An Experiment on The Time Variations of Cosmic Rays Underground
Ever since the discovery of cosmic rays, investigations of time variations in their intensity have been carried out in the hope of obtaining information on their nature and origin. Early experiments were somewhat contradictory, but it was soon clear that any variation present could be no longer than a few percent at the most. This meant that experiments had to be carefully planned and carried out over a long period of time to attain the statistical accuracy necessary for clear-cut results. In addition, the influence of the atmosphere and the earth's magnetic field made it very difficult to interpret the experiments in terms of properties of the primary radiation.