In a new study, two University of Massachusetts Amherst physicists are measuring some of the faintest and rarest particles ever detected, geo-neutrinos, from deep within Earth, with the greatest precision yet achieved.
The data, being collected using a delicate instrument located under a mountain in central Italy, reveal, for the first time, a well defined signal, above background noise, of the extremely rare geo-neutrino particle from deep within Earth.
Geo-neutrinos are anti-neutrinos produced in the radioactive decays of uranium, thorium, potassium and rubidium found in ancient rocks deep within our planet.
These decays are believed to contribute a significant but unknown fraction of the heat generated inside Earth, where this heat influences volcanic activity and tectonic plate movements, for example.
Borexino, the large neutrino detector, serves as a window to look deep into the Earth's core and report on the planet's structure.
Borexino is located at the Laboratorio Nazionale del Gran Sasso underground physics laboratory in a 10 km-long tunnel about 5,000 feet (1.5 km) under Gran Sasso, or Great Rock Mountain, in the Appenines and operated by Italy's Institute of Nuclear Physics.
The instrument detects anti-neutrinos and other subatomic particles that interact in its special liquid center, a 300-ton sphere of scintillator fluid surrounded by a thin, 27.8-foot diameter transparent nylon balloon.
The new Borexino data have stronger significance because of their purity and the absence of nuclear reactors.
According to UMass Amherst researcher Andrea Pocar, "The Borexino detector is very clean and has lower levels of radioactive impurities than ever achieved in experiments of this kind."
"It is indeed a very 'quiet' apparatus for the observation of low energy neutrinos, and exceptionally precise for distinguishing these particles by origin, either solar, geo or human-made," he said.
The small number of anti-neutrinos detected at Borexino, only a couple each month, helps to settle a long-standing question among geophysicists and geologists about whether our planet harbors a huge, natural nuclear reactor at its core.
Based on the unprecedently clear geo anti-neutrino data, the answer is no, say the UMass Amherst physicists.
"This is all new information we are receiving from inside the Earth from the geo-neutrino probe," explained UMass Amherst researchers Laura Cadonati.
"Our data are exciting because they open a new frontier. This is the beginning. More work is needed for a detailed understanding of Earth's interior and the source of its heat, with new geo-eutrino detectors above continental and oceanic crust," she said. (ANI)