5.2.1 Detection of radioactivity

CORE OBJECTIVES:

• Know what is meant by background radiation
• Know the sources that make a significant contribution to background radiation including:
• (a) radon gas (in the air)
• (b) rocks and buildings
• (c) food and drink
• (d) cosmic rays
•  Know that ionising nuclear radiation can be measured using a detector connected to a counter
•  Use count rate measured in counts/s or counts/minute Supplement 5 Use measurements of background radiation to determine a corrected count rate

5.2.2 The three types of nuclear emission

CORE OBJECTIVES:

• Describe the emission of radiation from a nucleus as spontaneous and random in direction
•  Identify alpha (?), beta (?) and gamma (?) emissions from the nucleus by recalling:
• (a) their nature
• (b) their relative ionising effects
• (c) their relative penetrating abilities (?+ are not included, ?-particles will be taken to refer to ?– )

EXTENDED/SUPPLEMENT OBJECTIVES:

•  Describe the deflection of ?-particles, ?-particles and ?-radiation in electric fields and magnetic fields
•  Explain their relative ionising effects with reference to: (a) kinetic energy (b) electric charge5.2.3 Radioactive decay

CORE OBJECTIVES:

• Know that radioactive decay is a change in an unstable nucleus that can result in the emission of ?-particles or ?-particles and/or ?-radiation and know that these changes are spontaneous and random
•  State that during ?-decay or ?-decay, the nucleus changes to that of a different element

EXTENDED/SUPPLEMENT OBJECTIVES:

• Know that isotopes of an element may be radioactive due to an excess of neutrons in the nucleus and/or the nucleus being too heavy
•  Describe the effect of ?-decay, ?-decay and ?-emissions on the nucleus, including an increase in stability and a reduction in the number of excess neutrons; the following change in the nucleus occurs during ?-emission neutron ? proton + electron
•  Use decay equations, using nuclide notation, to show the emission of ?-particles, ?-particles and ?-radiation

5.2.4 Half-life

CORE OBJECTIVES:

• Define the half-life of a particular isotope as the time taken for half the nuclei of that isotope in any sample to decay; recall and use this definition in simple calculations, which might involve information in tables or decay curves (calculations will not include background radiation)

EXTENDED/SUPPLEMENT OBJECTIVES:

• Calculate half-life from data or decay curves from which background radiation has not been subtracted
•  Explain how the type of radiation emitted and the half-life of an isotope determine which isotope is used for applications including:
• (a) household fire
• (smoke) alarms
• (b) irradiating food to kill bacteria
• (c) sterilisation of equipment using gamma rays
• (d) measuring and controlling thicknesses of materials with the choice of radiations used linked to penetration and absorption
• (e) diagnosis and treatment of cancer using gamma rays

.5.2.5 Safety precautions

CORE OBJECTIVES:

• State the effects of ionising nuclear radiations on living things, including cell death, mutations and cancer
•  Describe how radioactive materials are moved, used and stored in a safe way

EXTENDED/SUPPLEMENT OBJECTIVES:

• Explain safety precautions for all ionising radiation in terms of reducing exposure time, increasing distance between source and living tissue and using shielding to absorb radiation