In the days after returning from the Balloon Launch facility in Texas, the RET teachers took a preliminary look at a few of the particle events recorded by the GLAST detectors while aloft on the balloon in the high stratosphere. We'd like to thank the SCIPP Faculty for the crash course in particle physics and detector design which made it possible for us to guess what these events might represent. Of course, they bear no responsibility for any errors or outright blunders in what follows: five armchair physicists' speculations on a few of the things GLAST might have been seeing up there.

This set of pictures represents the traces of a single particle passing through the GLAST detection tower. The perspective drawing on the left is repeated from several angles in the rectilinear diagrams on the right.

In all the drawings, the blue-bordered region contains many layers of silicon detectors sandwiched between layers of lead. The black shapes within this regions shows which silicon detectors fired during the event.

The red-bordered region is a calorimeter, where particles deposit their energy once they've passed through the silicon layers. The rectangles within this region show where energy was deposited, and in what amounts. (Larger rectangles mean more energy.) Note that in this case, we can't tell the total energy of the incoming particle, since one of the daughter tracks escaped out the side of the detector without entering the calorimeter.

The black panels surrouinding the detector and calorimeters are ACDs, or anti-coincidence detectors. They are far more sensitive to charged particles than to gamma rays, so if any ACD fires as a particle enters the detector tower, then that particle was in all probability not a gamma ray, and the event is discarded. In the event shown here, one of the ACD's bordering the top half of the detector fired. (The ones which do not fire during a given event are not displayed in the diagram.) Thus, the tracks in the silicon were left by an ordinary cosmic ray, not by a gamma ray.

To see some more events, and read the Team's amateur assessment of what sorts of particles they seem to represent, click any of the links below...