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A list of experiments, which will be placed on board the Chinese space station, as a part of cooperation between China and ONZ, has been announced on 12th of June in Vienna. Among the nine experiments accepted for execution there is the POLAR-2: Gamma-Ray Burst Polarimetry on the China Space Station. The project has been prepared by a consortium with participation of NCBJ.

For over 50 years scientists have been observing strong gamma radiation bursts on the sky using satellite detectors. Their origin has been a mystery for many years, nowadays they are thought to be related to two most energetic explosion types in the Universe – first one are neutron star collisions or collisions of neutron star and a black hole and the second one are hypernovae, which end the lives of the most massive stars. „We know, that these bursts release tremendous amount of energy, but we are still not entirely sure what processes lead to emission of the most energetic part of the released radiation” – explains Professor Agnieszka Pollo, head of NCBJ Astrophysics Division. „We speculate, that the magnetic field of the origin system plays a big role in creation of the burst”. To test this hypothesis, we need to collect as much information about the polarisation of the gamma radiation that reaches us during a burst. Cosmic gamma rays are absorbed by the atmosphere and do not reach the ground, that is why observations of gamma ray bursts and measurements of their polarisation need to be done, for example, on a space station. „The first co-organized POLAR mission was placed on board of the Chinese space laboratory Tiangong-2 in 2016. It observed 55 bursts and managed to measure the polarisation of 5 of them” – adds Professor Pollo. „We hope, that the POLAR-2 will provide much more detailed information in larger quantity”.

Scientists and engineers from the National Centre for Nuclear Research participated in the first POLAR experiment by, among other things, preparing the electronics, prototyping the plastic scintillator detectors and analysing collected data. „For the POLAR-2 experiment, we want to design and build the electronics receiving data straight from the detector” – explains Dominik Rybka, MSc Eng from the NCBJ Electronics and Detection Systems Division, co-creator of the electronics used in 2016. „We fit our systems with suitable, custom made software. We also intend to design, build and program the electronics, which prepares the signals received from the detector for transmission back to Earth. Our next step will be construction of a specialised low voltage power supply, powering all of the instrumentation”.

Polish scientists will also be involved in analysis of data sent by the detector.

Apart from NCBJ, the POLAR-2 consortium includes: University of Geneva, Max Planck Institute For Extraterrestial Physics and Institute for High Energy Physics of the Chinese Academy of Sciences.

Researchers predict, that the new experiment will start operating in 2024.