Nuclear Physics Flashcards
Explain:
Scattering of Alpha Particles
When alpha particles are directed at a thin metal sheet, most pass straight through, while some are deflected at various angles.
Explain:
Nuclear Fission and Fusion
- Nuclear fission involves the splitting of a heavy nucleus into two or more lighter nuclei, accompanied by the release of energy and usually some neutrons. This process is used in nuclear reactors and atomic bombs.
- Nuclear fusion involves the joining of two lighter nuclei to form a heavier nucleus, releasing a large amount of energy. This process powers the sun and other stars.
Explain:
Background Radiation:
Background radiation refers to the ionizing radiation that is present in the environment at all times, originating from various natural and artificial sources.
Explain:
Measurement of Background Radiation:
- Ionizing nuclear radiation can be measured using a detector connected to a counter.
- The count rate, measured in counts per second (counts/s) or counts per minute (counts/min), indicates the rate at which radiation is detected.
Explain:
Correction of Count Rate:
Measurements of background radiation are used to determine a corrected count rate by subtracting the background count rate from the total count rate obtained during an experiment or observation.
Explain:
Relative Ionizing Effects:
- Kinetic Energy: Alpha particles have the highest kinetic energy among the three and transfer more energy to the atoms they interact with, causing more ionization. Beta particles have intermediate kinetic energy, while gamma radiation has the highest energy but interacts less frequently due to its electromagnetic nature.
- Electric Charge: Alpha particles have a double positive charge, leading to strong interactions and high ionization. Beta particles have a single negative (or positive in the case of β+) charge, resulting in less interaction and lower ionization compared to alpha particles. Gamma radiation is uncharged and interacts weakly, causing minimal ionization.
Explain:
Radioactive Decay
- Radioactive decay involves the spontaneous and random change in an unstable nucleus, resulting in the emission of α-particles, β-particles, and/or γ-radiation.
- During α-decay or β-decay, the nucleus transforms into that of a different element.
Explain:
Half - Life
- The half-life of a particular isotope is defined as the time taken for half of the nuclei of that isotope in any sample to decay. It represents the rate at which radioactive nuclei decay.
- For example, if the half-life of a radioactive isotope is 10 days, it means that after 10 days, half of the radioactive nuclei in the sample will have decayed.
- Half-life can be calculated from data or decay curves without background radiation subtraction. This involves analyzing the decay curve to determine the time it takes for the activity (number of decays per unit time) to decrease to half its initial value.
Explain:
The type of radiation emitted and the half-life of an isotope determine its applications:
- (a) Household fire alarms use isotopes with short half-lives that emit α-particles to detect smoke particles.
- (b) Irradiating food to kill bacteria uses isotopes with short half-lives and suitable penetrating radiation, such as γ-rays.
- (c) Sterilization of equipment uses γ-rays with longer half-lives to ensure thorough sterilization.
- (d) Measuring and controlling thicknesses of materials utilize isotopes with appropriate penetrating ability and half-lives.
- (e) Diagnosis and treatment of cancer use γ-rays due to their ability to penetrate tissue, with isotopes selected based on their half-life and emission properties.
Identification of Alpha (α)
Alpha (α) particles consist of two protons and two neutrons, essentially a helium nucleus.
Identification of Beta (β)
Beta (β) particles are high-energy electrons (β-) or positrons (β+).
Identification of Gamma (γ)
Gamma (γ) radiation consists of electromagnetic waves of very high frequency and energy.
