sentences:  Also in 1937, Blau and Wambacher jointly discovered "disintegration stars" in photographic plates that had been exposed to cosmic radiation at an altitude of 2300 m above sea level.These stars are the patterns of particle tracks from nuclear reactions (spallation events) of cosmic-ray particles with nuclei of the photographic emulsion.After Blau had to leave Austria in 1938, Hertha Wambacher continued working on the identification of particles from nuclear reactions of cosmic rays with the emulsion constituents.