Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chameleon particles from the Sun

22.04.2002


The Sun emits electron-neutrinos, elementary particles of matter that have no electric charge and very little mass, created in vast numbers by the thermonuclear reactions that fuel our parent star. Since the early 1970s, several experiments have detected neutrinos arriving on Earth, but they have found only a fraction of the number expected from detailed theories of energy production in the Sun. This meant there was either something wrong with our theories of the Sun, or our understanding of neutrinos. It turns out that our theories of how the Sun is powered look like being correct according to a team of scientists from the UK, the US and Canada whose latest results from research into solar neutrinos were announced on Saturday [20 April 2002]. What`s more, these ghostly particles have `chameleon` type capabilities, changing from one type of neutrino into another on their journey from the Sun to Earth.



The scientists used data taken entirely from the Sudbury Neutrino Observatory [SNO] in Canada which shows without doubt that the number of observed solar neutrinos is only a fraction of the total emitted from the Sun - clear evidence that they have chameleon type properties and change type en-route to Earth.

Says Project Director Art McDonald of Queen`s University, Canada, "These new results show in a clear, simple and accurate way that solar neutrinos change their type. The total number of neutrinos we observe is in excellent agreement with calculations of the nuclear reactions powering the Sun. The SNO team is really excited because these measurements enable neutrino properties to be defined with much greater certainty in fundamental theories of elementary particles."


Neutrinos are known to exist in three types related to three different charged particles - the electron, and its lesser known relatives the muon and the tau. The Sun emits electron neutrinos, which are created in the thermonuclear reactions in the solar core. Previous experiments have found fewer electron neutrinos than suggested by calculations based on how the Sun burns - the famous "solar neutrino problem".


The results announced on Saturday at the Joint American Physical Society/American Astronomical Society meetings in Albuquerque, New Mexico, show that the number of electron-neutrinos detected is about 1/3 of the number expected according to calculations based on the latest sophisticated models of the solar core. The SNO detector uses the unique properties of heavy water - where the hydrogen has an extra neutron in its nucleus - to detect not only electron neutrinos through one type of reaction, but also all three known neutrino types through a different reaction. The total number of all three types of neutrino agrees well with the calculations. This shows unambiguously that electron neutrinos emitted by the Sun have changed to muon or tau neutrinos before they reach Earth.

Dr. Andre Hamer, of Los Alamos National Laboratory, said, "In order to make these measurements we had to restrict the radioactivity in the detector to minute levels and determine both neutrino signals and the detector background very accurately - to show clearly that we are observing neutrinos from the Sun. The care taken throughout this experiment to minimise radioactivity, and the careful calibration and analysis of our data, has enabled us to make these neutrino measurements with great accuracy"

In June last year results from the detection of electron neutrinos at SNO first indicated, with a certainty of 99.9%, that neutrinos change type on their way from the Sun, thus solving the long-standing problem - or so it was thought. However, these conclusions were based on comparisons of the SNO results with those from a different experiment, the Super-Kamiokande detector, located in Japan.

Prof. Dave Wark of the University of Sussex and the Rutherford Appleton Laboratory, Oxford, commented, " Whenever a scientific conclusion relies on two experiments, and on the theory connecting them, it is twice as hard to be certain that you understand what is going on. We are therefore much more certain now that we have really shown that solar neutrinos change type".

The latest results, entirely from the SNO detector, (and which have been submitted to Physical Review Letters) are 99.999% accurate, and are of great importance because of the way in which physicists think that the neutrinos - long thought to be massless particles - change types only happens if the different types have different masses.

Gill Ormrod | alphagalileo

More articles from Physics and Astronomy:

nachricht Further Improvement of Qubit Lifetime for Quantum Computers
09.12.2016 | Forschungszentrum Jülich

nachricht Electron highway inside crystal
09.12.2016 | Julius-Maximilians-Universität Würzburg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>