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Evaluated Nuclear Reaction Data

Introduction

What is an Evaluated Library ?

Evaluated data sets are produced through the process of critical comparison, selection renormalization and averaging of the available experimental data, normally complemented by nuclear model calculations.

Evaluated Libraries are computer files of evaluated data which, appropriately processed, form the input data to computations for a wide variety of nuclear science and technology applications. Each of these evaluated libraries may consist of individual evaluated data sets for several hundred isotopes or elements (commonly referred to as 'materials').

What is the ENDF format ?

These computerised Evaluated Libraries are normally stored in a computer readable format called the ENDF format. The data set for each material is subdivided by data type (e.g. reaction cross section, angular distributions, energy distributions, covariance data...) and reactions type (e.g. total reaction cross section, elastic reaction cross sections, fission cross section...). Libraries are sometimes divided in to sub-libraries, each containing a specific type of data for particular applications (e.g. neutron cross section data, radioactive decay data, fission yield data...).

To make use of the data you retrieve, you will need to have some knowledge of the ENDF format in order to extract the information you are looking for. If you are not already familiar with the ENDF format we recommend that you download a copy of the ENDF Format Manual for reference.

What is EVA ?

EVA is the name of our database containing EVAluated data, taken from a large number of evaluated data libraries. The data are all stored in the ENDF format. The smallest unit of data that can be retrieved is a single type of data for a single reaction for a single nuclide.

Users may need complete libraries, containing data for a large number of materials, to be used as input for complex computations. In this case, our Download library service provides a means for retrieving complete evaluated libraries.

Alternatively, perhaps data is only needed only a single reaction for a particular nuclide. Our Search Database service allows users to interrogate our EVA database and select as much or little data as required using a range of selection specifiers including nuclide name, data type, reaction type and library name.

If you still can't manage to find what you are looking for, don't worry, just contact us and we'll try to help.

What about processed data ?

All the nuclear data offered by the Nuclear Data Services section of the NEA Data Bank are what are known as basic data i.e. as received from the point of origin. Many of these evaluated libraries are often also made available, already processed into a variety of different formats, ready for use with calculation codes for specific applications. Data which has already been processed in this way is available through our Nuclear application data website.

Search the database

The retrieval web page provides an easy way to make simple searches of the EVA database. To specify a nuclide, enter either the Atomic Number (Z) or Symbol (or a list, separated by commas but no spaces e.g. 3,4 or Li,Be). Likewise, enter the Atomic Mass (A). Alternatively, the nuclide can be specified according to it's ENDF Material number (see ENDF manual).

The Reaction Selection Menu allows the type of data (MF) and type of reaction (MT) to be selected from a scrolling list. You can choose which evaluated libraries you will search using the Library option; all libraries will be searched if this option is left blank. The range of libraries searched can also be restricted by making a selection in the Category option.

The database search is initiated by clicking on the Retrieve button.

An index of the available data corresponding to the specified search criteria will be displayed. This shows the source of the data (from which evaluated library it came), the category of the data, the ENDF tape number, the ENDF material identification number, nuclide name and mass, data type, reaction type and number of lines (or records) of data. If you are satisfied that these data meet your requirements, then the data may be retrieved by clicking on the Retrieve the output file button.

Index of libraries and download area

Format manuals

Last reviewed: 23 September 2010

Software JANIS-3.2 JANIS-3.3