UK pledges $88 million to gigantic U.S. particle physics experiment

Editor’s note: Today in Washington, D.C., UK Minister of State for Universities, Science, Research and Innovation Jo Johnson signed the first ever Science and Technology Agreement between the United Kingdom and the United States and announced a commitment of approximately $88 million for the international LBNF/DUNE project. We are pleased to distribute this press release on behalf of the British Embassy in Washington, D.C., and the U.S. State Department.

The U.S. Department of Energy’s Fermi National Accelerator Laboratory is the host laboratory for the LBNF/DUNE project, which will use Fermilab’s world-leading accelerator complex to send a beam of ghostly particles called neutrinos 800 miles through Earth to a massive detector that will be built a mile below the surface at the Sanford Underground Research Facility in South Dakota.

More than a thousand scientists from institutions in more than 30 countries around the world contribute to the LBNF/DUNE project. The UK has been an essential partner in the experiment since its inception, and the collaboration includes scientists from 16 UK institutions. The U.S. contribution to LBNF/DUNE is supported by the U.S. Department of Energy.  

“The United Kingdom has long been a leader in this area of science, starting with Ernest Rutherford in the early 20th century,” said Fermilab Director Nigel Lockyer. “This agreement ensures that LBNF/DUNE will have great scientific and technical strength on the team as we chart the bright future for neutrino research.”

Joint statement by the governments of the United States of America and United Kingdom of Great Britain and Northern Ireland on the U.S.-U.K. Science and Technology Agreement

U.S. Acting Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs Judith G. Garber and UK Minister of State for Universities, Science, Research and Innovation Jo Johnson signed the U.S.-UK Science and Technology Agreement on Sept. 20 in Washington, D.C. The signing ceremony marks the first ever umbrella agreement between the United States and United Kingdom outlining a commitment to collaborate on world-class science and innovation.  Accompanying Jo Johnson on the visit to the United States was Chief Executive Designate at U.K. Research and Innovation Sir Mark Walport.

Expanding the frontiers of physics

The first major project of the agreement is UK investment in the Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE), for which the UK government has confirmed approximately $88 million in funding. Construction for LBNF/DUNE is expected to create an estimated 4,000 jobs in the United States, about 2,000 in South Dakota and 2,000 in Illinois. The $88 million in funding makes the UK the largest country investor in the project outside of the United States.

The LBNF/DUNE project aims to answer some of the most important questions in science and advance our understanding of the origin and structure of the universe. One aspect of study is the behavior of neutrinos and their antimatter counterparts, antineutrinos. The project could provide insight as to why we live in a matter-dominated universe and inform the debate on why the universe survived the Big Bang.

The UK is a major scientific contributor to the DUNE collaboration, with 14 UK universities and two Science and Technology Facilities Council laboratories providing essential expertise and components to the experiment and facility. UK involvement in the project will also provide opportunities for UK industry to build capability in new and developing technologies, for example, in precision engineering, cryogenics and accelerator-based applications.

Improving digital research skills

Building on the U.S.-UK partnership, the U.S. Smithsonian Institution and the UK Arts Humanities Research Council are extending a successful history of partnerships by developing a new collaboration, based at the Smithsonian’s National Museum of American History, focused on increasing the use of digital research skills in museums. Enhancing these skills will benefit areas such as data analysis, curating, and accessibility of collections, and will also further audience engagement. This work will help achieve new best practices in digital scholarship and the application of digital technologies at research-led museums.

Breaking new ground together

The U.S.-UK scientific partnership is one of the world’s strongest, with bilateral collaborations resulting in 26 Nobel Prizes in science and economics. The investment in LBNF/DUNE is the most recent example from a long history of collaboration in industries ranging from aerospace to robotics to agriculture. U.S.-UK cooperation on science and innovation benefits both nations by sharing expertise to enhance our understanding of many important topics that have the potential to be world-changing, helping maintain our position as global leaders in research for years to come.

For further information, please contact Yoon Nam at namys@state.gov.

Read more from STFC: http://www.stfc.ac.uk/news/uk-signs-65m-science-partnership-agreement-with-us

 

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, Illinois, and operated under contract by the Fermi Research Alliance LLC, a joint partnership between the University of Chicago and the Universities Research Association, Inc. Visit Fermilab’s website at www.fnal.gov and follow us 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.

 

Technology proposed 30 years ago to search for dark matter is finally seeing the light.

Scientists are using innovative sensors, called skipper CCDs (short for charge-coupled devices) in a new type of dark matter detection project. Scientists will use the project, known as SENSEI, to find the lightest dark matter particles anyone has ever looked for.

Dark matter — so named because it doesn’t absorb, reflect or emit light — constitutes 27 percent of the universe, but the jury is still out on what it’s made of. The primary theoretical suspect for the main component of dark matter is a particle scientists have descriptively named the weakly interactive massive particle, or WIMP.

But since none of these heavy particles, which are expected to have a mass 100 times that of a proton, have shown up in experiments, it might be time for researchers to think small.

“There is a growing interest in looking for different kinds of dark matter that are additives to the standard WIMP model,” said Fermilab scientist Javier Tiffenberg, a leader of the SENSEI collaboration. “Lightweight, or low-mass, dark matter is a very compelling possibility, and for the first time, the technology is there to explore these candidates.”

Low-mass dark matter would leave a tiny, difficult-to-see signature when it collides with material inside a detector. Catching these elusive particles requires a dark-matter-detecting master: SENSEI.

Sensing the unseen

In traditional dark matter experiments, scientists look for a transfer of energy that would occur if dark matter particles collided with an ordinary nucleus, but SENSEI is different. It looks for direct interactions of dark matter particles colliding with electrons.

“That is a big difference — you get a lot more energy transferred in this case because an electron is so light compared to a nucleus,” Tiffenberg said.

If dark matter has low mass — much smaller than the WIMP model suggests — then it would be many times lighter than an atomic nucleus. So if it were to collide with a nucleus, the resulting energy transfer would be far too small tell us anything. It would be like throwing a ping pong ball at a boulder: the heavy object isn’t going anywhere, and there would be no sign the two had come into contact.

An electron is nowhere near as heavy as an atomic nucleus. In fact, a single proton has about 1,836 times more mass than an electron. So the collision of a low-mass dark matter particle with an electron has a much better chance of leaving a mark — more bowling ball than the nucleus’s boulder.

Even so, the electron is still a bowling ball compared to the low-mass dark matter particle. An energy transfer between the two would leave only a blip of energy, one either too small for most detectors to pick up or easily overshadowed by noise in the data. There is a small exchange of energy, but, if the detector isn’t sensitive enough, it could appear as though nothing happens.

“The bowling ball will move a very tiny amount,” said Fermilab scientist Juan Estrada, a SENSEI collaborator. “You need a very precise detector to see this interaction of lightweight particles with something that is much heavier.”

That’s where SENSEI’s sensitive skipper CCDs come in: They will pick up on that tiny transfer of energy.

CCDs have been used for other dark matter detection experiments, such as the Dark Matter in CCDs (or DAMIC) experiment operating at SNOLAB in Canada. These CCDs were a spinoff from sensors developed for use in the Dark Energy Camera in Chile and other dark energy search projects.

CCDs are typically made of silicon divided into pixels. When a dark matter particle passes through the CCD, it collides with silicon’s electrons, knocking them free, leaving a net electric charge in each pixel the particle passes through. The electrons then flow through adjacent pixels and are ultimately read as a current in a device that measures the number of electrons freed from each CCD pixel. That measurement tells scientists about the mass and energy of the particle — in this case the dark matter particle — that got the chain reaction going. A massive particle, like a WIMP, would free a gusher of electrons, but a low-mass particle might free only one or two.

Typical CCDs can measure the charge left behind only once, which makes it difficult to decide if a tiny energy signal from one or two electrons is real or an error.

Skipper CCDs are a new generation of the technology that helps eliminate the “iffiness” of a measurement that has a one- or two-electron margin of error. That allows for much higher precision thanks to a unique design.

“In the past, detectors could measure the amount of charge of the energy deposited in each pixel only once,” Tiffenberg said. “The big step forward for the skipper CCD is that we are able to measure this charge as many times as we want.”

The charge left behind in the skipper CCD by dark matter knocking electrons free can be sampled multiple times and then averaged, a method that yields a more precise measurement of the charge deposited in each pixel than the measure-one-and-done technique. That’s the rule of statistics: With more data, you get closer to a property’s true value.

SENSEI scientists take advantage of the skipper CCD architecture, measuring the number of electrons in a single pixel a whopping 4,000 times and then averaging them. That minimizes the measurement’s error — or noise — and clarifies the signal.

“This is a simple idea, but it took us 30 years to get it to work,” Estrada said.

From idea, to reality, to beyond

A small SENSEI prototype is currently running at Fermilab in a detector hall 385 feet below ground, and it has demonstrated that this detector design will work in the hunt for dark matter.

After a few decades existing as only an idea, skipper CCD technology and SENSEI were brought to life by Laboratory Directed Research and Development (LDRD) funds at Fermilab and Lawrence Berkeley National Laboratory (Berkeley Lab). The Fermilab LDRDs were awarded only recently — less than two years ago — but close collaboration between the two laboratories has already yielded SENSEI’s promising design, partially thanks to Berkeley lab’s previous work in skipper CCD design.

Fermilab LDRD funds allow researchers to test the sensors and develop detectors based on the science, and the Berkeley Lab LDRD funds support the sensor design, which was originally proposed by Berkeley Lab scientist Steve Holland.

“It is the combination of the two LDRDs that really make SENSEI possible,” Estrada said.

LDRD programs are intended to provide funding for development of novel, cutting-edge ideas for scientific discovery, and SENSEI technology certainly fits the bill — even beyond its search for dark matter.

Future SENSEI research will also receive a boost thanks to a recent grant from the Heising-Simons Foundation.

“SENSEI is very cool, but what’s really impressive is that the skipper CCD will allow the SENSEI science and a lot of other applications,” Estrada said. “Astronomical studies are limited by the sensitivity of their experimental measurements, and having sensors without noise is the equivalent of making your telescope bigger — more sensitive.”

SENSEI technology may also be critical in the hunt for a fourth type of neutrino, called the sterile neutrino, which seems to be even more shy than its three notoriously elusive neutrino family members.

A larger SENSEI detector equipped with more skipper CCDs will be deployed within the year. It’s possible it might not detect anything, sending researchers back to the drawing board in the hunt for dark matter. Or SENSEI might finally make contact with dark matter — and that would be SENSEI-tional.

On July 21, a group of dignitaries broke ground on the Long-Baseline Neutrino Facility (LBNF) 4,850 feet underground in a former goldmine, making a small dent in the roughly 800,000 tons of rock that will ultimately be excavated for Fermilab’s flagship experiment.

But a groundbreaking ceremony doesn’t always mean you can get straight to digging.

Removing 800,000 tons of rock from a mile underground and assembling a massive particle detector in its place is a big job. Many months of careful design and preparatory construction work have to happen before the main excavation can even start at the future site of the Deep Underground Neutrino Experiment (DUNE) at Sanford Underground Research Facility in Lead, South Dakota.

On Aug. 9, a new team officially signed on to help prepare for the excavation and construction of DUNE. Fermi Research Alliance LLC, which operates Fermilab, awarded Kiewit/Alberici Joint Venture (KAJV) a contract to begin laying the groundwork for the excavation for LBNF, the facility that will support DUNE.

“Our team is excited and honored to serve as the construction manager/general contractor on a project like the Long-Baseline Neutrino Facility,” said KAJV Project Manager Scott Lundgren. “We look forward to working with Fermi Research Alliance to support this groundbreaking physics experiment.”

Under the contract, over the next 12 months, KAJV will assist in the final design and excavation planning for LBNF/DUNE.

“We’re all very excited about this partnership,” said Troy Lark, LBNF procurement manager. “It’s great to be working with two premier international contracting companies on this project.”

The four-story-high, 70,000-ton DUNE detector at LBNF will catch neutrinos — subatomic particles that rarely interact with matter — sent through the Earth’s mantle from Fermilab, 800 miles away. This international megascience experiment will work to unravel some of the mysteries surrounding neutrinos, possibly leading to a better understanding of how the universe began.

Building such an ambitious experiment has some unique challenges.

“It’s kind of like building a ship in a bottle,” said Chris Mossey, Fermilab’s deputy director for LBNF. “We’re using a narrow shaft to move all the excavated rock up, and then all the parts and pieces of very large cryostats and detectors down to the 4850 level, about a mile underground.”

KAJV will have two main tasks. The first is to help finalize design and excavation plans for LBNF. The second is to use the finalized designs to create what are known as bid packages: specific projects that KAJV or other contractors will work on.

These bid packages will include jobs such as building site infrastructure and ensuring the structural integrity of the building above the shaft through which everything will enter or exit the mine.

“Before you excavate about 800,000 tons of rock, there’s a lot of things you’ve got to do. You have to have a system to move the rock safely from where it’s excavated to the surface, then horizontally about 3,700 feet to the large open pit where it will be deposited,” Mossey said. “All that has to be built.”

Construction on pre-excavation projects — such as the conveyor system to move the rock — is expected to begin in 2018. The main excavation for LBNF/DUNE is planned to start in 2019.

“We’re really happy to get this contract awarded,” Mossey said. “It was a lot of work to get to this point — a lot by the project, the lab and the DOE team. Everybody worked to be able to get this big, complicated contract in place.”

Editor’s note: The amount of rock to be excavated for LBNF at the South Dakota site mentioned in this article was updated on May 2, 2019.

Dr. Robert F. Betz was a biochemist. He was also a veteran of World War II and fought in the Battle of the Bulge. Dr. Betz was known, at Fermilab, for creating and overseeing the prairie planting project.

From the early 1970s until shortly before his death in 2007, Bob worked tirelessly with Fermilab Roads and Grounds to prepare, plant, burn and monitor the Fermilab prairies. Today, we have nearly 1,000 acres here. Species by species, year by year, Bob would collect and plant the seeds and advise the Prairie Committee on how to keep building. It was always to keep building prairie. He would tell us he had prairie fever, and, if we spent too much time with him, we would catch it as well. The only known cure, he said, was to see more prairie.

Bob Betz had an influence on hundreds of prairie projects in the Midwest, most notably here at Fermilab. He also touched the lives of tens of thousands, preaching the greatness and beauty of the nearly extinct tallgrass prairie. When I was a summer student with Roads and Grounds in 2002, I traveled with Bob Lootens, Mike Becker and Martin Valenzuela to a remnant prairie in Markham, Illinois. There, in the morning, we met with Betz to collect seeds from rare plants, growing in this never plowed prairie. After a few hours in the sun, we decided to go to the local Burger King for lunch. Betz didn’t want to go to the McDonalds, which was closer. As we placed our orders and waited, Lootens pointed to Betz. I looked to see him standing by the fountain drink dispenser with a large, empty cup in his hand. We watched as he placed the cup first under Coke, then root beer, and finally a splash of Dr. Pepper.

“He must be happy about the rare species we collected with that mix of pop,” Lootens leaned in and said. Betz turned around with his characteristic, large grin. Together, we laughed.

Today the prairies at Fermilab are named for Robert Betz. A plaque marking the dedication sits inside the Main Ring.

Para una versión en español, haga clic aquí. Para a versão em português, clique aqui.

Neutral-pion production is a major character in a story of mistaken identity worthy of an Agatha Christie novel.

First, the cast of characters: Neutrinos, the quarries of the MINERvA experiment, are subtle, difficult-to-capture particles. They come in three types, two of which play a prominent role in this story: the electron neutrino and the muon neutrino. Since neutrinos are hard to capture, scientists do the next best thing: study other types of particles resulting from the neutrino’s interaction with a nucleus in the detector.

One of these resulting particles is the pion. Pions can be electrically neutral or not. In this story, we focus on neutral pions, and they often transform into two photons, particles of light.

Then there’s the electron, a particle we all know and love, and its cousin the muon. An electron neutrino leaves behind electrons, and a muon neutrino leaves behind muons.

Finally, a twist: neutrinos can switch identities. An electron neutrino can flip and become a muon neutrino and vice versa. The behavior is called oscillation.

Oscillation experiments look for electron neutrinos (which leave electrons in their wake) that were originally muon neutrinos (which produce mostly muons). If they see an electron, they know their muon neutrino has oscillated into an electron neutrino. If they see a muon, they conclude the muon neutrino did not oscillate by the time it reached them.

Every good mystery has its red herrings, and in this case of mistaken identity, the culprit is the pion: Neutral pions can disguise themselves as electrons —the telltale sign that an electron neutrino has passed through — in a particle detector. So when scientists think they have identified electrons, they might actually be looking at pions.

Why does this happen? Pions decay into two photons. Let’s say that one photon escapes detection, and the other, as often happens, looks a lot like an electron. This can trick the experiment into counting what was really the arrival of two photons as an electron sighting —therefore counting an event as the arrival of an electron neutrino when it was really a muon neutrino. So it seem like the neutrino has oscillated when, really, it has not.

To avoid such misidentification, MINERvA scientists measured how often a neutrino interaction results in a muon and a neutral pion. This measurement gives us one handle on predicting the number of cases of mistaken identity that bigger Fermilab neutrino experiments, namely NOvA and DUNE, will see.

Measuring neutral-pion production can also help us understand the relationship between the neutrino’s energy and the resulting particles we see in our detectors. One of the biggest problems in oscillation experiments occurs when a neutrino of one energy masquerades as a neutrino of another energy. This happens frequently when some of the particles get stuck inside the nucleus of the detector material or transform into other particles. MINERvA’s measurement of neutral-pion production is sensitive to these kinds of effects and helps theorists improve their models of the nucleus.

The MINERvA collaboration is excited about these new results. The protons in our detector are also excited — they reach very high energy levels in the neutrino events studied in this analysis.

For the first time ever, we have a measurement where both a neutral pion and a proton are observed. These pion-proton events tell us about the behavior of a kind of excitation that occurs inside the nucleus. These measurements also contain information about the energy and angles of both the neutral pion and the muon that goes with it.

This level of detail is important both for oscillation experiments and for improving our theoretical models.

The MINERvA collaboration recently submitted for publication a paper on measurements of neutral pion production by neutrinos. This result was presented at the Fermilab wine and cheese seminar on July 7 by Ozgur Altinok of Tufts University, an analysis he performed along with Trung Le, also of Tufts.

Barbara Yaeggy is a physicist at Federico Santa María Technical University in Chile.

This article was translated from the Spanish by physicist Chris Marshall of Lawrence Berkeley National Laboratory.