Super-Kamiokande (Super-K) is a large underground neutrino detector in Japan, primarily used for studying neutrinos and searching for proton decay. It is located in the Kamioka Observatory, under Mount Ikeno in Gifu Prefecture, and operated by the Institute for Cosmic Ray Research (ICRR) at the University of Tokyo.

Key Features:

1.) Massive Water Tank:
Super-K consists of a 50,000-ton tank filled with ultra-pure water.

2.) Photomultiplier Tubes (PMTs):
About 13,000 highly sensitive PMTs surround the tank to detect tiny flashes of light (Cherenkov radiation) produced when neutrinos interact with water molecules.

3.) Depth:
It is situated 1,000 meters (3,300 ft) underground to shield it from cosmic rays and other background radiation.

Scientific Contributions:

1.) Neutrino Oscillations:
Super-K played a crucial role in proving that neutrinos have mass by detecting neutrino oscillations, leading to the 2015 Nobel Prize in Physics.

2.)Solar and Atmospheric Neutrinos:
It studies neutrinos coming from the Sun and cosmic sources.

3.) Supernova Neutrino Detection:
It can detect neutrinos from supernova explosions, providing early warning for astronomers.

4.) Proton Decay Search:
One of its original goals is to detect proton decay, which could provide insights into Grand Unified Theories (GUTs).

It has undergone upgrades, with the latest being **Super-Kamiokande-Gd**, where gadolinium was added to improve neutron detection, enhancing its sensitivity to supernova neutrinos and other rare events.