Compton polarimeter for 10–30 keV x rays

Weber, Sebastian Mario; Beilmann, C.; Shah, Chintan; Tashenov, S.

doi:10.1063/1.4931165

Cited by 12 publications

(13 citation statements)

References 69 publications

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“…Our straightforward, but sensitive, experimental technique reduces greatly the time required for such comprehensive measurements compared to direct polarization measurements which require a dedicated x-ray polarimeter [84,96]. The present method is simple to implement and can be applicable to all elements of astrophysical and fusion research interest.…”

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confidence: 98%

Strong higher-order resonant contributions to x-ray line polarization in hot plasmas

et al. 2016

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We studied angular distributions of x rays emitted in resonant recombination of highly charged iron and krypton ions, resolving dielectronic, trielectronic, and quadruelectronic channels. A tunable electron beam drove these processes, inducing x rays registered by two detectors mounted along and perpendicular to the beam axis. The measured emission asymmetries comprehensively benchmarked full-order atomic calculations. We conclude that accurate polarization diagnostics of hot plasmas can only be obtained under the premise of inclusion of higher-order processes that were neglected in earlier work. 32.30.Rj, 31.30.jc, 34.80.Lx The observation of x-ray polarization in emissions from the Crab Nebula [1,2], with synchrotron radiation as its origin, fueled a strong interest in the astrophysics community for launching an x-ray polarimetry (XRP) mission [3][4][5][6][7]. X-ray Imaging Polarimetry Explorer (XIPE) has recently been selected as one of three candidates for the next medium-size satellite mission by the European Space Agency ESA. Its aim is studying the anisotropies of astrophysical plasmas which are found in the most extreme yet poorly understood sites in the Universe [8,9]. Up to now anisotropic plasmas were found in active galactic nuclei [10][11][12], pulsars [13], gamma-ray bursts [14][15][16], neutron stars [17,18], and solar flares [19][20][21]. They appear prominently also in the laboratory: in experiments with strong lasers [22,23], magnetic cusps [24], z -pinches [25], and fusion devices [25][26][27] such as tokamaks [28][29][30] and stellarators. The directionality of the electron-ion collisions leaves an imprint in the polarization of the plasma x rays [31][32][33][34][35][36]. Polarization measurements may therefore reveal the presence and orientation of particle beams, magnetic fields and, hence, provide information on the plasma heating and confinement mechanisms [25][26][27] in instances where spatial resolution is insufficient. In astrophysics, indeed, XRP is often the only technique for deriving information on the geometry of angularly unresolved sources [8,37].Ideally, the XRP data should be analyzed with detailed knowledge of the atomic polarization mechanisms. Until now, however, no or little experimental information is available for most atomic processes. Only very few studies of x-ray polarization and angular distributions have been performed for astrophysically relevant ions using electron beam ion traps (EBITs) [38][39][40][41][42][43][44][45][46]. Other studies with EBITs [47][48][49][50], electron accelerators [32, 51, 52] and storage ring [34,53] have focused on heavy ionic systems. Moreover, the photoelectric gas polarimeter [4,54] of the XIPE mission will not resolve individual x-ray transitions. This limitation is rather general, even if high resolution detectors were used, since Doppler shifts will most likely blur the signal. Thus, the polarization signal will contain contributions from many transitions and continuum radiation due to bremsstrahlung and recombination of plas...

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confidence: 98%

Strong higher-order resonant contributions to x-ray line polarization in hot plasmas

et al. 2016

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“…It was ob- tained by Monte-Carlo simulations using the GEANT4 toolkit [49,50] together with the Livermore low-energy electromagnetic model for the scattering processes [51]. The simulations take Compton scattering, Rayleigh scattering, photoelectric effect and bremsstrahlung into account along with the dimensions of the collimator, the scatterer and the SiPIN diodes [47]. They confirm that the azimuthal scattering distribution of 13 keV x rays has a form of Eq.…”

Section: Discussionmentioning

confidence: 71%

Polarization measurement of dielectronic recombination transitions in highly charged krypton ions

et al. 2015

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We report linear polarization measurements of x rays emitted due to dielectronic recombination into highly charged krypton ions. The ions in the He-like through O-like charge states were populated in an electron beam ion trap with the electron beam energy adjusted to recombination resonances in order to produce K α x rays. The x rays were detected with a newly developed Compton polarimeter using a beryllium scattering target and 12 silicon x-ray detector diodes sampling the azimuthal distribution of the scattered x rays. The extracted degrees of linear polarization of several dielectronic recombination transitions agree with results of relativistic distorted-wave calculations. We also demonstrate a high sensitivity of the polarization to the Breit interaction, which is remarkable for a medium-Z element like krypton. The experimental results can be used for polarization diagnostics of hot astrophysical and laboratory fusion plasmas.

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“…These Compton detectors allow (linear) polarization measurements in the energy range of about 10 keV to 10 MeV. [ 429 ] Above 10 MeV, pair‐production polarimetry can be used. [ 430,431 ]…”

Section: Gamma Polarimetrymentioning

confidence: 99%

Expanding Nuclear Physics Horizons with the Gamma Factory

et al. 2022

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The Gamma Factory (GF) is an ambitious proposal, currently explored within the CERN Physics Beyond Colliders program, for a source of photons with energies up to ≈400 MeV and photon fluxes (up to ≈1017 photons s−1) exceeding those of the currently available gamma sources by orders of magnitude. The high‐energy (secondary) photons are produced via resonant scattering of the primary laser photons by highly relativistic partially‐stripped ions circulating in the accelerator. The secondary photons are emitted in a narrow cone and the energy of the beam can be monochromatized, down to 10−3–10−6 level, via collimation, at the expense of the photon flux. This paper surveys the new opportunities that may be afforded by the GF in nuclear physics and related fields.

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Compton polarimeter for 10–30 keV x rays

Cited by 12 publications

References 69 publications

Strong higher-order resonant contributions to x-ray line polarization in hot plasmas

Strong higher-order resonant contributions to x-ray line polarization in hot plasmas

Polarization measurement of dielectronic recombination transitions in highly charged krypton ions

Expanding Nuclear Physics Horizons with the Gamma Factory

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