Segrè's group set up its equipment in a disused Forest Service cabin in the Pajarito Canyon near Los Alamos in August 1943. His group's task was to measure and catalog the radioactivity of various fission products. An important line of research was determining the degree of isotope enrichment achieved with various samples of enriched uranium. Initially, the tests using mass spectrometry, used by Columbia University, and neutron assay, used by Berkeley, gave different results. Segrè studied Berkeley's results and could find no error, while Kenneth Bainbridge likewise found no fault with New York's. However, analysis of another sample showed close agreement. Higher rates of spontaneous fission were observed at Los Alamos, which Segrè's group concluded were due to cosmic rays, which were more prevalent at Los Alamos due to its high altitude.