Delayed Neutrons fromU235After Short Irradiation

The decay curve of the delayed neutrons from ${\mathrm{U}}^{235}$ after an approximately 10-millisecond irradiation is measured for times from 0.2 second to 10 minutes. This curve is resolved into 5 periods, and their relative intensities are determined. When the data are converted to the conventional case of infinite irradiation, we may represent the decay curve on a relative basis by the following formula where t is in seconds. $N\left(t\right)=0.076\mathrm{} \exp \left(\frac{-t}{0.52}\right)+0.279\mathrm{} \exp \left(\frac{-t}{2.5}\right)+0.279\mathrm{} \exp \left(\frac{-t}{7.9}\right)+0.294\mathrm{} \exp \left(\frac{-t}{32.4}\right)+0.054\mathrm{} \exp \left(\frac{-t}{79.9}\right).\mathrm{}$