Delivering science and technology to protect our nation and promote world stability

TOPS Opacities

Opacities of mixtures (calculated by TOPS using ATOMIC or LEDCOP elemental opacities)

The material data were last updated on August 19, 2015. This latest update includes OPLIB tables generated with the ATOMIC code, which (compared to the earlier LEDCOP release) cover additional temperatures and extend to higher densities.

Users are encouraged to view the File of currently available materials page to learn about the new data options.

Fill in form, then submit. Multiple values (where appropriate) must be separated by spaces. Leave field empty for default value. As a help to new users, the initial Web page defaults to calculating gray mean opacities for aluminum.

Relevant information:

In specifying a mix, the fraction represents relative numbers of atoms if the number fraction box is checked. If the mass fraction box is checked, the fraction represents relative masses of the specified elements. The fractions need not be normalized.

The element specification can be the atomic number, the chemical symbol (case insensitive) or the OPLIB matid. Thus aluminum can be specified as Al, al, 13, or n13719.

If the "Fraction, Element, Isotope" box is checked, a specific isotopic weight must be entered for each element of the mixture. If this box is not checked, no isotopic weight should be entered, the Web Page will use the normal values.

User can choose to supply a name for the mixture, up to 15 characters.

Fraction by
Input format:
Up to 450 characters may be used for the mixture specification.
User supplied, maximum of 15 characters

Temperatures (in keV)

Min
keV
Max
keV

Densities (in g/cm3)

Read Standard SESAME densities to get normal SESAME library density grid.

g/cm3
Min
g/cm3
Max
g/cm3
Spacing:

Photon energy group bounds (in keV)

Photon energy grid need not be specified for gray mean opacities or frequency dependent opacities.

keV
Min
keV
Max
keV
Spacing:

All options provide the Gray mean opacities but users should restrict the number of temperature-density-multigroup energy points to maintain a reasonable size data base for plotting and transmitting the data.

No more than 6 temperature-density points for the last 2 options.

Useful Links

Group T-1 Home Page

Please mail questions or comments to:

LANL T-1 Opacities

opacity@lanl.gov
Los Alamos Report No.

LA-UR-01-1257