Source code for PyMca5.PyMcaPhysics.xrf.CoherentScattering

#/*##########################################################################
#
# The PyMca X-Ray Fluorescence Toolkit
#
# Copyright (c) 2004-2014 European Synchrotron Radiation Facility
#
# This file is part of the PyMca X-ray Fluorescence Toolkit developed at
# the ESRF by the Software group.
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# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
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# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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__author__ = "V.A. Sole - ESRF Data Analysis"
__contact__ = "sole@esrf.fr"
__license__ = "MIT"
__copyright__ = "European Synchrotron Radiation Facility, Grenoble, France"
import os
import numpy
from PyMca5.PyMcaIO import ConfigDict
from PyMca5 import PyMcaDataDir

dirmod = PyMcaDataDir.PYMCA_DATA_DIR
ffile = os.path.join(dirmod, "attdata")
ffile = os.path.join(ffile, "atomsf.dict")
if not os.path.exists(ffile):
    #freeze does bad things with the path ...
    dirmod = os.path.dirname(dirmod)
    ffile = os.path.join(dirmod, "attdata")
    ffile = os.path.join(ffile, "atomsf.dict")
    if not os.path.exists(ffile):
        if dirmod.lower().endswith(".zip"):
            dirmod = os.path.dirname(dirmod)
            ffile = os.path.join(dirmod, "attdata")
            ffile = os.path.join(ffile, "atomsf.dict")
    if not os.path.exists(ffile):
        print("Cannot find file ", ffile)
        raise IOError("Cannot find file %s" % ffile)
COEFFICIENTS = ConfigDict.ConfigDict()
COEFFICIENTS.read(ffile)
KEVTOANG = 12.39852000
R0 = 2.82E-13 #electron radius in cm

[docs]def getElementFormFactor(ele, theta, energy): """ Usage: getFormFactor(ele,theta, energy): ele - Element theta - Scattering angle or array of scattering angles in degrees energy- Photon Energy in keV This routine calculates the atomic form factor in electron units using a four gaussians approximation """ wavelength = KEVTOANG / energy x = numpy.sin(theta*(numpy.pi/360.0)) / wavelength x = x * x c0= COEFFICIENTS[ele]['c'][0] c = COEFFICIENTS[ele]['c'][1:] b = COEFFICIENTS[ele]['b'] return c0 + (c[0] * numpy.exp(-b[0]*x)) + \ (c[1] * numpy.exp(-b[1]*x)) + \ (c[2] * numpy.exp(-b[2]*x)) + \ (c[3] * numpy.exp(-b[3]*x))
[docs]def getElementCoherentDifferentialCrossSection(ele, theta, energy, p1=None): if p1 is None: p1=0.0 if (p1 > 1.0) or (p1 < -1): raise ValueError(\ "Invalid degree of linear polarization respect to the scattering plane") thetasin2 = pow(numpy.sin(theta*numpy.pi/180.0),2) return (1.0+ 0.5 *(p1-1.0) * thetasin2) * \ pow(R0*getElementFormFactor(ele, theta, energy),2)
if __name__ == "__main__": import sys if len(sys.argv) > 3: ele = sys.argv[1] theta = float(sys.argv[2]) energy= float(sys.argv[3]) print(getElementFormFactor(ele, theta, energy)) else: print("Usage:") print("python CoherentScattering.py Element Theta(deg) Energy(kev)")