1. RADIOACTIVE DECAY Preliminary information:
--alpha decay ejects a He nuclei
--when an nucleus emits an alpha particles, the atomic number goes down by two (two fewer protons) while its atomic mass goes down by four (two neutrons, two protons)
--beta decay produces high energy electrons--these are ejected when one neutron in a nucleus turns itself into a proton (and electron, which gets emitted)
--when an nucleus emits a beta particles, the atomic number goes up by one (one more proton than before) while its atomic mass stays the same
--gamma decay produces a high energy photon
--when an atomic nucleus is “excited” (same as when an atom is excited), the nucleus will de-excite by emitting a photon in the keV to MeV range

2. FISSION
--U-238 is a non-fissionable form of uranium--it is also the most common form of uranium
--U-235 is a fissionable material
--in being fissionable, a neutron that strikes U-235 can make the atom elongate and split (why will it split if elongated?)
--the reaction looks like 1
235 91
142 1 n U Kr Ba 3
( n) 92 36 56
--in other words, with fusion diminishing at the core, the star gets brighter

3. --a TNT reaction produces 30 eV’s worth of energy
--a typical fission reaction produces 200,000,000 eV’s worth of energy
--when critical mass is generated, every fission reaction that occurs will spawn one other reaction
--when super critical mass is generated, every fission reaction produces multiple reactions and energy is released
--Enrico Fermi, on Dec. 2, 1942, generated the first controlled fission reaction in the world on a squash court located underneath Stagg Field at the University of Chicago
--in other words, with fusion diminishing at the core, the star gets brighter

4. -plutonium is more fissionable than U-235
--to produce plutonium
--make a U-238 atom absorb a neutron making U-239
--U-239 has a half-life of 24 minutes--it goes through beta decay producing Np-239
--Np-239 has a half-life of 2.3 days--it also goes through beta decay producing Pu-239
--Pu-239 has a half-life of 24,000 years and is more fissionable than U-235
--in other words, with fusion diminishing at the core, the star gets brighter