Center for Astroparticle Physics and Space Science (CAPSS)

National facility at Darjeeling : Program

1. Cosmic ray studies at high altitude :

The quark structure of hadrons suggest the existence of Strange Quark Matter (SQM), containing a large amount of strangeness as postulated by various authors quite a few years ago. In a seminal work in 1984, Witten proposed that SQM with roughly equal numbers of up, down and strange quarks could be the true ground state of Quantum Chromodynamics (QCD), the accepted theory of strong interactions. The occurrence of stable (or metastable) lumps of SQM, would lead to many rich consequences; for example, the SQM, which may exist as relics of the cosmic quark-hadron phase transition during the microsecond epoch of the early universe, could provide a natural and viable explanation for the dark matter as well as the large amount of dark energy found by WMAP observation.

The final proof of SQM will be its experimental detection. Especially, the existence of smaller lumps of SQM would make the task of detection a lot easier, as these would then be detectable in cosmic ray flux.

1.1 Passive Detectors :

The primary objective of the programme is to set up a 400 m2 array of passive solid-state nuclear track detectors (SSNTD) and expose them to cosmic rays for a long period (2-3 years). Parts of the detector array will be replaced with fresh detectors at regular intervals, the exposed ones brought back to the laboratory in Kolkata for chemical processing and microscopic examination. This way, data collection and analysis will proceed simultaneously. The analysis will require a number of optical microscopes with automatic stage movement and a sophisticated image analyzing software. The programme requires the following sub-projects as integral parts.

1.2 Active Detectors :

In addition to the passive detectors (SSNTD), we also plan to use an active detector setup. This will consist of 1m2 plastic scintillators coupled with 2 inch photomultipler tubes. To increse the efficiency of light collection, we plan to use wavelength shifting fibers on the surface of the scintillators. This setup can be used for the study of the strangelets, having energy above the breakup threshold. These strangelets after entering the atmosphere will disintegrate due to the collision with atmospheric nuclei, which may result in the formation of smaller strangelets as well as unusually large showers. We plan to beging with 7 detectors in a hexagonal pattern, with one at the center. Later on we will increase the number to 50.

2. Changing Airspace Environment in Eastern Himalayas :

The Himalaya braces the northern periphery of the Indo-Gangetic plains region. This region acts as the main source of all kinds of atmospheric pollutants and also vulnerable from changing environment. This complex two-way interactive mechanism needs to be understood to get qualitative as well as quantitative information useful for proper policy formulations to mitigate emissions of pollutants as well to reduce vulnerability. In this regard, the Himalayas offer a unique place to monitor airspace environment as it is not only subject to emissions coming out from IGP Region but also to the pollutants transported from long distances from other source regions.

The establishment of monitoring facilities at Darjeeling will help in the setup of a network of monitoring stations in eastern part of Indian sub-continent covering the altitudinal variations to decipher the source strength and source apportionment.

In the phase-I of the program, the initial focus is on the following two aspects:

  1. Chemistry of atmospheric environment over the Eastern Himalayas.
  2. Darjeeling and Sandakphu stations as reference site for monitoring trans-boundary flow of atmospheric pollutants.
The philosophy behind these two aspects of the proposed program is to study all the interactive parameters playing their respective roles in the biosphere, troposphere, and upper space because each one of them influence others and the net effect is a resultant of all these interactions. The ‘Chemistry of atmospheric environment over the Eastern Himalayas’ has again three major parts. The objectives of these three parts are mentioned as hereunder.

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