Collection of data from the Trinity Test, the world's first detonation of a nuclear weapon, conducted on July 16th 1945 in the Jornada del Muerto in New Mexico; this is one of two barrage balloons used to carry special cameras aloft for the duration of the test. These instruments recorded the neutron flux above the ground as a function of time. A burst of neutrons is released by the nuclear chain reaction which produces the explosion. Hence study of this flux provides information about the extent of the reaction. The test involved the Fat Man" atomic fission bomb of the type later used to destroy Nagasaki, Japan."