How heavy is a neutrino?

In the midst of the verdant French countryside is a workshop the size of an aircraft hangar bustling with activity. In a well-lit new extension, technicians cut through thick slices of steel with electric saws and blast metal joints with welding torches.

Inside this building sits its newest occupant — a two-story-tall cube with thick steel walls that resemble castle turrets. This cube will eventually hold a prototype detector for the Deep Underground Neutrino Experiment, or DUNE — the flagship research program hosted at the Department of Energy Office of Science’s Fermilab to better understand the weird properties of neutrinos.

Neutrinos are the second-most abundant fundamental particle in the visible universe, but because they rarely interact with atoms, little is known about them. The little that is known presents a daunting challenge for physicists since neutrinos are exceptionally elusive and incredibly lightweight.

They’re so light that scientists are still working to pin down the masses of their three different types. They also continually morph from one of their three types into another — a behavior known as oscillation, one that keeps scientists on their toes.

“We don’t know what these masses are or have a clear understanding of the flavor oscillation,” said Stefania Bordoni, a CERN researcher working on neutrino detector development. “Learning more about neutrinos could help us better understand how the early universe evolved and why the world is made of matter and not antimatter.”

In 2015 CERN and the United States signed a new cooperation agreement that affirmed the United States’ continued participation in the Large Hadron Collider research program and a commitment from CERN to serve as the European base for the U.S.-hosted neutrino program. Since this agreement, CERN has been chugging full-speed ahead to build and refurbish neutrino detectors.

“Our past and continued partnerships have always shown the United States and CERN are stronger together,” said Marzio Nessi, the head of CERN’s neutrino platform. “Our big science project works only because of international collaboration.”

The primary goal of CERN’s neutrino platform is to provide the infrastructure to test two large prototypes for DUNE’s far detectors. The final detectors will be constructed at Sanford Lab in South Dakota. Eventually they will sit one-and-a-half kilometers underground, recording data from neutrinos generated 1,300 kilometers away at Fermilab.

Two 8-meter-tall cubes, currently under construction at CERN, will each contain 770 metric tons of liquid argon permeated with a strong electric field. The international DUNE collaboration will construct two smaller, but still large, versions of the DUNE detector to be tested inside these cubes.

In the first version of the DUNE detector design, particles traveling through the liquid knock out a trail of electrons from argon atoms. This chain of electrons is sucked towards the 16,000 sensors lining the inside of the container. From this data, physicists can derive the trajectory and energy of the original particle.

In the second version, the DUNE collaboration is working on a new type of technology that introduces a thin layer of argon gas hovering above the liquid argon. The idea is that the additional gas will amplify the signal of these passing particles and give scientists a higher sensitivity to low-energy neutrinos. Scientists based at CERN are currently developing a three cubic meter model, which they plan to scale up into the much larger prototype in 2017.

In addition to these DUNE prototypes, CERN is also refurbishing a neutrino detector, called ICARUS, which was used in a previous experiment at the Italian Institute for Nuclear Physics’ Gran Sasso National Laboratory in Italy. ICARUS will be shipped to Fermilab in March 2017 and incorporated into a separate experiment.

CERN plans to serve as a resource for neutrino programs hosted elsewhere in the world as scientists delve deeper into this enigmatic niche of particle physics.

John Conway knows the exact width of airplane aisles (15 inches). He also personally knows the Transportation Security Administration operations manager at Chicago’s O’Hare Airport. That’s because Conway has spent the last decade transporting extremely sensitive detector equipment in commercial airline cabins.

“We have a long history of shipping particle detectors through commercial carriers and having them arrive broken,” said Conway, who is a physicist at the University of California, Davis. “So in 2007 we decided to start carrying them ourselves. Our equipment is our baby, so who better to transport it than the people whose work depends on it?”

Their instrument isn’t musical, but it’s just as fragile and irreplaceable as a vintage Italian cello, and it travels the same way. Members CMS (Compact Muon Solenoid) experiment collaboration tested different approaches for shipping the instrument by embedding accelerometers in the packages. Their best method for safety and cost-effectiveness? Reserving a seat on the plane for the delicate cargo.

This November Conway accompanied parts of the new CMS pixel detector from Fermilab in Chicago, Illinois, to CERN in Geneva, Switzerland. The pixels are very thin silicon chips mounted inside a long cylindrical tube. This new part will sit in the heart of the CMS experiment and record data from the high-energy particle collisions generated by the Large Hadron Collider.

“It functions like the sensor inside a digital camera,” Conway said, “except it has 45 megapixels and takes 40 million pictures every second.”

Scientists and engineers assembled and tested these delicate silicon disks at Fermilab before Conway and two colleagues escorted them to Geneva. The development and construction of the component pieces took place at the Department of Energy’s Fermilab and universities around the United States.

Conway and his colleagues reserved each custom-made container its own economy seat and then accompanied these precious packages through check-in, security and all the way to their final destination at CERN. And although these packages did not leave Fermilab through the shipping department, each carried its own official paperwork.

“We’d get a lot of weird looks when rolling them onto the airplane,” Conway says. “One time the flight crew kept joking that we were transporting dinosaur eggs.”

After four trips by three people across the Atlantic, all 12 components of the U.S.-built pixel detectors are at CERN and ready for integration with their European counterparts. This winter the completed new pixel detector will replace its time-worn predecessor currently inside the CMS detector.

Welcome to 2017! As part of our year-long recognition of Fermilab’s 50th anniversary, we will feature a few important milestones in the laboratory’s history every month.

A walk down January lane takes us all the way to the first laboratory design report.