# 1. Cross Sections Listing – cross_sections.xml¶

## 1.1. <directory> Element¶

The <directory> element specifies a root directory to which the path for all files listed in a <library> Element are given relative to. This element has no attributes or sub-elements; the directory should be given within the text node. For example,

<directory>/opt/data/cross_sections/</directory>


## 1.2. <library> Element¶

The <library> element indicates where an HDF5 data file is located, whether it contains incident neutron, incident photon, thermal scattering, or windowed multipole data, and what materials are listed within. It has the following attributes:

materials

A space-separated list of nuclides or thermal scattering tables. For example,

<library materials="U234 U235 U238" />
<library materials="c_H_in_H2O c_D_in_G2O" />


Often, just a single nuclide or thermal scattering table is contained in a given file.

path

Path to the HDF5 file. If the <directory> Element is specified, the path is relative to the directory given. Otherwise, it is relative to the directory containing the cross_sections.xml file.

type

The type of data contained in the file. Accepted values are ‘neutron’, ‘thermal’, ‘photon’, and ‘wmp’.

## 1.3. <depletion_chain> Element¶

The <depletion_chain> element indicates the location of the depletion chain file. This file contains information describing how nuclides decay and transmute to other nuclides through the depletion process. This element has a single attribute, path, pointing to the location of the chain file.

<depletion_chain path="/opt/data/chain_endfb7.xml"/>


The structure of the depletion chain file is explained in Depletion Chain – chain.xml.