Cross section for fast-neutron fission of 242mAm and angular distribution of fragments

The fission cross section of 242mAm and the angular distribution of the fragments were studied with an electrostatic accelerator over the neutron energy interval 0.16-1.6 MeV and also at 5 MeV. The cross section varies smoothly, having a value of 1.5 b at En > 1 MeV and increasing to 2.9 b at 0.16 MeV. The cross section of this nucleus, which has several exceptional properties, conforms to the systematics which relates the cross section exclusively to the A and Z values of the nuclei. This result confirms that the magnitude of the cross section for fast-neutron fission is not influenced by such nuclear properties as a large spin, the isomer state, a large cross section for thermal-neutron fission, and the presence of a long-lived fission isomer. As expected, the angular anisotropy of the fragments is extremely small because of the large nuclear spin (5-). This anisotropy is 2.3% at En < 1.5 MeV