Understanding Alpha Decay
Alpha decay is a type of radioactive decay in which an unstable nucleus emits an alpha particle (consisting of 2 protons and 2 neutrons). The process results in a new nucleus and the release of energy.
Given Data
- Mass number of element X (A) = 220
- Q value of the reaction = 5.5 MeV
Alpha Decay Reaction
The alpha decay of element X can be represented as:
X (A=220) → Y (A=216) + α (alpha particle)
This reaction indicates that the original nucleus loses an alpha particle, resulting in a new nucleus Y with a reduced mass number.
Q Value Explanation
The Q value represents the total energy released during the decay process. It is the difference in mass-energy between the parent nucleus and the sum of the mass-energy of the daughter nucleus and the emitted alpha particle.
Kinetic Energy Distribution
The Q value is shared between the kinetic energies of the daughter nucleus (Y) and the emitted alpha particle (α). In most cases, the alpha particle carries away a significant portion of this energy due to its much smaller mass compared to the daughter nucleus.
Calculating Kinetic Energy of Alpha Particle
In a typical alpha decay:
- The kinetic energy of the alpha particle (Tα) is approximately equal to the Q value.
- The kinetic energy of the daughter nucleus (TY) is relatively small due to its larger mass.
Given that the Q value is 5.5 MeV, we can assume:
- Tα ≈ Q = 5.5 MeV
Conclusion
Thus, the kinetic energy of the emitted alpha particle is approximately 5.5 MeV. This indicates that the alpha particle retains most of the energy released during the decay process.