When evaluating the quality of a design for an ILC detector, scientists use a large suite of advanced, custom-built computer programs. Event generators simulate the interactions of an electron-position collision and the resulting cascade of particle decays, which end in the stable particles that can be measured by an ILC detector. Some event generators are simple extrapolations of physics that is well understood at lower energies, while other event generators describe the predicted production and decay dynamics of hitherto unobserved particles. Detector simulation programs compute the response of a proposed detector to the stable particles that travel through it. The ultimate output of a detector simulation program is simulated data, which looks almost exactly like that from a real detector. Reconstruction programs sort through the output of simulation programs to untangle the direction, energy and species of the stable particles that traversed the detector. These reconstruction programs will eventually do the same job on data from an ILC detector. Calibration programs look for the subset of electron-positron interactions that produce only well understood processes and use these interactions to fine-tune the simulation and reconstruction programs. Finally, physics analysis programs look at correlations among the measured particles found by the reconstruction programs. Among those correlations scientists hope to find evidence for new and exciting particles that solve the outstanding riddles in high energy physics.
As the results of tests of prototypes become available, as the understanding of background processes is improved, and as results from other accelerators guide the expectations for what will be observed at the ILC, new ideas for improved detectors will emerge. These simulation programs are constantly updated to incorporate progress in detector technology as well as physics understanding to improve the detector designs.
Fermilab has a team of people working, with other scientists from around the world, to develop these software tools and to use it to perform simulated physics analysis of benchmark processes.
Detailed information on ILC detector simulation and reconstruction software and on how to contribute to the development effort is also available.