The Majorana nature of neutrinos and the neutrinoless double-beta decay
Neutrinos are tiny, neutral elementary particles that, contrary to the standard model of physics, have been proven to have mass. One possible explanation for this mass could be that neutrinos are their own antiparticles, so-called Majorana particles.
Though experimental evidence for this is still lacking, many theoretical extensions of the standard model of physics predict the Majorana nature of neutrinos. If this hypothesis proves to be true, many previously unanswered questions about the origin of our universe and the origin of matter could be answered.
650 meters of shielding
In the EXO-200 experiment (Enriched Xenon Observatory), which is operated in the U.S. state of New Mexico, 650 meters below the earth's surface, scientists are looking for the evidence. Physicists from the research group of Professor Peter Fierlinger of the Excellence Cluster Universe at the Technische Universitaet Muenchen are major contributors to this experiment.
The most sensitive method to experimentally verify the Majorana question is the search for a process called "neutrinoless double-beta decay". This process is a special radioactive decay that may only occur if neutrinos are their own antiparticles.
The EXO-200 experiment has searched for these decays over several years. From the fact that not one of these decays has been detected, the scientists can now deduce a lower limit for the half-life of the decay of at least 1025 years – around one million-billion years more than the age of the universe.
"Although this measurement attains unprecedented accuracy, the question about the nature of neutrinos can still not be answered," says Dr. Michael Marino, member of the research group of Professor Peter Fierlinger and responsible for the analysis of the now published data. "That's why this open issue remains one of the most exciting questions in physics."
This result demonstrates the high sensitivity of the detector and also the future potential of this method. Hence the EXO-200 measurements are also the basis for a much larger future experiment that finally could confirm or refute the Majorana nature of neutrinos."
The EXO-200 experiment uses liquid xenon that was enriched to 80.6 percent of xenon-136 in Russian centrifuges. Xenon-136 is an isotope that is allowed by theory to undergo neutrinoless double-beta decay. The experiment's location in the Waste Isolation Pilot Plant (WIPP) 650 meters below ground provides shielding against radioactive decays and cosmic radiation.
EXO-200 is a collaboration of research groups from Canada, Switzerland, South Korea, Russia and the USA; the Technische Universitaet Muenchen is the only German partner.
J. B. Albert, et.al., The EXO-200 Collaboration: Search for Majorana neutrinos with the first two years of EXO-200 data, Nature, Adv. online publication, June 5, 2014
Dr. Andreas Battenberg | Eurek Alert!
Applicability of dynamic facilitation theory to binary hard disk systems
08.12.2016 | Nagoya Institute of Technology
Will Earth still exist 5 billion years from now?
08.12.2016 | KU Leuven
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:...
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...
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...
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...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences