GRAPES-3
   HOME

TheInfoList



OR:

The GRAPES-3 experiment (or Gamma Ray Astronomy PeV EnergieS phase-3) located at
Ooty Ooty (), officially known as Udhagamandalam (also known as Ootacamund (); abbreviated as Udhagai), is a city and a municipality in the Nilgiris district of the South Indian state of Tamil Nadu. It is located north west of Coimbatore and so ...
in India started as a collaboration of the Indian
Tata Institute of Fundamental Research Tata Institute of Fundamental Research (TIFR) is a public deemed research university located in Mumbai, India that is dedicated to basic research in mathematics and the sciences. It is a Deemed University and works under the umbrella of the ...
and the Japanese
Osaka City University , abbreviated to , is a public university in Japan. It is located in Sumiyoshi-ku, Osaka. It is one of the most prestigious universities in Japan regarding Applied Linguistics. The university will merge with Osaka Prefecture University to form ...
, and now also includes the Japanese
Nagoya Women's University is a private university, private Women's colleges, women's university in Nagoya, Aichi, Japan with campus at Mizuho-ku, Nagoya, Mizuho-ku.The campus at Tempaku-ku, Nagoya, Tempaku-ku was closed in 2015 and integrated into the campus at Mizuho-ku, ...
. GRAPES-3 is designed to study
cosmic ray Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
s with an array of air shower
detector A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
s and a large area muon detector. It aims to probe acceleration of cosmic rays in the following four astrophysical settings. These include acceleration of particles to, (i) ~100 MeV in atmospheric electric fields through muons, (ii) ~10 GeV in the
Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
through muons, (iii) ~1 PeV in our galaxy, (iv) ~100 EeV in the nearby universe through measurement of diffuse
gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...
flux. The GRAPES-3 is located at N11.4o, E76.7o, 2200m above mean sea level. The observations began with 217 plastic scintillators and a 560 m2 area muon detector in 2000. The scintillators detect
charged particle In physics, a charged particle is a particle with an electric charge. It may be an ion, such as a molecule or atom with a surplus or deficit of electrons relative to protons. It can also be an electron or a proton, or another elementary pa ...
s contained in extensive air showers produced by interaction of high energy cosmic rays in the atmosphere. At present the array is operating with ~400 scintillators that are spread over an area of 25,000 m2. The energy threshold of muon detectors is 1 GeV.


Objectives

Study of # The origin, acceleration and propagation of >1014 eV cosmic rays in the galaxy and beyond. # Existence of "Knee" in the energy spectrum of cosmic rays. # Production and/or acceleration of highest energy (~1020 eV) cosmic rays in the universe. # Astronomy of multi-TeV γ-rays from neutron stars and other compact object. # Sun the closest astrophysical object, accelerator of energetic particles and its effects on the Earth.


Overview

The first cosmic ray experiment was started in 1955 by B. V. Sreekantan by setting up
cloud chamber A cloud chamber, also known as a Wilson cloud chamber, is a particle detector used for visualizing the passage of ionizing radiation. A cloud chamber consists of a sealed environment containing a supersaturated vapour of water or alcohol. An ...
s that heralded the beginning of research at the Cosmic Ray Laboratory (CRL) in Ooty. The next decade witnessed a variety of experiments involving high energy interactions and extensive air shower studies in this laboratory. The world's largest multiplate cloud chamber was operated here as part of an air shower array and significant results on the high energy nuclear interactions and cores of extensive air showers were obtained. A triple set-up comprising an air Cherenkov counter, a multiplate cloud chamber and a total absorption spectrometer was operated in the early seventies to study the differences in the characteristics of interactions with nuclei of protons and pions in the energy range 10-40 GeV. This enabled the time structure study of nuclear active components of air showers and led to the discovery that the nucleon-anti-nucleon production cross-section considerably increases with energy. In continuation of the work on cosmic ray research at CRL, GRAPES-1 experiment was upgraded in various stages to GRAPES-2. However, due to the technical and administrative problem in its further expansion, a new experiment was set up at the RAC site 8 km from the old site which is called GRAPES-3. The GRAPES-3 experiment at present is operating with ~400 (each 1 m2) plastic scintillator detectors with a separation of 8 meters, to record the density and arrival time of particles in cosmic ray showers, and in continuous operation. At present, GRAPES-3 array is the highest density conventional EAS array in the world, and also, this experiment associated with a huge 560 m2 area tracking muon detector, is also the largest area tracking detector anywhere.


Results

Several results have recently been obtained from the GRAPES-3 experiment on a variety of topics, a few of which are listed below. * Measurement of primary composition in the energy 50 TeV - 1 PeV overlapping with direct measurements * Precision measurements of Forbush decrease events including rigidity dependence of its amplitude * Measurement of turbulent magnetic field in the shock-sheath region in the Coronal mass ejections (CMEs) by using multi-rigidity muon data * Precision measurement of the solar diurnal anisotropy and its higher harmonics including its rigidity dependence * Precision measurement of the density gradient of cosmic rays in the solar system by probing Swinson flow * Precision measurement of the anti-correlation between changes in solar wind velocity and cosmic ray intensity * Measurement of the electrical potential, size and height of a thundercloud, which broke the existing record.


References


Publications

* *
"How India uses recycled pipes to detect ferocious solar storms"
— BBC News article, 1.03.2017


External links


Homepage


{{DEFAULTSORT:Grapes-3 Cosmic-ray experiments Research projects Science and technology in Tamil Nadu