NuDat 2 Description
NuDat 2 is a software product that allows to search and plot nuclear structure and nuclear decay data interactively. NuDat 2 was developed by the National Nuclear Data Center (NNDC) in Brookhaven National Laboratory. It provides an interface between web users and several databases containing nuclear structure, nuclear decay and some neutron-induced nuclear reaction information.
Using NuDat 2, it is possible to search for nuclear level properties (energy, half-life, spin-parity), gamma-ray information (energy, intensity, multipolarity, coincidences), radiation information following nuclear decay (energy, intensity, dose), and neutron-induced reaction data from the ENDF/B-VII.0 library (thermal cross section and fission yields).
The information provided by NuDat 2 can be seen in tables, level schemes and an interactive chart of nuclides.
New features for version 2.6
Searching NuDat 2
There are three different search forms: one for levels and gammas, a second one for decay-related information, and a third one for searching the Nuclear Wallet Cards file. A description of the search capabilities can be found by clicking the help link at the top of each form, or by following the following links:
We expect that most searches can be handled by the search forms provided; users with interests that can't be accomodated with these forms should not hesitate to contact us
NuDat 2 contents
The sections of NuDat 2 related to levels, gammas and decay are obtained from the Evaluated Nuclear Structure Data File (ENSDF). Physicists from around the world have been contributing to this effort. The management of ENSDF resides at the NNDC. NuDat 2 is periodically updated to reflect changes in ENSDF.
A table with a brief statistics on NuDat 2 can be found below:
NuDat 2 contains evaluated nuclear data, that is, recommended values following a careful analysis of the available data. We can not, however, guarantee the accuracy of the data or the absence of errors in the application. Users are urged to promptly report any problems encountered when using NuDat 2.
User should be aware that NuDat 2 contents change often as new data are incorporated.
Users should feel free to use the information from NuDat 2 (tables and plots) in their work, reports,
presentations, articles and books.
For those interested in quoting NuDat 2, we suggest the use of the following citation format:
National Nuclear Data Center, information extracted from the NuDat 2 database, http://www.nndc.bnl.gov/nudat2/
Interactive Chart of Nuclides
Experimentally known nuclei are represented by a cell in a chart with the number of neutrons on the horizontal axis and the number of protons on the vertical axis.
The color of the cell is used to indicate different ground state properties:
The following quantities are obtained from the Nuclear Wallet Cards database:
The following quantities are obtained or derived from the ENSDF database:
The following quantities are obtained or derived from the 2011 update of the Atomic Mass Evaluation by
Audi et al.:
The following quantities are obtained or derived from the ENDF/B-VII.0 database:
It should be kept in mind that there are nuclei whose ground state have more than one decay mode, or nuclei that have levels with a wide range of half-lives. The color scheme used here over-simplifies the description of a nucleus by choosing just one color. As a result, the chart should be only used as a visualization tool. It is advised to use the full list of levels for a complete information about decay modes and half-lives.
A logarithmic scale is used when the color code is equal to Half-life, E1st ex. st., E2+, E4+, E3-, σ(n,γ), σ(n,F), 235U FY and 239Pu FY, since these data can quickly change by several orders of magnitude and a linear scale would leave some details hidden. The other numerical data are plotted in a linear scale.
The color scale is fixed when the color code is "Half-life", "Decay Mode", any of the excited states and fission yields. That is, the cell color will be the same regardless of the zooming condition. For all the other coloring possibilities, the color scale floats around the view port, that is, a dark red is assigned to the highest most positive value in the view port, while a dark purple is assigned to the most negative one.
Please don't hesitate to contact us if you would like to see some other coloring possibilites.
The chart can be seen with 7 different zooming options. With the largest zoom value, the entire chart is displayed and the magic numbers 8, 20, 28, 50, 82 and 126 are indicated. For smaller zoom values, only a fraction of the chart is displayed; the nucleus at the center of the viewing window is marked with a magenta border; neutron ( horizontal axis ) and proton numbers ( vertical axis ) are indicated. When the zoom level is equal to 1, the name of the nucleus, the ground state half-life, the two decay modes with the highest probability and its natural abundance are displayed.
Ground and isomeric state information can be obtained by clicking on a given nucleus. This information is displayed under the chart of nuclides. Links to a list of levels, a level scheme, and decay radiation information are provided when available.
Unless the zoom is at the largest value, clicking on a given nucleus also re-centers the chart. Further navigation possibilities can be obtained by using the arrows on the right-top corner of the window, as well as the 'Nucleus' textbox under the zoom control.
Slow computers and slow internet browsers will be challenged by the tooltips, specially at the largest zoom. Users can choose to turn the tooltips feature off using the control menu on the right side in the main page. Fast browsers, such as Mozilla Firefox, respond well on slow computers and internet connections.
The chart images can be produced with two width values. In the wide screen mode, images are around 920 pixels in width, while in the narrow screen mode, images are around 740 pixels in width. In order to view the whole screen properly, the monitor should be set at a resolution width larger than the image width plus 200 pixels.
As mentioned before, a link to a web page with a levels plot is provided after clicking on a given nucleus. An example of it can be seen in the figure below:
The level scheme is rendered in a single image. Most nuclei, however, have complex level schemes that won't fit in just one image. As a consequence, only selected parts of the level scheme should be plotted at a time using the interactive features provided
Levels are plotted in vertical groups; each band is assigned one such a group; levels that are not known to belong to a band, labeled as "Non-band levels", are also plotted in vertical groups. The way these non-band levels are plotted is based solely on energy-spacing considerations to avoid overwriting, that is, there is no physics behind how these levels are grouped in vertical structures; a change of image size or energy limits will likely modify the way these levels appear plotted.
The first time the level scheme is plotted, all levels will be included. A form at the top of the plot can be used to replot with the following possibilities:
Levels with unknown value of absolute energy but with a known relative energy, for instance levels noted as X+500, are plotted at an arbitrarily choosen value of 200 keV from the ground state, i.e. X+500 will appear at 700 keV. Additionally, the neutron separation Energy (Sn) and the proton separation energy (Sp) are indicated in the level scheme.
Please, don't hesitate to email your comments
NuDat 2 database manager and web programming: Alejandro A. Sonzogni, NNDC, Brookhaven National Laboratory (email@example.com)