Why did the Big Bang produce more matter than it did anti-matter, and are the neutrino and the anti-neutrino identical particles? A new germanium detector developed by researchers from the US Department of Energy may hold the key to answering those questions.
According to the DOE’s Office of Science, an experiment currently running in a clean-room lab located more than 4,800 feet beneath the Sanford Underground Research Facility in Lead, South Dakota is now online and searching for neutrinoless double beta decay in germanium-76.
If it is can observe this phenomenon, it would significantly change our understanding of the field of physics by proving that the neutrino is its own antiparticle, providing new data on the absolute mass scale of the neutrino and demonstrating that the lepton number is not conserved, the authors of a paper published recently in the journal Advances in High Energy Physics explained.
The experiment is known as Majorana Demonstrator (MJD), and the first of two modules, which contain more than 22 kilograms of high purity germanium detectors, were activated in May. The module contains 29 germanium detectors, and a second module with another 30 detectors will be installed into the MJD’s lead/copper shield later on this year, they added.
Why is the lab so deep underground?
The reason that the MJD has to be located so deep underground and in an ultra-clean laboratory is to eliminate “background” events which could be mistaken for the extremely rare 0νββ decays, the DOE team said. The project team members hope achieve very low background rates in order to prove that a larger, more sensitive future version of the experiment is feasible.
“Double-beta decay is… possible and has been observed in a dozen different isotopes since 1986, but it happens at a really low rate, and not too many nuclei can do it.” Alan Poon of the Nuclear Science Division at the DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab) said in a 2012 statement, when he was executive-committee chair of the Majorana Collaboration.
Poon added that germanium-76 is not the only element capable of undergoing double-beta decay, as other detectors use isotopes of tellurium, xenon, neodymium or other elements. He said that it’s important to establish that any instance of neutrinoless double-beta decay accurately reflects the property of the neutrino, and that if the process is observed in multiple elements, it would be “very strong evidence that the neutrino is indeed its own antiparticle.”
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Feature Image: Sanford Underground Research Facility
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