20.4 Measurements of the fast neutron cycle time were made on EBR-I, the first reactor to pro- duce electricity. Calculate its value in two different ways: (a) With the ratio Br/l, called the Rossi-a, with a value of 1.74 x 105/s and r of 0.0068; (b) With a rough formula =1/(v) with an average energy of 500 keV neutrons. At that energy, 6=0.12 barn and of 0.62 barn. Note Nu=0.054 x 1024/cm, and v=2200 m/s for E=0.0253 eV.