Screenshot and information provided by Peter Biryukov.

The investigation of hadron properties inside nuclear matter at normal and high densities and temperatures is one of the main goals of current nuclear physics studies. Hadron induced reactions on heavy nuclei (e.g., Au, Pb) are the proper tool to probe particle properties in long-living ground state nuclear matter. Heavy ion collisions at energies of 1-2 GeV per nucleon can be used to create a reaction region of increased density for as long as 10 fm/c. Under these conditions, considerable modifications of basic hadron properties (masses, decay widths, etc.) are expected and probably can be verified for the first time experimentally by high-resolution lepton pair decay measurements.

In order to investigate this phenomenon, the new electron-positron pair spectrometer HADES (High Acceptance Di-Electron Spectrometer) is set up at the Gesellschaft für Schwerionenforschung mbH, Darmstadt, Germany (GSI) by an international collaboration of 19 institutions from 9 European countries.

To visualize data from HADES, Laboratory of Information Technologies, JINR, Dubna, Russia; and GSI created the HADES Event Display tool.  The Event Display provides facilities for visually inspecting dependencies between data from different detectors.  It may also be used during experiments to visually check proper operation of the various detectors in the system.

When the software architects responsible for the Event Display evaluated tools to use, they early on decided on tools that are licensed as Free Software, but have the productivity gains and quality that typically come with extensive use in demanding, commercial customer organizations.  They ended up using Coin (which is released under GPL, and which offers significant productivity gains over OpenGL) in combination with Qt (which is also released under GPL, and which in the same way offers significant productivity gains over Motif). Says Peter Biryukov, one of the key software programmers behind the Event Display, about his design choice: 

“We have used Coin for visualization in HADES Event Display to create complex, interactive 3D scenes that contain large amount of different items, and in which many of the items should react to user activity.  We found it helpful that Coin has tools to handle complex, heterogeneous scenes and provides easy and comfortable way to access every part of scene. We recommend it to any organization with a need for 3D graphics in their projects, both free and commercial.  In my opinion Coin 3D is well suited to acquaint students with modern use of computer graphics.”

In fact, Peter’s story is not unique.  There are many, many academic projects at great research institutions worldwide that have ended up with a combination of Coin and Qt for various combinations of the following advantages:

• significant productivity gains relative to lower-level and/or less modern tools
• full cross-platform capability for Unix, Linux, Windows, and Mac OS X (write once, compile everywhere)
• access to the source code
• appropriate licensing model
• large and tightly knit user community within academia

Some of these projects use the GPL license, others have opted to join our educational program, in which eligible institutions get proprietary licenses, with our standard commercial support package, at a significant academic/educational discount.