Description: Set of functions providing the attenuation and energy absorption coefficients of xray and gammaray photons in various materials, based on NIST report 5632, by J. Hubbell and S.M. Seltzer.
X = PhotonAttenuation(Material, Energy, Options, Thickness) Function providing the attenuation and energy absorption of xray and gammaray photons in various materials including mixtures and compounds, based on NIST report 5632, by J. Hubbell and S.M. Seltzer.
Input: 1) Material  string, number or array of strings, numbers or cells describing material type.  Element atomic number Z  in 1 to 100 range  Element symbols  'Pb', 'Fe'  Element names  'Lead', 'Iron', 'Cesium' or 'Caesium'  Some common names and full compound names  'Water', 'Polyethylene' (see function PhysProps for more details)  Compound formulas  'H2SO4', 'C3H7NO2' those are case sensitive  Mixtures of any of above with fractions by weight ? like 'H(0.057444)C(0.774589)O(0.167968)' for Bakelite or 'B(10)H(11)C(58)O(21)' for Borated Polyethylene (BPE10) 2) Energy  Energy of the photons. Can be single energy or vector of energies. Several formats are allowed:  Energy in MeV, should be in [0.001, 20] MeV range.  Wavelengths in nanometers. Encoded as negative numbers. The valid range is 6.1982e5 to 1.2396 nm;  Continuous Spectrum  Encoded in 2 columns: column one contains energy and column two contains relative number of photons at that energy. Spectrum is assumed to be continuous and output is calculated through integration using 'trapz' function. 3) Options  specifies what to return. String or number: 1. 'mac'  function returns Mass Attenuation Coefficients in cm^2/g 2. 'meac'  function returns Mass EnergyAbsorption Coefficients in cm^2/g. See link below for more info: http://physics.nist.gov/PhysRefData/XrayMassCoef/chap3.html 3. 'cross section'  function returns cross section in barns per atom (convert to cm^2 per atom by multiplying by 10^24). Available only for elements. 4. 'mean free path'  function returns mean free path (in cm) of photon in the given material . Available only for chemicals recognized by 'PhysProps' function (since density is needed). 5. 'transmission'  fraction of protons absorbed by given thickness of material 4) Thickness  Thickness of material in cm. Either scalar or vector of the same length as number of materials. Negative numbers indicate mass thickness measured in g/cm^2 (density*thickness). Needed only if energy spectrum is used or in case of Options set to 'Transmission'.
There are 3 other functions in the set that are used by 'PhotonAttenuation' function: 1) PhysProps  index of physical properties (density and atomic mass) and names of elements and compounds 2) ParseChemicalFormula  function converting many different styles of names used for elements, compounds and mixtures to uniform list of elements and their weight ratios. 3) PhotonAttenuationQ  lowlevel version of 'PhotonAttenuation' function with very few input options. 4) PhotonAttenuation_examples  a script with many examples of how to use this package.
References: Tables are based on "XRay Attenuation and Absorption for Materials of Dosimetric Interest" (XAAMDI) database (NIST 5632 report): J. Hubbell and S.M. Seltzer, "Tables of XRay Mass Attenuation Coefficients and Mass EnergyAbsorption Coefficients 1 keV to 20 MeV for Elements Z = 1 to 92 and 48 Additional Substances of Dosimetric Interest, "National Institute of Standards and Technology report NISTIR 5632 (1995). http://physics.nist.gov/PhysRefData/XrayMassCoef/cover.html
MAC values for elements 93 to 100 (Neptunium to Fermium) came from XCOM: Photon Cross Sections Database (NBSIR 873597): Those tables give photon's "total attenuation coefficients" for elements with atomic number (Z) smaller than 100. Photon energy range is from 0.001 MeV to 100 GeV. http://physics.nist.gov/PhysRefData/Xcom/Text/XCOM.html
History: Written by Jarek Tuszynski (SAIC), 2006 Inspired by John Schweppe Mathematica code avaiable at http://library.wolfram.com/infocenter/MathSource/4267/
License: Freeware Related: densitythickness, measured, needed, Spectrum, Transmission, Negative, thickness, scalar, Length, photonattenuation, Converting, styles, uniform, parsechemicalformula, compounds O/S:BSD, Linux, Solaris, Mac OS X File Size: 163.8 KB Downloads: 6

