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Influence of environmental parameter variations on X‐ray beam intensities: a time‐dependent absorption correction
Author(s) -
Weigel Tina,
Leisegang Tilmann,
Zschornak Matthias,
Herrmann Marco,
Rothenberger Manuel,
Wünsche Andreas,
Stöcker Hartmut,
Meyer Dirk C.
Publication year - 2015
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576715018452
Subject(s) - intensity (physics) , relative humidity , beam (structure) , absorption (acoustics) , humidity , scintillation , optics , analytical chemistry (journal) , atmospheric pressure , chemistry , noise (video) , materials science , physics , meteorology , environmental chemistry , artificial intelligence , detector , computer science , image (mathematics)
Essential to the quality of X‐ray analysis in crystallography, such as diffractometry and spectrometry, is a stable and reproducible X‐ray source. Commonly, different optical elements are utilized to provide a dedicated X‐ray beam. The stable alignment of all these components is a prerequisite in order to reduce aberrations and to achieve high signal‐to‐noise ratios. Besides such aberrations and electronically induced variations of the X‐ray primary beam intensity, the environmental conditions are of particular importance, most prominently the barometric pressure, humidity and temperature. In a qualitative as well as quantitative study, the influence of the environmental conditions on the primary beam intensity of a sealed tube with a Cu anode and their correlations are determined. For a common setup, utilizing a scintillation counter, laboratory as well as external conditions are monitored simultaneously for 28 d. Their individual influence on the X‐ray intensity and their correlations are evaluated by statistical analysis including time lag. By this comprehensive study, experimental intensity variations of up to Δ I / I = 1.153 ± 0.001% are determined during density of air changes of Δρ/ρ = 3.7 ± 0.6%. This is interpreted in terms of air transmission variations of up to T X‐ray = 1.137 ± 0.001% for a typical X‐ray analysis setup due to ambient barometric pressure, temperature and humidity changes for natural mid‐ and long‐term variations. Significant correlations with respect to daily and weekly cycles and in particular with ambient conditions are determined. These results are used for a time‐dependent absorption correction of the measured intensity, which reduces the standard error by about 25%.