Absorption of Slow Mesotrons in Lead, Iron, Aluminum, and Water

Abstract

The absorption of slow mesotrons in lead, iron, aluminum, and water was measured by means of counters arranged in anticoincidence. In all cases, the statistical error in the number of mesotrons stopped by the absorbing layers was less than 3 percent. This accuracy was made possible by the high efficiency (about 99 percent) of the anticoincidence group of counters. The values obtained for the relative absorptions in the different substances were compared with those calculated from the theory of energy losses by collision. As is well known, the theory predicts a smaller absorption in heavier elements for a given superficial mass. The uncorrected experimental values did not agree with the theory. However, by taking into account the effect of scattering, which is of particular importance in heavy elements, the experimental data were brought into satisfactory agreement with the theory. For water, no reliable theoretical value could be calculated.