#nutrinos

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   A trio of researchers from CSIC-Universitat de València and Universitat de Barcelona has used data from the IceCube detector in Antarctica to measure Earth's mass. In their paper published in the journal Nature Physics, Andrea Donini, Sergio Palomares-Ruiz and Jordi Salvado describe using data describing neutrinos passing through the Earth to learn more about the interior of the planet. Véronique Van Elewyck with Paris Diderot University has written a News and Views piece on the work done by the team in the same journal issue.                                

Currently, scientists use calculations based on gravitational pull and readings from seismic detectors to measure the mass of the Earth and its density. In this new effort, the researchers have taken a different approach—looking at the number of neutrinos that make their way through the planet.

The IceCube Neutrino Observatory was established back in 2005. It is made up of thousands of sensors situated under the ice to detect neutrinos that have passed through the Earth. Neutrinos are weakly interacting particles—those that pass through the Earth are known as atmospheric neutrinos because they arise from collisions between cosmic rays and the Earth's atmosphere. In this new effort, the researchers used data from IceCube from 2011 to 2012—it was not publicly released until 2016. IceCube detects low-energy neutrinos—high-energy neutrinos are not able to make it all the way through the planet.

To calculate the Earth's mass, the researchers measured how much of the neutrino stream produced by atmospheric collisions made it through the planet. To calculate the density of Earth's layers, they counted how many neutrinos were able to get through the planet at different angles to IceCube.

The researchers report that their findings agreed with measurements of the planet taken using traditional methods. But they also note that as the years pass and IceCube collects more data, measurements of the planet using neutrinos will become more precise. Van Elewyck suggests that as other neutrino-sensing stations are set up in other places, it should be possible to conduct a full tridimensional analysis of the planet offering information not available through other means.                                                                

Hunting the Ghosts of the Universe: Unraveling the Neutrino Enigma.

International Research Conference on High Energy Physics

Around a million, billion neutrinos from the Sun will pass through your body while you read this sentence.

A nutrino is a neutral sub-atomic particle of such small mass that it passes through matter undisturbed.

Its mass has never before been measured accurately and this picture is a device that was set up to detect nutrinos, as VERY ocasionaly they will colide with matter producing energy in the form of light/heat. but this energy is so small that it is virtually undetectable.

A team of scientists who last year suggested neutrinos could travel faster than light conceded Friday that Einstein was right and the sub-atomic particles are - like everything else - bound by the universe's speed limit.

Researchers working at the European Centre for Nuclear Research (CERN) caused a storm when they published experimental results showing the particles could out-pace light by some six kilometres (3.7 miles) per second.

The findings threatened to upend modern physics and smash a hole in Albert Einstein's 1905 theory of special relativity, which described the velocity of light as the maximum speed in the cosmos.

The neutrinos were timed on the journey from CERN's giant underground lab near Geneva to the Gran Sasso Laboratory in Italy, after travelling 732 kilometres through the Earth's crust.

To do the trip, the neutrinos should have taken 0.0024 seconds. Instead, the particles were recorded as hitting the detectors in Italy 0.00000006 seconds sooner than expected, the preliminary experiment had shown.

But on Friday the OPERA team told the International Conference on Neutrino Physics and Astrophysics, being held in Japan's ancient capital of Kyoto, that the earlier results were wrong.

"The previous data taken up to 2011 with the neutrino beam from CERN to Gran Sasso were revised taking into account understood instrumental effects," the team said.

"A coherent picture has emerged with both previous and new data pointing to a neutrino velocity consistent with the speed of light."

The initial findings had been greeted with a combination of excitement and scepticism, even from those involved in the experiment, who urged other physicists to carry out their own checks to corroborate or refute what had been seen.

As part of this verification, an experiment called ICARUS at the Gran Sasso Laboratory took a separate look at the flight of seven neutrinos that had also been recorded by the OPERA team.