Workshop for young scientists with research interests focused on physics at FAIR

Studies of the polarization of hard x-rays emitted in energetic heavy-ion atom collisions provide detailed information of the collision dynamics as well as of the atomic structure at high-Z [1]. Moreover, hard x-ray polarimetry also opens a route for polarization diagnosis of spin-polarized ion and electron beams as are discussed for future PNC experiments at FAIR [2]. However, due to the lack of efficient polarimeters previous studies of the radiation stemming from highly-charged ions were mainly restricted to measurements of the spectral and angular distribution. Owing to recent progress in the development of highly segmented solid-state detectors, a novel type of polarimeter for the hard x-ray regime has become available. Applied as Compton polarimeters, two-dimensional position-sensitive x-ray detectors now allow for precise and efficient measurements of photon linear polarization properties in the energy region between 70 and a few 100 keV [3,4,5]. An overview on recent measurements performed at the ESR storage ring at GSI [6,7,8], the polarized electron source SPIN at TU Darmstadt [9] and the PETRA III synchrotron at DESY will be presented. Also future experimental possibilities at the HESR of the FAIR facility will be discussed. [1] Th. Stöhlker et al., Eur. Phys. J.-Spec. Top. 169, 5 (2009) [2] A. Bondarevskaya et al., J. Phys. B 43, 245001 (2010) [3] S. Tashenov et al., J. Phys. B 97, 223202 (2006) [4] U. Spillmann et al., Rev. Sci. Instrum. 79, 083101 (2008) [5] G. Weber et al., JINST 5, C07010 (2010) [6] S. Hess et al., J. Phys. Conf. Ser. 163, 012072 (2009) [7] S. Hess et al., J. Phys. Conf. Ser. 194, 012025 (2009) [8] G. Weber et al., Phys. Rev. Lett. 105, 243002 (2010) [9] R. Märtin et al., Phys. Rev. Lett. 108, 264801 (2012)