First physics results from prototype detector published

The DUNE collaboration has published its first scientific article based on data collected with the ProtoDUNE single-phase detector located at CERN’s Neutrino platform. The results show that the detector operates at an efficiency greater than 99%, making it not only the largest liquid-argon time projection chamber, but also the most performing to date. Scientists are now using their findings to refine their experimental techniques and prepare for the construction of the international deep underground neutrino experiment at the long-base neutrino plant, a next-generation neutrino experimental program hosted by the Department’s Fermilab. of Energy in the United States.

“These first results are great news for us,” said DUNE co-spokesperson Stefan Söldner-Rembold, a professor at the University of Manchester in the UK. “They show that the ProtoDUNE-SP detector works even better than expected. We are now ready to build the first components for the DUNE detector, which will feature detector modules based on this prototype, but 20 times larger.”

DUNE is an ambitious international experiment that will measure the properties of tiny fundamental particles called neutrinos. Neutrinos are the most abundant particle of matter in the universe, but because they rarely interact with other particles, they are incredibly difficult to study. There are at least three different types of neutrinos, and every second 65 billion of them pass through every square centimeter of the Earth. While they travel, they do something strange: they change from one type to another. Scientists believe these neutrino oscillations, as well as oscillations involving antimatter neutrinos, could help answer some of the big questions in physics, such as the matter-antimatter asymmetry observed in the universe. DUNE will also look for supernova neutrinos and look for rare subatomic processes such as proton decay.

“ProtoDUNE-SP shows that we can scale this type of technology to the size and resolution we need to finally put neutrinos under a very powerful microscope,” said Marzio Nessi, coordinator of CERN’s Neutrino platform.

Accurately measuring these oscillations will limit and even exclude some theoretical models and open new avenues for discovering and exploring rare subatomic phenomena. But to get these precise measurements, scientists need incredibly large, sensitive and reliable detectors.

“The ProtoDUNE results show that we have designed a detector that will enable us to achieve our scientific goals in DUNE,” said Elizabeth Worcester, scientist at the Brookhaven National Laboratory in the Department of Energy and physics coordinator at DUNE.

DUNE is designed to reveal the nature of neutrino oscillations by firing an intense beam of neutrinos from Fermilab near Chicago across 1,300 kilometers (800 miles) of land and into four giant underground detector modules located 1.5 kilometers deep at the Sanford Underground. Research Facility in South Dakota. Two ProtoDUNE detectors at CERN, one based on single-phase technology and the other based on two-phase liquid argon technology, are a step towards the construction of the huge DUNE detector modules, each filled with 17,000 tons of liquid argon. The DUNE Technical Design Report, published in February, is the model for the construction of these modules.

At CERN, DUNE scientists from around the world used cosmic rays and an 800 GeV test beam to evaluate the ProtoDUNE-SP detector. The test beam from CERN’s SPS accelerator passed through two separate targets to create beams of electrons, protons and other types of particles. Particle detectors located just outside ProtoDUNE measured the energy and identity of these test beam particles before they entered ProtoDUNE-SP. Inside the detector, delicate layers of wires interspersed with photon detectors are suspended within 800 tons of transparent liquid argon. When a passing particle interacts with argon, it emits free electrons which are attracted by a high voltage electric field for several meters to the wire planes near the detector walls. From the signal on the wires, scientists create a 3-D image of the particle’s trajectory and can determine its energy and identity. By comparing this information from within ProtoDUNE-SP with the known properties of the original test beam particle, they were able to precisely calibrate the apparatus and optimize the complex reconstruction software.

Just as the quality of a photo varies significantly based on the quality of a photographer’s camera and editing software, the quality of the physical data is as good as the detector and its reconstruction tools. Scientists working on ProtoDUNE-SP have learned from previous neutrino experiments and have achieved a level of performance that was previously impossible. All detector data contains small variations, called noise, which can sometimes be difficult to distinguish from the signals created by particles. This is a common problem in all physics experiments, and scientists are constantly thinking of innovative ways to improve data quality through a combination of increasing the signal strength and decreasing the amount of noise. In this first article from DUNE, the scientists show how they were able to achieve a signal-to-noise ratio of 50 to 1, which was previously impossible to achieve for liquid argon weather projection chambers. They also evaluated the detector’s reliability and found that more than 99% of its 15,360 detector channels work as they should.

“If some channels in a detector don’t work, scientists get gaps in their data,” said Tingjun Yang, a DUNE collaborator at Fermilab who led ProtoDUNE’s data analysis. “Data analysis tools can help fill in these gaps, but there is a limit. The number of inactive channels in ProtoDUNE is less than 1%, giving us highly efficient event reconstruction. ProtoDUNE-SP shows that we can reach and exceed our physical goals. ”