Lineshape, linewidth and spectral density of parametric x-radiation at low electron energy in diamond

Freudenberger, J.; Genz, H.; Morokhovskii, V.V.; Richter, A.; Morokhovskii, V. L.; Nething, U.; Zahn, R.; Sellschop, J.P.F.

doi:10.1063/1.118359

Cited by 16 publications

(8 citation statements)

References 14 publications

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“…In view of the fact that such a narrow bandwidth source could be of extreme interest for many applications, a number of experiments were performed to determine the line width of PXR. Measurements at the low electron beam energy of 6.8 MeV result in a line width of 48 eV for a 55 µm thick diamond crystal at a photon energy of 8.98 keV [58]. This rather large line width originates from the multiple scattering of electrons in the crystal.…”

Section: Parametric X-radiationmentioning

confidence: 99%

Coherent X-rays at MAMI

et al. 2006

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Abstract. Coherent radiation in the range from soft X-rays up to hard X-rays, produced by the lowemittance electron beam of MAMI, can be used for various applications. Novel types of interferometers have been developed for the measurement of the complex index of refraction of thin self-supporting foils. For the vacuum ultraviolet and soft X-ray region the interferometer consists of two collinear undulators, and a grating spectrometer. A foil placed between the undulators causes a phase shift and an attenuation of the oscillation amplitude. The complex index of refraction has been measured at the L 2,3-absorption edges of nickel. A novel method is described for the measurement of the X-ray magnetic circular birefringence. For the hard X-ray region the interferometer consists of two foils at which the 855 MeV electron beam produces transition radiation. Distinct interference oscillations have been observed as a function of both, the photon emission angle and the distance between the foils. The refractive index decrement δ(ω) of a 2 µm thick nickel sample foil has been measured at X-ray energies around the K absorption edge at 8333 eV and at 9930 eV with an accuracy of better than 1.5 %. The line width of parametric X radiation (PXR) was measured in backward geometry with a Si single-crystal monochromator. Upper limits of the line width of 42 meV, 50 meV, and 44 meV, have been determined for the (333), (444) and (555) reflections at photon energies of 5932 eV, 7909 eV, and 9887 eV, respectively. Small angle scattering of the electrons in the crystal leads to a stochastic frequency modulation of the exponentially damped wave train which results in the line broadening. To elucidate the quest if the production of PXR is a kinematical or a dynamical process the radiation from silicon single-crystal targets, emitted close to the electron direction, has been studied. The observed interference structures and the narrow-band radiation in forward direction shows that PXR is produced in a dynamical process. .Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) -41.60.-m Radiation by moving charges -41.50.+h X-ray beams and X-ray optics PACS.

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Section: Parametric X-radiationmentioning

confidence: 99%

Coherent X-rays at MAMI

et al. 2006

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“…The energy of PXR depends on the Bragg angle and the crystal structure. For instance, PXR with an energy of about 8 keV has been produced by using electron beams with energies below 10 MeV [6,7]. Thus, the required electron beam energy is considerably lower than what is required for SR.…”

Section: Introductionmentioning

confidence: 99%

Compact and intense parametric x-ray radiation source based on a linear accelerator with cryogenic accelerating and decelerating copper structures

Hyun

Satoh

Yoshida

et al. 2018

Phys. Rev. Accel. Beams

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This paper describes a proposal for a compact x-ray source based on parametric x-ray radiation (PXR). The PXR, which is produced when a single crystal is bombarded with relativistic electrons, has good monochromaticity and spatial coherence, and is expected to be well suited for imaging of low-Z materials and medical application. The proposed system employs a pair of copper accelerating structures which are operated at a cryogenic temperature of 20 K and arranged to form a resonant ring configuration. The electron beam is once accelerated up to 75 MeV in one of the structures, being decelerated down to lower than 7 MeV in the other structure after generating PXR at a single crystal, and then dumped. The expected x-ray yield is 10 9 photons=s at a center energy of 15 keV or higher.

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“…Measurements of the linewidth have been performed up to now at the low beam energy of 6.8 MeV only. A variance of the linewidth of 48 eV has been determined for a 55 mm thick diamond crystal at a photon energy of 8.98 keV [9]. This rather large linewidth originates at low electron energy from the multiple scattering of electrons in the crystal.…”

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confidence: 99%

How Narrow is the Linewidth of Parametric X-Ray Radiation?

et al. 1997

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Parametric x-ray or quasi-Cherenkov radiation is produced by the passage of an electron through a crystal. A critical absorber technique has been employed to investigate its linewidth. Experiments have been performed with the 855 MeV electron beam from the Mainz Microtron MAMI. Thin absorber foils were mounted in front of a CCD camera serving as a position sensitive photon detector. Upper limits of the linewidth of 1.2 and 3.5 eV were determined for the (111) and (022) reflections of silicon at photon energies of 4966 and 8332 eV. These limits originate from geometrical line broadening effects that can be optimized to reach the ultimate limit given by the finite length of the wave train.[S0031-9007(97)04050-7] PACS numbers: 41.50. + h, 78.70.Dm Parametric x-ray radiation (PXR) is produced when charged particles traverse a crystal. This radiation can be understood as the coherent superposition of the elementary waves emitted from the atoms which are induced by the electromagnetic field of the passing particle. In an equivalent picture they can be described as the diffraction of the virtual photons associated with the moving particles or as a quasi-Cherenkov radiation in a medium with a periodic dielectricity. The most intriguing feature of PXR is the appearance of a sharp quasimonochromatic x-ray beam close to the Bragg angle. The narrow angular distribution consists of one peak above and one below the symmetry plane of the crystal. Their widths are characterized by the angle u ph ͓1͞g 2 1 ͑v p ͞v͒ 2 ͔ 1͞2 , with g the Lorentz factor of the moving particle, v the angular frequency of the emitted photon, and v p the plasma frequency of the crystal, 31 eV for Si. The theoretical description of the intensity distribution of PXR [1-5], suitably modified for self-absorption and multiple scattering effects, have been tested in a broad range of electron energies extending from 3.5 MeV [6,7] to about 1 GeV [8]. It was found to be accurate within 12%. On the other hand, very little is known about the energy width of PXR. The various theoretical descriptions of PXR predict a very narrow linewidth of less than a few meV. Actually, if it is assumed that a charged particle passes a very thick and perfect single crystal on a straight line and if self-absorption of the photons in the crystal can be neglected, simply a d function results for the line shape. Measurements of the linewidth have been performed up to now at the low beam energy of 6.8 MeV only. A variance of the linewidth of 48 eV has been determined for a 55 mm thick diamond crystal at a photon energy of 8.98 keV [9]. This rather large linewidth originates at low electron energy from the multiple scattering of electrons in the crystal.In this Letter a measurement of PXR at the Mainz Microtron MAMI with a silicon crystal at photon energies of about 5.0 and 8.3 keV is presented. For the high beam energy of MAMI of 855 MeV a line broadening by multiple scattering of the electrons in the crystal can be neglected. This fact originates from the rather surprising result ...

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Lineshape, linewidth and spectral density of parametric x-radiation at low electron energy in diamond

Cited by 16 publications

References 14 publications

Coherent X-rays at MAMI

Coherent X-rays at MAMI

Compact and intense parametric x-ray radiation source based on a linear accelerator with cryogenic accelerating and decelerating copper structures

How Narrow is the Linewidth of Parametric X-Ray Radiation?

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