New results on geo-neutrinos from Borexino

Mar 14, 2013

(Phys.org) —Borexino is a liquid scintillator detector mainly built for solar neutrino searches. Due to its high level of radiopurity, a worldwide record, Borexino can also detect rare events such as electron-antineutrinos from the interior of the Earth, namely geo-neutrinos.

Geo-neutrinos are electron anti-neutrinos produced in beta decays of long-lived radioactive elements (40K, 238U and 232Th) in the Earth. Electron anti-neutrinos are detected by searching for their interactions on protons in massive organic liquid scintillators. These neutrinos have already been observed in underground laboratories by at Gran Sasso, Italy, and KamLAND in the Kamioka mine, Japan.

By measuring the geo-neutrino flux on surface the contribution of radioactive elements to the Earth's heat budget can be explored. The radiogenic heat is of high interest to help understanding a number of geophysical processes such as mantle convection and

Today the Borexino has released results from a new measurement with 2.4 times higher exposure with respect to 2010, corresponding to 1352.60 live days and about 187 tons of liquid scintillator after all selection criteria have been applied (3.7×1031 proton×year).

In the data collected, 46 electron anti-neutrino candidates have been selected with about 30% of geo-neutrinos contribution. Together with geo-neutrinos Borexino has detected electron anti-neutrinos from from all over the World. These latter neutrinos give a signal of about 31 events well in agreement with what expected from 446 nuclear cores operating in the period of interest, from December 2007 to August 2012, and with our present knowledge of the parameters of neutrino . In Borexino the total expected background for electron anti-neutrinos is determined to be of about 0.7 events. The very small background is due to the high level of radiopurity reached in the Borexino liquid scintillator.

For the present measurement the null geo-neutrino hypothesis has a probability of 6×10-6.

Geo-neutrinos detection offers a unique tool to probe the uranium and thorium abundances within the mantle. By considering the contribution from the local (around the Gran Sasso region) and the rest of the crust to the geo-neutrino signal, the signal due to the radioactivity of uranium and thorium in the mantle can be extracted. The present results from Borexino together with the measurement by KamLAND give an indication for the signal from the mantle, Smantle = 14.1±8.1 TNU (1 TNU = 1 event/year/1032 ).

The new results from Borexino mark a breakthrough for the Earth Sciences and in particular for the comprehension of the origin and thermal evolution of the Earth. The good agreement of the Th/U ratio between geoneutrino signals and the chondritic value has fundamental implications on the cosmochemical models and on the planetary formation processes in the early Solar System.

The origin of the terrestrial heat is a missing piece of knowledge for the full comprehension of which drives plate tectonics and thus earthquakes. For the first time two independent geo-neutrino detectors (Borexino and KamLAND) placed in different sites around the planet (Italy and Japan) give the same constraints on radiogenic heat power of the Earth due to the decays of U and Th. The multisite probing of the Earth's interior with geoneutrinos is now a reality which can unveil new constrains on radioactivity content of the mantle, Bulk Silicate Earth models and geo-reactors.

Prof. Giampaolo Bellini (INFN and University of Milan), the former Borexino spokesperson, said: "These new Borexino results confirm the strong potentiality of the geoneutrinos as unique probes: through geoneutrinos we have the important chance to understand the Earth thermal power and what happens below the crust. But not only. The comparison between the relative abundance of the within the Earth and the chondritic ratio can enlighten on the structure of the Solar planets.

experiment will continue to accumulate data opening further possible achievements. We hope that also the Kamland experiment will release new data and that other experiments can reach such sensitivity and radiopurity levels to allow the study of the geoneutrinos also in different geological sites of the Earth".

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User comments : 13

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SethD
1.4 / 5 (9) Mar 14, 2013
Hand-waving.
ValeriaT
1.6 / 5 (7) Mar 14, 2013
The geoneutrinos are of low energy due the recoil of atom nuclei (bellow 3 MeV) and as such notoriously difficult to catch. Borexino is currently the most sensitive detector of these low energy neutrinos. The geoneutrinos from 40K decay could reveal the geothermal origin of global warming, but their energy is even lower (bellow 1.4 MeV). Currently the most perspective detector is using the liquid helium (Helium Roton Observation of Neutrinos) but IMO the most perspective could be the measurement of speed of decay of some radioisotopes, which is selectively affected with neutrinos of particular energies due the neutrino oscillations inside of atom nuclei.
Maggnus
3 / 5 (4) Mar 14, 2013
Lol so the Earth's atmosphere is warming from the inside out is it! I didn't realize you were also a comedian Zephyr!
Q-Star
3.2 / 5 (11) Mar 14, 2013
Lol so the Earth's atmosphere is warming from the inside out is it! I didn't realize you were also a comedian Zephyr!


A few days ago he was telling me that global warming was due to aether getting clogged up with solar neutrinos. His science is so cutting edge, it's outdated in hours.
ValeriaT
2 / 5 (8) Mar 14, 2013
Lol so the Earth's atmosphere is warming from the inside out is it! I didn't realize you were also a comedian Zephyr!
From the oceans which do contain lotta radioactive potassium 40K and the total activity of ocean water exceeds 3.8 x 10E11 Curie i.e. 14000 EBq - the nuclear explosion in Hiroshima (14 kt or 60 TJ) produced 8E24 Bq). Which could serve as the supposed explanation of so-called heat content anomaly.

Because you don't know about many anomalies which I do know, this model appears nonsensical for you in this moment. Whereas the mainstream science formulates the hypothesis from causal dependencies, I'm constructing the dual description of universe from anomalies (causality bubbles of negative curvature). When the number of anomalies will exceed the critical level, my models will become mainstream and the another effects will become anomalies instead.
Q-Star
2.8 / 5 (9) Mar 14, 2013
Because you don't know about many anomalies which I do know, this model appears nonsensical for you in this moment. Whereas the mainstream science formulates the hypothesis from causal dependencies, I'm constructing the dual description of universe from anomalies (causality bubbles of negative curvature). When the number of anomalies will exceed the critical level, my models will become mainstream and the another effects will become anomalies instead.


Zephyr, I say this with all sincerity, your anomalies will be studied for years to come. (But not by physicists.)
ValeriaT
2.3 / 5 (6) Mar 14, 2013
The above model was actually a subject of the 2012 movie, which has been labeled as the most flawed and unscientific film ever by NASA. This is rather suspicions stance by itself - why just this movie raised such a sharp open dismissal (BTW NASA is traditional proponent of AGW)? I personally do know about many way more freaky films. And who actually designed the script of this movie?
Q-Star
2.6 / 5 (10) Mar 14, 2013
I personally know many way more freeky movies. And who actually designed the script of this movie?


I'm quite sure that ya personally do.

But as for who designed the script, I don't usually pay much attention to the credits when they roll by, so I have no idea. Ya might try googling up the movie and seeing if Wiki knows who designed/wrote the script, they sometimes have that information.
Maggnus
1 / 5 (2) Mar 14, 2013
This is rather suspicions stance by itself - why just this movie raised such a sharp open dismissal (BTW NASA is traditional proponent of AGW)?


Holy. Gawd.

And Jesus wept!
SethD
1.7 / 5 (6) Mar 19, 2013
The above model was actually a subject of the 2012 movie, which has been labeled as the http://www.aolnew...lm-ever/ ever by NASA. This is rather suspicions stance by itself - why just this movie raised such a sharp open dismissal (BTW NASA is traditional proponent of AGW)? I personally do know about many way more freaky films. And who actually designed the script of this movie?

That's how it is in a Hollywood-nurtured nation.

Q-Star (and his 8 false accounts) is a classical example of that mental malnutrition.
Q-Star
2.3 / 5 (9) Mar 19, 2013
Q-Star (and his 8 false accounts) is a classical example of that mental malnutrition.


Instead of accusing me of what ya do so generally,,, maybe ya might do the site a service by exposing the eight false accounts? Can ya name them? Can ya name five of them? Can ya name three of them? Can ya name even one of them?

If ya will name eight of my "false accounts", I'll double your pleasure by naming sixteen of yours.
SethD
1.7 / 5 (6) Mar 19, 2013
Q-Star (and his 8 false accounts) is a classical example of that mental malnutrition.


Instead of accusing me of what ya do so generally,,, maybe ya might do the site a service by exposing the eight false accounts? Can ya name them? Can ya name five of them? Can ya name three of them? Can ya name even one of them?

If ya will name eight of my "false accounts", I'll double your pleasure by naming sixteen of yours.

You're so ridiculous you're not even wrong.
Q-Star
2.5 / 5 (8) Mar 19, 2013
Q-Star (and his 8 false accounts) is a classical example of that mental malnutrition.


Instead of accusing me of what ya do so generally,,, maybe ya might do the site a service by exposing the eight false accounts? Can ya name them? Can ya name five of them? Can ya name three of them? Can ya name even one of them?

If ya will name eight of my "false accounts", I'll double your pleasure by naming sixteen of yours.

You're so ridiculous you're not even wrong.


I didn't think ya could. Thanks for verifying it. Carry on with what ever it is that ya do.