Accurate miscut angle determination for spherically bent Bragg crystals

Covita, D. S.; Ay, M.; Schlesser, S.; Gotta, D.; Simons, L. M.; Bigot, E.-O. Le; Santos, J.M.F. dos

doi:10.1063/1.2884149

Cited by 17 publications

(12 citation statements)

References 13 publications

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“…Pions were stopped in the center of the cyclotron trap [18,19] in a cylindrical gas cell, where the density of H 2 and D 2 gas was adjusted by means of a cold finger. X-rays emitted after pionic-atom formation were measured by using a Bragg spectrometer equipped with spherically bent silicon and quartz crystals characterized precisely by various methods [20,21]. As X-ray detector, an array of charge-coupled devices was used [22,23].…”

Section: Methodsmentioning

confidence: 99%

Pionic hydrogen and deuterium

Gotta

Amaro²,

Anagnostopoulos³

et al. 2011

Hyperfine Interact

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Section: Methodsmentioning

confidence: 99%

Pionic hydrogen and deuterium

Gotta

Amaro²,

Anagnostopoulos³

et al. 2011

Hyperfine Interact

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“…The nominal focal position is given by the focusing condition R · sin Θ B = 2621.7 mm for the horizontal plane. It takes into account a miscut angle of (0.228±0.006) • and its orientation relative to the symmetry plane of (−87.4 ± 1.2) • as found from a dedicated measurement [69]. The distance crystal -detector, chosen to be at the assumed Kβ focal length ( fig.…”

Section: Crystal Spectrometermentioning

confidence: 99%

“…The remaining difference is due to the additional Gaussian contribution. Details on the experimental set-up and analysis may be found elsewhere [69].…”

Section: Spectrometer Resolutionmentioning

confidence: 99%

Line shape analysis of the Kβ transition in muonic hydrogen

et al. 2018

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The Kβ transition in muonic hydrogen was measured with a high-resolution crystal spectrometer. The spectrum is shown to be sensitive to the ground-state hyperfine splitting, the corresponding triplet-to-singlet ratio, and the kinetic energy distribution in the 3p state. The hyperfine splitting and triplet-to-singlet ratio are found to be consistent with the values expected from theoretical and experimental investigations and, therefore, were fixed accordingly in order to reduce the uncertainties in the further reconstruction of the kinetic energy distribution. The presence of high-energetic components was established and quantified in both a phenomenological, i. e. cascade-model-free fit, and in a direct deconvolution of the Doppler broadening based on the Bayesian method.PACS. 36.10.-k, 07.85.Nc Exotic atoms, X-ray spectrometers a present address: Bosch Termotecnologia, S.A., EN 16 -Km 3,weak, or strong interactions but also collision-induced processes at quite distinctive conditions, because the distance scale in the case of exotic hydrogen is smaller by a factor m e /m X while the energy scale is larger by a factor m X /m e in comparison with usual atoms. Here, m e and m X denote the mass of electron and captured particle X, respectively.An exotic atom formed with hydrogen isotopes is exceptional, because it is electrically neutral. Hence, during its life time it is able to penetrate deeply into the atomic shells when colliding with other molecules. Various collisional processes strongly influence the development of the atomic de-excitation cascade, which manifests experimentally in a strong density dependence of the K X-ray yields [1,2,3,4]. Amongst others, in the Coulomb de-excitation process the energy released is transferred to kinetic energy [5] leading to a Doppler broadening for subsequently emitted X-rays.First evidence for such high-velocity exotic atoms was found in the charge-exchange reaction π − p → π 0 n with arXiv:1709.05950v2 [physics.atom-ph]

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“…The miscut is measured according to the lines given by Covita. 4 For this measurement, the crystal is placed on a rotary device, the center of the spherical crystal as well as the Rowland sphere must coincide with the axis. The center of the crystal sphere is found by autocollimation, the center coincides with the axis if the focal point does not change, when the axis is rotated.…”

Section: Alignment Of Imaging Bragg Spectrometersmentioning

confidence: 99%

Alignment and absolute wavelength calibration of imaging Bragg spectrometers

Bertschinger¹,

Marchuk²,

Barnsley

2016

Review of Scientific Instruments

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In the present and the next generation of fusion devices, imaging Bragg spectrometers are key diagnostics to measure plasma parameters in the hot core, especially ion temperature and plasma rotation. The latter quantities are routinely obtained using the Doppler-width and -shift of the emitted spectral lines, respectively. Line shift measurements require absolute accuracies Δλ/λ of about 10 ppm, where λ-is the observed wavelength. For ITER and the present fusion devices, spectral lines of He-and H-like argon, iron, and krypton as well as Ne-like tungsten are foreseen for the measurements. For these lines, Kα lines can be found, some in higher order, which fit into the narrow energy window of the spectrometers. For arbitrary wavelength settings, Kα lines are also used to measure the miscut of the spherical crystals; afterwards the spectrometers can be set according to the geometrical imaging properties using coordinate measurement machines. For the spectrometers measuring Lyα lines of H-like ions, fluorescence targets can provide in situ localized calibration lines on the spectra. The fluorescence targets are used best in transmission and are excited by the thermal x-ray radiation of the plasma. An analytic theory of fluorescence is worked out.

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Accurate miscut angle determination for spherically bent Bragg crystals

Cited by 17 publications

References 13 publications

Pionic hydrogen and deuterium

Pionic hydrogen and deuterium

Line shape analysis of the Kβ transition in muonic hydrogen

Alignment and absolute wavelength calibration of imaging Bragg spectrometers

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