Go underground to see the sun

These photos seem to be screenshots from some computer game, but this is a real construction site in a dungeon. At a depth of 1.5 km in the former deepest gold mine in North America Homestake located astrophysical research laboratory Sanford Underground Research Facility.





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A rather strange combination: underground galleries and space exploration, but the unique location of the laboratory allows for research that is practically impossible or very difficult on the surface.



Astrophysical research in the mine began in the 60s, when chemist Ray Davis began experiments to search for solar neutrinos. Hundreds of meters of rock allowed screening detectors from cosmic-ray fluxes, and only all-penetrating neutrinos could get there. The search turned out to be successful, moreover, it allowed to establish that the ideas about neutrinos that existed by that time need to be refined - the actually detected particles turned out to be almost three times smaller than theoretical models assumed. This phenomenon has become known in science as the problem of solar neutrinos . At the end of the twentieth century, it was solved by finding the effect of neutrino oscillations. For his discovery, Ray Davis received the Nobel Prize in 2002.







In 2001, Homestake became unprofitable for gold mining and closed. Four years later, the owners transferred it to the state of South Dakota. In 2005, American millionaire banker Denny Sanford allocated $ 70 million for the construction of a laboratory and $ 45 million was added by various scientific foundations. Later, US scientists and South Dakota authorities made a proposal to the state to create an underground research complex, worth $ 1 billion dollars. The officials did not support the idea, but the laboratory was funded by the Ministry of Energy.







With these funds, full-fledged research laboratories and even a campus were built so that scientists and students could live directly underground during the experiments.







Now at Sanford Underground Research Facility, research is being carried out in three areas.



Large Underground Xenon (LUX) experiment







Search for dark matter particles. Dark matter is determined indirectly by the masses of galaxies, but it is not known directly what is its carrier. In the mine Homestake is located a tank of liquid xenon inert gas weighing a third of a ton. Theoretically, detectors placed around are able to determine the interaction of hypothetical dark matter particles of the WIMP (Weakly Interacting Massive Particle) with xenon atoms.











So far, no such events have been recorded. Now the experiment was developed by joining with the British group Zeplin, the result of the work of the joint team LUX-Zeplin should be the detector VIMPov unprecedented accuracy.







Majorana experiment







Attempt to catch antineutrino. More precisely, this experiment must establish that a neutrino is capable of being an antiparticle to itself — the so-called. Majorana fermion . Inside the block of thick plates of high purity copper, dozens of detectors made of germanium crystals are located, which theoretically are able to detect the event of neutrinoless double beta decay, which will confirm the Majorano nature of the neutrino and will prove the fact of its mass.







As in the case of the LUX experiment, so far no such phenomena have been recorded, although they are trying to catch them in several laboratories around the world.



Compact Accelerator System for Performing Astrophysical Research (CASPAR)







Small accelerator of charged particles, which should simulate the processes in stars, leading to the formation of heavy chemical elements. The accelerator will create a directed beam of low-energy particles, so it is important for it to be protected from natural flows of charged particles. For the purity of the study, the experiment hid underground from cosmic rays, and to protect the soil from radioactivity, the laboratory has half-meter walls lined with lead sheets. The experiment has not yet been launched, but the developers are already close to the start of the program.



Currently, the Deep Underground Neutrino Experiment (DUNE) project is under consideration and approval, which is to develop and continue the search for antineutrino by registering neutrinoless double beta decay. This time it is planned not to catch solar neutrino fluxes, but to register an artificially created neutrino flux from an underground source in the Fermi laboratory for 1,300 km.





The scale of the project is comparable to the Large Hadron Collider, in particular, it includes a reservoir for detectors filled with 50 thousand tons of liquid argon. The project cost is estimated at $ 1 billion, and along with the United States, the United Kingdom has expressed willingness to participate.



Based on Space.com .



Here is a photo report from the Russian equivalent.