Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Major steps forward in understanding neutrino properties

06.09.2019

In the quest to prove that matter can be produced without antimatter, the GERDA experiment at the Gran Sasso Underground Laboratory is looking for signs of neutrinoless double beta decay. The experiment has the greatest sensitivity worldwide for detecting the decay in question. To further improve the chances of success, a follow-up project, LEGEND, uses an even more refined decay experiment.

While the Standard Model of Particle Physics has remained mostly unchanged since its initial conception, experimental observations for neutrinos have forced the neutrino part of the theory to be reconsidered in its entirety.


Working on the germanium detector array in the clean room of the Gran Sasso underground laboratory.

J. Suvorov / GERDA

Neutrino oscillation was the first observation inconsistent with the predictions and proves that neutrinos have non-zero masses, a property that contradicts the Standard Model. In 2015, this discovery was rewarded with the Nobel Prize.

Are neutrinos their own antiparticles?

Additionally, there is the longstanding conjecture that neutrinos are so-called Majorana particles: Unlike all other constituents of matter, neutrinos might be their own antiparticles. This would also help explain why there is so much more matter than antimatter in the Universe.

The GERDA experiment is designed to scrutinize the Majorana hypothesis by searching for the neutrinoless double beta decay of the germanium isotope 76-Ge: Two neutrons inside a 76-Ge nucleus simultaneously transform into two protons with the emission of two electrons. This decay is forbidden in the Standard Model because the two antineutrinos – the balancing antimatter – are missing.

The Technical University of Munich (TUM) has been a key partner of the GERDA project (GERmanium Detector Array) for many years. Prof. Stefan Schönert, who heads the TUM research group, is the speaker of the new LEGEND project.

The GERDA experiment achieves extreme levels of sensitivity

GERDA is the first experiment to reach exceptionally low levels of background noise and has now surpassed the half-life sensitivity for decay of 10^26 years. In other words: GERDA proves that the process has a half-life of at least 10^26 years, or 10,000,000,000,000,000 times the age of the Universe.

Physicists know that neutrinos are at least 100,000 times lighter than electrons, the next heaviest particles. What mass they have exactly, however, is still unknown and another important research topic.

In the standard interpretation, the half-life of the neutrinoless double beta decay is related to a special variant of the neutrino mass called the Majorana mass. Based the new GERDA limit and those from other experiments, this mass must be at least a million times smaller than that of an electron, or in the terms of physicists, less than 0.07 to 0.16 eV/c^2 [1].

Consistent with other experiments

Also other experiments limit the neutrino mass: the Planck mission provides a limit on another variant of the neutrino mass: The sum of the masses of all known neutrino types is less than 0.12 to 0.66 eV/c^2.

The tritium decay experiment KATRIN at the Karlsruhe Institute of Technology (KIT) is set-up to measure the neutrino mass with a sensitivity of about 0.2 eV/c^2 in the coming years. These masses are not directly comparable, but they provide a cross check on the paradigm that neutrinos are Majorana particles. So far, no discrepancy has been observed.

From GERDA to LEGEND

During the reported data collection period, GERDA operated detectors with a total mass of 35.6 kg of 76-Ge. Now, a newly formed international collaboration, LEGEND, will increase this mass to 200 kg of 76-Ge until 2021 and further reduce the background noise. The aim is to achieve a sensitivity of 10^27 years within the next five years.

More information:

GERDA is an international European collaboration of more than 100 physicists from Belgium, Germany, Italy, Russia, Poland and Switzerland. In Germany, GERDA is supported by the Technical Universities of Munich and Dresden, the University of Tübingen and the Max Planck Institutes for Physics and for Nuclear Physics. German funding is provided by the German Federal Ministry of Education and Research (BMBF), the German Research Foundation (DFG) via the Excellence Cluster Universe and SFB1258, as well as the Max Planck Society.

Prof. Schönert received an ERC Advanced Grant for preparatory work on the LEGEND project in 2018. A few days ago, Prof. Susanne Mertens received an ERC grant for her work on the KATRIN experiment. In the context of that experiment, she will search for so-called sterile neutrinos.

[1] In particle physics masses are specified not in kilograms, but rather in accordance with Einstein’s equation E=mc^2: electron volts [eV] divided by the speed of light squared. Electron volts are a measure of energy. This convention is used to circumvent unfathomably small units of mass: 1 eV/c^2 corresponds to 1.8 × 10^-37 kilograms.

Wissenschaftliche Ansprechpartner:

TU Munich
Prof. Dr. Stefan Schönert
Tel.: +49 89 289 12511
E-Mail: schoenert@ph.tum.de

TU Dresden
Prof. Dr. Kai Zuber
Tel.: +49 351 463 42250
E-Mail: zuber@physik.tu-dresden.de

University of Tübingen
Prof. Dr. Josef Jochum
Tel.: +49 7071 297 4453
E-Mail: Josef.Jochum@uni-tuebingen.de

MPI for Physics, Munich
Prof. Dr. Allen Caldwell
Tel.: +49 89 323 54207
E-Mail: caldwell@mpp.mpg.de

MPI for Nuclear Physics, Heidelberg
Prof. Dr. Werner Hoffmann
Tel.: +49 6221 516 330
E-Mail: Werner.Hofmann@mpi-hd.mpg.de

Prof. Dr. Manfred Lindner
Tel.: +49 6221 516 800
E-Mail: lindner@mpi-hd.mpg.de

University of Zürich
Prof. Dr. Laura Baudis
Tel.: +41 44 635 5777
E-Mail: lbaudis@physik.uzh.ch

Originalpublikation:

The GERDA collaboration: Probing Majorana neutrinos with double beta decay
Science, published online on Thursday 5 September, 2019
DOI: 10.1126/science/ aav8613

Weitere Informationen:

https://science.sciencemag.org/lookup/doi/10.1126/science.aav8613 Link to original publication (available after lift of embargo: Sept. 5, 2019, 8 pm)
https://www.tum.de/nc/en/about-tum/news/press-releases/details/35672/ Link to press release on the TUM-homepage (available after lift of embargo)
https://www.mpi-hd.mpg.de/gerda/home.html Homepage of the GERDA Collaboration

Dr. Ulrich Marsch | Technische Universität München

More articles from Physics and Astronomy:

nachricht Pulsar emission map thanks to Einstein
06.09.2019 | Max-Planck-Institut für Radioastronomie

nachricht Silicon as a semiconductor: silicon carbide would be much more efficient
06.09.2019 | Universität Basel

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: Next generation video: WDR and Fraunhofer HHI present significantly improved video quality at IFA 2019

The demand for even higher resolution videos will continue to increase in the coming years. For this reason, the German public service broadcaster WDR and the Fraunhofer Heinrich Hertz Institute HHI will collaborate in the coming months to test the Video Coding possibilities offered by the next international standard VVC/H.266.

VVC/H.266 is the successor standard to HEVC/H.265. The latter is currently the most modern and efficient standard for Video Coding and is used, for example, in...

Im Focus: Nanodiamonds in the brain

The recording of images of the human brain and its therapy in neurodegenerative diseases is still a major challenge in current medical research. The so-called blood-brain barrier, a kind of filter system of the body between the blood system and the central nervous system, constrains the supply of drugs or contrast media that would allow therapy and image acquisition. Scientists at the Max Planck Institute for Polymer Research (MPI-P) have now produced tiny diamonds, so-called "nanodiamonds", which could serve as a platform for both the therapy and diagnosis of brain diseases.

The blood-brain barrier is a physiological boundary layer that works highly selectively and thus protects the brain: On the one hand, pathogens or toxins are...

Im Focus: Entanglement sent over 50 km of optical fiber

For the first time, a team led by Innsbruck physicist Ben Lanyon has sent a light particle entangled with matter over 50 km of optical fiber. This paves the way for the practical use of quantum networks and sets a milestone for a future quantum internet.

The quantum internet promises absolutely tap-proof communication and powerful distributed sensor networks for new science and technology. However, because...

Im Focus: Hamburg and Kiel researchers observe spontaneous occurrence of skyrmions in atomically thin cobalt films

Since their experimental discovery, magnetic skyrmions - tiny magnetic knots - have moved into the focus of research. Scientists from Hamburg and Kiel have now been able to show that individual magnetic skyrmions with a diameter of only a few nanometres can be stabilised in magnetic metal films even without an external magnetic field. They report on their discovery in the journal Nature Communications.

The existence of magnetic skyrmions as particle-like objects was predicted 30 years ago by theoretical physicists, but could only be proven experimentally in...

Im Focus: Physicists create world's smallest engine

Theoretical physicists at Trinity College Dublin are among an international collaboration that has built the world's smallest engine - which, as a single calcium ion, is approximately ten billion times smaller than a car engine.

Work performed by Professor John Goold's QuSys group in Trinity's School of Physics describes the science behind this tiny motor.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

AI for Laser Technology Conference: optimizing the use of lasers with artificial intelligence

29.08.2019 | Event News

The power of thought – the key to success: CYBATHLON BCI Series 2019

16.08.2019 | Event News

 
Latest News

A molecular 'atlas' of animal development

06.09.2019 | Life Sciences

New study tracks sulfur-based metabolism in the open ocean

06.09.2019 | Earth Sciences

Innovative Fine-Line Screen Printing Metallization Reduces Silver Consumption for Solar Cell Contacts

06.09.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>