| Name: | Kiran Jayasurya |
| Affiliation: | U R Rao Satellite Centre |
| Conference ID: | ASI2025_640 |
| Title: | GEM-TPC Soft X-ray Polarimeter: Demonstration of Polarimetric Capability |
| Authors: | Kiran M. Jayasurya 1, Koushal Vadodariya 1, Radhakrishna V. 1 |
| Authors Affiliation: | 1 Space Astronomy Group, ISITE Campus, U. R. Rao Satellite Center, ISRO, Bengaluru 560037, India |
| Mode of Presentation: | Oral |
| Abstract Category: | Facilities, Technologies and Data science |
| Abstract: | The Soft X-ray Polarimeter (SXP) is a Gas Electron Multiplier (GEM) based Time Projection Chamber (TPC) type polarimeter being developed in the 2-10 keV energy band by the Space Astronomy Group, U R Rao Satellite Centre. X-ray photons enter the gas chamber between a cathode and a standard GEM in the direction parallel to an anode strip readout below the GEM. The photons undergo photoelectric absorption in the gas volume and produce an electron charge cloud which drifts towards the GEM under the influence of an electric field. The charge cloud gets amplified via avalanche multiplication across a GEM and a signal is induced at the anode strip readout. The time of drift and the strip number at the readout gives the projection of the electron track in the azimuthal plane with respect to the incident photon beam. The tracks are then reconstructed to get the initial photoelectron emission directions and thereby, the phase angle of polarization. A distribution of the phase angles can be fit with a cosine function to get the modulation curve and thereby the polarization properties of the beam. Here, we present the results from the lab model of SXP and the modulation obtained for polarized X-ray input at 4.0 and 6.15 keV energies. Further progress is being made to optimize the operating parameters and maximize the modulation factor within the energy band of interest. |
