The neutron capture cross section of ${\mathrm{Pa}}^{231}$ has been determined to be 293 barns, the largest uncertainty in this determination being due to the uncertainty in the half-life of ${\mathrm{U}}^{232}$ and being of the order of 15 percent.

The neutron capture cross section of ${\mathrm{Pa}}^{232}$ was determined to be about $40\left(\{+40\mathrm{}\}\{-20\mathrm{}\}\right)$ barns.

• Received 3 December 1952

DOI:https://doi.org/10.1103/PhysRev.90.102