The bound coherent neutron scattering length of the oxygen isotopes

The technique of neutron interferometry was used to measure the bound coherent neutron scattering length bcoh of the oxygen isotopes 17O and 18O. From the measured difference in optical path between two water samples, either H2 17O or H2 18O versus H2 natO, where nat denotes the natural isotopic com...

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Published inJournal of physics. Condensed matter Vol. 24; no. 50
Main Authors Fischer, Henry E, Simonson, J Michael {Mike}, Neuefeind, Joerg C, Lemmel, Hartmut, Rauch, Helmut, Zeidler, Anita, Salmon, Phil
Format Journal Article
LanguageEnglish
Published United States 01.01.2012
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Summary:The technique of neutron interferometry was used to measure the bound coherent neutron scattering length bcoh of the oxygen isotopes 17O and 18O. From the measured difference in optical path between two water samples, either H2 17O or H2 18O versus H2 natO, where nat denotes the natural isotopic composition, we obtain bcoh , 17O = 5.867(4) fm and bcoh , 18O = 6.009(5) fm, based on the accurately known value of bcoh , natO = 5.805(4) fm which is equal to bcoh , 16O within the experimental uncertainty. Our results for bcoh , 17O and bcoh , 18O differ appreciably from the standard tabulated values of 5.6(5) fm and 5.84(7) fm, respectively. In particular, our measured scattering length contrast of 0.204(3) fm between 18O and natO is nearly a factor of 6 greater than the tabulated value, which renders feasible neutron diffraction experiments using 18O isotope substitution and thereby offers new possibilites for measuring the partial structure factors of oxygen-containing compounds, such as water.
Bibliography:DE-AC05-00OR22725
USDOE Office of Science (SC)
ISSN:0953-8984
1361-648X
DOI:10.1088/0953-8984/24/50/505105