Kamiokande
Kamiokande stands for Kamioka Nucleon Decay Experiment and is a nuclear physics experiment near the Japanese community of Kamioka (now Hida ), which was originally intended to prove the hypothetical proton decay . The experiment was designed by the Japanese physicist Masatoshi Koshiba and set up from 1982 to 1983. Proton decays could not be detected, but they provided the then best lower bounds for the lifetime of the proton, which was later continued in Kamiokande II. Soon afterwards, the operators came up with the idea of using the experimental facility as a neutrino detector. In particular, the sun's neutrino deficit (solar neutrino problem ), first observed by Ray Davis in the Homestake experiment , should be confirmed. In Davis experiment radiochemical methods were used, in Kamiokande neutrinos could be observed in real time in the Cerenkov detector. Kamiokande was upgraded to Kamiokande II and was in operation from 1985, but had to struggle with background radioactivity, especially from radon , so that the actual data acquisition began in 1987. Since the experiment was able to resolve the direction of origin of the neutrinos, they detected neutrinos directly from the sun for the first time and they came to around forty percent of the predicted value, which confirmed the solar neutrino problem (Davis came to a third in the Homestake experiment). In 1987 twelve neutrinos of the supernova 1987A could be detected. This was also the first direct experimental confirmation of the theories about the processes involved in the collapse of a star, particularly neutrino cooling. The first atmospheric neutrinos could also be detected.
Lead scientist Masatoshi Koshiba received the Nobel Prize in Physics for his discoveries at Kamiokande in 2002 with Ray Davis. Kamiokande II received the Asahi Prize in 1987 and the Bruno Rossi Prize in 1989 .
In a tank with 3,000 tons of ultrapure water there are approx. 1,000 photomultipliers that register the Cherenkov radiation from electrons that have been accelerated through interaction with neutrinos . In order to shield the cosmic rays as much as possible, the tank is located deep underground.
In 1996, the successor Super-Kamiokande went into operation. Later came KamLAND added (data acquisition from 2002).
Gravitational wave detectors are also located in today's Kamioka Observatory. (CLIO for test purposes and under construction and probably from 2018 [obsolete] active KAGRA ).
Web links
Individual evidence
- ↑ KS Hirata et al. a. (Kamiokande II collaboration), Real-time, directional measurement of 8B solar neutrinos in the Kamiokande II detector, Phys. Rev. D, Vol. 44, 1991, pp. 2241-2260.