Science Current Events | Science News | Brightsurf.com
 

Neutrinos: Ghostly particles with unstable egos

September 06, 2011

They were always mysterious. 26 years had to pass before the prediction of theoretical physics was confirmed and the existence of neutrinos was finally proven experimentally in 1956. The reason for this ordeal: Neutrinos only interact by the weak interaction with other particles of matter. When a cosmic neutrino approaches the earth, it has the best chance of passing through the whole globe unhindered. It is correspondingly difficult to find direct evidence of neutrinos with the help of a detector. Further decades passed in the discussion about their masses: None or small but finite mass? In the meantime it is considered certain that the ghostly particles are carrying mass, if only a virtually infinitesimal amount: According to today's knowledge, no neutrino should exist that is heavier than 1 eV (an electron "weighs" about 500,000 eV!). There are three types of neutrinos. This is also believed to be true today, so that neutrinos can each easily be classified in one of the three particle families in the framework of the standard model.

The knowledge of the neutrino mass is based on numerous experiments, in which so-called neutrino oscillations were observed. Neutrinos freely flying through the space of a particular family (i.e. the electron neutrino) can transform themselves spontaneously into a neutrino of another family affiliation (the muon neutrino or tau neutrino). One refers to an oscillation because the neutrino may change its family affiliation periodically during an extended journey. Such oscillations are only possible if the particles are carrying mass. The experimental evidence of neutrino oscillations (and thus a neutrino mass other than zero) is among the greatest breakthroughs of modern particle physics in the past 20 years.

The conversion process among different neutrino flavors depends on three so-called mixing angles Theta 12, Theta 23 and Theta 13. In interplay with the neutrino mass-squared differences they regulate the transition probabilities among different flavors. Of the three mixing angles only two are well known and have large values, while the third one Theta 13 is at the focus of current searches. So far, it was known that its value had to be small compared to the other two neutrino mixing angles. That is, Theta 13 = 0 could not be excluded. In the past, several independent projects have tried to measure this elusive parameter without success. The most important piece of information came in 1998 from the Chooz experiment in France, which established that the oscillation evoked by Theta 13 cannot be larger than approximately one tenth of those induced by the each of the other two neutrino mixing angles.

Three years ago a group of theoretical physicists of whom one, Antonio Palazzo, is now at the Excellence Cluster Universe, the others at the University and INFN of Bari, evidenced for the first time a weak hint of non-zero Theta 13 thanks to an accurate work of global analysis of all the existing neutrino oscillation data. In the meantime, two accelerator experiments (MINOS and T2K) were at work to nailing down Theta 13 and they have recently released their results. Notably, both experiments point towards a non-zero Theta 13, in agreement with the hint evidenced by the group of theorists. By combining their previous findings with the new accelerator data, in June 2011 the same group came for the first time to a statistically clear conclusion according to which sin² Theta 13 ≈ 0.02 with a confidence level of at least 3 Sigma. This means that the odds against Theta 13 > zero are 1:400.

However, physicists are very prudent and, before claiming a discovery, need to have a higher confidence level of 5 Sigma, diminishing the odds against Theta 13 > zero to 1:1 million. In order to provide secure evidence, the researchers are performing other experiments. Among these, the reactor experiment Double-Chooz, in which physicists of the Universe Clusters are strongly involved, will have a crucial role. For this purpose, it has been developed a particularly effective, terrestrial neutrino source: The particles (more precisely: anti-neutrinos) are generated and emitted during the fission processes in a nuclear power plant in particularly high flux. About 1020 antineutrinos leave a typical reactor every second. For this reason, a new experiment, the inheritor of the forerunning Chooz experiment, has started in the vicinity of the nuclear power plant in the French municipality Chooz. Thanks to this setup the value of Theta 13 will be measured with a precision that hitherto has not been achieved.

The principle behind the Double-Chooz experiment is very simple: Immediately after their generation in the reactor, several anti-neutrinos collide with a detector located 400 meters away. The spatial proximity ensures that no oscillations (or only extremely few) occur between emission and initial detection. The first detector thus measures the electron anti-neutrinos, which haven't transformed to muon and or tau neutrinos yet. A second detector of identical construction is located approximately 1,050 meters away from the reactor. If the value of the neutrino mixing angle Theta 13 is large enough, a part of the electron anti-neutrinos will become muon or tau anti-neutrinos as a result of the oscillations. The electron-anti-neutrino rate observed at the second detector therefore is much smaller than expected without oscillations.

Both detectors are filled with about 10 tons of scintillation fluid. If an electron-anti-neutrino interacts with a proton within the fluid, this will lead to inverse-beta decay: The proton captures the electron-anti-neutrino thereby transforming into one neutron by emitting one positron. Both particles generate one quick flash each in the liquid in a set time sequence. 390 photo sensors mounted on the walls of the vessel record the events. The Double Chooz experiment started physics data taking in April 2011 and will search for corresponding signals for five years. The detector performance and the status of data taking will be reported at the TAUP conference in Munich from 5 to 9 September 2011. First results are expected by the end of this year.

Establishing that Theta 13 is effectively different from zero would entail that all the three mixing angles are non-vanishing. This would provide the three neutrino flavors with maximal freedom of flipping one to each other. In turn, such a high degree of freedom is the necessary condition to generate CP-violation in the leptonic sector, i.e. to give rise to a different behavior of neutrinos and anti-neutrinos. The observation of CP-violation is now the next target of neutrino physicists as it would have significant consequences for several unanswered questions of modern physics. It could soon be clarified, in particular, whether neutrinos were responsible for the minimal surplus of matter compared to anti-matter in the early Universe. Without this asymmetry, all matter would have been transformed to radiation shortly after the birth of the Universe. There would be no galaxies, no stars or planets and no one who could measure Theta 13.

Technische Universitaet Muenchen


Related Neutrino Current Events and Neutrino News Articles


NASA's Fermi Telescope helps link cosmic neutrino to blazar blast
Nearly 10 billion years ago, the black hole at the center of a galaxy known as PKS B1424-418 produced a powerful outburst. Light from this blast began arriving at Earth in 2012.

A view of the colorful microcosm within a proton
The proton sounds like a simple object, but it's not. Inside, there's a teeming microcosm of quarks and gluons with properties such as spin and "color" charge that contribute to the particle's seemingly simplistic role as a building block of visible matter.

Most precise measurement of reactor Antineutrino spectrum reveals intriguing surprise
Members of the International Daya Bay Collaboration, who track the production and flavor-shifting behavior of electron antineutrinos generated at a nuclear power complex in China, have obtained the most precise measurement of these subatomic particles' energy spectrum ever recorded.

Most precise measurement of energy range for particles produced by nuclear reactors
An international team that includes researchers from the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) has captured the most precise--and puzzling--energy measurements yet of ghostly particles called reactor antineutrinos produced at a nuclear power complex in China.

New results from world's most sensitive dark matter detector
The Large Underground Xenon (LUX) dark matter experiment, which operates nearly a mile underground at the Sanford Underground Research Facility (SURF) in the Black Hills of South Dakota, has already proven itself to be the most sensitive detector in the hunt for dark matter, the unseen stuff believed to account for most of the matter in the universe.

NASA's Swift spots its thousandth gamma-ray burst
NASA's Swift spacecraft has detected its 1,000th gamma-ray burst (GRB). GRBs are the most powerful explosions in the universe, typically associated with the collapse of a massive star and the birth of a black hole.

Perfectly accurate clocks turn out to be impossible
Can the passage of time be measured precisely, always and everywhere? The answer will upset many watchmakers.

New precise particle measurement improves subatomic tool for probing mysteries of universe
Physicists at Southern Methodist University, Dallas, have achieved a new precise measurement of a key subatomic particle, opening the door to better understanding some of the deepest mysteries of our universe.

Best precision yet for neutrino measurements at Daya Bay
In the Daya Bay region of China, about 55 kilometers northeast of Hong Kong, a research project is underway to study ghostlike, elusive particles called neutrinos.

New data from Antarctic detector firms up cosmic neutrino sighting
Researchers using the IceCube Neutrino Observatory have sorted through the billions of subatomic particles that zip through its frozen cubic-kilometer-sized detector each year to gather powerful new evidence in support of 2013 observations confirming the existence of cosmic neutrinos.
More Neutrino Current Events and Neutrino News Articles

Neutrino

Neutrino
by Frank Close (Author)


Neutrinos are perhaps the most enigmatic particles in the universe. These tiny, ghostly particles are formed by the billions in stars and pass through us constantly, unseen, at almost the speed of light. Yet half a century after their discovery, we still know less about them than all the other varieties of matter that have ever been seen.

In this engaging, concise volume, renowned scientist and writer Frank Close gives a vivid account of the discovery of neutrinos and our growing understanding of their significance, touching on speculative ideas concerning the possible uses of neutrinos and their role in the early universe along the way. Close begins with the discovery of radioactivity by Henri Becquerel and Marie and Pierre Curie, the early model of the atom by Ernest...

Neutrino Hunters: The Thrilling Chase for a Ghostly Particle to Unlock the Secrets of the Universe

Neutrino Hunters: The Thrilling Chase for a Ghostly Particle to Unlock the Secrets of the Universe
by Ray Jayawardhana (Author)


Winner of the Canadian Science Writers Association 2014 Science in Society Book Award
A Publishers Weekly Top 10 Science Book of the Season
A Book to Watch Out For, The New Yorker's Page-Turner Blog
A Los Angeles Times Gift Guide Selection
One of the Best Physics Books of 2013, Cocktail Party Physics Blog, Scientific American

Detective thriller meets astrophysics in this adventure into neutrinos and the scientists who pursue them

The incredibly small bits of matter we call neutrinos may hold the secret to why antimatter is so rare, how mighty stars explode as supernovae, what the universe was like just seconds after the big bang, and even the inner workings of our own planet.For more than eighty years, adventurous minds from around the world have been chasing...

Neutrinos - die perfekte Welle: Vom Nobelpreis in die Welt von Higgs, Extra-Dimensionen und Zeitreisen (German Edition)

Neutrinos - die perfekte Welle: Vom Nobelpreis in die Welt von Higgs, Extra-Dimensionen und Zeitreisen (German Edition)
by Heinrich Päs (Author)


Dieses Buch handelt von den wohl rätselhaftesten Teilchen des Universums: den Neutrinos. Wie Chamäleons wechseln sie nach den Gesetzen von Quantentheorie und Teilchenphysik ihre Identität. Dabei sind sie nicht wahrnehmbar und kaum nachweisbar und können dennoch entscheidend dazu beitragen, die größten Rätsel des Universums zu entschlüsseln: die Struktur von Raum und Zeit und die Existenz und Vielfältigkeit der materiellen Welt.Wieso liegt die Natur der Neutrino-Masse immer noch im Dunkeln? Wie stehen die Teilchen zu Higgs, Extradimensionen und Supersymmetrie? Was hat das alles mit Zeitmaschinen zu tun?
Unterhaltsam und allgemeinverständlich nimmt Heinrich Päs den Leser mit auf eine spannende Entdeckungsreise in die Welt der kleinsten Teilchen - eine Geschichte mit...

Nuggets to Neutrinos: The Homestake Story

Nuggets to Neutrinos: The Homestake Story
by Steven T Mitchell (Author)


no description

Experimental Studies of Neutrino Oscillations

Experimental Studies of Neutrino Oscillations
by WSPC


Takaaki Kajita and Arthur McDonald have been jointly awarded the 2015 Nobel Prize in Physics "for the discovery of neutrino oscillations, which shows that neutrinos have mass". Takaaki Kajita is a Japanese physicist who is well known for neutrino experiments at the Kamiokande and the even more outsized Super-Kamiokande.This volume of collected works of Kajita on neutrino oscillations provides a good glimpse into the rise of Asian research in the frontiers of neutrino physics. Japan is now a major force in the study of the three families of neutrinos. Much remains to be done to clarify the Dirac vs. Majorana nature of the neutrino, and the cosmological implications of the neutrino. The collected works of Kajita and his Super-Kamiokande group will leave an indelible footprint in the history...

The Neutrino: Ghost Particle of the Atom

The Neutrino: Ghost Particle of the Atom
by Isaac Asimov (Author)




Physics and Astrophysics of Neutrinos

Physics and Astrophysics of Neutrinos
by Masataka Fukugita (Editor), Atsuto Suzuki (Editor)


Observations of neutrinos being emitted by the supernova SN1987A, star neutrinos, and atmospheric neutrinos have provided new insights into astronomy, as well as new unresolved phenomena such as the solar neutrino problem, spurring investigative studies among particle physicists and astrophysicists. One of the most important features of this book is its enumeration of a number of basic properties of neutrinos and their relationship to Grand Unified Theories, focusing on the origin of the neutrino's mass and the generation mixing of neutrinos. All the kamiokande results, detector performances, and complete references are included.

Neutrino Oscillations: A Practical Guide to Basics and Applications (Lecture Notes in Physics)

Neutrino Oscillations: A Practical Guide to Basics and Applications (Lecture Notes in Physics)
by Springer


Neutrino oscillation (N.O.) is the only firm evidence of the physics beyond the Standard Model of particle physics and is one of the hottest topics in elementary particle physics today. This book focuses on the N.O., from its history to the future prospects, from the basic theories to the experiments. Various phenomena of N.O. are described intuitively with thorough explanations of the fundamental physics behind well-known formulations. For example, while many textbooks start with a discussion of the mixing matrix, this book stresses that N.O. is caused by the transition amplitudes between different neutrino flavors, and that the purpose of N.O. experiments is to measure transition amplitudes and think of its origin. The current understanding of neutrino oscillation is also summarized...

  The Neutrino
by ISAAC ASIMOV (Author)




The Neutrino

The Neutrino
by Joseph M. Brown (Author), First (Editor), Brittney Whitaker (Editor)


The Neutrino brings to reality the Impossible Dream of mankind and mechanical engineers throughout the world. We all dream of obtaining useful energy from a uniform gas. The practical solution would be to take atmospheric air with its energy of almost 3000 ft-lb per cubic foot of air and use that energy to drive our generators and factories. We do not yet know how to do that, but on a microscopic scale, nature does just that. We prove that the neutrino takes energy from the ether gas, organizes it, and then produces matter in fact, it produces everything we observe in the universe. All the useful energy in the universe stems from the microscopic neutrino.

© 2016 BrightSurf.com