This result is the first evidence for lepton number violation and proves the neutrino to be a Majorana particle. Since then, many experiments have observed ordinary double beta decay in other isotopes. For some nuclei, the process occurs as conversion of two protons to neutrons, emitting two electron neutrinos and absorbing two orbital electrons double electron capture. It is already now probing the TeV scale, on which new physics should manifest itself according to theoretical expectations. With only two electrons in the final state, the electrons' total would be approximately the difference of the initial and final nuclei, with the nuclear recoil accounting for the rest.
Our observation which at the same time means evidence that the neutrino is a Majorana particle, will be of fundamental importance for neutrino physics. Double beta decay has become indispensable nowadays for solving the problem of the neutrino mass spectrum and the structure of the neutrino mass matrix — together with present and future solar and atmospheric neutrino oscillation experiments. The only emitted products in this process are two electrons, which can occur if the neutrino and antineutrino are the same particle i. Where two uncertainties are specified, the first one is statistical uncertainty and the second is systematic. New results for the double beta decay of 76Ge are presented.
Today, double beta decay is indispensable for solving the problem of the neutrino mass spectrum and the structure of the neutrino mass matrix. In practice, the decay can be observed when the single beta decay is forbidden by energy conservation. This edition also gives expanded coverage of solar and supernova neutrinos. Furthermore, he had numerous visits and collaborations with the in , Russia, and naturally with the in Moscow. This site is like a library, you could find million book here by using search box in the widget. All books are in clear copy here, and all files are secure so don't worry about it. Majorana neutrinos so the same neutrino can be emitted and absorbed within the nucleus.
Springer, Heidelberg, 2001 , pp. If the neutrino is a i. In 2006, a refined estimate by the same authors stated the half-life was 2. The process can be thought as two simultaneous. Bw Weak-interaction and lepton including neutrino aspects 23. These theoretical decay branches have not been observed.
In 1997 he was again at Osaka by invitation of the Center of Excellence of the Japanese Ministry of Technology. Uncertainties in the nuclear matrix elements may widen the range given for the effective neutrino mass by at most a factor 2. Search for the Neutrinoless double beta decay can answer this question and provide the absolute mass of the neutrinos, which is the most important unknown parameter in neutrino physics at present. This result allows neutrinos to still play an important role as dark matter in the Universe. In 1956, after the was established, it became clear that the half-life of neutrinoless double beta decay would significantly exceed that of ordinary double beta decay.
Further the effective mass measured allows to put an absolute scale of the neutrino mass spectrum. The table below contains nuclides with the latest experimentally measured half-lives, as of December 2016. Neutrinoless double beta decay is a process. These subjects are considered in detail by authors, who also discuss such topics as neutrino mixing, neutrino decay, neutrino oscillations, double beta decay and related ideas. The evidence for this decay mode is 97% 2. He received his in Hamburg in 1971 and in Heidelberg two years later.
In addition, proper interpretation of the results require calculation of complicated nuclear structure matrix elements from nuclear models. Lee, Bayesian Statistics: An Introduction, 2nd edn. At present, the sharpest bound for the electron neutrino mass arises from this process. In particular it includes a thorough discussion of the varieties of seesaw mechanism, with or without supersymmetry. Thirteen isotopes have been experimentally observed undergoing two-neutrino double beta decay β —β — or double electron capture εε. Considering the importance, many new neutrinoless double beta decay experiments are planned all over the world.
The two neutrino accompanied double beta decay is evaluated for the first time for all five detectors with a statistical significance of 47. This second edition contains an expanded coverage of new experimental results and recent theoretical advances. In India also there is an effort to perform this experiment in the underground laboratory of the proposed India-based Neutrino Observatory. In this effort the main problem is to detect this extremely rare process. However, the double beta decay of also an alpha emitter has been measured radiochemically.
Please click button to get double beta decay book now. Each chapter includes summaries and set of problems, as well as further reading. Only in the early 1980s was it known that double beta decay yields information on the Majorana mass of the exchanged neutrino. In 1994 he became a member of the. Double beta decay was first observed in a laboratory in 1987 by the group of at in. At present, the sharpest bound for the electron neutrino mass arises from this process.
Comments: 14 pages, psfile, 7 figures, Published in Modern Physics Letters A, Vol. We give the present status of the analysis in this report. This claim was criticized by outside physicists as well as other members of the collaboration. Springer, Heidelberg, 2001 , pp. He proposed and was subsequently spokesperson of the Heidelberg-Moscow experiment, which ran from 1990 until 2003 in the , near.