Nuclear Data Libraries from Los Alamos National Laboratory

Lib80x—Library based on ENDF/B-VIII.0

See the bottom of this page for specific help for MCNP users.

This library is based on ENDF/B-VIII.0. It contains ACE files for continuous-energy incident neutrons. These have been processed to the following temperatures (with the respective ZAID extensions).

  • .00c — 293.6 Kelvin (room temperature)
  • .01c — 600 Kelvin
  • .02c — 900 Kelvin
  • .03c — 1200 Kelvin
  • .04c — 2500 Kelvin
  • .05c — 0.1 Kelvin
  • .06c — 250 kelvin

The full documentation for the Lib80x library can be found in the docs directory after decompressing the download.


Lib80x can be downloaded either as a zip file or as a compressed tarball

  • Lib80x.tgz (md5sum f0372b1530fdbc542d3497ff943fff27)
  • (md5sum 8a52bb92c7044f11e4cbd3cb869e3a1e)

Thermal Scattering Data (S(α,β))

The thermal scattering library based on ENDF/B-VIII.0 contains 34 materials. The material identifiers (for use on the MTn card in MCNP) are given in the table below. For those that have a room temperature evaluation, that data table has extension 40t. The full documentation for the ENDF80SaB library can be found in the docs directory after decompressing the download.

al-27 aluminum-27 metal
be-beo beryllium in beryllium-oxide
be-met beryllium metal
benz benzene
c-sic carbon in silicon carbide
d-d2o deuterium in heavy water
fe-56 iron-56 metal
grph10 10% porous graphite
grph30 30% porous graphite
grph crystalline graphite
h-h2o hydrogen in light water
h-ice hydrogen in solid light water (ice)
h-luci hydrogen in Lucite
h-poly hydrogen in polyethylene
h-yh2 hydrogen in yttrium-hydride
h-zrh hydrogen in zirconium-hydride
lmeth hydrogen in liquid methane
n-un nitrogen in uranium-nitride
o-beo oxygen in beryllium-oxide
o-d2o oxygen in heavy water
o-ice oxygen in solid light water (ice)
orthoD liquid ortho-deuterium
orthoH liquid ortho-hydrogen
o-uo2 oxygen in uranium-dioxide
paraD liquid para-deuterium
paraH liquid para-hydrogen
sio2 silicon-dioxide
si-sic silicon in silicon-carbide
smeth hydrogen in solid methane
u-un uranium in uranium-nitride
u-uo2 uranium in uranium-dioxide
y-yh2 yttrium in yttrium-hydride
zr-zrh zirconium in zirconium-hydride


ENDF80SaB can be downloaded either as a zip file or as a compressed tarball. Links to the tarball and the associated md5sums are:

There was a typo in the header of the o-d2o files of this library from July to October 2020; The typos were fixed in late October 2020. If you downloaded the files in that time frame, we recommend that you download the library again and replace toe o-d2o files with the newly downloaded ones.

Alternatively, you can manually edit the files yourself. The ZAID is the very first string on the very first line of each file. In the ENDF80SaB2 directory

  • Change file o-d2o.40t from ZAID o-d2o.80t to o-d2o.40t
  • Change file o-d2o.41t from ZAID o-d2o.81t to o-d2o.41t
  • Change file o-d2o.42t from ZAID o-d2o.82t to o-d2o.42t
  • Change file o-d2o.43t from ZAID o-d2o.83t to o-d2o.43t
  • Change file o-d2o.44t from ZAID o-d2o.84t to o-d2o.44t
  • Change file o-d2o.45t from ZAID o-d2o.85t to o-d2o.45t
  • Change file o-d2o.46t from ZAID o-d2o.86t to o-d2o.46t
  • Change file o-d2o.47t from ZAID o-d2o.87t to o-d2o.47t
  • Change file o-d2o.48t from ZAID o-d2o.88t to o-d2o.48t

Updated Thermal Scattering Library

The Nuclear Data Team originally released a thermal scattering library based on ENDF/B-VIII.0 in Spring of 2018. We received a few comments that some things were not processed correctly. We have spent a lot of time identifying the issues and have released an updated and fixed library. The library that is now available for download is the updated library. For more information regarding the updated please see the documentation available as part of the download or see the technical report LA-UR-20-24456 for the documentation by itself.


For issues with ENDF/B-VIII.0-based data, please contact the Nuclear Data Team (

MCNP Users

Some additional information which may be of use for MCNP users: