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SMU physicist and her students join national laboratories, other universities in high-stakes hunt for elusive dark matter

The future SuperCDMS SNOLAB experiment will hunt for weakly interacting massive particles (WIMPs), hypothetical components of dark matter. If a WIMP (white trace) strikes an atom inside the experiment's detector crystals (gray), it will cause the crystal lattice to vibrate (blue). The collision will also send electrons (red) through the crystal that enhance the vibrations. (Greg Stewart/SLAC National Accelerator Laboratory)

“One of our major concerns is background particles that can mimic the dark matter signature in our detectors.” — Jodi Cooley

SMU physicist Jodi Cooley is a member of the international scientific team that will use a powerful new tool to understand one of the biggest mysteries of modern physics.

The U.S. Department of Energy has approved funding and start of construction for SuperCDMS SNOLAB, a $34 million experiment designed to detect dark matter.

SuperCDMS will begin operations in the early 2020s to hunt for hypothetical dark matter particles called weakly interacting massive particles, or WIMPs.

“Understanding the nature of dark matter is one of the most important scientific puzzles in particle astrophysics today,” said Cooley, an associate professor of experimental particle physics. “The experiment will have unprecedented sensitivity to dark matter particles that are hypothesized to have very low mass and interact very rarely. So they are extremely challenging to detect. This challenge has required us to develop cutting edge detectors.”

Cooley is one of 111 scientists from 26 institutions in the SuperCDMS collaboration. SMU graduate students on the experiment include Matt Stein (Ph.D. ’18) and Dan Jardin; and also previously Hang Qiu (Ph.D. ’17).

Physicists are searching for dark matter because although it makes up the bulk of the universe it remains a mystery. They theorize that dark matter could be composed of dark matter particles, with WIMPs a top contender for the title.

If dark matter WIMP particles exist, they would barely interact with their environment and fly right through regular matter. However, every so often, they could collide with an atom of our visible world, and dark matter researchers are looking for these rare interactions.

The SuperCDMS experiment will be the world’s most sensitive for detecting the relatively light WIMPs.

Cooley and her students in the SMU Department of Physics have been working with Washington-based Pacific Northwest National Laboratory on the challenge of background control and material selection for the experiment’s WIMP detectors.

Understanding background signals in the experiment is a major challenge for the detection of the faint WIMP signals.

“One of our major concerns is background particles that can mimic the dark matter signature in our detectors,” Cooley said. “As such, the experiment is constructed from radiopure materials that are carefully characterized through a screening and assay before they are selected.”

The SMU research team also has performed simulations of background particles in the detectors.

“Doing this helps inform the design of the experiment shield,” Cooley said. “We want to select the right materials to use in construction of the experiment. For example, materials that are too high in radioactivity will produce background particles that might produce fake dark matter signals in our detectors. We are extremely careful to use materials that block background particles. We also take great care that the material we use to hold the detectors in place — copper — is very radiopure.”

The experiment will be assembled and operated within the existing Canadian laboratory SNOLAB – 6,800 feet underground inside a nickel mine near the city of Sudbury. That’s the deepest underground laboratory in North America.

The experiment’s detectors will be protected from high-energy particles, called cosmic radiation, which can create the unwanted background signals that Cooley’s team wants to prevent.

SuperCDMS SNOLAB will be 50 times more sensitive than predecessor
Scientists know that visible matter in the universe accounts for only 15 percent of all matter. The rest is the mysterious substance called dark matter.

Due to its gravitational pull on regular matter, dark matter is a key driver for the evolution of the universe, affecting the formation of galaxies like our Milky Way. It therefore is fundamental to our very own existence.

The SuperCDMS SNOLAB experiment will be at least 50 times more sensitive than its predecessor, exploring WIMP properties that can’t be probed by other experiments.

The search will be done using silicon and germanium crystals, in which the collisions would trigger tiny vibrations. However, to measure the atomic jiggles, the crystals need to be cooled to less than minus 459.6 degrees Fahrenheit — a fraction of a degree above absolute zero temperature.

The ultra-cold conditions give the experiment its name: Cryogenic Dark Matter Search, or CDMS. The prefix “Super” indicates an increased sensitivity compared to previous versions of the experiment.

Experiment will measure “fingerprints” left by dark matter
The collisions would also produce pairs of electrons and electron deficiencies that move through the crystals, triggering additional atomic vibrations that amplify the signal from the dark matter collision. The experiment will be able to measure these “fingerprints” left by dark matter with sophisticated superconducting electronics.

Besides Pacific Northwest National Laboratory, two other Department of Energy national labs are involved in the project.

SLAC National Accelerator Laboratory in California is managing the construction project. SLAC will provide the experiment’s centerpiece of initially four detector towers, each containing six crystals in the shape of oversized hockey pucks. SLAC built and tested a detector prototype. The first tower could be sent to SNOLAB by the end of 2018.

Fermi National Accelerator Laboratory is working on the experiment’s intricate shielding and cryogenics infrastructure.

“Our experiment will be the world’s most sensitive for relatively light WIMPs,” said Richard Partridge, head of the SuperCDMS group at the Kavli Institute for Particle Astrophysics and Cosmology, a joint institute of SLAC and Stanford University. “This unparalleled sensitivity will create exciting opportunities to explore new territory in dark matter research.”

Close-knit network of strong partners is crucial to success
Besides SMU, a number of U.S. and Canadian universities also play key roles in the experiment, working on tasks ranging from detector fabrication and testing to data analysis and simulation. The largest international contribution comes from Canada and includes the research infrastructure at SNOLAB.

“We’re fortunate to have a close-knit network of strong collaboration partners, which is crucial for our success,” said Project Director Blas Cabrera from KIPAC. “The same is true for the outstanding support we’re receiving from the funding agencies in the U.S. and Canada.”

Funding is from the DOE Office of Science, $19 million, the National Science Foundation, $12 million, and the Canada Foundation for Innovation, $3 million.

SuperCDMS to search for dark matter in entirely new region
“Together we’re now ready to build an experiment that will search for dark matter particles that interact with normal matter in an entirely new region,” said SuperCDMS spokesperson Dan Bauer, Fermilab.

SuperCDMS SNOLAB will be the latest in a series of increasingly sensitive dark matter experiments. The most recent version, located at the Soudan Mine in Minnesota, completed operations in 2015.

”The project has incorporated lessons learned from previous CDMS experiments to significantly improve the experimental infrastructure and detector designs for the experiment,” said SLAC’s Ken Fouts, project manager for SuperCDMS SNOLAB. “The combination of design improvements, the deep location and the infrastructure support provided by SNOLAB will allow the experiment to reach its full potential in the search for low-mass dark matter.” — SLAC National Laboratory; and Margaret Allen, SMU

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WFAA Verify: Is West Texas sinking?

A new research report, from Southern Methodist University and funded by NASA, found a “…large swath of West Texas oil patch is heaving and sinking at alarming rates.”

WFAA-TV Channel 8’s Verify journalist David Schechter covered the phenomenon of the ground sinking at alarming rates in West Texas, according to the research of SMU geophysicists Zhong Lu, professor, Shuler-Foscue Chair, and Jin-Woo Kim research scientist, both in the Roy M. Huffington Department of Earth Sciences.

The Dedman College researchers are co-authors of a new analysis using satellite radar images that discovered decades of oil production activity in West Texas have destabilized localities in an area of about 4,000 square miles populated by small towns, roadways and a vast network of oil and gas pipelines and storage tanks.

Schechter’s WFAA ABC report, “Verify: Is West Texas sinking?” aired April 18, 2018.

Lu and Kim reported their findings in the Nature publication Scientific Reports, in the article “Association between localized geohazards in West Texas and human activities, recognized by Sentinel-1A/B satellite radar imagery.”

The researchers analyzed satellite radar images that were made public by the European Space Agency, and supplemented that with oil activity data from the Railroad Commission of Texas.

The study is among the first of its kind to identify small-scale deformation signals over a vast region by drawing from big data sets spanning a number of years and then adding supplementary information.

The research is supported by the NASA Earth Surface and Interior Program, and the Shuler-Foscue Endowment at SMU.

An earlier study by the researchers revealed significant ground movement of two giant sinkholes near Wink, Texas. The SMU geophysicists found that the movement suggests the two existing holes are expanding, and new ones are forming as nearby subsidence occurs at an alarming rate.

Watch the WFAA Verify news segment.

EXCERPT:

By David Schechter
WFAA-TV Verify
A new research report, from Southern Methodist University and funded by NASA, found a “…large swath of West Texas oil patch is heaving and sinking at alarming rates.”

To find out if West Texas is sinking, first I’m going to the guy who wrote the report, Dr. Zhong Lu. He’s a geophysicist who studies the earth using satellites.

By shooting a radar beam from space — like a measuring stick — a satellite can calculate elevation changes down to the centimeter. Lu did that over a 4000 square mile area.

“This area is sinking at half meter per year,” Dr. Lu says.

That’s more than a foot-and-a-half. Lu says, that’s alarming because that much change to the earth’s surface might normally take millions of years.

One of the images in his reports shows an area of sinking earth, near Wink, TX from 2011. Five years later, the satellite shows the sunken area had spread almost 240%.

“In this area that you are studying, is oil and gas the cause of the sinking?” I ask.

“Related to the oil and gas activities,” he says.

“Oil and gas activity is causing the sinking in West Texas?” I clarify.

“Yes,” he says.

Watch the WFAA Verify news segment.

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The Guardian: Texas sinkholes — oil and gas drilling increases threat, scientists warn

Ground rising and falling in region that has been ‘punctured like a pin cushion’ since the 1940s, new study finds.

The Guardian and other news outlets covered the West Texas sinkhole and ground movement research of SMU geophysicists Zhong Lu, professor, Shuler-Foscue Chair, and Jin-Woo Kim research scientist, both in the Roy M. Huffington Department of Earth Sciences at SMU.

The Dedman College researchers are co-authors of a new analysis using satellite radar images that shows decades of oil production activity in West Texas have destabilized localities in an area of about 4,000 square miles populated by small towns, roadways and a vast network of oil and gas pipelines and storage tanks.

An earlier study by the researchers revealed significant ground movement of two giant sinkholes near Wink, Texas. The SMU geophysicists found that the movement suggests the two existing holes are expanding, and new ones are forming as nearby subsidence occurs at an alarming rate.

The Guardian article by journalist Tom Dart was published March 27, 2018, “Texas sinkholes: oil and gas drilling increases threat, scientists warn.”

Other coverage includes articles by Forbes, Tech Times, Phys.org, Ecowatch, Fox San Antonio, The Dallas Morning News and the Texas Tribune.

Others include EarthSky.org, Live Science, KERA News, San Antonio Express, Houston Chronicle, Science Daily, The Energy Mix, Digital Journal, Homeland Security News Wire and the Science Bulletin.

Lu is world-renowned for leading scientists in InSAR applications, short for a technique called interferometric synthetic aperture radar, to detect surface changes that aren’t visible to the naked eye. Lu is a member of the Science Definition Team for the dedicated U.S. and Indian NASA-ISRO InSAR mission, set for launch in 2020 to study hazards and global environmental change.

InSAR accesses a series of images captured by a read-out radar instrument mounted on the orbiting satellite Sentinel-1A. Sentinel-1A was launched in April 2014 as part of the European Union’s Copernicus program.

Lu and Kim reported their latest findings in the Nature publication Scientific Reports, in the article “Association between localized geohazards in West Texas and human activities, recognized by Sentinel-1A/B satellite radar imagery.”

Lu and Kim reported the earlier findings in the scientific journal Remote Sensing, in the article “Ongoing deformation of sinkholes in Wink, Texas, observed by time-series Sentinel-1A SAR Interferometry.”

The research is supported by the U.S. Geological Survey Land Remote Sensing Program, the NASA Earth Surface & Interior Program, and the Shuler-Foscue Endowment at Southern Methodist University.

Read the full story.

EXCERPT:

By Tom Dart
The Guardian
Oil and gas activity is contributing to alarming land movements and a rising threat of sinkholes across a huge swath of west Texas, a new study suggests.

According to geophysicists from Southern Methodist University, the ground is rising and falling in a region that has been “punctured like a pin cushion with oil wells and injection wells since the 1940s”.

There were nearly 297,000 oil wells in Texas as of last month, according to the state regulator. Many are in the Permian Basin, described in a Bloomberg article last September as the “world’s hottest oil patch”.

But the Southern Methodist report warns of unstable land and the threat of sinkholes.

“These hazards represent a danger to residents, roads, railroads, levees, dams, and oil and gas pipelines, as well as potential pollution of ground water,” Zhong Lu, a professor, said in a statement.

Wink – a tiny town 400 miles west of Dallas best known as the childhood home of the singer Roy Orbison – attracted national headlines in 2016 when the same scientists warned that the land between two expanding sinkholes a mile apart was deteriorating, risking the formation of more sinkholes or even the creation of a colossal single hole.

Injection of wastewater and carbon dioxide increases pore pressure in rocks, a likely cause of uplift. Lu told the Guardian that cracks and corrosion from ageing wells may help explain the sinking.

A “subsidence bowl” near one of the Wink sinkholes has sunk at a rate of more than 15.5in a year, probably as a result of water leaks through abandoned wells causing salt layers to dissolve, the report found. Elsewhere, a lake formed after 2003 as a result of sinking ground and rising water.

Read the full story.

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Radar images show large swath of West Texas oil patch is heaving and sinking at alarming rates

Analysis indicates decades of oil production activity have destabilized localities in an area of about 4,000 square miles populated by small towns, roadways and a vast network of oil and gas pipelines and storage tanks

Two giant sinkholes near Wink, Texas, may just be the tip of the iceberg, according to a new study that found alarming rates of new ground movement extending far beyond the infamous sinkholes.

That’s the finding of a geophysical team from Southern Methodist University, Dallas that previously reported the rapid rate at which the sinkholes are expanding and new ones forming.

Now the team has discovered that various locations in large portions of four Texas counties are also sinking and uplifting.

Radar satellite images show significant movement of the ground across localities in a 4000-square-mile area — in one place as much as 40 inches over the past two-and-a-half years, say the geophysicists.

“The ground movement we’re seeing is not normal. The ground doesn’t typically do this without some cause,” said geophysicist Zhong Lu, a professor in the Roy M. Huffington Department of Earth Sciences at SMU and a global expert in satellite radar imagery analysis.

“These hazards represent a danger to residents, roads, railroads, levees, dams, and oil and gas pipelines, as well as potential pollution of ground water,” Lu said. “Proactive, continuous detailed monitoring from space is critical to secure the safety of people and property.”

The scientists made the discovery with analysis of medium-resolution (15 feet to 65 feet) radar imagery taken between November 2014 and April 2017. The images cover portions of four oil-patch counties where there’s heavy production of hydrocarbons from the oil-rich West Texas Permian Basin.

The imagery, coupled with oil-well production data from the Railroad Commission of Texas, suggests the area’s unstable ground is associated with decades of oil activity and its effect on rocks below the surface of the earth.

The SMU researchers caution that ground movement may extend beyond what radar observed in the four-county area. The entire region is highly vulnerable to human activity due to its geology — water-soluble salt and limestone formations, and shale formations.

“Our analysis looked at just this 4000-square-mile area,” said study co-author and research scientist Jin-Woo Kim, a research scientist in the SMU Department of Earth Sciences.

“We’re fairly certain that when we look further, and we are, that we’ll find there’s ground movement even beyond that,” Kim said. “This region of Texas has been punctured like a pin cushion with oil wells and injection wells since the 1940s and our findings associate that activity with ground movement.”

Lu, Shuler-Foscue Chair at SMU, and Kim reported their findings in the Nature publication Scientific Reports, in the article “Association between localized geohazards in West Texas and human activities, recognized by Sentinel-1A/B satellite radar imagery.”

The researchers analyzed satellite radar images that were made public by the European Space Agency, and supplemented that with oil activity data from the Railroad Commission of Texas.

The study is among the first of its kind to identify small-scale deformation signals over a vast region by drawing from big data sets spanning a number of years and then adding supplementary information.

The research is supported by the NASA Earth Surface and Interior Program, and the Shuler-Foscue Endowment at SMU.

Imagery captures changes that might otherwise go undetected
The SMU geophysicists focused their analysis on small, localized, rapidly developing hazardous ground movements in portions of Winkler, Ward, Reeves and Pecos counties, an area nearly the size of Connecticut. The study area includes the towns of Pecos, Monahans, Fort Stockton, Imperial, Wink and Kermit.

The images from the European Space Agency are the result of satellite radar interferometry from recently launched open-source orbiting satellites that make radar images freely available to the public.

With interferometric synthetic aperture radar, or InSAR for short, the satellites allow scientists to detect changes that aren’t visible to the naked eye and that might otherwise go undetected.

The satellite technology can capture ground deformation with an accuracy of sub-inches or better, at a spatial resolution of a few yards or better over thousands of miles, say the researchers.

Ground movement associated with oil activity
The SMU researchers found a significant relationship between ground movement and oil activities that include pressurized fluid injection into the region’s geologically unstable rock formations.

Fluid injection includes waste saltwater injection into nearby wells, and carbon dioxide flooding of depleting reservoirs to stimulate oil recovery.

Injected fluids increase the pore pressure in the rocks, and the release of the stress is followed by ground uplift. The researchers found that ground movement coincided with nearby sequences of wastewater injection rates and volume and CO2 injection in nearby wells.

Also related to the ground’s sinking and upheaval are dissolving salt formations due to freshwater leaking into abandoned underground oil facilities, as well as the extraction of oil.

Sinking and uplift detected from Wink to Fort Stockton
As might be expected, the most significant subsidence is about a half-mile east of the huge Wink No. 2 sinkhole, where there are two subsidence bowls, one of which has sunk more than 15.5 inches a year. The rapid sinking is most likely caused by water leaking through abandoned wells into the Salado formation and dissolving salt layers, threatening possible ground collapse.

At two wastewater injection wells 9.3 miles west of Wink and Kermit, the radar detected upheaval of about 2.1 inches that coincided with increases in injection volume. The injection wells extend about 4,921 feet to 5,577 feet deep into a sandstone formation.

In the vicinity of 11 CO2 injection wells nearly seven miles southwest of Monahans, the radar analysis detected surface uplift of more than 1 inch. The wells are about 2,460 feet to 2,657 feet deep. As with wastewater injection, CO2 injection increased pore pressure in the rocks, so when stress was relieved it was followed by uplift of about 1 inch at the surface.

The researchers also looked at an area 4.3 miles southwest of Imperial, where significant subsidence from fresh water flowing through cracked well casings, corroded steel pipes and unplugged abandoned wells has been widely reported.

Water there has leaked into the easily dissolved Salado formation, created voids, and caused the ground to sink and water to rise from the subsurface, including creating Boehmer Lake, which didn’t exist before 2003.

Radar analysis by the SMU team detected rapid subsidence ranging from three-fourths of an inch to nearly 4 inches around active wells, abandoned wells and orphaned wells.

“Movements around the roads and oil facilities to the southwest of Imperial, Texas, should be thoroughly monitored to mitigate potential catastrophes,” the researchers write in the study.

About 5.5 miles south of Pecos, their radar analysis detected more than 1 inch of subsidence near new wells drilled via hydraulic fracturing and in production since early 2015. There have also been six small earthquakes recorded there in recent years, suggesting the deformation of the ground generated accumulated stress and caused existing faults to slip.

“We have seen a surge of seismic activity around Pecos in the last five to six years. Before 2012, earthquakes had not been recorded there. At the same time, our results clearly indicate that ground deformation near Pecos is occurring,” Kim said. “Although earthquakes and surface subsidence could be coincidence, we cannot exclude the possibility that these earthquakes were induced by hydrocarbon production activities.”

Scientists: Boost the network of seismic stations to better detect activity
Kim stated the need for improved earthquake location and detection threshold through an expanded network of seismic stations, along with continuous surface monitoring with the demonstrated radar remote sensing methods.

“This is necessary to learn the cause of recent increased seismic activity,” Kim said. “Our efforts to continuously monitor West Texas with this advanced satellite technique can help sustain safe, ongoing oil production.”

Near real-time monitoring of ground deformation possible in a few years
The satellite radar datasets allowed the SMU geophysicists to detect both two-dimension east-west deformation of the ground, as well as vertical deformation.

Lu, a leading scientist in InSAR applications, is a member of the Science Team for the dedicated U.S. and Indian NASA-ISRO (called NISAR) InSAR mission, set for launch in 2021 to study hazards and global environmental change.

InSAR accesses a series of images captured by a read-out radar instrument mounted on the orbiting satellite Sentinel-1A/B. The satellites orbit 435 miles above the Earth’s surface. Sentinel-1A was launched in 2014 and Sentinel-1B in 2016 as part of the European Union’s Copernicus program.

The Sentinel-1A/B constellation bounces a radar signal off the earth, then records the signal as it bounces back, delivering measurements. The measurements allow geophysicists to determine the distance from the satellite to the ground, revealing how features on the Earth’s surface change over time.

“Near real-time monitoring of ground deformation at high spatial and temporal resolutions is possible in a few years, using multiple satellites such as Sentinel-1A/B, NISAR and others,” said Lu. “This will revolutionize our capability to characterize human-induced and natural hazards, and reduce their damage to humanity, infrastructure and the energy industry.” — Margaret Allen, SMU

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The Dallas Morning News: Earthquakes at DFW Airport continued for years after oil and gas wastewater well was shut

“Faults are not like a light switch – you don’t turn off a well and automatically stop triggering earthquakes.” — Heather DeShon, SMU seismologist.

Science journalist Anna Kuchment covered the earthquake research of a team of SMU seismologists led by SMU Associate Professor Heather DeShon and SMU Post-doctoral Researcher Paul Ogwari, who developed a unique method of data analysis that yielded the study results.

Kuchment wrote Earthquakes at DFW Airport continued for years after oil and gas wastewater well was shut for The Dallas Morning News.

The results of the analysis showed that efforts to stop human-caused earthquakes by shutting down wastewater injection wells that serve adjacent oil and gas fields may oversimplify the challenge. The seismologists analyzed a sequence of earthquakes at DFW Airport and found that even though wastewater injection was halted after a year, the earthquakes continued.

The sequence of quakes began in 2008, and wastewater injection was halted in 2009. But earthquakes continued for at least seven more years.

“This tells us that high-volume injection, even if it’s just for a short time, when it’s near a critically stressed fault, can induce long-lasting seismicity,” said Ogwari. The earthquakes may be continuing even now, he said.

The article by Kuchment, “Earthquakes at DFW Airport continued for years after oil and gas wastewater well was shut,” published Feb. 21, 2018.

Read the full story.

EXCERPT:

By Anna Kuchment
The Dallas Morning News
Earthquakes beneath DFW International Airport continued for seven years after an oil and gas company shut a nearby wastewater injection well that had been linked to the quakes, according to a new study by scientists at Southern Methodist University.

A wastewater well that continues to operate at the northern end of the airport – and which some area residents have said should be closed — was probably not involved in the events and poses little earthquake hazard, the researchers concluded.

“Faults are not like a light switch – you don’t turn off a well and automatically stop triggering earthquakes,” said Heather DeShon, a seismologist at Southern Methodist University and co-author of the paper, in an email.

The earthquakes at DFW Airport started on Halloween 2008, seven weeks after Chesapeake Energy began injecting wastewater into a well at the southern end of the airport. Scientists at SMU and the University of Texas at Austin investigated the quakes at the time and concluded they were most likely associated with the well.

Though Chesapeake shut its well in August 2009, earthquakes continued through at least the end of 2015. The largest, a 3.4-magnitude event, struck three years after the well was closed.

“It’s very surprising that one year of injection could produce earthquakes running for more than seven years,” said Paul Ogwari, the study’s lead author and a post-doctoral researcher at SMU. The paper was published in the Journal of Geophysical Research.

While earthquake magnitudes did not decline, Ogwari said, earthquake rates did: More than 80 percent of quakes in the sequence occurred during the first seven months of seismicity.

The DFW quakes are significant, because they mark the start of an unprecedented surge of earthquakes in North Texas and across the middle of the country.

Read the full story.