Python code and resources used in APS 2016 Python lecture 5
Make basic characterizations of diffraction peak from HDF5 file data
- print peak position
- print center of mass (COM)
- print full-width at half maximum (FWHM)
- data describes a diffraction peak profile: intensity vs. angle
- use actual data from an APS beam line
- use HDF5 data file
The functions to compute these terms have been coded in Python directly and are placed in a library file with the code. The h5py package used to read the data file stores data from the file in memory using data structures from the numpy package. For the purposes of demonstration, the library functions created for this lecture have been written to avoid direct calls to numpy routines.
The data file chosen for this example is from the NeXus manual. A graph of this data is provided.
graph of writer_1_3.hdf5:/Scan/data
Physically, the data are from a Si (220) crystal Bragg reflection rocking curve measurement using 10.5 keV X-rays from the USAXS instrument when it was at APS beam line 32ID, recorded by SPEC on 2010-04-25. This scan is part of a routine alignment process of the USAXS instrument.
FWHM: https://en.wikipedia.org/wiki/Full_width_at_half_maximum
h5py: http://www.h5py.org
numpy: http://www.numpy.org
NeXus: http://download.nexusformat.org/doc/html/examples/h5py/index.html
SPEC: http://certif.com