The Fermi National Accelerator Laboratory’s Short-Baseline Neutrino Program has a full plate, with a mandate to seek for physics outside the standard model and investigate the behavior of the universe’s most elusive particles.
The Short-Baseline Near Detector, MicroBooNE, and ICARUS detectors are part of the initiative, which will build on Fermilab’s internationally recognized neutrino research. Scientists will learn more about the function of neutrinos in the cosmos by examining their characteristics using these detectors.
The three detectors will be staggered along a straight line on the Fermilab campus, each probing a strong neutrino beam. SBND, which is now under construction, will be the nearest neutrino beam source, being just 110 meters from the region where protons collide with a target to produce a beam of muon neutrinos. MicroBooNE, which started collecting data in 2015, is 360 meters away from SBND, and ICARUS, which will start collecting data this autumn, is 130 meters away.
These detectors will work together to examine neutrino oscillations in unprecedented depth. As it travels across space, a single neutrino can switch between the three known neutrino kinds. Scientists anticipate to find evidence for this novel physics in the neutrino oscillation patterns seen by the three detectors if there is a fourth kind of neutrino or if neutrinos act differently than current theory predicts.
The SBND’s detector will be hung in a chamber filled with liquid argon once it is finished. When a neutrino enters the chamber and collides with an argon atom, a spray of charged particles and light is released, which is recorded by the detector. Scientists will be able to recreate an accurate 3D picture of the paths of all the particles that came from a neutrino-argon collision using these signals.
Scientist Anne Schukraft, the project’s technical coordinator, said, “You’ll see an image that gives you so much detail, and at such a small scale.” “When you compare it to prior generation trials, it truly opens up a whole new universe of possibilities.”
Electrons move between the negative and positive terminals in battery-powered circuits. The electrons produced by neutrino collisions in SBND will follow the electric field established inside the detector, which consists of two positively charged anode planes and one negatively charged cathode plane. This isn’t a small circuit, though. Each plane is 5 by 4 meters, with a 500 volts per centimeter electric field between the cathode and each anode, with the cathode conducting 100,000 volts.
The two anode planes will cover two opposite-side walls of the cube-shaped detector, each composed of tiny wires spaced 3 millimeters apart. They’ll gather the electrons produced by particles colliding inside the detector, while photons, or light particles, will be recorded by light sensors behind them.
The cathode will be an upright plane coated with reflective foil in the centre of the detector. In late July, the assembly crew dropped the heavy cathode plane into the detector’s steel frame, and the first anode plane is expected to be installed in early October. Each of the light-sensitive layers is stored in a separate, clean location until installation.
The detector will weigh more than 100 tons when fully built and be filled with argon at minus 190 degrees Celsius. The entire system will be housed in a cryostat, which is composed of strong steel and insulated panels to keep everything cold. To keep the liquid argon pure, a complex piping system will circulate and filter it.
Assemble the neutrino physicists
The detector pieces were manufactured and transported to Fermilab by several groups across the world, notably in the United States, the United Kingdom, Brazil, and Switzerland. The detector frame is being constructed in a warehouse-like facility, although it will not be the detector’s permanent home.
The team will carry the detector several kilometers across the Fermilab site to the SBND building, where technicians are constructing the cryostat and where the detector will actually gather its data, after the components are installed in the steel frame. SBND is expected to launch in early 2023, according to Schukraft.
Mônica Nunes, a postdoctoral researcher at Syracuse University, remarked, “The wonderful thing about SBND is that we are creating it from the ground up.” “Everything we understand about this process will be extremely valuable for the future generation of neutrino experiments,” says the researcher.
As part of the trio of probes investigating physics beyond the Standard Model, SBND will join MicroBooNE and ICARUS. Researchers are specifically looking for sterile neutrinos, which are neutrinos that do not interact with the weak force. Two previous studies, the Los Alamos National Lab’s Liquid Scintillator Neutrino Detector and Fermilab’s MiniBooNE, revealed abnormalities that suggest the presence of these elusive particles. The SBN Program attempts to validate or refute these anomalies and offer further evidence for or against the existence of sterile neutrinos by monitoring how neutrinos oscillate and shift kinds.
Roberto Acciarri, co-manager of the detector assembly, explained, “The aim is to setup a detector extremely close to the source of neutrinos in the hopes of detecting this sort of neutrino.” “Then we have a distant detector and a medium detector to check whether we can observe sterile neutrinos when they’re created and when they’re oscillating away,” says the researcher.
SBND researchers will also investigate how neutrinos interact with the argon atoms that fill the detector with extreme accuracy. SBND will record over a million neutrino-argon interactions each year due to its proximity to the neutrino beam’s origin. Future neutrino investigations that use liquid-argon detectors, such as the Deep Underground Neutrino Experiment, will need to understand the physics of these interactions.
“It’s exciting to see improvement virtually every day,” Schukraft added. “We’re all looking forward to seeing this project begin to collect data.”