E.3 Radioactive decay HL Flashcards
What evidence do we have for discrete nuclear energy levels?
Specific energies of alpha and gamma radiation suggest nuclei have quantized energy states. For example, gamma ray spectra from nuclear transitions show distinct energy lines, not a continuum.
Why was the neutrino proposed in physics?
To conserve energy in beta decay, accounting for the missing energy not carried by the electron alone. It shares the decay energy, explaining the continuous energy spectrum of beta particles.
How is Technetium-99m used in medicine and why is it ideal?
As a tracer for diagnosing organ function because its 6-hour half-life and gamma radiation make it detectable yet relatively safe for patients, minimizing radiation exposure.
Explain the role of conservation of energy in beta decay discoveries.
It led to identifying the neutrino, ensuring energy, momentum, and spin conservation laws are upheld in nuclear reactions, solving the beta decay energy distribution puzzle.
What does a gamma camera do, and how does it contribute to medicine?
Creates images from gamma radiation emitted by tracers within the body, offering insights into organ and tissue function, crucial for diagnosing diseases like cancer.
How does the decay constant (λ) relate to a nucleus’s stability?
It indicates decay probability per unit time. A high λ means rapid decay, reflecting low stability. This constant helps predict how long a radioactive substance will remain active.
Describe the radioactive decay law’s formula and its significance
showing how the quantity of undecayed nuclei decreases exponentially over time. It’s crucial for understanding the predictability of radioactive substances’ behavior.
What is activity (A) in the context of radioactive decay, and how is it calculated?
It’s the decay rate, calculated by A=λN. This measures how fast a radioactive sample loses its nuclei, helping gauge its radiation hazard.
How do half-life and decay constant interrelate?
Through T_1/2 = ln(2)/λ showing that as the decay constant increases, indicating faster decay, the half-life decreases, meaning the substance becomes stable quicker.
Where else can we apply the exponential decay model outside nuclear physics?
In processes like population decline or the concentration decrease in a chemical reaction, illustrating its broad applicability in modeling phenomena that decrease over time.
