This text has been reviewed in keeping with Science X’s editorial course of
and insurance policies.
Editors have highlighted the next attributes whereas making certain the content material’s credibility:
fact-checked
trusted supply
proofread
Okay!
An array of photomultiplier tubes, used to detect faint sources of sunshine, mounted contained in the metal tank of the Eos detector. The photomultiplier tubes will ultimately be submerged in water admixed with a novel scintillator that function targets for particles resembling neutrinos passing by. The particle interactions produce bursts of sunshine that can be captured by the photomultiplier tubes. Credit score: Thor Swift/Berkeley Lab
× shut
An array of photomultiplier tubes, used to detect faint sources of sunshine, mounted contained in the metal tank of the Eos detector. The photomultiplier tubes will ultimately be submerged in water admixed with a novel scintillator that function targets for particles resembling neutrinos passing by. The particle interactions produce bursts of sunshine that can be captured by the photomultiplier tubes. Credit score: Thor Swift/Berkeley Lab
Neutrinos and antineutrinos are almost massless particles produced in lots of nuclear reactions, together with the fission of uranium in nuclear energy vegetation on Earth and the fusion reactions on the core of the solar.
However they’re devilishly laborious to detect—most go by Earth with out stopping—making it tough to check the nuclear reactions going down on the core of stars or in stellar explosions or to observe nuclear energy vegetation for illicit manufacturing of bomb materials.
A brand new sort of neutrino detector now being examined in an enormous underground lab on the College of California, Berkeley, is designed to leverage the most recent applied sciences to boost the sensitivity and capabilities of antineutrino detectors. Such improved detectors wouldn’t solely assist detect, localize and characterize undeclared particular nuclear materials getting used opposite to federal or worldwide rules, but additionally assist scientists discover the elemental physics of particles and their interactions deep within the nucleus of the atom.
Referred to as Eos, for the Titan goddess of daybreak, the equipment alerts “the daybreak of a brand new period of neutrino detection expertise,” in keeping with Gabriel Orebi Gann, a UC Berkeley affiliate professor of physics and the chief of the Eos collaboration.
The prototype detector might detect and characterize nuclear actions and supplies remotely, that’s, at distances higher than about 100 meters. Whereas radioactivity from nuclear materials will be shielded from detection, antineutrinos produced in fission reactions can not. As a result of billions are produced in a reactor every nanosecond, Eos ought to be capable of detect sufficient antineutrinos to determine clandestine manufacturing of bomb-grade materials.
“The concept of neutrino detection is you’ll be able to’t spoof it, you’ll be able to’t protect it, you’ll be able to’t pretend it. Neutrinos journey at nearly the pace of sunshine, so they supply near-instantaneous detection, even at distance. They provide a novel signature of nuclear exercise,” stated Orebi Gann, who can also be a school scientist at Lawrence Berkeley Nationwide Laboratory (Berkeley Lab).
“For those who’re both a good distance away otherwise you’ve obtained a really weak signature, then you definitely want an enormous detector. And for an enormous detector, you want liquid.”
Eos is a 10-meter-tall, 5-meter-wide cylinder crammed with water and an natural scintillator and surrounded by gentle detectors 3 times extra delicate than these utilized in physics experiments right this moment. Eos’s improved sensitivity and better decision come from combining two of right this moment’s greatest methods for detecting neutrinos: scintillation and Cherenkov emission.
The enhancements could possibly be a game-changer for future neutrino physics tasks, such because the Deep Underground Neutrino Experiment (DUNE) now being constructed in an deserted gold mine in Lead, South Dakota, to detect neutrinos emitted by a particle accelerator at Fermi Nationwide Laboratory, 500 miles away in Illinois. UC Berkeley and Berkeley Lab are members of the DUNE collaboration.
“What we might finally prefer to construct is a a lot larger detector known as Theia,” she stated. “Theia is the Titan goddess of sunshine and Eos’s mom within the pantheon of gods. The perfect location for Theia is in that mine in South Dakota, seeing these neutrinos from Fermilab.”
It stays to be seen whether or not Theia—which might make use of a tank massive sufficient to almost swallow the Statue of Liberty—will exchange certainly one of DUNE’s 4 deliberate liquid argon “far” detectors.
Orebi Gann argues {that a} hybrid detector like Theia, whereas offering comparable sensitivity for finding out the high-energy beam of neutrinos that’s the main goal of DUNE, would add new capabilities past an argon detector, together with the flexibility to detect antineutrinos. Theia additionally would have a 2-degree pointing accuracy for the situation of a supernova through the neutrino burst and would have the capability to seek for low-energy photo voltaic neutrinos and Majorana neutrinos.
A hybrid neutrino detector
Eos is exclusive in being a hybrid of the 2 predominant sorts of liquid neutrino detectors, each of which begin with a tank of liquid.
One method is predicated on a scintillator—on this case, linear alkylbenzene—that emits gentle in response to the charged particles produced throughout interactions with a neutrino or antineutrino.
Neutrinos and antineutrinos also can work together with different supplies, resembling water, to supply an electron, which then emits its personal gentle, although a lot fainter than scintillation gentle. The latter is named Cherenkov radiation and is emitted when the electron plows by the liquid quicker than the pace of sunshine within the liquid, akin to the acoustic power of a sonic increase produced by a airplane touring quicker than the pace of sound.
UC Berkeley physicist Gabriel Orebi Gann and Berkeley Lab engineer Joe Saba inspected the Eos detector—242 photomultiplier tubes surrounding an acrylic tank—because it was lowered right into a metal tank on Jan. 26, 2024. Throughout testing, the tank can be crammed with water and ultimately a scintillator that may generate pulses of sunshine when neutrinos or antineutrinos go by. The photomultiplier tubes detect the sunshine and assist decide the energies of the particles and the route from which they arrived. Credit score: Zara Bagdasarian/UC Berkeley
× shut
UC Berkeley physicist Gabriel Orebi Gann and Berkeley Lab engineer Joe Saba inspected the Eos detector—242 photomultiplier tubes surrounding an acrylic tank—because it was lowered right into a metal tank on Jan. 26, 2024. Throughout testing, the tank can be crammed with water and ultimately a scintillator that may generate pulses of sunshine when neutrinos or antineutrinos go by. The photomultiplier tubes detect the sunshine and assist decide the energies of the particles and the route from which they arrived. Credit score: Zara Bagdasarian/UC Berkeley
In each methods, delicate gentle detectors known as photomultiplier tubes are arrayed across the tank to file the depth of the faint gentle. The depth of the scintillation supplies details about the power of the neutrino or antineutrino.
Cherenkov radiation, nevertheless, is emitted in a cone, so it will probably present info on the route from which the neutrino got here, a vital piece of knowledge for finding out nuclear reactor sources in addition to cosmic neutrino sources.
“Photomultiplier tubes are delicate to single photon ranges of sunshine,” Orebi Gann stated. “However a liquid scintillator offers you much more gentle: For those who’ve obtained an electron on the similar power, you will get 50 instances extra gentle, relying on the scintillator, than from Cherenkov emission. Meaning you get higher precision for understanding the place the power was deposited and the way a lot power there was.”
“We stated, OK, we do not wish to choose and select. We do not like compromise. We wish each. And that is the purpose right here. We wish the topology of Cherenkov gentle, however the decision of scintillation,” she stated.
The issue is that gentle from scintillation is so shiny it overwhelms the Cherenkov gentle.
Fortunately, Cherenkov gentle comes out in a picosecond burst, whereas scintillation gentle lingers for nanoseconds.
“If in case you have very quick photon detectors, you should use the time distinction to assist separate these two signatures,” she stated. Eos will encompass the liquid tank with 242 photomultiplier tubes made by the Japanese agency Hamamatsu which are 3 times quicker than present photomultipliers.
The seen area of Cherenkov gentle has a redder colour spectrum than scintillation gentle, which is generally blue. The staff takes benefit of this by surrounding the entrance row of photomultipliers with a “dichroic” filter that displays crimson Cherenkov gentle into the photomultiplier however lets blue scintillation gentle go by to photomultipliers within the again.
“You are principally sorting your photons by wavelength and directing them to completely different photon detectors primarily based on the wavelength,” she stated.
Orebi Gann and her staff started assembling Eos in September, delayed for six weeks by the destruction of the primary metal tank when the truck carrying it collided with an overpass. The tanks are so massive that the researchers needed to home the experiment in a big basement lab—previously occupied by a nuclear reactor—operated by UC Berkeley’s Division of Nuclear Engineering.
They surrounded the acrylic tank with the photomultiplier tubes, then lifted the entire meeting right into a cylindrical metal tank. The inner acrylic tank and the hole between the acrylic and metal tanks had been then crammed with pure water, submerging the photomultiplier tubes within the hole.
As soon as the staff checks the flexibility of Eos to detect Cherenkov gentle from synthetic radioactive sources and pure, cosmic muons, they are going to steadily add scintillator materials to check the experiment’s potential to discriminate between the 2 sorts of gentle emissions.
“Now we have additionally designed our detector so we are able to deploy pure liquid scintillator,” Orebi Gann stated. “This may be the final word take a look at: if we are able to nonetheless see the Cherenkov signature even with the maximal scintillation part.”
Plans name for exploring how nicely Eos can monitor small modular reactors and nuclear-powered maritime vessels and verify take a look at website transparency.
Orebi Gann is raring additionally to make use of the Eos design usually neutrino physics research, resembling measuring the flux of neutrinos from the core of the solar to confirm the anticipated nuclear reactions powering it; investigations of terrestrial sources of neutrinos; mapping the diffuse supernova neutrino background within the Milky Approach and past; and the continuing seek for neutrinoless double beta decay, which might point out {that a} neutrino is its personal antiparticle.
All of those questions are already being explored with both the scintillator or Cherenkov detectors, however Orebi Gann is hoping {that a} hybrid detector will pace progress.
“The identical form of physics that every of these detectors has carried out prior to now, we might do higher,” she stated. “That is the purpose. It is R&D for the following era.”