Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First result from a new generation of reactor neutrino experiments

09.11.2011
Physicists of the Double Chooz experiment detected a short-range disappearance of electron antineutrinos.

They presented this result on Wednesday 9 November 2011 at the LowNu conference in Seoul, Korea. It helps determine the so-far unknown third neutrino mixing angle which is a fundamental property with important consequences for particle and astro-particle physics. The Double Chooz experiment is looking for neutrinos produced in the nearby nuclear power plant. A measurement of this third angle would complete our picture of neutrino oscillations as reported by other experiments and will open new perspectives in understanding why we find matter and no antimatter in our today’s Universe.


Fig. 1: Overview of the Double Chooz experiment with the nuclear power plant and the two detectors. Graphics: Double Chooz Collaboration


Fig. 2: Photomultipliers inside the Double Chooz detector. Photo: Double Chooz Collaboration

Neutrinos are the most common particles existing in the Universe, but they are the least visible. They exist in three kinds called “flavours” and they have been known since the late 90’s for their special ability to transform from one type into another. This phenomenon is called neutrino oscillation and it implies that neutrinos do have a mass. Neutrino oscillations are currently an intensive field of research with several experiments aiming at a full description of the mechanism.

Neutrinos are produced in various ways such as by fusion processes inside the Sun and by cosmic rays bombarding the atmosphere. The Double Chooz experiment is dedicated to measure neutrino oscillations with unprecedented precision, by looking at anti-neutrinos being produced in the nearby nuclear reactor at Chooz in the French Ardennes. Double Chooz started taking data six months ago. At the 2011 LowNu conference in Korea the collaboration just announced its first results, reporting new data consistent with short-range oscillations. This result is based on the observation of the “disappearance” of (anti-)neutrinos in the expected flux observed from the nuclear reactor.

The three different flavours of neutrinos are related to their charged lepton counterparts: electron, muon and tau. Oscillations depend on three mixing parameters, of which two are large and have been measured before. The third mixing angle called è_13 (theta13) was not well measured up to now and restricted by an upper limit. The Double Chooz collaboration, by measuring the “disappearance” of electron antineutrinos, presents hints for oscillation also involving the third angle with the following value: sin^2(2è_13) = 0.085 ± 0.051. The probability given by preliminary results that there is no oscillation is only 7.9%.

The measurement of the last mixing angle è_13 (theta13) is crucial for future experiments aimed at measuring the difference between neutrino and anti-neutrino oscillations (leptonic CP violation). Furthermore, it relates indirectly to the origin of the asymmetry between matter and antimatter in the Universe.

“The third mixing angle is currently the missing link of neutrino physics. Measuring it precisely is the key to open the door to new physics beyond the standard model of particle physics and we are now very close to it” said Herve de Kerret from CNRS in France, and spokesman of the Double Chooz collaboration.

In June 2011, first hints of oscillation of neutrino muon neutrinos to neutrino electron neutrinos, involving this third angle, have been reported by accelerator experiments. The Double Chooz collaboration, by measuring the “disappearance” of electron antineutrinos, presents complementary and important evidence of oscillation also involving the third angle.

Double Chooz uses currently a detector located at a distance of about 1000 m from the reactor cores. The precision of the measurement will further increase over time and after the start of operation in 2012, of a second or “near” detector located at a distance of 400 m from the reactor. At these distances, no significant transformation into another neutrino species is expected. But by combining the results from both detectors, sin^2(2è_13) can be determined with even higher precision.

The detector target is composed of 10 m^3 of liquid scintillator developed specifically for this experiment. The scintillator is doped with gadolinium in order to tag neutrons from inverse beta decays induced by the reactor anti-neutrinos. The target is surrounded by layers of other liquids protecting against other particles and environmental radioactivity. The target is observed by 390 immersed photomultipliers, converting the interactions into electronic signals. These signals are processed in a data acquisition system, which is ready to take data over the next five years. The new detectors will ensure that neutrino physics will stay one of the most fruitful areas of particle physics, as it has been for the past 50 years.

An essential contribution to the project was the development of the gadolinium-doped liquid scintillator by the researchers at the Max Planck Institute for Nuclear Physics in Heidelberg. Their task was to find, test, produce and purify a gadolinium compound which is solvable in an organic liquid and chemically stable for many years. In collaboration with their colleagues from Japan they checked the photomultipliers in a specially built testbed. These central contributions will also play a crucial role for the interpretation and data analysis.

The Double Chooz collaboration is composed of universities and research institutes from Brazil, England, France, Germany, Japan, Russia, Spain and the USA.

Contact:

Prof. Dr. Manfred Lindner
Phone: +49 6221 516800
e-mail: manfred.lindner@mpi-hd.mpg.de
Dr. Christian Buck
Phone: +49 6221 516829
e-mail: christian.buck@mpi.hd.mpg.de

Dr. Bernold Feuerstein | Max-Planck-Institut
Further information:
http://www.doublechooz.org/
http://www.mpi-hd.mpg.de/lin/research_dc.en.html
http://orkshop.kias.re.kr/lownu11/

More articles from Physics and Astronomy:

nachricht New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>