/usr/share/pyshared/PyMca/CoherentScattering.py is in pymca 4.5.0-4.
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) 2004-2011 European Synchrotron Radiation Facility
#
# This file is part of the PyMCA X-ray Fluorescence Toolkit developed at
# the ESRF by the Beamline Instrumentation Software Support (BLISS) group.
#
# This toolkit is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your option)
# any later version.
#
# PyMCA 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 General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# PyMCA; if not, write to the Free Software Foundation, Inc., 59 Temple Place,
# Suite 330, Boston, MA 02111-1307, USA.
#
# PyMCA follows the dual licensing model of Trolltech's Qt and Riverbank's PyQt
# and cannot be used as a free plugin for a non-free program.
#
# Please contact the ESRF industrial unit (industry@esrf.fr) if this license
# is a problem for you.
#############################################################################*/
import os
import numpy.oldnumeric as Numeric
from PyMca import ConfigDict
from PyMca import Scofield1973
dirmod = os.path.dirname(Scofield1973.__file__)
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 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 = Numeric.sin(theta*(Numeric.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] * Numeric.exp(-b[0]*x)) + \
(c[1] * Numeric.exp(-b[1]*x)) + \
(c[2] * Numeric.exp(-b[2]*x)) + \
(c[3] * Numeric.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(Numeric.sin(theta*Numeric.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))
import Tkinter
import SimplePlot
root = Tkinter.Tk()
e=range(int(energy+1))[1:]
y=[getElementFormFactor(ele, theta, x) for x in e]
SimplePlot.plot([e,y])
root.mainloop()
else:
print("Usage:")
print("python FormFactor.py Element Theta(deg) Energy(kev)")
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