Nuclear structure data


What is nuclear structure data ?

Nuclear stucture data refer to the properties of single nuclei, as opposed to reaction data which deals with the properties of a nucleus interacting with radiation or another nucleus.

Numerical data related to nuclear structure are available in the ENSDF and NUDAT databases, and bibliographic information on nuclear structure is found in the NSR database.

The Nuclear Structure and Decay Data Network

The International Nuclear Structure and Decay Data (NSDD) Network was formed under the auspices of the International Atomic Energy Agency, and co-ordinated by the IAEA Nuclear Data Section. The NSDD Network is responsible for the evaluation of all the mass-chains on a continual basis. A mass-chain is formed by all the nuclides of the same mass and different chemical elements. Each of the data centres of the network has a permanent assignment of mass-chains depending on the number of evaluators, their research interests, or special expertise in a particular mass region. Evaluations produced by the NSDD Network are stored in the Evaluated Nuclear Structure Data File (ENSDF) database that is managed by the NNDC (BNL). Links to data centres of the NSDD Network is available from NNDC or IAEA.

The Expermental Unevaluated Nuclear Data List (XUNDL)

XUNDL is a list of critical compilations of recent nuclear structure and decay data measurements published in peer-reviewed journals. On average, the time lapse between publication and compilation is a month. The database contains data from over 3 500 recent publications in ENSDF format.

The ENSDF database

Contents of the ENSDF database

ENSDF contains evaluated experimental data summarizing the present knowledge on the structure and decay of nuclei. It contains information on nuclear level properties, radiations, radioactive decay, and reaction data for all known nuclides. For masses A ≥ 45, this information is documented in the Nuclear Data Sheets; for A < 45 ENSDF is based on compilations published in the journal Nuclear Physics.

If there are gaps in experimental data, they are not filled with theoretical or nuclear model calculations. While the emphasis is on experimental data, the evaluations do use well-founded systematics or theory.

General organisation of ENSDF data

The Evaluated Nuclear Structure Data File is made up of a collection of "data sets" which present one of the following kinds of information:

The data sets in ENSDF are organised by their mass number. Within a mass number the data sets are of two kinds:

Data sets (ii) i.e., for a given nucleus (Z-value), consist of the following:

If the is more than one data set of type (1) or (2) for a given nucleus, then an adopted data set is required for that nucleus. If there is only one data set for a given nucleus, then that set is assumed also to present the adopted properties for that nucleus.

ENSDF format manual

A full and detailed description of the ENSDF format is provided in:

"Evaluated Nuclear Structure Data File – A Manual for Preparation of Data Sets", J.K.Tulli, Feb 2001, BNL-NCS-51655-01/02-Rev
Searching the ENSDF database

This mode of access provides an easy way to make simple searches of the ENSDF database. Simply enter a mass number (1 through 266) or a nuclide in the form ZZAAA (e.g.,235U) or ZZ-AAA (e.g., U-235). Search the ENSDF database.

ENSDF analysis and checking programs

A number of analysis and utility codes for use with ENSDF data are available from NNDC. Instructions on retrieving the codes from NNDC are described in "ENSDF Analysis and Checking Codes" (Postscript) or "ENSDF Analysis and Checking Codes".

The NUDAT database

Contents of the NUDAT database

The NUDAT database contains data extracted from several databases maintained at the National Nuclear Data Center (NNDC). The table below lists the type of data contained in NUDAT, and their origin:

Adopted levels – adopted nuclear level information from ENSDF

Adopted gammas – adopted gamma rays from levels in ENSDF

Adopted levels and gammas – levels and gamma ray information combined

Ground and metastable state properties – properties of ground/metastable states from Nuclear Wallet Cards

Decay radiations – ENSDF decay radiations from decay data processed by the code RADLST

Thermal neutron data and resonance integrals – thermal neutron cross sections and resonance integrals from BNL325

Searching the NUDAT database

This mode of access provides an easy way to make simple searches of the NUDAT database. The opening screen invites the user to select the type of data desired (selected from the list of data types shown above). For all data types the chemical symbol (or atomic number) and mass number are offered as search parameters. The other search parameters available are dependent on the data type. A full desciption of possible search criteria, together with examples, can be found on the web page "The NuDat2 Description".

Search the NUDAT database.

The 2012 Atomic Mass Evaluation (AME2012)

The AME2012 atomic mass evaluation is presented in the form of four files:

Any work using the files above should make reference to the papers below and not to the electronic files.


For more information, visit

Nubase Evaluation (Nubase2012)

The Nubase2012 table provides experimentally-known nuclear properties, including some that have been estimated by an extrapolation of 3827 nuclides: mass, isomeric excitation energy, half-life, spin, parity, decay modes and intensities.

nubase.mas12 – Nubase table

Any work using the file above should make reference to the paper below and not to the electronic file.


For more information, visit

Last reviewed: 25 October 2016