From DOE’s Fermi National Accelerator Laboratory (US) : “DUNE prototype detector ArgonCube crosses the globe”

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From DOE’s Fermi National Accelerator Laboratory (US) , an enduring source of strength for the US contribution to scientific research worldwide.

June 30, 2021
Brianna Barbu

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The ArgonCube collaboration assembled the first of four prototype neutrino detector modules for the DUNE near detector at the University of Bern [Universität Bern](CH). The module now is on its way to Fermilab for testing with a neutrino beam. Photo: Igor Kreslo.

Imagine you’re standing at one end of a long, windowless hallway. The only light is the beam from a flashlight in your hand, illuminating the length of the hall. In the beam’s path are two clear boxes: one right in front of you, the other at the far end of the hall. Because the beam’s light spreads out as it travels, the far box is lit only dimly, while the near box is blindingly bright.

That, in a nutshell, is the difference between what the near and far detectors will see when the international Fermi National Accelerator Laboratory DUNE/LBNF experiment (US) hosted by the U.S. Department of Energy’s Fermi National Accelerator Laboratory starts up later this decade.

But instead of light from a flashlight, DUNE will send a particle beam through multiple detectors to tackle big mysteries in particle physics — including why the universe evolved the way it did.

At the heart of the experiment are elusive particles called neutrinos, which scientists will study using detectors underground at Fermilab in Illinois and the Sanford Underground Research Facility, or SURF, in South Dakota.

The far detector, 800 miles (1,300 kilometers) from the source of the beam, will detect about one neutrino for every four hours of data collection — the dim light in our analogy. The near detector, about 2,000 feet (600 meters) from the beam source, will be bombarded with neutrinos, capturing about a dozen every second.

For the past six years, an international collaboration of more than 100 scientists and engineers from 31 institutions has been working on ArgonCube, a new type of detector that will make sure the near detector can successfully see all of the neutrino interactions clearly without “glare” from overlapping signals. A prototype is now traveling from the University of Bern in Switzerland to Fermilab for testing with the lab’s neutrino beams.

“A lot of people were involved, including a lot of students and postdocs,” said Michele Weber, who leads the team at Bern working on the near detector. “We’re all very excited about creating something new.”

Creating something new

Neutrinos come in three varieties, called flavors. But thanks to some of nature’s quantum shenanigans known as oscillation, they change flavor as they travel. DUNE’s near and far detectors will record what flavors make up the beam at the beginning and end of their journey from Fermilab to SURF. Looking at how the neutrinos change during their journey will give scientists clues about the fundamental building blocks of matter and how the universe began.

Two main innovations will help ArgonCube sort out a deluge of neutrino data. The first is a pixelated charge readout, which adds a third dimension to data collection. Current state-of-the art detectors such as ProtoDUNE, an enormous testbed for DUNE’s far detectors, use wires for charge collection.

While powerful, these systems only create a 3D view of the particle interactions by overlaying several 2D images. In the flurry of chaotic and overlapping particle interactions in the near detector, the extra spatial dimension provided by ArgonCube will make it easier for scientists to tell apart near-simultaneous neutrino events. Each ArgonCube protype module has around 80,000 pixels.

The other ArgonCube feature that will help scientists distinguish between multiple neutrino interactions in the near detector is modularity. The final detector will be made up of 35 independent ArgonCube modules sharing a single cryogenic argon bath.

“Having multiple search volumes helps us see each single interaction separately,” said Weber. Despite the name, ArgonCube modules are actually rectangular. The prototype currently en route to Fermilab is nearly 6 feet tall with a 2.5-by-2.5-foot base (1.8 meters tall with about a three-quarter meter square base). The final modules for the near detector will be about twice as tall and 5 times bigger in volume.

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Four ArgonCube prototype modules will undergo testing with the NuMI neutrino beam, powered by Fermilab’s Main Injector accelerator. Each module is nearly 6 feet tall. The DUNE near detector will feature 35 modules, each one five times larger in volume than a prototype module. Illustration: Gary Smith, Fermilab.

The modular setup means the charge and light produced by neutrino interactions won’t have as far to travel to reach the electronics that record them. Hence, the electric field voltage doesn’t have to be as high to draw those particles along. This reduces the demand on high-voltage supply and makes the detector easier and safer to operate.

ArgonCube also includes an improved light detection system, important for reconstructing the timing of particle interactions. It also features a new, more compact way of producing the internal electric field.

Building blocks

Researchers tested the first complete ArgonCube prototype module at Bern earlier this year. The prototype module successfully picked up particle tracks from cosmic ray muons, high-energy particles produced in Earth’s atmosphere. With that basic functionality confirmed, the team used cosmic rays to check that the detector’s charge and light detection systems work together to capture 3D particle trajectories.

That same module, with its accompanying cryogenic system, is now on its journey by truck and ship to Fermilab for the next phase of testing. This will be the first large DUNE prototype module to arrive at Fermilab. A second module will come in early fall, followed by two more by the end of 2021.

The Fermilab team plans to first test two ArgonCube modules side-by-side above ground at the Liquid Argon Test Facility. There they will check the cryogenic systems and do initial troubleshooting related to connecting the modules and combining their signals. Then the team needs to work out how best to install and operate modules in tandem. The next step is to take all four modules 300 feet (100 meters) underground to the refurbished MINOS hall for testing with a neutrino beam powered by Fermilab’s Main Injector accelerator, known as the NuMI beamline.

“From one module to two and two to four is a big change,” said Ting Miao, the Fermilab scientist serving as project manager for the prototype installation and testing. “We want to flesh out all the details of operation and installation before we do things underground.”

The NuMI beam will simulate the intense onslaught of neutrinos that the DUNE near detector will see and make sure the detector can disentangle overlapping signals. Beginning next year, these tests will look at every aspect of the detection process — including beam timing, event selection and data processing. The results will confirm whether the modular approach works. They will help the ArgonCube team prepare for analyzing the data from the 35 full-size modules that will go into the final DUNE near detector.

Though it will be a few years before the ArgonCube technology fulfills its DUNE destiny, it’s already made remarkable strides since the idea for a next-generation modular neutrino detector was first sketched out during a coffee hour at Bern in 2014.

“The most amazing thing is to see the journey of this detector, coming together from first ideas on a blackboard and pieces of paper to recording particle events,” said Weber.

The international Deep Underground Neutrino Experiment hosted by Fermilab is supported by the DOE Office of Science.

See the full article here.


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Fermi National Accelerator Laboratory (US), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association (URA). Fermilab is a part of the Illinois Technology and Research Corridor.

Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

In addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE (Micro Booster Neutrino Experiment), NOνA (NuMI Off-Axis νe Appearance) and SeaQuest. Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment). The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year. SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector. In 2017, the ICARUS neutrino experiment was moved from CERN to Fermilab.
In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.
Asteroid 11998 Fermilab is named in honor of the laboratory.
Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.

The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.
After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.
The later directors include:

John Peoples, 1989 to 1996
Michael S. Witherell, July 1999 to June 2005
Piermaria Oddone, July 2005 to July 2013
Nigel Lockyer, September 2013 to the present

Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid.

DOE’s Fermi National Accelerator Laboratory(US)/MINERvA Reidar Hahn.

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