IVAS Feedback/2.2

From Northwestern University Center for Atom-Probe Tomography
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1-D Composition Profile

  1. For the compositional profiles derived from Raw Atom Profile and Raw Atom Slice standard error bars based on <math>s=\sqrt{\frac{c_i\left(1-c_i\right)}{N_{TOT}}}</math> for each element in a bin in the .csv export.
  2. An integral profile where the ordinate has the cumulative number of ions of each element and the abscissa has the cumulative total number of atoms. The data is already there but just needs to be put into the right format and output. This is similar to p.6150 in Krakauer, B. W. and D. N. Seidman, Subnanometer Scale Study of Segregation at Grain Boundaries in an Fe(Si) alloy, Acta mater. (1998) V. 46, No. 17, pp. 6145-6161.

Note: There IS already a script to get a ladder diagram in this manner. See Rick to see if it is adequate or can be easily modified to become adequate

Precipitate Analysis Function

  1. Concentric Concentration needs standard error bars at each data point and in the .csv export.
  2. Need the precipitate panel (precipitate number, ions, principle axes) exported as a text file. Note for others: Rick made a work-around that dumps this to your temp directory, but it is useful enough to be integrated in IVAS
  3. Include approximation of each ellipsoid radius using

Envelope Function

The Guinier radius calculated from the radius of gyration, <math>r_G=\sqrt{\frac{5}{3}}l_g</math>, is not physically correct. The Guinier radius is found from the Guinier approximation for scattering and is given by<math>r_G=\sqrt{\frac{3}{5}}R</math>, where <math>R</math> is the radius of a homogenous spherical body. It has the same form as the Newtonian mechanics radius of gyration. By calculating <math>R</math> from SANS data using the Guinier radius and <math>R</math> from APT data the two can be compared. A direct comparison or conversion between the Guinier radius and the radius of gyration is not physically correct as the former is in reciprocal space while the latter is in direct space.

Segmented POS file

When one selects regions of interest from an analysis (typically ppts.—currently by the envelope method & eventually by an isosurface), we can end up with a single POS for all of the regions of interest (so, one obtains one POS which contains ALL ppts., which is used by the Precip Analysis script). It would be useful to OPTIONALLY export one POS for each individual region of interest (each ppt., rather than all ppts.). This way, we can easily perform compositional analyses on each individual ppt.

Detail Panel

Would like standard errors based on <math>s=\sqrt{\frac{c_i\left(1-c_i\right)}{N_{TOT}}}</math> for each element.