Particle experiments at Kolar Gold Fields
Encyclopedia
Kolar Gold Fields
Kolar Gold Fields is a town in Bangarpet Taluk, in the Kolar District of Karnataka state, India. It includes the township of the same name, viz. KGF, where reside mainly the families of the employees of BGML. To the east of KGF is a ridge of hills of which Dod Betta hill, 3195 feet above sea...
(KGF), located in the Kolar district
Kolar district
Kolar district is a district in Karnataka state of India. The town of Kolar is the district headquarters. Kolar district is located in the southern region of the State and is the eastern-most district of the Karnataka State...
of the state of Karnataka
Karnataka
Karnataka , the land of the Kannadigas, is a state in South West India. It was created on 1 November 1956, with the passing of the States Reorganisation Act and this day is annually celebrated as Karnataka Rajyotsava...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, are a set of defunct gold mines known for the neutrino
Neutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
particle experiments and observations that took place here starting in 1960. The experiments ended with the closing of the mine in 1992.
Initial experiments
The initial experiments that took place in KGF were related to the study of cosmic rayCosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
muon
Muon
The muon |mu]] used to represent it) is an elementary particle similar to the electron, with a unitary negative electric charge and a spin of ½. Together with the electron, the tau, and the three neutrinos, it is classified as a lepton...
s. KGF was chosen because the depths of its mines allowed muons to be studied in a better environment than what was possible with magnet
Magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...
spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
s operated at sea-level. KGF also allowed the scientists to study the energy spectrum and angular distributions of muons even at very high energies. The mines had abundance of Kolar rock whose special characteristics with respect to density and chemical composition (different from that of normal rock) were also a useful advantage in the experiments. The first experiments involving variations of muon fluxes (a measurement of muons passing through a given media) with depth was conducted by Sreekantan. These were followed by experiments in 1961 by Miyake, Narasimham and Ramanamurty and sponsored by TIFR. During 1984, Naba Kumar Mondal, TIFR, and Prof. Ito, Osaka City University, Japan, performed experimental studies on proton decay
Proton decay
In particle physics, proton decay is a hypothetical form of radioactive decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron...
and indirectly observed the scatter of muons. Murali and Balasubramaniam briefly assisted Mondal and Ito as research assistants.
Neutrino find
Neutrino-related experiments were started in KGF in 1964. The main goal was the detection of atmospheric neutrinos, with an understanding that cosmic rays contain high energy pionPion
In particle physics, a pion is any of three subatomic particles: , , and . Pions are the lightest mesons and they play an important role in explaining the low-energy properties of the strong nuclear force....
s and muon
Muon
The muon |mu]] used to represent it) is an elementary particle similar to the electron, with a unitary negative electric charge and a spin of ½. Together with the electron, the tau, and the three neutrinos, it is classified as a lepton...
s which decay in the Earth's atmosphere to produce billions of neutrinos. The experiments were conducted by groups from TIFR, Durham University
Durham University
The University of Durham, commonly known as Durham University, is a university in Durham, England. It was founded by Act of Parliament in 1832 and granted a Royal Charter in 1837...
and Osaka University
Osaka University
, or , is a major national university located in Osaka, Japan. It is the sixth oldest university in Japan as the Osaka Prefectural Medical College, and formerly one of the Imperial Universities of Japan...
using basic trigger with scintillation counter
Scintillation counter
A scintillation counter measures ionizing radiation. The sensor, called a scintillator, consists of a transparent crystal, usually phosphor, plastic , or organic liquid that fluoresces when struck by ionizing radiation. A sensitive photomultiplier tube measures the light from the crystal...
s and Neon Flash Tubes (NFT) for tracking detectors. Seven detectors were deployed at a depth of 2.3 km in Heathcote shaft and Champion Reefs
Champion Reefs
Champion Reefs is one of the main mining areas in the Kolar Gold Fields in India. The area is situated near Andersonpet in Kolar District. It has got in it the deepest mining shaft in Asia. Once again this place is named after a British officer called Champion...
mines. The experiment discovered the first atmospheric neutrinos in an iron calorimeter
Calorimeter (particle physics)
In particle physics, a calorimeter is an experimental apparatus that measures the energy of particles. Most particles enter the calorimeter and initiate a particle shower and the particles' energy is deposited in the calorimeter, collected, and measured. The energy may be measured in its...
here about the same time as a similar discovery in a mine in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
.