Borexino

from Wikipedia, the free encyclopedia

Borexino is an experiment of particle physics , which from the sun coming neutrinos low energy are explored. The term “Borexino” is the Italian diminutive of BOREX ( Boron solar neutrino experiment). The experiment is located in the Laboratori Nazionali del Gran Sasso and represents an international group with researchers from Italy , the United States , Germany , France and Russia . The experiment is funded by various national institutions such as INFN and NSF .

The Borexino experiment in September 2015

The detector is a liquid scintillator located in a stainless steel sphere , shielded by a water tank. The main aim of the experiment is to precisely measure the monoenergetic neutrinos from the sun, which are produced when beryllium -7 captures electrons , in order to compare the results with the theoretical predictions (see article on proton-proton reaction ). This would give the researchers a better understanding of the nuclear fusion processes in the core of the sun, and the properties of the neutrino oscillation should also be better understood. Other goals of the experiment are the measurement of solar neutrinos from boron -8, pep and CNO . Antineutrinos from the earth's interior and nuclear power plants are also to be measured. The project could also find neutrinos from supernovae in the Milky Way. Borexino is part of the Supernova Early Warning System .

As part of the Borexino experiment, the SOX project to search for sterile neutrinos is currently in preparation. This concept provides for an artificial neutrino or antineutrino source to be installed below or inside the detector. Although a sterile neutrino cannot participate in the weak interaction, it would participate in the neutrino oscillation . This offers the possibility of recording an oscillation pattern inside a detector for the first time.

Gianpaolo Bellini was the speaker from 1990 to 2011 .

Results

The gray bands compare the regions where the solar neutrino telescopes, which are able to measure the energy of the events, are sensitive. It should be noted that the predictions of solar models are given on a logarithmic scale: Super-Kamiokande and SNO can observe about 0.02% of the total, while Borexino can observe any type of predicted neutrino from the sun.

In May 2007 the Borexino detector began to record data. In August 2007, beryllium-7 neutrinos from the sun were measured for the first time, with the measurement taking place in real time. The data were expanded and refined in 2008.

In 2010, neutrinos from the Earth's interior were observed for the first time. They are antineutrinos that arise from the decay of uranium , thorium , potassium and rubidium .

In 2011 the experiment published a precision measurement of beryllium-7 neutrinos from the sun, and in the same year solar neutrinos from pep reactions.

In 2012 they published the results of measurements of the speed of CNGS neutrinos from CERN to Gran Sasso . The results were in agreement with the speed of light . See measurements of neutrino velocity .

At the end of August 2014, the Borexino collaboration published the results of measuring the primary proton-proton fusion process in the sun. This represents the first direct measurement of the so-called primary pp neutrinos.

SOX project

SOX is the English acronym for " s hort distance neutrino o scillations with Bore x ino". The project plans to install an artificial antineutrino source in the tunnel below the Borexino detector. The activity of the radioactive beta emitter (Cer-144) will be approx. 100 kCi. Ce-144 breaks down into praseodymium-144 with a half-life of approx. 285 days. The long half-life allows the antineutrino source to be transported and installed, while the high Q value of Pr-144 (above the threshold for inverse beta decay) ultimately provides the antineutrinos for detection. The proof should be provided by the inverse beta decay. A prompt signal consisting of the positron annihilation and a delayed signal due to the capture of the neutron on the hydrogen are detected. This is intended to enable a measurement with particularly little background.
The installation of an artificial neutrino source (chromium-51) is being considered as a further option. The proof will be analogous to the analysis of the solar beryllium-7 neutrinos.
The CeSOX exposure phase is scheduled to begin at the end of 2016. The project has since been canceled as the necessary neutrino source cannot be supplied due to "technical" problems in the Mayak reprocessing plant.

An international working group published a paper on July 26, 2019, according to which an accident in the Mayak nuclear complex in the southern Urals during the production of a component of the neutrino experiment in 2017 led to high ruthenium concentrations, which environmental laboratories in many countries have shown. As early as 2017, the evidence indicated that the accident was related to a delivery of the Ce-144 radioisotope for the neutrino experiment. The analysis of the working group consisting of 68 authors now specifies this circumstantial evidence. However, Russia continues to deny this.

Web links

Individual evidence

  1. ^ Georg G. Raffelt: BOREXINO . In: Stars As Laboratories for Fundamental Physics: The Astrophysics of Neutrinos, Axions, and Other Weakly Interacting Particles . University of Chicago Press, 1996, ISBN 0-226-70272-3 , pp. 393-394.
  2. ^ Borexino experiment . In: Borexino, official website . INFN. Archived from the original on October 16, 2007. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved August 12, 2011. @1@ 2Template: Webachiv / IABot / borex.lngs.infn.it
  3. ^ Borexino collaboration: The Borexino detector at the Laboratori Nazionali del Gran Sasso . In: Nuclear Instruments and Methods in Physics Research Section A . 600, No. 3, 2008, pp. 568-593. arxiv : 0806.2400 . bibcode : 2009NIMPA.600..568B . doi : 10.1016 / j.nima.2008.11.076 .
  4. ↑ Borexino collaboration: SOX: Short distance neutrino Oscillations with BoreXino . In: JHEP . 1308, No. 038, 2013. arxiv : 1304.7721 . doi : 10.1007 / JHEP08 (2013) 038 .
  5. ^ The Borexino experiment at Gran Sasso begins the data taking . Laboratori Nazionali del Gran Sasso press release. May 29, 2007. Retrieved October 9, 2012.
  6. ↑ Emiliano Feresin: Low-energy neutrinos spotted . In: Nature news . 2007. doi : 10.1038 / news070820-5 .
  7. ↑ Borexino collaboration: First real time detection of 7Be solar neutrinos by Borexino . In: Physics Letters B . 658, No. 4, 2007, pp. 101-108. arxiv : 0708.2251 . bibcode : 2008PhLB..658..101B . doi : 10.1016 / j.physletb.2007.09.054 .
  8. ↑ Borexino collaboration: Direct Measurement of the Be7 Solar Neutrino Flux with 192 Days of Borexino Data . In: Physical Review Letters . 101, No. 9, 2008, p. 091302. arxiv : 0805.3843 . bibcode : 2008PhRvL.101i1302A . doi : 10.1103 / PhysRevLett.101.091302 .
  9. ^ A first look at the Earth interior from the Gran Sasso underground laboratory . INFN press release. March 11, 2010. Retrieved October 9, 2012.
  10. ^ Borexino collaboration: Observation of geo-neutrinos . In: Physics Letters B . 687, No. 4-5, 2010, pp. 299-304. arxiv : 1003.0284 . bibcode : 2010PhLB..687..299B . doi : 10.1016 / j.physletb.2010.03.051 .
  11. ↑ Precision measurement of the Beryllium solar neutrino flux and its day / night asymmetry, and independent validation of the LMA-MSW oscillation solution using Borexino-only data. . Borexino Collaboration press release. April 11, 2011. Retrieved October 9, 2012.
  12. ↑ Borexino collaboration: Precision Measurement of the Be7 Solar Neutrino Interaction Rate in Borexino . In: Physical Review Letters . 107, No. 14, 2011, p. 141302. arxiv : 1104.1816 . bibcode : 2011PhRvL.107n1302B . doi : 10.1103 / PhysRevLett.107.141302 .
  13. ↑ Borexino Collaboration succeeds in spotting pep neutrinos emitted from the sun . PhysOrg.com. February 9, 2012. Retrieved October 9, 2012.
  14. ^ Borexino collaboration: First Evidence of pep Solar Neutrinos by Direct Detection in Borexino . In: Physical Review Letters . 108, No. 5, 2011, p. 051302. arxiv : 1110.3230 . bibcode : 2012PhRvL.108e1302B . doi : 10.1103 / PhysRevLett.108.051302 .
  15. ↑ Borexino collaboration: Measurement of CNGS muon neutrino speed with Borexino . In: Physics Letters B . 716, No. 3–5, 2012, pp. 401-405. arxiv : 1207.6860 . bibcode : 2012arXiv1207.6860B . doi : 10.1016 / j.physletb.2012.08.052 .
  16. ↑ Borexino collaboration: neutrinos from the primary proton-proton fusion process in the Sun . In: nature . 512, No. 7515, 2014. doi : 10.1038 / nature13702 .
  17. ↑ a b Mikko Meyer: Search for Sterile Neutrinos with the Borexino Detector . In: DESY-PROC-2014-4 . 2014. doi : 10.3204 / DESY-PROC-2014-04 / 7 .
  18. ^ M. Pallavicini: The SOX project: a search for sterile neutrinos with BoreXino . In: PoS Neutel2013 (2013) 026 . 2013.
  19. ↑ Christoph Seidler: Ruthenium: The physics experiment and the radiation cloud. In: Spiegel.online. February 16, 2018, accessed March 18, 2018 .
  20. ↑ Analysis of the ruthenium cloud from 2017 - "Europe does not point a finger at Russia". Retrieved on July 29, 2019 (German).