Astrophysical plasma study benefits from new soft X-ray transition
energies benchmark

Date:
April 5, 2022
Source:
Springer
Summary:
The analysis of astrophysical plasmas is vital in the quest to
learn about some of the Universe's most powerful and mysterious
objects and events such as stellar coronae and winds, cataclysmic
variables, X-ray binaries containing neutron stars and black holes,
supernova remnants, or outflows in active galactic nuclei. The
success of such research will lead to future astrophysical X-ray
observatories enabling scientists to access techniques that are
currently not available to X-ray astronomy. A key requirement for
the accurate interpretation of high-resolution X-ray spectra is
accurate knowledge of transition energies.



FULL STORY ==========================================================================
The analysis of astrophysical plasmas is vital in the quest to learn
about some of the Universe's most powerful and mysterious objects and
events such as stellar coronae and winds, cataclysmic variables, X-ray
binaries containing neutron stars and black holes, supernova remnants,
or outflows in active galactic nuclei. The success of such research will
lead to future astrophysical X-ray observatories enabling scientists to
access techniques that are currently not available to X-ray astronomy. A
key requirement for the accurate interpretation of high-resolution X-ray spectra is accurate knowledge of transition energies.


==========================================================================
A new paper published in EPJ Dauthored by J. Stierhof, of the Dr. Karl
Remeis- Observatory and Erlangen Centre for Astroparticle Physics of
Friedrich- Alexander-Universt Erlangen-Nu"rnberg, Bamberg, Germany, and coauthors utilizes a newly introduced experimental setup at the BESSY
II synchrotron facility to provide precise calibration references in the
soft X-ray regime of neon, carbon dioxide, and sulfur hexafluoride gases.

"In many research fields involving X-rays or any wavelength of light,
insights are obtained by comparing measurements of emission or absorption
line wavelengths with known values of transitions in various elements. A
shift of the observed wavelength with respect to the known one can occur because of the velocity of the emitter or absorber," says Stierhof. "Our
work demonstrates a setup to measure transition energies of gases
simultaneous with known transitions in highly charged ions having
only two remaining electrons that are precisely known from theoretical calculations." Monochromatic X-rays from a synchrotron beamline pass
through an electron beam ion trap (EBIT), where they interact with
the low-density plasma produced and trapped inside the EBIT and then
enter a gas photoionization cell containing the atoms or molecules under investigation. Fluorescence emission from the ions in the EBIT provides
the basis for the absolute calibration of the monochromator energy scale
in the experiment.

In the paper, the authors found results for the energy transition in the
k- shell of carbon dioxide that agree well with previous findings. The
results in the transitions demonstrated by sulfur hexafluoride showed
that previous experiments have a shift of around 0.5 eV, more than twice
their claimed uncertainty.

The team concludes that the statistical uncertainty in principle allows calibrations in the desired range of 1 to 10 meV, with systematic
contributions currently limiting the uncertainty to around 40 to100 meV.

"Our proposed setup provides an absolute calibration for the X-ray beam,
but we found that the total uncertainty is dominated by relative changes
of the beam," Stierhof concluded. "Providing an additional setup to
measure these relative changes will bring us closer to the resolution
limit of 10 meV."

========================================================================== Story Source: Materials provided by Springer. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. J. Stierhof, S. Ku"hn, M. Winter, P. Micke, R. Steinbru"gge,
C. Shah, N.

Hell, M. Bissinger, M. Hirsch, R. Ballhausen, M. Lang, C. Gra"fe, S.

Wipf, R. Cumbee, G. L. Betancourt-Martinez, S. Park, J. Niskanen, M.

Chung, F. S. Porter, T. Sto"hlker, T. Pfeifer, G. V. Brown,
S. Bernitt, P. Hansmann, J. Wilms, J. R. Crespo Lo'pez-Urrutia,
M. A. Leutenegger. A new benchmark of soft X-ray transition energies
of $$\mathrm {Ne}$$, $$\mathrm {CO}_2$$, and $$\mathrm {SF}_6$$:
paving a pathway towards ppm accuracy. The European Physical
Journal D, 2022; 76 (3) DOI: 10.1140/ epjd/s10053-022-00355-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220405115228.htm

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