Moving Neutrino Detector

Editor’s note: At 4:40 p.m. today, the neutrino detection system was placed inside the SBND detector hall after a successful move.

After years of construction, testing and planning, an exciting move is now underway at the US Department of Energy’s Fermi National Accelerator Laboratory.

A neutrino detection system built for the short-base near detector will travel 3 miles today, December 1, from the warehouse-like building in which it was built to its final home in the hall of the SBND detector. There, scientists will use a beam of particles called neutrinos to examine the collisions of these particles with atoms. Their goal is to learn more about the mysterious properties of neutrinos.

Moving the system is no easy feat. As a nearly 20-foot cube, it’s the size of a small house. It weighs 20,000 pounds and contains delicate sensors and cables that, if shaken too much, could compromise the integrity of the system.

Scientists, engineers and staff at Fermilab have anticipated this movement for years and spent countless hours preparing for it. Now is the day. The move began at 6 a.m. and is expected to take 8-10 a.m. Staff began by running the detection system through a large roll-up door with only a few centimeters of clearance. Then they will load it onto a flatbed trailer using a crane. The public can get updates on the go via the lab’s social media platforms.

Once in place on the trailer, the truck will travel at a top speed of approximately 2.5 miles per hour on its 3-mile journey through the Fermilab campus to the detector hall, where the crane will lift it trailer and bring it back to solid ground. . Finally, teams will roll the detection system through a garage door into its new home.

In the coming months, the system will be placed inside a large cryostat, a vessel to cool the system to low temperatures which will be filled with liquid argon and full SBND. In the fall of 2023, scientists expect to start receiving data that will shed light on the strange behavior of ghostly neutrinos.

A large group of people – including scientists, engineers, riggers and security personnel – have meticulously planned the move for years – even from the very design of the detector. Now they are thrilled that the process is finally coming to fruition.

“It’s like taking your baby to the first day of school,” said Fermilab’s Shishir Shetty, a mechanical engineer who helped design the carrier system. “So many people have put their time and effort into building the detector and planning the move, and now we’re finally at the point where we can see the results of those efforts.”

Measurements that have never been done before

SBND will play a key role in understanding neutrinos: subatomic particles that have very little interaction with matter but may hold the answers to many mysteries surrounding our universe. So far, scientists have discovered three types of neutrinos. SBND, as part of Fermilab’s Short-Baseline Neutrino program, will help confirm or refute the existence of a potential fourth type, called a sterile neutrino.

The Short-Baseline Neutrino program analyzes a neutrino beam with three liquid argon time-projection chamber detectors, including the new SBND. (It’s the same technology scientists will use for the much larger detectors in the Deep Underground Neutrino experiment.) All three detectors measure neutrinos as they move along a straight path, looking for signs of oscillations – the way neutrinos change into different types as they travel. At 110 meters from the beam source, SBND is the closest detector and will help scientists better understand the original composition of the neutrino beam. (The other detectors are MicroBooNE at 470 meters and ICARUS at 600 meters.)

Scientists can predict the number of neutrinos and the types of neutrinos they should expect if they know the original composition of the beam with great precision. A divergence could provide evidence for the existence of sterile neutrinos, or it could lay the groundwork for the discovery of new particles in model physics beyond the norm.

“This will give us a dataset that will be 20 to 30 times larger than the current neutrino-argon interaction dataset, allowing us to make measurements that have never been done before,” said Ornella Palamara, neutrino scientist at Fermilab and co-spokesperson for the international SBND collaboration.

Construction of the detector in a transport frame

SBND was first proposed in 2014. Construction of the detection system, which involved scientists around the world, began in the following years. Parts began arriving at Fermilab in 2018.

From the beginning, scientists and engineers knew that the detection system could not be built in the detector room. They needed a large assembly building to construct the system – which consists of anode and cathode wire plans, as well as light detection systems – before it was placed in the large cryostat of the experiment, located inside Fermilab’s Neutrino Beam Booster. The cryostat will be filled with liquid argon.

“It’s like taking your baby to the first day of school. So many people have put their time and effort into building the detector and planning the move, and now we are finally at the point where we can see the results of those efforts. – Shishir Shetty, mechanical engineer at Fermilab

The team therefore began assembling the system in Fermilab’s DZero assembly building and designed and built a transport frame that would house the system from the start. To construct the steel frame, the engineering team needed to ensure it both supported the heavy sensing system, which hangs from the top beams of the frame, while ensuring it could be easily moved in good time. The frame includes stabilizers for support, a tow bar for pulling, transport stops to prevent the detector from swinging, and a hinged door to remove the system once it arrives in the detector lobby.

To facilitate transportation, the detection system itself relies on movable devices called Hilman rollers. In the days leading up to the move, Fermilab staff laid sheet steel rails for the rollers to ensure minimal friction. To get it out of the building, the frame was pulled with a forklift over the plates, up a ramp, and out of the building, while another forklift acted as a brake behind the frame. A specially designed guide system along the ramp ensured that the rollers did not deviate from their tracks.

The frame with the detection system – completely wrapped in black plastic to protect the photosensitive components of the detector – moved through the garage door of the building with only a few centimeters of free space. Once outside the building and lifted onto a flatbed trailer, the frame will be driven to its new home.

Find the right route

Last summer, scientists and engineers conducted three trials to find the best transport route. They loaded the trailer with 66,900 pounds of concrete blocks, equal to the weight of the detector and the transport frame. They then used accelerometers and inclinometers, including iPads, to monitor bumps in the route, as well as the trailer’s roll and pitch when cornering.

Since the sensing system has a high center of gravity – about 10 feet up – engineers had to ensure that the route did not include any inclines or turn angles that would alter the level of the trailer more than 5 degrees.

“During transport, we have to keep everything aligned,” said Monica Nunes, a visiting scientist who coordinated the assembly of the SBND. “The detector was built to be transported, but a move like this – with a system that has such a high center of gravity – has never been done at Fermilab before.”

The data showed that the preferred route was along the Fermilab ring road. At a top speed of around 2.5 miles per hour, and with a Fermilab security escort, this part of the journey should take around 90 minutes. Scientists and engineers will walk alongside the truck as it moves, monitoring the load in real time with accelerators and inclinometers that will transmit data to their cell phones.

The course was well prepared. In the days leading up to the move, Fermilab’s Infrastructure Services Division inspected the road for potholes, trimmed trees and removed power lines to prepare the route.

“Many people at Fermilab worked together to make this happen – physicists, students, technical staff, administration, purchasing,” said Anne Schukraft, neutrino scientist and SBND technical coordinator. “It was great to hear from everyone and learn from everyone’s expertise. It’s real teamwork. »

After the move

Once the detection system arrives at the detection hall, the crane will unload it from the trailer, placing it on steel tracks to be rolled 82 feet into the detection hall. This will complete the move for the day.

“That’s when we’ll be extremely happy,” Shetty said. “You will see a lot of smiles.”

In the days and weeks to come, Fermilab scientists and engineers will unpack the detector, set up stabilizers and install fall protection to be able to work safely above the detector. They will also test each of the subsystems to ensure that they were not compromised during the move.

In the coming months, the detector will be fitted with a top cap and placed inside the cryostat. Next summer, the cryostat will be filled with liquid argon. Scientists will test the system to characterize the signals it receives before it begins receiving live data from the neutrino beam in the fall of 2023. Eventually, SBND will record more than one million neutrino interactions per year.

“Finally having data will be really exciting,” Palamara said. “We have been working on it for eight years.

The Fermi National Accelerator Laboratory is supported by the US Department of Energy’s Office of Science. The Office of Science is the largest supporter of basic physical science research in the United States and works to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.