Matprop
Last modified: 6 February 2004
Matprop is a material properties calculator based on CEPack, a detector simulation toolkit developed in the context of the fast detector simulation program Lelaps. It will calculate and display various constants for most elements and any compounds of those elements or mixtures of such compounds. See the instructions for usage details. See definitions for information about the calculated quantities. In order to see plots, your browser must support SVG.
DISCLAIMER: Neither the author, nor Stanford Linear Accelerator Center, nor Stanford University, nor the Department of Energy guarantees that the results of the calculations are correct, accurate, or usable for any purpose whatsoever. No liability is assumed by any party.
If you want the properties of an element or compound, enter its name in the first column in first row under "Material". A material can be an element (e.g. H, H2, He, Fe, etc.) or chemical formula for a compound (e.g. SiO2). You may use floating point numbers (YBa2Cu3O6.6) but not parentheses. If the material is a solid or liquid, enter the density in column 2, unless the material is an element and you want the default. If the material is a gas, enter the pressure and temperature in columns 3 and 4. For elemental gasses the default values 1 atm and 298.3 K (NTP) are used.
If you want the properties of a mixture of elements or compounds, continue entering them in the next rows, and enter a number in column 5 for all components that gives the relative abundance by weight or by volume. The default is that all materials contribute equally by volume, but you can select "By weight". You may also specify a mixture name and whether the mixture is a gas or a solid (liquids are treated the same as solids). Finally, you may select to print information about all listed materials but not the mixture, only the mixture, or all listed materials and the mixture ("print all").
The last column allows you to select the color of the curve that will be shown in a plot if at least one material has this set to something other than "Not Plotted". Other plot options can be selected in the Plot Options panel.
Once you are done, click on Submit.
The (optional) plot(s) require that your browser is either "SVG enabled" (Netscape, Mozilla) or you have an appropriate SVG plugin installed (IE, Opera).
| Z |
Atomic number for elements. For compounds and mixtures Z is computed as an effective atomic number as is useful for multiple scattering (see Lynch and Dahl). It is calculated using the formula: Z (Z + 1) n = S Zi (Zi + 1) ni where the Zi are the effective Z's and ni the partial number densities of the constituent materials: ni = (Ni/NA)/V mol/cm3, and n is the overal number density of the compound n = (N/NA)/V = (S Ni / NA) / V = S ni. NA is Avogadro's constant and V is the overall volume. |
| A |
Atomic weight of the material in g/mol. For compounds it is calculated as A = density / n = density / S ni where n and ni are defined as before. |
| Average Z/A |
Average Z / A is used in energy loss calculations. For
elements, it is simply Z / A, but for compounds it is Average Z/A = S ni Zi / S ni Ai |
| Molecular weight |
Molecular weight W of the material in g/mol. This is equal to A for simple elements (but for e.g. O2 it is 2 * A). For mixtures it is computed as W = S ni Wi / S ni |
| Density | Density of the material in g/cm3. For gasses, the density is calculated from pressure and temperature using the ideal gas law. The density for elements is built in to matprop. In the case of elemental gasses, the built-in density is evaluated at NTP (1 atm, 25o C). For compounds the density (or alternatively pressure and temperature) needs to be given by the user. The density of mixtures is then calculated by matprop. |
| Density (STP) | Density this material would have at Standard Temperature and Pressure (STP, 1 atm and 0o C), if this is a gas. If it is a solid temperature and pressure are ignored. |
| Ionization potential | Mean ionization potential in V, calculated using the methods of Sternheimer and Peierls. |
| Plasma energy |
Plasma energy in eV, calculated using the methods of Sternheimer and Peierls. |
| Radiation length | Radiation length in g/cm2 and in cm, calculated using the methods of Tsai. |
| Hadronic interaction length |
Hadronic interaction length H. For elements this is calculated from a fit to the values for a number of elements. For compounds it is calculated in the following way: 1 / H = S Ai / Hi and for mixtures it is calculated using: 1 / H = S Mi / Hi where Mi is the mass fraction of compound i. |
| Critical energy |
The critical energy is calculated as follows: Critical energy = 2.66 * (Radiation Length * Z / A) 1.1 |
| Moliere radius |
The Moliere radius is calculated using : Moliere radius = 21.2052 * Radiation Length / Critical energy |
| A, B, Cbar, Xa, a, m, X0, X1 |
Sternheimer/Peierls variables, to be used in the dE/dx formula. |
| dE/dx | The average Bethe-Bloch energy loss in MeV. Note that no corrections are applied, not even for electrons. |
1. G.R. Lynch and O.I. Dahl, Nucl. Instr.
And Meth. B58, 6 (1991).
2. R.M. Sternheimer and R.F. Peierls, Phys. Rev. B3,
3681 (1971).
3. Y.T. Tsai, Rev. Mod. Phys. 46, 815 (1974).