Siberian scientists have for the first time in the world have high-quality crystals for experiments that could show the fallacy of modern fundamental physical theory — the Standard Model of elementary particles.
Molybdate crystals of zinc and cadmium tungstate grown at the Institute of Inorganic Chemistry SB RAS (Novosibirsk), planned to be used for the development of detector experiment to search for the so-called neutrinoless double beta decay. If an extremely rare event will be recorded, it would mean that what was previously considered massless elementary particle, the neutrino has mass and is the antiparticle for itself, which means that the Standard Model is in need of revision. "The first in the world we grew crystals of cadmium tungstate and molybdate, zinc, have the necessary properties for rare events, in particular, to study the elusive neutrino particle," — said the head of the laboratory of crystal growth Inorganic Chemistry SB RAS Vladimir Schlegel.
According to him, testing molybdate crystals of zinc at the Institute of Nuclear and mass spectrometry in Orsay (France), as well as one of the largest underground laboratories in the world — the National Laboratories of Gran Sasso Italian National Institute of Nuclear Physics, have shown that this material is now one of the best candidates for use in detectors for double beta decay.
Schlegel and colleagues from Ukraine, France, Italy and the United States in an article published in the Journal Physics Letters B, showed that the crystals of these detectors have extremely high sensitivity in the background signal close to zero.
"Low-temperature scintillating bolometers of zinc molybdate are suitable candidates for future experiments to search for neutrinoless double beta decay" — the article says.
Double beta decay is a type of radioactive decay of an atomic nucleus, which is very rare and is accompanied by the emission of two electrons and two neutrinos. Some theories predict the existence of neutrinoless double beta decay, which until now has not been reliably detected in the experiment.
Study co-author, Fyodor Danevych of the Kiev Institute for Nuclear Research, RIA Novosti said that more than 10 years ago, a group of scientists from Germany and Russia conducted in Italy experiment to search for neutrinoless decay detectors made of germanium-76 isotope.
In 2001, the German leader of the research group, Hans-Klapdor Klyayngrothauz (Hans Klapdor-Kleingrothaus) and several of his colleagues, without the consent of the other members of the collaboration, published an article which claimed that they were able to fix the neutrinoless decay.
"Collaboration in general, this result is not accepted. He went against collaboration, part of the Russian did not even warned. Still remains unclear, they observed an effect or not, up to now, this result is intriguing," — said Danevych.
Experiments that explore the double-beta decay, require a very long observation time, because even the resolution of a standard model of two-neutrino double beta decay process is the most rare in the universe, mankind registered. Under the half-lives, which are now better targeted experiments, trying to see the elusive process in desyatikilogrammovom detector for several years of observations expected only a few decays Danevych said.
STANDARD MODEL AND "Superchips" in Novosibirsk
It may or may not occur neutrinoless beta decay depends on the properties of neutrinos, the scientists explain. If this type of decay is secure, it will mean that the neutrino has mass and is a Majorana particle is identical to its antiparticle. Danevych notes that this will be the opening of a new type of matter.
According to him, before the presence of neutrino mass has been reliably demonstrated in experiments with neutrino oscillation, but they do not allow us to determine its value.
"The value of the neutrino mass can be measured in an experiment with neutrinoless double beta decay," — said the source.
Cryogenic scintillating bolometers based on the "Novosibirsk crystals" open up new possibilities in this field of research. "This is a very promising and innovative technology," — said Danevych.
The experiment suggests that several dozen kilograms of zinc molybdate crystals will be put in place, safely isolated from cosmic rays and refined from all sources of radiation. It may be, for example, underground tunnels Gran Sasso laboratory, where many other neutrino experiments, including the famous discovery of geo-neutrinos (that is, the neutrinos from the depths of the earth) experiment Borexino.
When the nucleus of an atom of molybdenum is neutrinoless double beta decay, it emits two electrons, causing the scintillation flash and a slight fever, which are fixed extremely sensitive sensors.
"We receive and signal light and heat, and most importantly, that the energy resolution obtained is very high," — said the scientist. He added that for the reliable evidence for the existence of neutrinoless decay is required to fix at least 10-15 events.
For a successful search for neutrinoless decay is the very small number of isotopes — no more than a dozen. Molybdenum-100 — one of the best, it has a higher energy decay and, therefore, more likely to "catch" the event.
"It is a great achievement of Novosibirsk, they made this crystal is of sufficient quality and sufficiently large sizes. They used to say that it is impossible to grow a crystal. Attempts have been made in Moscow and Kharkov, but in Novosibirsk it was brought to an almost perfect conditions," — said Danevych.
According to him, the Siberian colleagues are working to create a technology that can provide the required amount for the experiment and the quality of the crystals.
"We need hundreds of pounds to carry out the experiment, able to see the mass of the neutrino mass states if the scheme of the particle is inverted, and to increase the chances to see this decay, we need crystals enriched in the isotope molybdenum-100" — said Danevych.
After a couple of years, scientists expect to begin a demonstration experiment with a few kilos of crystal to test how well they "work." After that decision will be made about the beginning of full-scale test, which will be held, most likely on the European money. As noted Danevych, detectors based on crystals of zinc molybdate can also be used to search for dark matter and the solar neutrino.
"For the construction of the full neutrino detector requires hundreds or thousands of pounds of crystal produced by us, but because the cost of the desired isotope molybdenum is several times higher than platinum, until we made a small experimental samples weighing 200-300 grams," — said Schlegel.