Chart of Nuclides

NOTE: This is early in development, expect some issues...

An offline viewer of isotope and nuclear structure data, presented in the familiar Chart of Nuclides / Segrè chart format. The data comes from various sources, most notably ENSDF. The UI is implemented in SDL (so you can browse nuclear half-lives using some of the same code that powers Half-Life).

The goal is to develop a simple, performant, and multiplatform tool that will be useful in both professional (nuclear structure research) and educational contexts.

Features

• Display nuclear chart with various color schemes: half-life/lifetime, E(2+)...
• Select individual nuclides to browse ground and excited state data, including:
  • Level energies, half-lives/lifetimes, decay modes, spin-parities...
  • Gamma energies, branching fractions, multipolarities...
• Runs locally, with no network connection needed.
• Fast hardware accelerated rendering using SDL_Renderer, HI-DPI scaling support.
• More to come...

Building and installing from source

The current version has been tested under Arch Linux and Debian 12 as of August 2024. In principle most other recent Linux distros should work as well. The plan is to eventually support other platforms (Windows especially) once a stable SDL3 release is available.

Build dependencies

• C compiler: gcc (or clang)
• GNU make
• SDL3, SDL3_image, SDL3_ttf
  • SDL3 should be built with libdecor on Linux when using GNOME Wayland, as discussed below.

For now you'll probably have to manually compile SDL3 and its libraries, as they aren't (yet) packaged for major Linux distros.

Build the application

Install all build dependencies listed above, then build the application binaries using make (from the source tree root directory):

# using gcc:
make all -j
# alternatively, using clang:
make all -j CC=clang

Two executables will be built: proc_data (which generates the data package containing the nuclear structure database used by the main application), and con (the main application). Build the data files if necessary, then run the application:

./con

To install the application for all users, on a Linux system:

sudo make install-linux

Have fun!

Build data files

In order for the application to run, it requires a data file (con.dat) containing the nuclear structure database and graphics/font resources. The application will look for the data file in any of the following locations (in order of preference):

Location Name	Path
User-specific data path	~/.local/share/con/ (Linux)
Executable directory	The same directory that the executable was run from.
System-wide data path	/usr/share/con/ (Linux)

If you don't have the con.dat data file, it can be built from the original data files using the proc_data program (built during the previous step). First you must obtain the required data files:

Data	Source location	Instructions
Nuclear structure data	ENSDF	Download the zip archive from the link in the 'Latest Dataset' section. Unzip it in the source tree into the directory data/ensdf/ (such that the ensdf subdirectory contains the files ensdf.001, ensdf.002, etc.).
Isotope abundance data	NIST	Under 'Search the Database', select 'All Elements', output type 'Linearized ASCII Output', with the option 'Most common isotopes'. Select 'Get Data'. Copy the resulting plaintext data into a text file, save the text file in the source tree under data/abundances.txt.

Once the data files are properly set up, run:

./proc_data

This will build the data package file con.dat in the same directory (you can then get rid of the original data files if you don't want them anymore).

Using the program

Zoom and pan with the mouse, the controls are basically identical to Google Maps.

Keyboard shortcuts

Key	Action
Arrow keys	Pan chart view
W / A / S / D	Pan selected nuclide (in chart and level list views)
+ / -	Zoom in/out on chart
] / [	Cycle between view modes for the chart (half-life, 2+ energy, etc.)
F7 / F8	Adjust user interface size
Enter	Show full list of levels/gammas for selected nuclide
Escape / backspace	Exit out of open menus, cancel selection, etc.
F11	Toggle fullscreen mode
P	Toggle performance stats debug overlay

Troubleshooting

The application window has no titlebar on Linux

You're probably running the application on GNOME Wayland without libdecor support. GNOME won't automatically draw window decorations for apps and mandates that they draw their own decorations instead, perhaps because they enjoy making life more difficult for their app developers and users. You'll have to either install libdecor (libdecor-0-dev on Debian) and rebuild SDL3, or run the application in X11 mode (at the cost of potential input and display latency) by setting the environment variable:

SDL_VIDEO_DRIVER=x11

Disclaimer

The author(s) make no guarantee of the accuracy or completeness of the information provided. As stated in the license, this program is provided without any warranty. Please file a bug report if you spot any inaccuracies (eg. the data reported by the program differs from the source ENSDF/NIST data). Some inaccuracies are likely, since the program remains in active development.

Credits

Developed and maintained by Jonathan Williams.

A slightly modified version of the SDL_FontCache library by Jonathan Dearborn is used for fast text rendering.

The font used in this program (data/font.ttf) is a modified version of Oxygen with some additional unicode glyphs from Noto Sans. Both fonts are made available under the Open Font License (as described here and here).