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{{Use dmy dates|date=December 2019}}
{{Use Indian English|date=December 2019}}
[[File:Champion Reef Mine shaft.jpg|thumb|The Champion Reefs [[Shaft mining|mine shaft]] at KGF]]

The '''[[Kolar Gold Fields]] (KGF)''', located in the [[Kolar district]] of the state of [[Karnataka]], [[India]], are a set of defunct [[gold mine]]s known for the [[neutrino]] '''particle experiments''' and observations that took place there starting in 1960.<ref name="pd">
{{cite arXiv
|author1=H. Adarkar
|display-authors=etal
|year=2000
|title=Experimental Evidence for G.U.T Proton decay
|eprint=hep-ex/0008074
}}</ref> The experiments ended with the closing of the mine in 1992.<ref>
{{cite journal
|author=N. K. Mondal
|year=2004
|title=Status of India-based Neutrino Observatory (INO)
|journal=[[Proceedings of the Indian National Science Academy]]
|volume=70 |issue=1 |pages=71–77
|url=http://www.imsc.res.in/~ino/OpenReports/Insa/naba.pdf
}}</ref>

==Initial experiments==
The initial experiments that took place in ''KGF'' were related to the study of [[cosmic ray]] [[muon]]s.<ref name="nar">
{{cite journal
|author=V. S. Narasimhan
|year=2004
|title=Perspective of Experimental Neutrino Physics in India
|url=http://www.imsc.res.in/~ino/OpenReports/Insa/naras.pdf
|journal=[[Proceedings of the Indian National Science Academy]]
|volume=70 |issue=1 |pages=11–25
}}</ref> KGF was chosen because the depths of its mines allowed muons to be studied in a better environment than what was possible with [[magnet]] [[spectrometer]]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.<ref name="nar"/> 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 [[B. V. Sreekantan]]<ref name="nar"/> in 1950s. These were followed by experiments in 1961 by S. Miyake, V. S. Narasimham, P. V. Ramana Murty (also spelled Ramanamurty in some occasions), the trio sometimes called MNR, and sponsored by [[TIFR]]. During 1984, Naba Kumar Mondal, TIFR, and Prof. Ito, Osaka City University, Japan, performed experimental studies on [[proton decay]] 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 [[pion]]s and [[muon]]s which decay in the Earth's atmosphere to produce billions of neutrinos. The experiments were conducted by groups from [[TIFR]], [[Durham University]] and [[Osaka University]] ('''Bombay-Osaka-Durham collaboration''') using basic trigger with [[scintillation counter]]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]] mines. The experiment, using an iron [[Calorimeter (particle physics)|calorimeter]], discovered the first atmospheric neutrinos about the same time (in 1965) as a similar discovery took place in the [[East Rand Mine|East Rand Proprietary Mines]] ('''ERPM experiment''') in [[South Africa]].<ref name="disco">
{{cite journal
|author=T. K. Gaisser
|year=2005
|title=Atmospheric Neutrino Fluxes
|journal=[[Physica Scripta]]
|volume=T121 |pages=51–56
|arxiv=astro-ph/0502380
|bibcode = 2005PhST..121...51G
|doi=10.1088/0031-8949/2005/T121/007
|s2cid=119512931
}}</ref>
The South African experiment begun in 1965, took place 3200 meters underground and was managed by groups from [[Case Institute of Technology]], [[University of California, Irvine]] and [[University of the Witwatersrand]]. The effort was led by [[Frederick Reines]] and the liquid scintillator detector used was called the '''Case-Witwatersrand-Irvine''' or '''CWI detector'''.

Although the KGF group detected neutrino candidates two months later than Reines CWI, they were given formal priority for first discovery of atmospheric neutrinos due to publishing their findings two weeks earlier.<ref name="arxiv">
{{cite journal
|last=Spiering |first=C.
|date=2012
|title=Towards High-Energy Neutrino Astronomy
|journal=[[European Physical Journal H]]
|volume= 37|issue= 3|pages=515–565
|arxiv=1207.4952
|bibcode= 2012EPJH...37..515S
|doi=10.1140/epjh/e2012-30014-2
|s2cid=115134648
}}</ref>

==Kolar events==
Some experimental observations, called '''Kolar events''', have yet to be explained. They suggest the existence of massive (>3 GeV) particles having a long life (10<sup>−9</sup> secs). These massive particles are also seen to decay into 2–3 particles.<ref name="ke">
{{cite book
|author1=S. L. Glashow
|author2=H. van Dam
|author3=P. H. Frampton
|title=Third Workshop on Grand Unification, University of North Carolina, Chapel Hill
|year=1982
|publisher=[[Birkhäuser Verlag]]
|isbn=978-3-7643-3105-4
|url-access=registration
|url=https://archive.org/details/thirdworkshopong0000work
}}</ref> It has been postulated that they could be the result of [[neutrino]] interactions or [[dark matter]] decay.<ref>
{{cite journal
|author1=M. V. N. Murthy
|author2=G. Rajasekaran
|year=2014
|title=Anomalous Kolar events revisited: Dark Matter?
|journal=[[Pramana (journal)|Pramana]]
|volume=82 |issue= 3|pages=609
|arxiv=1305.2715
|bibcode=2014Prama..82..609M
|doi=10.1007/s12043-014-0718-5
|s2cid=118585552
}}</ref>

==References==
{{reflist}}

{{neutrino detectors}}
{{Proton decay experiments}}
{{Underground laboratories}}

[[Category:Particle experiments]]
[[Category:Underground laboratories]]
[[Category:Science and technology in Karnataka]]
[[Category:Osaka University research]]

Particle experiments at Kolar Gold Fields - Revision history

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