English: In 1937, Marietta Blau and Hertha Wambacher discovered nuclear disintegration stars (Zertrümmerungsterne) due to spallation in nuclear emulsions that had been exposed to cosmic radiation at a height of 2300m on the Hafelekarspitze above Innsbruck, Austria. 8 charged particle tracks are identified (diagram) from the disintegration of a Silver or Bromine nucleus; tracks moving at a steep angle w.r.t. the nuclear emulsion are less well focussed by the camera optics. Higher grain density = lower velocity, for equal electric charge.