead ‘Caucasoid,’ implying a very different population had once been in the Americas, one that was unrelated to contemporary Native Americans.

But Native Americans long have claimed Kennewick Man as theirs and had asked for repatriation of his remains for burial according to their customs.

Meltzer, collaborating with his geneticist colleague Eske Willerslev and his team at the Centre for GeoGenetics at the University of Copenhagen, in June reported the results of their analysis of the DNA of Kennewick in the prestigious British journal Nature in the scientific paper “The ancestry and affiliations of Kennewick Man.”

The results were announced at a news conference, settling the question based on first-ever DNA evidence: Kennewick Man is Native American.

The announcement garnered national and international media attention, and propelled a new push to return the skeleton to a coalition of Columbia Basin tribes. Sen. Patty Murray (D-WA) introduced the Bring the Ancient One Home Act of 2015 and Washington Gov. Jay Inslee has offered state assistance for returning the remains to Native Tribes.

Science named the Kennewick work one of its nine runners-up in the highly esteemed magazine’s annual “Breakthrough of the Year” competition.

The research article has been viewed more than 60,000 times. It has achieved a ranking of 665, which puts it in the 99th percentile of 169,466 tracked articles of a similar age in all journals, and in the 94th percentile of 958 tracked articles of a similar age in Nature.

In “Kennewick Man: coming to closure,” an article in the December issue of Antiquity, a journal of Cambridge University Press, Meltzer noted that the DNA merely confirmed what the tribes had known all along: “We are him, he is us,” said one tribal spokesman. Meltzer concludes: “We presented the DNA evidence. The tribal members gave it meaning.”

Click here to read more about the research.

Prehistoric vacuum cleaner captures singular award

Paleontologists Louis L. Jacobs, SMU, and Anthony Fiorillo, Perot Museum, have identified a new species of marine mammal from bones recovered from Unalaska, an Aleutian island in the North Pacific. (Hillsman Jackson, SMU)
Paleontologists Louis L. Jacobs, SMU, and Anthony Fiorillo, Perot Museum, have identified a new species of marine mammal from bones recovered from Unalaska, an Aleutian island in the North Pacific. (Hillsman Jackson, SMU)

Science writer Laura Geggel with Live Science named a new species of extinct marine mammal identified by two SMU paleontologists among “The 10 Strangest Animal Discoveries of 2015.”

The new species, dubbed a prehistoric hoover by London’s Daily Mail online news site, was identified by SMU paleontologist Louis L. Jacobs, a professor in the Roy M. Huffington Department of Earth Sciences, Dedman College of Humanities and Sciences, and paleontologist and SMU adjunct research professor Anthony Fiorillo, vice president of research and collections and chief curator at the Perot Museum of Nature and Science.

Jacobs and Fiorillo co-authored a study about the identification of new fossils from the oddball creature Desmostylia, discovered in the same waters where the popular “Deadliest Catch” TV show is filmed. The hippo-like creature ate like a vacuum cleaner and is a new genus and species of the only order of marine mammals ever to go extinct — surviving a mere 23 million years.

Desmostylians, every single species combined, lived in an interval between 33 million and 10 million years ago. Their strange columnar teeth and odd style of eating don’t occur in any other animal, Jacobs said.

SMU campus hosted the world’s premier physicists

The SMU Department of Physics hosted the “23rd International Workshop on Deep Inelastic Scattering and Related Subjects” from April 27-May 1, 2015. Deep Inelastic Scattering is the process of probing the quantum particles that make up our universe.

As noted by the CERN Courier — the news magazine of the CERN Laboratory in Geneva, which hosts the Large Hadron Collider, the world’s largest science experiment — more than 250 scientists from 30 countries presented more than 200 talks on a multitude of subjects relevant to experimental and theoretical research. SMU physicists presented at the conference.

The SMU organizing committee was led by Fred Olness, professor and chair of the SMU Department of Physics in Dedman College, who also gave opening and closing remarks at the conference. The committee consisted of other SMU faculty, including Jodi Cooley, associate professor; Simon Dalley, senior lecturer; Robert Kehoe, professor; Pavel Nadolsky, associate professor, who also presented progress on experiments at CERN’s Large Hadron Collider; Randy Scalise, senior lecturer; and Stephen Sekula, associate professor.

Sekula also organized a series of short talks for the public about physics and the big questions that face us as we try to understand our universe.

Click here to read more about the research.

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Top Quark: Precise particle measurement improves subatomic tool probing mysteries of universe

In post-Big Bang world, nature’s top quark — a key component of matter — is a highly sensitive probe that physicists use to evaluate competing theories about quantum interactions

Physicists at Southern Methodist University, Dallas, have achieved a new precise measurement of a key subatomic particle, opening the door to better understanding some of the deepest mysteries of our universe.

The researchers calculated the new measurement for a critical characteristic — mass — of the top quark.

Quarks make up the protons and neutrons that comprise almost all visible matter. Physicists have known the top quark’s mass was large, but encountered great difficulty trying to clearly determine it.

The newly calculated measurement of the top quark will help guide physicists in formulating new theories, said Robert Kehoe, a professor in SMU’s Department of Physics. Kehoe leads the SMU group that performed the measurement.

Top quark’s mass matters ultimately because the particle is a highly sensitive probe and key tool to evaluate competing theories about the nature of matter and the fate of the universe.

Physicists for two decades have worked to improve measurement of the top quark’s mass and narrow its value.

“Top” bears on newest fundamental particle, the Higgs boson
The new value from SMU confirms the validity of recent measurements by other physicists, said Kehoe.

But it also adds growing uncertainty about aspects of physics’ Standard Model.

The Standard Model is the collection of theories physicists have derived — and continually revise — to explain the universe and how the tiniest building blocks of our universe interact with one another. Problems with the Standard Model remain to be solved. For example, gravity has not yet been successfully integrated into the framework.

The Standard Model holds that the top quark — known familiarly as “top” — is central in two of the four fundamental forces in our universe — the electroweak force, by which particles gain mass, and the strong force, which governs how quarks interact. The electroweak force governs common phenomena like light, electricity and magnetism. The strong force governs atomic nuclei and their structure, in addition to the particles that quarks comprise, like protons and neutrons in the nucleus.

The top plays a role with the newest fundamental particle in physics, the Higgs boson, in seeing if the electroweak theory holds water.

Some scientists think the top quark may be special because its mass can verify or jeopardize the electroweak theory. If jeopardized, that opens the door to what physicists refer to as “new physics” — theories about particles and our universe that go beyond the Standard Model.

Other scientists theorize the top quark might also be key to the unification of the electromagnetic and weak interactions of protons, neutrons and quarks.

In addition, as the only quark that can be observed directly, the top quark tests the Standard Model’s strong force theory.

“So the top quark is really pushing both theories,” Kehoe said. “The top mass is particularly interesting because its measurement is getting to the point now where we are pushing even beyond the level that the theorists understand.”

He added, “Our experimental errors, or uncertainties, are so small, that it really forces theorists to try hard to understand the impact of the quark’s mass. We need to observe the Higgs interacting with the top directly and we need to measure both particles more precisely.”

The new measurement results were presented in August and September at the Third Annual Conference on Large Hadron Collider Physics, St. Petersburg, Russia, and at the 8th International Workshop on Top Quark Physics, Ischia, Italy.

“The public perception, with discovery of the Higgs, is ‘Ok, it’s done,’” Kehoe said. “But it’s not done. This is really just the beginning and the top quark is a key tool for figuring out the missing pieces of the puzzle.”

The results were made public by DZero, a collaborative experiment of more than 500 physicists from around the world. The measurement is described in “Precise measurement of the top quark mass in dilepton decays with optimized neutrino weighting” and is available online at arxiv.org/abs/1508.03322.

SMU measurement achieves surprising level of precision
To narrow the top quark measurement, SMU doctoral researcher Huanzhao Liu took a standard methodology for measuring the top quark and improved the accuracy of some parameters. He also improved calibration of an analysis of top quark data.

“Liu achieved a surprising level of precision,” Kehoe said. “And his new method for optimizing analysis is also applicable to analyses of other particle data besides the top quark, making the methodology useful within the field of particle physics as a whole.”

The SMU optimization could be used to more precisely understand the Higgs boson, which explains why matter has mass, said Liu.

The Higgs was observed for the first time in 2012, and physicists keenly want to understand its nature.

“This methodology has its advantages — including understanding Higgs interactions with other particles — and we hope that others use it,” said Liu. “With it we achieved 20-percent improvement in the measurement. Here’s how I think of it myself — everybody likes a $199 iPhone with contract. If someday Apple tells us they will reduce the price by 20 percent, how would we all feel to get the lower price?”

Another optimization employed by Liu improved the calibration precision by four times, Kehoe said.

Shower of Top quarks post Big Bang
Top quarks, which rarely occur now, were much more common right after the Big Bang 13.8 billion years ago. However, top is the only quark, of six different kinds, that can be observed directly. For that reason, experimental physicists focus on the characteristics of top quarks to better understand the quarks in everyday matter.

To study the top, physicists generate them in particle accelerators, such as the Tevatron, a powerful U.S. Department of Energy particle accelerator operated by Fermi National Laboratory in Illinois, or the Large Hadron Collider in Switzerland, a project of the European Organization for Nuclear Research, CERN.

SMU’s measurement draws on top quark data gathered by DZero that was produced from proton-antiproton collisions at the Tevatron, which Fermilab shut down in 2011.

The new measurement is the most precise of its kind from the Tevatron, and is competitive with comparable measurements from the Large Hadron Collider.

Critical question: Universe isn’t necessarily stable at all energies
“The ability to measure the top quark mass precisely is fortuitous because it, together with the Higgs boson mass, tells us whether the universe is stable or not,” Kehoe said. “That has emerged as one of today’s most important questions.”

A stable universe is one in a low energy state where particles and forces interact and behave according to theoretical predictions forever. That’s in contrast to metastable, or unstable, meaning a higher energy state in which things eventually change, or change suddenly and unpredictably, and that could result in the universe collapsing. The Higgs and top quark are the two most important parameters for determining an answer to that question, Kehoe said.

Recent measurements of the Higgs and top quark indicate they describe a universe that is not necessarily stable at all energies.

“We want a theory — Standard Model or otherwise — that can predict physical processes at all energies,” Kehoe said. “But the measurements now are such that it looks like we may be over the border of a stable universe. We’re metastable, meaning there’s a gray area, that it’s stable in some energies, but not in others.”

Are we facing imminent doom? Will the universe collapse?
That disparity between theory and observation indicates the Standard Model theory has been outpaced by new measurements of the Higgs and top quark.

“It’s going to take some work for theorists to explain this,” Kehoe said, adding it’s a challenge physicists relish, as evidenced by their preoccupation with “new physics” and the possibilities the Higgs and Top quark create.

“I attended two conferences recently,” Kehoe said, “and there’s argument about exactly what it means, so that could be interesting.”

So are we in trouble?

“Not immediately,” Kehoe said. “The energies at which metastability would kick in are so high that particle interactions in our universe almost never reach that level. In any case, a metastable universe would likely not change for many billions of years.”

Top quark — a window into other quarks
As the only quark that can be observed, the top quark pops in and out of existence fleetingly in protons, making it possible for physicists to test and define its properties directly.

“To me it’s like fireworks,” Liu said. “They shoot into the sky and explode into smaller pieces, and those smaller pieces continue exploding. That sort of describes how the top quark decays into other particles.”

By measuring the particles to which the top quark decays, scientists capture a measure of the top quark, Liu explained

But study of the top is still an exotic field, Kehoe said. “For years top quarks were treated as a construct and not a real thing. Now they are real and still fairly new — and it’s really important we understand their properties fully.” — Margaret Allen

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Fermilab experiment observes change in neutrinos from one type to another over 500 miles

Scientists have sorted through millions of cosmic ray strikes and zeroed in on neutrino interactions in their quest to learn more about the abundant yet mysterious particles that flit through ordinary matter as though it isn’t there.

Initial data from a new U.S.–based physics experiment indicates scientists are a step closer to understanding neutrinos, the second most abundant particle in the universe.

Neutrinos are little understood, but indications are they hold clues to why matter overwhelmingly survived after the Big Bang instead of just energy in the form of light.

The first data from NOvA, the experiment in northern Minnesota, indicates that NOvA’s massive particle detector — designed to observe and measure the behavior of neutrinos — is functioning as planned.

“In the 18 or so months the experiment has been up and running we’ve analyzed about 8 percent of the data we anticipate collecting over the life of the experiment,” said physicist Thomas Coan, Southern Methodist University, Dallas.

Coan, a professor in SMU’s Department of Physics, is a principal investigator on NOvA, a collaboration of the U.S. Department of Energy’s Fermi National Laboratory. “So we’re really just at the beginning. But it’s a great start, and it’s gratifying that the beginning has begun so well.”

More than 200 scientists from the U.S. and six other countries make up the collaboration.

Specifically, they predict that the experiment’s data will tell them the relative weight of the three different types or “flavors” of neutrinos, as well as reveal whether neutrinos and antineutrinos interact in the same way.

Answers to those questions will add information to theories of matter’s existence and why it wasn’t annihilated during the Big Bang, Coan said.

The completed NOvA far detector in Ash River, Minnesota, stands 50 feet tall, 50 feet wide and 200 feet long. The pivoting machine that was used to move each block of the detector into place now serves as the capstone on the end of the completed structure. Photo: Fermilab
The completed NOvA far detector in Ash River, Minnesota, stands 50 feet tall, 50 feet wide and 200 feet long. The pivoting machine that was used to move each block of the detector into place now serves as the capstone on the end of the completed structure. Photo: Fermilab

“If we want to understand the universe on a large scale, we have to understand how neutrinos behave,” he said. “Experimental observations from NOvA will be an important input into the overarching theory.”

Neutrinos flit through ordinary matter almost as if it weren’t there, so it takes a massive detector to capture evidence of their behavior. Coan likens NOvA to a gigantic pixel camera with its honeycomb array of thousands of plastic tubes encasing highly purified mineral oil.

Neutrinos are not observed directly, so scientists only see the tracks of their rare interactions with atoms. An accelerator at Fermilab in Illinois shoots a neutrino beam, observed first by a near detector there, then by a far detector some 500 miles away in Minnesota.

The far detector, or “pixel camera,” is 50 feet tall by 50 feet wide and 200 feet long.

Oscillating neutrinos change from one “type” to another: electron, muon or tau
As the neutrinos travel they change from one type or “flavor” to another. That “oscillation” confirms the NOvA detector is functioning as designed.

The first NOvA results were released this week at the American Physical Society’s Division of Particles and Fields conference in Ann Arbor, Mich.

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A graphic representation of one of the first neutrino interactions captured at the NOvA far detector in northern Minnesota. The dotted red line represents the neutrino beam, generated at Fermilab in Illinois and sent through 500 miles of earth to the far detector. The image on the left is a simplified 3-D view of the detector, the top right view shows the interaction from the top of the detector, and the bottom right view shows the interaction from the side of the detector. Illustration: Fermilab
A graphic representation of one of the first neutrino interactions captured at the NOvA far detector in northern Minnesota. The dotted red line represents the neutrino beam, generated at Fermilab in Illinois and sent through 500 miles of earth to the far detector. The image on the left is a simplified 3-D view of the detector, the top right view shows the interaction from the top of the detector, and the bottom right view shows the interaction from the side of the detector. Illustration: Fermilab

The results were culled by scientists who sorted through millions of cosmic ray strikes to zero-in on neutrino interactions.

“People are ecstatic to see our first observation of neutrino oscillations,” said NOvA co-spokesperson Peter Shanahan, Fermilab. “For all the people who worked over the course of a decade on the designing, building, commissioning, and operating this experiment, it’s beyond gratifying.”

Researchers have collected data aggressively since February 2014, recording neutrino interactions in the 14,000-ton far detector in Ash River, Minnesota, while construction was still underway. This allowed the collaboration to gather data while testing systems before starting operations with the complete detector in November 2014, shortly after the experiment was completed on time and under budget. NOvA construction and operations are supported by the DOE’s Office of Science.

The neutrino beam generated at Fermilab passes through the underground near detector, which measures the beam’s neutrino composition before it leaves the Fermilab site.

The particles then travel more than 500 miles straight through the earth, changing types along the way. About once per second, Fermilab’s accelerator sends trillions of neutrinos to Minnesota, but the elusive neutrinos interact so rarely that only a few will register at the far detector.

Neutrino-atom interaction releases a signature trail of particles and light
The beam fires neutrinos every 1.5 seconds, but only for 10 microseconds, Coan said. Including downtime for maintenance, neutrinos are produced two minutes total over the course of a year.

“We could make the detector out of iron or granite to get more target atoms and have more interactions, but we’d never be able to observe the interactions in iron and granite,” Coan said. “So the detector has to be transparent somehow, a sort of camera. Those two goals are somewhat contradictory. So it takes some cleverness to figure out how to have a massive detector and still see events in it.”

When a neutrino bumps into an atom in the NOvA detector, it releases a signature trail of particles and light depending on which type it is: an electron, muon or tau neutrino. The beam originating at Fermilab is made almost entirely of one type – muon neutrinos – and scientists can measure how many of those muon neutrinos disappear over their journey and reappear as electron neutrinos.

If oscillations had not occurred, experimenters predicted they would see 201 muon neutrinos arrive at the NOvA far detector in the data collected; instead, they saw a mere 33, proof that the muon neutrinos were disappearing as they transformed into the two other flavors

Similarly, if oscillations had not occurred scientists expected to see only one electron neutrino appearance, due to background interactions, but the collaboration saw six such events, which is evidence that some of the missing muon neutrinos had turned into electron neutrinos.

NOvA observations are nearly equivalent results to those at world’s other neutrino experiments
Similar long-distance experiments such as T2K in Japan and MINOS at Fermilab have seen these muon neutrino-to-electron neutrino oscillations before. NOvA, which will take data for at least six years, is seeing nearly equivalent results in a shorter time frame, something that bodes well for the experiment’s ambitious goal of measuring neutrino properties that have eluded other experiments so far.

“One of the reasons we’ve made such excellent progress is because of the impressive Fermilab neutrino beam and accelerator team,” said NOvA co-spokesperson Mark Messier of Indiana University. “Having a beam of that power running so efficiently gives us a real competitive edge and allows us to gather data quickly.”

Fermilab’s flagship accelerator recently set a high-energy neutrino beam world record when it reached 521 kilowatts, and the laboratory is working on improving the neutrino beam even further for projects such as NOvA and the upcoming Deep Underground Neutrino Experiment. Researchers expect to reach 700 kilowatts early next calendar year, accumulating a slew of neutrino interactions and tripling the amount of data recorded by year’s end.

Most abundant massive particle in the universe is still poorly understood
Neutrinos are the most abundant massive particle in the universe, but are still poorly understood. While researchers know that neutrinos come in three types, they don’t know which is the heaviest and which is the lightest. Figuring out this ordering — one of the goals of the NOvA experiment — would be a great litmus test for theories about how the neutrino gets its mass.

While the famed Higgs boson helps explain how some particles obtain their masses, scientists don’t know yet how the Higgs is connected to neutrinos, if at all.

The measurement of the neutrino mass hierarchy is also crucial information for neutrino experiments trying to see if the neutrino is its own antiparticle.

Like T2K, NOvA can also run in antineutrino mode, opening a window to see whether neutrinos and antineutrinos are fundamentally different. An asymmetry early in the universe’s history could have tipped the cosmic balance in favor of matter, making the world we see today possible. Soon, scientists will be able to combine the neutrino results obtained by T2K, MINOS and NOvA, yielding more precise answers about scientists’ most pressing neutrino questions.

“The rapid success of the NOvA team demonstrates a commitment and talent for taking on complex projects to answer the biggest questions in particle physics,” said Fermilab Director Nigel Lockyer. “We’re glad that the detectors are functioning beautifully and providing quality data that will expand our understanding of the subatomic realm.”

The NOvA collaboration comprises 210 scientists and engineers from 39 institutions in the United States, Brazil, the Czech Republic, Greece, India, Russia and the United Kingdom. — Fermi National Laboratory, SMU

NOvA stands for NuMI Off-Axis Electron Neutrino Appearance. NuMI is itself an acronym, standing for Neutrinos from the Main Injector, Fermilab’s flagship accelerator. The Fermilab Accelerator Complex is an Office of Science User Facility.

For more information, visit the NOvA web site.
Watch live particle events recorded by the NOvA experiment.
Learn how the NOvA detector sees neutrinos.
Follow the experiment on Facebook and Twitter, @novaexperiment.

Follow SMUResearch.com on Twitter, @smuresearch.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Ill., and operated under contract by the Fermi Research Alliance LLC. Visit Fermilab’s website at www.fnal.gov, and follow Fermilab on Twitter at @Fermilab.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

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