We are developing a Thomson X-ray Polarimeter (POLIX) for a Small Astronomy Satellite.

X-ray Polarimeter Experiment (POLIX):

The X-ray Polarimeter Experiment (POLIX) is part of the ISRO's ''Small Satellites Programme'' recommended by Advisory committee for Space Sciences (ADCOS)*. An X-ray polarimeter based on the principle of Thomson scattering of X-rays is being developed at the Raman Research Institute (RRI). Currently, development of a laboratory model and the design of an engineering model has been completed. Fabrication of the engineering model is in progress.

Scientific Objectives:

X-ray polarimetry is an unexplored area in high energy astrophysics. The Crab nebula is the only X-ray source for which a definite polarisation measurement exists. X-ray polarisation measurements can give a valuable insight about:

The Experiment:

This experiment will be suitable for X-ray polarisation measurement of hard X-ray sources like accretion powered pulsars, black hole X-ray binaries, active galactic nuclei, nonthermal supernova remnants, pulsar wind nebulae etc. For about 50 brightest hard X-ray sources, a Minimum Detectable Polarisation of 2-3% will be achieved. The instrument is made with a Lithium/Beryllium scatterer and surrounding proportional counter detectors and it is sensitive in the 5-30 keV energy band.

Development Status:

A laboratory unit of the instrument has been built at RRI and X-ray polarisation measurements have been successfully carried out with it.

See current development status of the Polarimeter.

Based on the test results obtained with the laboratory unit, an engineering model has been designed. Fabrication of the POLIX engineering model with funding from ISRO is under progress. Detector electronics and signal processing electronics for the engineering model has also been designed and is under development.


Here is a not so recent newspaper report on POLIX.

* Reference: 2011-2012 Annual Report of the Govt of India, Department of Space