Topic 10

Energy equivalent to mass deficit. The energy holding nucleons together to form a nucleus.

1u = 1.66 x 10^-27 kg

1u = 931.5 MeV

High Temperature - All nuclei have positive charge so need enough kinetic energy to overcome the repulsion between nuclei

High Pressure/Density -Nuclei need to get close enough for strong force to fuse so needs to be dense enough for nuclei to achieve high enough collision rate to start/maintain fusion reaction

Binding energy curve.

Fusion gains nucleons increasing binding energy so energy is released

Fission loses nucleons increasing binding energy so energy is released

GM tube not as efficient for gamma so placing tube on side increases count rate due to more area exposed

1. Fixed decay constant

2. Predictable pattern

3. Fraction of nuclei decaying in next second is same as decay constant

4. So number of nuclei decaying depends on number of unstable nuclei

5. Unstable nuclei decreases exponentially

6. Rate of decay decreases exponentially

Happens without external stimuli

Cannot predict when it will happen