First particle tracks at neutrino detector

Caption: Interior of the ProtoDUNE detector.

The giant cube-shaped neutrino detector of the size of a three-storey building and the largest liquid-argon neutrino detector in the world, called ProtoDUNE, the first of the two prototypes for an even larger detector to be built for the Deep Underground Neutrino Experiment (DUNE), just recorded its first particle tracks.

This heralds the start of a new chapter in what is the largest international collaboration working on cutting-edge neutrino research. DUNE’s scientific mission is aimed at understanding the mysteries of neutrinos …which should answer major outstanding questions in physics, astronomy and cosmology including “why we are here at all?”, as the press release from CERN, the European Laboratory for Particle Physics based in Geneva, and Fermilab of the United States said.

ProtoDUNE was built at CERN and the facility is being hosted by Fermilab. The DUNE detector itself, which will be 20 times larger than these prototypes, is targeted for 2026.

The ProtoDUNE took two years to build and eight weeks to fill with 800 tonnes of liquid argon, which needs to be kept at temperatures below -184°C. The detector records traces of particles in that argon, from both cosmic rays and a beam created at CERN’s accelerator complex. Now that the first tracks have been seen, scientists will operate the detector over the next several months to test the technology in depth.

“Now we have the first detector taking beautiful data, and the second detector, which uses a different approach to liquid-argon technology, will be online in a few months,” said Marzio Nessi, head of the Neutrino Platform at CERN. The prototypes will form the building blocks for the DUNE detector.

The first of the DUNE detector modules will be built a mile underground at the Sanford Underground Research Facility in South Dakota. Fermilab’s Long-Baseline Neutrino Facility will house the experiment and its upcoming PIP-II particle accelerator will power the neutrino beam for the experiment. When neutrinos enter the detectors and smash into the argon nuclei, they produce charged particles. Those particles leave ionisation traces in the liquid, which can be seen by sophisticated tracking systems able to create three-dimensional pictures of otherwise invisible subatomic processes.

DUNE will not only study neutrinos, but their antimatter counterparts as well to study the differences in behaviour between neutrinos and antineutrinos, which could give us clues as to why the visible universe is dominated by matter. DUNE will also watch for neutrinos produced when a star explodes, which could reveal the formation of neutron stars and black holes, and will also investigate whether protons live forever or eventually decay.

More than 1,000 scientists and engineers from 175 institutions in 32 countries are part of the DUNE project. Indian scientists too are participating in this project.