BOREXINO IN THE PHYSICS WORLD TOP TEN 2014

"To the Borexino collaboration for being the first to detect neutrinos from the main nuclear reaction that powers the Sun", this id the motivation with which Physics World has included the experiment in his top ten 2014 of the main scientific results.
The Borexino's study was published last August in the prestigious international journal Nature. The neutrino experiment in the INFN Gran Sasso Laboratories has managed to measure the energy of our star in real time: the energy released today at the centre of the Sun is exactly the same as that produced 100,000 years ago. For the first time in the history of scientific investigation of our star, solar energy has been measured at the very moment of its generation. This has been announced by the Borexino experiment at the Gran Sasso National Laboratories (LNGS) of the Italian National Institute for Nuclear Physics (INFN).
"This recognition - says Gianpaolo Bellini, scientist among the fathers of Borexino - rewards excellence of the Borexino experiment, to which INFN research groups have given a fundamental contribution. But it rewards the excellance also of the INFN Gran Sasso National Laboratories, that is a large infrastructure with unique features in the world and a research center of prestige on the international scene. "

 

 

 

ICARUS ON THE ROAD

Last night ICARUS, the world’s largest liquid argon neutrino detector, left the Gran Sasso Laboratories of the Italian Institute for Nuclear Physics (INFN) and is now on its way to CERN (European Organisation for Nuclear Research) in Geneva. Since 2010, ICARUS T600 – that is its full name– has been observing the neutrino beam sent from CERN to the Gran Sasso underground Laboratories passing through 730 km of the Earth’s crust. Now ICARUS has been carefully loaded onto two special equipment transporters and is being transferred to CERN to be overhauled and upgraded, in view of its probable future use in the United States. Physicists believe it is an essential and as yet inimitable element for an experiment with low-energy neutrinos at Fermilab in Chicago. ICARUS is the only detector in the world with more than 600 tonnes of argon, and has been found to be entirely suitable. The technology of ICARUS, first proposed in 1977 by the Nobel prize winner Carlo Rubbia, who is still the spokesperson of the experiment, is an example of record-breaking performance by Italian scientists at the INFN, who have developed a unique solution. The experiment at the Gran Sasso National Laboratories has demonstrated its precision in detecting neutrinos artificially produced in an accelerator, such as those in the CNGS (CERN Neutrinos to Gran Sasso) beam, which ran from 2006 to 2012. The experiment is capable of combining the originality of the idea with technical precision and efficiency.

THE SUN AS BOREXINO SEES IT IN REAL TIME

The neutrino experiment in the INFN Gran Sasso Laboratories has managed to measure the energy of our star in real time: the energy released today at the centre of the Sun is exactly the same as that produced 100,000 years ago.
For the first time in the history of scientific investigation of our star, solar energy has been measured at the very moment of its generation. This has been announced by the Borexino experiment at the Gran Sasso National Laboratories (LNGS) of the Italian National Institute for Nuclear Physics (INFN). The study is published in the prestigious international journal Nature.
Borexino has managed to measure the Sun’s energy in real-time, detecting the neutrinos produced by nuclear reactions inside the solar mass: these particles, in fact, take only a few seconds to escape from it and eight minutes to reach us. Previous measurements of solar energy, on the other hand, have always taken place on radiation (photons) which currently illuminate and heat the Earth and which refer to the same nuclear reactions, but which took place over a hundred thousand years ago: this, in fact, is the time it takes, on average, for the energy to travel through the dense solar matter and reach its surface. The comparison between the neutrino measurement now published by Borexino and the previous measurements concerning the emission of radiant energy from the Sun shows that solar activity has not changed in the last one hundred thousand years. “Thanks to the results of this new Borexino research we have seen, via the neutrinos produced in the proton-proton (pp) reaction, that it is the chain of pp nuclear fusions which makes the Sun work, providing precisely the energy that we measure with photons: in short, this proves that the Sun is an enormous nuclear fusion plant,” says Gianpaolo Bellini, one of the fathers of the Borexino experiment.
The Borexino detector, installed in the INFN underground Laboratories of Gran Sasso, has managed to measure the flux of neutrinos produced inside the Sun in the fusion reaction of two hydrogen nuclei to form a deuterium nucleus: this is the seed reaction of  the nuclear fusion cycle which produces about 99% of the solar energy. Up until now, Borexino had managed to measure the neutrinos from nuclear reactions that were part of the chain originated by this reaction or belonging to secondary chains, which contribute significantly less to the generation of solar energy, but which were key to the discovery of certain crucial physical properties of this “ephemeral” elementary particle, the neutrino.
The difficulty of the measurement just made is due to the extremely reduced energy of these neutrinos (they have, in fact, a maximum energy of 420 keV), the smallest one compared to the other neutrinos emitted by the Sun, which also have energy levels so low as to make it almost impossible to measure them and which only Borexino was and is able to measure. This performance makes Borexino a detector unique in the world, and it will remain so for a number of years, thanks to state-of-the-art technologies used in its construction, which have allowed not only the neutrinos emitted from the Sun but also those produced by our Earth to be studied.
The Borexino experiment is the result of a collaboration between European countries (Italy, Germany, France, Poland), the United States and Russia and it will take data for at least another four years, improving the accuracy of measurements already made and addressing others of great importance for both particle physics as well as astrophysics.

 

 

CUORE: THE COLDEST HEART IN THE KNOWN UNIVERSE

The CUORE collaboration at the INFN Gran Sasso National Laboratory has set a world record by cooling a copper vessel with the volume of a cubic meter to a temperature of 6 milliKelvins: it is the first experiment ever to cool a mass and a volume of this size to a temperature this close to absolute zero (0 Kelvin). The cooled copper mass, weighing approx. 400 kg, was the coldest cubic meter in the universe for over 15 days.

CUORE is an international collaboration involving some 130 scientists mainly from Italy, USA, China, Spain, and France. CUORE is supported by the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; the Department of Energy Office of Science (Office of Nuclear Physics), the National Science Foundation, and Alfred P. Sloan Foundation in the United States. CUORE (which stands for Cryogenic Underground Observatory for Rare Events, but is also Italian for Heart) is an experiment being built at the INFN Gran Sasso underground laboratory to study the properties of neutrinos and search for rare processes.

The CUORE cryostat is the only one of its kind in the world, not only in terms of its dimensions, extreme temperatures, and cooling power, but also for the selected materials and for the building techniques that both guarantee very low levels of radioactivity. CUORE is seeking to observe a hypothesized rare process called neutrinoless double-beta decay. Detection of this process would allow researchers to demonstrate, for the first time, the transformation of antineutrinos to neutrinos, thereby offering a possible explanation for the abundance of matter over anti-matter in our Universe. These transitions are only possible if the neutrinos are so-called Majorana particles, as suggested by Italian physicist Ettore Majorana in 1930s. The experiment will also be sensitive to the miniscule value of the neutrino mass.

CUORE is designed to work in ultra-cold conditions at the temperatures of around 10 mK, i.e. ten thousandths of a degree above absolute zero. It consists of tellurium dioxide crystals serving as bolometers (radiation detectors which measure energy by recording tiny fluctuations in detector’s temperature). The cryostat was realized and funded by the Italian National Institute for Nuclear Physics (INFN); the University of Milano Bicocca coordinated the research team in charge of the design of the cryogenic system.

When complete, CUORE will consist of approximately 1000 instrumented tellurium dioxide crystals. It will be covered by shielding made of ancient Roman lead, a material characterized by a very low level of intrinsic radioactivity. The mass of materials at the frigid temperatures near absolute zero will be almost two tonnes.

 

An international team of physicists, including students and postdoctoral scholars from Italy and the US, worked tirelessly for over a year to assemble the cryostat, iron out the kinks, and successfully demonstrate its record-breaking performance. In the most recent operational test of the cryostat, the temperature reached 6 milliKelvins, equal to – 273.144 degrees centigrade. This is stunningly close to absolute zero, which is equal to – 273.15 degrees C. No experiment on Earth has ever cooled a similar mass or volume to temperatures this low; similar conditions are also not expected to arise in Nature.

This gives CUORE the distinction of being the coldest cubic meter in the known Universe. The successful solution to a technological challenge of cooling the entire experimental mass of almost 2 tonnes to the temperature of a few millinKelvin was made possible through a strong collaboration with industrial partners of high profile such as the Leiden Cryogenics BV (the Netherlands), which designed and built the unique refrigeration system, and the Simic SpA (Italy), which built the cryostat vessels

THE FOURTH TRANSFORMATION OF NEUTRINOS

Now the scientists of the OPERA experiment can claim the observation of the extremely rare neutrino oscillation in the tau channel

The OPERA international experiment at the INFN Gran Sasso Laboratory (Italy) has detected a fourth tau neutrino. The neutrino indeed started its flight at CERN as muon neutrino and, after travelling 730 km through the Earth, it arrived at the Gran Sasso laboratory transformed into a tau neutrino.

This important result was announced today during a seminar held at the Gran Sasso Laboratory.

According to the head of the international research team, Giovanni De Lellis, from Federico II University and INFN in Naples, “The detection of the fourth tau neutrino is a very important confirmation of the previously seen events. This transition is now seen for the first time with a statistical significance exceeding the 4 sigma level: beyond the scientific jargon, this is equivalent to say that for the first time we have observed the extremely rare oscillation phenomenon of muon neutrinos to tau neutrinos, the aim of the OPERA project.” “If other tau neutrinos will be found in the data still to be analysed, an even higher significance level could be achieved. The important result reported today was made possible thanks to the dedication of all the researchers involved in the project”, De Lellis finally says.

 

The international OPERA experiment (involving 140 physicists from 28 research institutes in 11 countries) was designed to observe this exceptionally rare phenomenon. Neutrino oscillations have been a poorly known phenomenon for several decades. More than 15 years ago, it was demonstrated that muon neutrinos produced in cosmic-ray interactions arrive at the Earth fewer than expected. The result reported today explains why: the “missing” neutrinos are indeed those muon neutrinos oscillating into tau neutrinos.

 

The OPERA experiment with the CNGS (CERN Neutrinos to Gran Sasso)

 

Neutrinos produced at CERN, Geneva, travel toward the Gran Sasso underground laboratory. Thanks to their extremely small probability to interact with matter, after travelling for about 730 km through the Earth, neutrinos arrive unperturbed at the OPERA detector, a giant of about 4000 tons, with a 2000 m3 volume and nine million photographic films: here all the particles that are caught get observed. There are three kinds of neutrinos in nature, named “flavours”: electron, muon and tau.

OPERA looks for tau neutrinos knowing that all those leaving CERN are muon neutrinos since they are on purpose produced that way. If neutrinos of a different flavour are detected, this is a proof of the oscillation occurring during their 730 km flight. After the first neutrinos arrived at the INFN Gran Sasso laboratory in 2006, the experiment gathered data for five consecutive years, from 2008 to 2012. The first tau neutrino was observed in 2010, the second and third ones in 2012 and 2013, respectively. Scientists will complete the analysis of all the data collected, searching for other tau neutrinos to achieve the ultimate significance in the appearance of tau neutrinos from the oscillation of muon neutrinos.

 

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