In a significant breakthrough in the field of astronomy, India unveiled its groundbreaking Gamma-ray telescope—MACE (Major Atmospheric Cherenkov Experiment) at Hanle in Ladakh on 9 October.
The importance of MACE lies in the fact that it’s the world’s tallest, measuring 4270 meters above sea level.
It is India’s largest and the world’s highest gamma-ray telescope, which will provide a new window into distant stars and galaxies in the universe.
It is also the world’s second-largest, ground-based gamma-ray telescope with a 21-metre-diameter dish. The largest telescope of the same class is the 28-metre-diameter telescope, which is part of the High Energy Stereoscopic System (HESS) in Namibia.
MAJOR ATMOSPHERIC CHERENKOV EXPERIMENT (MACE) TELESCOPE
It is an imaging atmospheric Cherenkov telescope (IACT) located near Hanle, Ladakh, India. It has been built by Bhabha Atomic Research Centre (BARC), Department of Atomic Energy with technical support from Electronics Corporation of India, Hyderabad. It was assembled at the campus of Indian Astronomical Observatory at Hanle.
The telescope will help the scientific community enhance its understanding in the fields of astrophysics, fundamental physics, and particle acceleration mechanisms.
The MACE Telescope consists of a large-area tessellated light collector of 356 m², made up of 356 mirror panels. A high-resolution imaging camera weighing about 1200 kg, for detection and characterisation of the atmospheric Cherenkov events, forms the focal plane instrumentation of the telescope. The telescope, which weighs about 180 tons, is supported on six wheels which move on a 27-metre-diameter track.
The telescope has an integrated imaging camera, which contains 1088 photo multiplier-based pixels and all the signal processing and data acquisition electronics. The camera communicates the acquired data to the computer system in the control room over optical fibre.
Images Courtesy: Wikimedia Commons
Gamma rays have so much energy that they pass through mirrors used in ordinary optical telescopes. These rays require specialised detectors.
Moreover, the Earth’s atmosphere blocks most of the incoming gamma rays from space, at a height of 10 kilometres from the surface, which makes it difficult for ground-based telescopes to detect them.
Placing the telescope at higher altitudes gives them a significant advantage to observe Cherenkov radiation, which is produced when cosmic gamma rays strike the Earth’s upper atmosphere.
It is a lightweight construction and features high strength and temperature endurance. Reflector surface measuring over 350 square meters (sqm) comprises highly reflective diamond-turned custom-built metallic mirror facets that are required to be aligned with an accuracy of 2 mm over parabolic surface. The camera at the focal point contains a number of photomultiplier tubes mounted with specialised assembly to enhance light collection efficiency.
THE NAME
The telescope is named after the Soviet scientist Pavel Cherenkov, who predicted that charged particles moving at high speeds in a medium emit light. The high-energy gamma rays emitted from black holes, centres of galaxies and pulsars do not reach the land as they get absorbed in the atmosphere. Upon interaction with the atmosphere, these photons produce electron–positron pairs, leading to a cascade of particles which while moving at very high speed give rise to Cherenkov radiation.
Cherenkov radiation causes the characteristic blue glow in underwater nuclear reactors. Cherenkov shared the Nobel Prize in Physics in 1958 with Ilya Frank and Igor Tamm for this discovery.
WHY AT HANLE, LADAKH?
The location of Hanle was finalised, considering its remarkable conditions for astronomical observations. The region’s dark and intense skies, minimal light pollution, and low humidity provide a perfect and conducive environment for studying the universe. The chairman of the Atomic Energy Commission, Dr AK Mohanty mentioned it as “heaven for gamma-ray astronomers”.
According to sources, the project is a collaboration of scientists from BARC, Tata Institute of Fundamental Research (TIFR) and the Indian Institute of Astrophysics, along with the Electronics Corporation of India Limited.
