 "India to get world's third LIGO facility")
The Union Cabinet gave "in principle" clearance for the location of a Laser Interferometer Gravitational-Wave Observatory (LIGO) facility in India, on Wednesday, within a week of the historic announcement that gravitational waves had been directly observed by the US LIGO.
There are two LIGO facilities in the US. This third LIGO facility will be set up and managed by The IndIGO Consortium (Indian Initiative in Gravitational-wave Observations), which is a group of scientists drawn from a dozen institutions, including the IITs at Gandhinagar, Madras (Chennai), Kanpur; IISERs at Trivandrum, Kolkata and Pune; The Chennai Mathematical institute, the ICTS Centre of TIFR, Bangalore and the University of Delhi.
IndIGO has been lobbying for this since 2011. But the file was in limbo for years. The announcement of the breakthrough imparted momentum and the Prime Minister's Office reportedly pushed the file through. LIGO India will be jointly funded by the Department of Atomic Energy (DAE) and the Department of Science and Technology (DST).
IndIGO Spokesperson Tarun Souradeep of Inter-University Centre for Astronomy and Astrophysics (IUCAA) said, "We have done fairly detailed studies, and developed timelines for setting up the facility. We have also inspected multiple potential locations and shortlisted three or four sites. Our best guess is that, once the funds are actually made available, it will take somewhere between six-and-a-half years to eight years to get India's LIGO operational".
The three key institutions in the IndIGO consortium are the IUCAA, Pune, the Institute of Plasma Research, Ahmedabad (IPR) and the Raja Ramanna Centre for Advanced Technologies (RRCATS), Indore.
The IUCAA faculty has many of the best Indian astronomers and cosmologists including several scientists who have already contributed to the LIGO. The IPR, which is run by the Department of Atomic Energy (DAE), is the premier Indian institution when it comes to design and fabrication of vacuum tubes. The RRCATS is also run by the DAE and expertises in handling lasers and optical detectors.
The Indian facility will be similar in design to the two American LIGO labs though it may incorporate a "few new tricks" according to the IUCAA Director Somak Raychaudhury. The LIGO labs consist of two L-shaped tunnels, with each arm of the "L" exactly 4 km long. Each tunnel has a vacuum tube running through it. A laser beam is run through the vacuum tubes and split at the intersection of the arms. Each arm has mirrors to bounce that laser beam back and forth. A photo-detector device is placed at such an angle that it will receive no light so long as the two arms remain of exactly the same length.
The passage of gravity wave changes the dimensions of the arms and the photo detector picks up the changes. The apparatus is very delicate and a lot of ingenuity is involved in suspending mirrors, creating a vacuum, etc., to reduce potential interference from other sources. The signals also have to be adjusted to eliminate "noise" from phenomena such as ocean waves, lightning strikes, earthquakes, passing trucks, etc.
The US LIGO received sufficient funding to design lasers and seismic isolation equipment for three facilities but it did not receive approval to set up three facilities. So India can use some of that excess equipment. The US LIGO will transfer equipment worth $140 million to India. But a great deal of equipment, and all the civil engineering, of course, will be done by IndIGO. It is hoped that Indian industry will participate in this initiative.
Apart from sheer size, there are other daunting requirements for a LIGO facility. It must be located, away from the ocean, in a zone of low seismic activity, and at a distance of at least 15 km from the nearest railway line and preferably nowhere near a busy road. The US facilities are located in a swamp (Livingston, Louisiana) and a disused nuclear plant (Hanford, Washington). Ideally, it should not be anywhere near a major city. This is a logistic issue as well since hundreds of personnel will have to be housed. Obviously environmental clearances will be required but IndIGO has spent a lot of time surveying sites to find potentially suitable places - this could still be a major stumbling block.
The US labs took around nine years to be set up, and are now undergoing upgrades. Costs are difficult to estimate at this stage but ballpark estimates by IndIGO scientists suggest that, apart from land acquisition, this facility could cost about Rs 1,260 crore over 8-10 years. The US LIGO is providing equipment worth $140 million. It could be a 'Discover in India' initiative, aiming to put India at the forefront of gravitational research.
