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Publikationen von
Marco Vockert

Alle Publikationen des HI Jena


W. Middents, G. Weber, U. Spillmann, T. Krings, M. Vockert, A. Volotka, A. Surzhykov, and T. Stöhlker
Possible Polarization Measurements in Elastic Scattering at the Gamma Factory Utilizing a 2D Sensitive Strip Detector as Dedicated Compton Polarimeter
Annalen der Physik 2100285, 2100285 (2021)
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P.-M. Hillenbrand, K. N. Lyashchenko, S. Hagmann, O. Andreev, D. Banas, E. P. Benis, I. Bondarev, C. Brandau, E. De Filippo, O. Forstner, J. Glorius, R. E. Grisenti, A. Gumberidze, D. L. Guo, M. O. Herdrich, M. Lestinsky, Y. Litvinov, V. Pagano, N. Petridis, M. S. Sanjari, D. Schury, U. Spillmann, S. Trotsenko, M. Vockert, A. B. Voitkiv, G. Weber, and T. Stoehlker
Electron-loss-to-continuum cusp in collisions of U89+ with N-2 and Xe
Physical Review A 104, 012809 (2021)

Abstract: We study the electron-loss-to-continuum (ELC) cusp experimentally and theoretically by comparing the ionization of U89+ projectiles in collisions with N-2 and Xe targets, at a beam energy of 75.91 MeV/u. The coincidence measurement between the singly ionized projectile and the energy of the emitted electron is used to compare the shape of the ELC cusp at weak and strong perturbations. A significant energy shift for the centroid of the electron cusp is observed for the heavy target of Xe as compared to the light target of N-2. Our results provide a stringent test for fully relativistic calculations of double-differential cross sections performed in the first-order approximation and in the continuum-distorted-wave approach.


P.-M. Hillenbrand, S. Hagmann, M. Groshev, D. Banaś, E. Benis, C. Brandau, E. De Filippo, O. Forstner, J. Glorius, R. Grisenti, A. Gumberidze, D. Guo, B. Hai, M. Herdrich, M. Lestinsky, Y. Litvinov, E. Pagano, N. Petridis, M. Sanjari, D. Schury, U. Spillmann, S. Trotsenko, M. Vockert, G. Weber, V. Yerokhin, and Th. Stöhlker
Radiative electron capture to the continuum in U89+ + N2 collisions: Experiment and theory
Physical Review A 101, 022708 (2020)

Abstract: For U89+ projectiles colliding at a beam energy of 75.91 MeV/u with a N2 target, we present a coincidence measurement between the cusp electrons emitted under an angle of 0° with respect to the projectile beam and the photons emitted under a polar angle of 90°. This radiative-electron-capture-to-continuum cusp directly probes the theory of electron-nucleus bremsstrahlung up to the high-energy endpoint in inverse kinematics. In the present study, significant improvement with respect to the experimental accuracy has been achieved, resulting in a finer agreement between experimental and theoretical results.


M. Vockert, G. Weber, H. Bräuning, A. Surzhykov, C. Brandau, S. Fritzsche, S. Geyer, S. Hagmann, S. Hess, C. Kozhuharov, R. Märtin, N. Petridis, R. Hess, S. Trotsenko, Yu. A. Litvinov, J. Glorius, A. Gumberidze, M. Steck, S. Litvinov, T. Gassner, P.-M. Hillenbrand, M. Lestinsky, F. Nolden, M. S. Sanjari, U. Popp, C. Trageser, D. F. A. Winters, U. Spillmann, T. Krings, and Th. Stöhlker
Radiative electron capture as a tunable source of highly linearly polarized x rays
Physical Review A 99, 052702 (2019)

Abstract: The radiative electron capture (REC) into the K shell of bare Xe ions colliding with a hydrogen gas target has been investigated. In this study, the degree of linear polarization of the K-REC radiation was measured and compared with rigorous relativistic calculations as well as with the previous results recorded for U92+. Owing to the improved detector technology, a significant gain in precision of the present polarization measurement is achieved compared to the previously published results. The obtained data confirms that for medium-Z ions such as Xe, the REC process is a source of highly polarized x rays which can easily be tuned with respect to the degree of linear polarization and the photon energy. We argue, in particular, that for relatively low energies the photons emitted under large angles are almost fully linear polarized.


M. Vockert, G. Weber, U. Spillmann, T. Krings, and Th. Stöhlker
Polarization reconstruction algorithm for a Compton polarimeter
Journal of Physics: Conference Series 1024, 012041 (2018)

Abstract: We present the technique of Compton polarimetry using X-ray detectors based on double-sided segmented semiconductor crystals that were developed within the SPARC collaboration. In addition, we discuss the polarization reconstruction algorithm with particular emphasis on systematic deviations between the observed detector response and our model function for the Compton scattering distribution inside the detector.


M. Vockert, G. Weber, U. Spillmann, T. Krings, M. Herdrich, and Th. Stöhlker
Commissioning of a Si(Li) Compton polarimeter with improved energy resolution
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 408, 313 (2017)

Abstract: Abstract On the basis of a double-side segmented Si(Li) crystal a new Compton polarimeter was developed within the SPARC collaboration. The new detector is equipped with a cryogenic first stage of the preamplifiers to improve the energy resolution compared to previous detectors with preamplifiers operating at room temperature. We present first results from a commissioning measurement of the new instrument at the ESR storage ring of GSI in Darmstadt, Germany and contrast it with the performance of an precursor polarimeter system.