January 21, 2020
The Borexino experiment has doubled its knowledge on neutrinos generated inside Earth, offering new constraints on geological fashions of the mantle.
Neutrinos bombard us from all instructions, together with from Earth’s inside, the place decays of radioactive parts, similar to uranium and thorium, produce neutrinos. The Borexino experiment, positioned in Gran Sasso Nationwide Laboratory in Italy, has now measured a complete of 53 of those “geoneutrinos,” greater than doubling the mission’s earlier depend (see 7 August 2015 Focus). The brand new outcomes higher pinpoint the origin of the noticed geoneutrino flux, displaying that roughly half of the detected particles originate from Earth’s mantle and that the remainder come from the crust.
The Borexino experiment consists of an 18-m-wide sphere containing 280 tons of liquid scintillator that’s surrounded by photodetectors. Incoming neutrinos can—on uncommon events—work together with a nucleus within the scintillator, producing a detectable gentle sign. Initially constructed to review photo voltaic neutrinos, the detector additionally serves as a geoneutrino observatory. Earlier outcomes confirmed that our planet emits about 1025 geoneutrinos per second (roughly a trillionth of the neutrinos that the Solar places out).
For his or her new geoneutrino examine, the Borexino Collaboration analyzed knowledge from 2007 to 2019, using improved methods for distinguishing neutrino occasions from background alerts brought on by different particles, like muons. Additionally they estimated the variety of background neutrinos coming from nuclear reactors. From their ensuing geoneutrino counts, the group calculated that the anticipated power from the radioactive decays that produce the particles accounts for greater than half of Earth’s complete warmth output (47,000 GW). This estimated heating price range favors geological fashions that predict—relative to different fashions—a excessive focus of radioactive parts within the mantle.
This analysis is printed in Bodily Overview D.
Michael Schirber is a Corresponding Editor for Physics based mostly in Lyon, France.