/usr/lib/python2.7/dist-packages/PyMca/CoherentScattering.py is in pymca 4.7.1+dfsg-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# Copyright (C) 2004-2012 European Synchrotron Radiation Facility
#
# This file is part of the PyMca X-ray Fluorescence Toolkit developed at
# the ESRF by the Software group.
#
# This file is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your option)
# any later version.
#
# This file is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
#############################################################################*/
__author__ = "V.A. Sole - ESRF Data Analysis"
import os
import numpy
from PyMca import ConfigDict
from PyMca 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
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))
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)")
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