It has been possible to extend the usefulness of the rotating shutter mechanism of Fermi, Marshall, and Marshall for velocity selection of neutrons by increasing the number of photoelectrically activated gate circuits. With the modifications here described data can be obtained simultaneously in six well-resolved velocity intervals. In this way the cross sections of gold, gadolinium, and dysprosium have been measured as a function of velocity for low energy neutrons.

• Received 16 June 1947

DOI:https://doi.org/10.1103/PhysRev.72.585