SANS FAQ for FENAC Applicants

Frequently Answered Questions:

  1. How much material do I need for a SANS measurement?

Typically not more than 1 ml per sample.

  1. How long does a single SANS measurement take?

This depends on factors like the concentration and the contrast, but typically reasonable quality data can be obtained in about 15 minutes to 1 hour.

  1. What types of sample can I study?

Solutions of macromolecules, colloidal dispersions of particles, slurries, pastes, powders, porous solids...

  1. What are SANS sample containers made of?

Materials containing elements with low neutron capture cross-sections.

Solutions, dispersions, slurries and fine powders can be contained in fused silica ('synthetic quartz') - but not glass - cuvettes; pastes, coarse powders and solids can simply be wrapped in thin aluminium foil.

For more specialised applications, single crystal sapphire, aluminium alloy (eg, Grade HE30), titanium (Grade V) or pure vanadium are all fairly transparent to the neutron wavelengths used in SANS. Copper is another possibility but it will activate.

Brass and steel scatter strongly and so whilst they can be used in the construction of a sample container, neutron transparent 'windows' will be needed.

ISIS can loan FENAC SANS applicants suitable fused silica cuvettes.

  1. Can I make SANS measurements on samples in normal (light) water?

Yes. The contrast conditions may be sub-optimal, leading to poorer quality data, but it is perfectly possible. The SANS instruments at ISIS have already studied samples in river water and even waste water!

  1. Waste water? You mean sewage?!

Yes. However because of the potential biological hazards inherent in such a sample a secondary sample containment regime was necessary. Such a sample would not lend itself to a simple SANS Xpress measurement.

  1. What if my sample contains uranium or thorium?

This is not a problem, ISIS is used to handling such samples! However, we are obliged by Government to log the movement of all samples containing uranium or thorium irrespective of the concentration or activity of the radionuclides present. What this means in practice is a little extra paperwork.

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