Angular distribution of X-ray emission from resonant coherently excited highly-charged heavy ions

The magnetic interaction between the crystallites of weak ferromagnetic α-Fe2O3 has been studied by combining SR based X-ray diffraction with an externally applied magnetic field. The measurements were performed with several polycrystalline α-Fe2O3 [1,2] samples (dry or in suspensions) placed in a half-filled cylindrical container in ambient conditions. The axis of the cylindrical container was oriented vertically parallel to the applied dc magnetic field. The polycrystalline sample had a free surface, so the α-Fe2O3 crystallites were free to move. The full Debye-Scherrer diffraction rings were measured with a 2D pixel detector at the beamline ID-15B at ESRF. In the absence of the magnetic field the intensity distribution over azimuthal angle was a uniform, i.e. there was no texture. The applied maximal field, B=0.9T was too small to change the magnetic ordering of α-Fe2O3 but it was sufficiently strong to reorient large amount of crystallites in order to minimize the angle between their ferromagnetic moment direction and the external field. Pronounced texture patterns with clear maxima in the angular distribution of the intensity across each Debye-Scherrer ring were observed. The observed textured intensity distribution was analyzed quantitatively by using a model based on the magnetic anisotropy observed in single crystals of α-Fe2O3. The analysis yielded two important parameters: (i) the width of the angular distribution of the ferromagnetic moments directions around the external field direction, and (ii) the relative quantity of the crystallites that did reorient in the external field. The α-Fe2O3 samples were also characterized with TEM technique. The analysis of X-ray and TEM studies provide new conclusions about the magnetic interaction between the α-Fe2O3 crystallites [3]. The proposed measurement technique can be applied to study other weak ferromagnetic materials.

Download Full-text

HIGH-RESOLUTION PIXE USING BRAGG’S SPECTROMETER

International Journal of PIXE ◽

10.1142/s0129083591000172 ◽

1991 ◽

Vol 01 (03) ◽

pp. 251-258 ◽

Cited By ~ 8

Author(s):

M. TERASAWA

Keyword(s):

High Resolution ◽

Heavy Ions ◽

X Rays ◽

Light Elements ◽

Element Analysis ◽

X Ray ◽

Peak Intensity ◽

Moderate Energy ◽

Practical Analysis ◽

Wavelength Selectivity

K, L, and M X-rays in the wavelengths between 6Å and 130Å generated by the bombardment of 200 keV protons and other heavy ions were measured by means of a wavelength dispersive Bragg’s spectrometer. The X-ray peak intensity was fairly high in general, while the background was very low. The technique was favorably applied to a practical analysis of several light elements (Be, B, C, N, O, and F). Use of moderate-energy heavy ions considering the wavelength selectivity in X-ray generation was effective for the element analysis. The high-resolution spectrometry in the analytical application of ion-induced X-ray generation was found to be useful for the study of fine electronic structure, e.g. satellite and hypersatellite X-ray study, and of the chemical state of materials.

Download Full-text

Target centred coupled channel calculations for LIsubshell X-ray production cross sections by heavy ions

Journal of Physics B Atomic Molecular and Optical Physics ◽

10.1088/0953-4075/25/9/012 ◽

1992 ◽

Vol 25 (9) ◽

pp. 2055-2063 ◽

Cited By ~ 11

Author(s):

R Shingal ◽

N B Malhi ◽

T J Gray

Keyword(s):

Cross Sections ◽

Heavy Ions ◽

Production Cross ◽

X Ray ◽

Coupled Channel

Download Full-text

Improvements in the sensitivity of screen-type X-ray films for cascade showers and the charge resolution for heavy ions

Il Nuovo Cimento A ◽

10.1007/bf02812490 ◽

1991 ◽

Vol 104 (12) ◽

pp. 1753-1770 ◽

Cited By ~ 4

Author(s):

T. Kobayashi ◽

M. Fujii ◽

J. Nishimura ◽

T. Taira ◽

H. Aizu ◽

...

Keyword(s):

Heavy Ions ◽

X Ray ◽

Charge Resolution

Download Full-text

The use of X-ray CT to measure diffusion coefficients of heavy ions in water-saturated porous media

Developments in Geotechnical Engineering - Engineering Geological Advances in Japan for the New Millennium ◽

10.1016/s0165-1250(00)80003-6 ◽

2000 ◽

pp. 11-17

Author(s):

Yoshito Nakashima

Keyword(s):

Porous Media ◽

Diffusion Coefficients ◽

Heavy Ions ◽

Saturated Porous Media ◽

X Ray ◽

Water Saturated

Download Full-text

Effects of Compton scattering on the neutron star radius constraints in rotation-powered millisecond pulsars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935442 ◽

2019 ◽

Vol 627 ◽

pp. A39 ◽

Cited By ~ 3

Author(s):

Tuomo Salmi ◽

Valery F. Suleimanov ◽

Juri Poutanen

Keyword(s):

Angular Distribution ◽

Neutron Star ◽

Energy Spectrum ◽

Compton Scattering ◽

Electron Scattering ◽

Exact Formulation ◽

Millisecond Pulsars ◽

X Ray ◽

Synthetic Phase ◽

Neutron Star Radius

The aim of this work is to study the possible effects and biases on the radius constraints for rotation-powered millisecond pulsars when using Thomson approximation to describe electron scattering in the atmosphere models, instead of using exact formulation for Compton scattering. We compare the differences between the two models in the energy spectrum and angular distribution of the emitted radiation. We also analyse a self-generated, synthetic, phase-resolved energy spectrum, based on Compton atmosphere and the most X-ray luminous, rotation-powered millisecond pulsars observed by the Neutron star Interior Composition ExploreR (NICER). We derive constraints for the neutron star parameters using both the Compton and Thomson models. The results show that the method works by reproducing the correct parameters with the Compton model. However, biases are found in both the size and the temperature of the emitting hotspot, when using the Thomson model. The constraints on the radius are still not significantly changed, and therefore the Thomson model seems to be adequate if we are interested only in the radius measurements using NICER.

Download Full-text