7.2+A+RADIOACTIVITY+-+PROPERTIES+OF+ALPHA,+BETA+AND+GAMMA

IB Physics > 7 Atomic and Nuclear Physics [|IB Physics Atomic and Nuclear Physics objectives in Word] - link to Google doc [|IB ATOMIC AND NUCLEAR PHYSICS DEFINITIONS AND CONCEPTS] - link to Google doc = This section is split into two here. = 7.2 B RADIOACTIVITY: EFFECTS, STABILITY AND HALF-LIFE
 * 1 Measure || 2 Mech || 3 Therm || 4 Waves || 5 Electric || 6 Fields || 7 Atomic || 8 EPCC || 9 MIF || 10 Therm AHL || 11 Wave Phen || 12 EMI || 13 QNP || 14 Digital || OPT || PRAC || REVISE ||
 * 7.1 ATOM || ** 7.2 RADIOACTIVE DECAY ** || 7.3 NUCLEAR REACTIONS ||

**7.2 A RADIOACTIVITY - PROPERTIES OF ALPHA, BETA AND GAMMA**
media type="custom" key="23175926" Vocabulary - these words are roughly equivalent in this topic: random = spontaneous; decay = disintegration; unstable = radioactive Also, before decay, nuclide is called PARENT, Afterwards, it is the DAUGHTER.

ACTIVITY: Here are links to simulations at the [|PHET] website. Play with them to see alpha and beta decays. ALPHA DECAY SIM LINK || media type="custom" key="23214406" BETA DECAY SIM LINK ||
 * media type="custom" key="23175620"

7.2.1 Describe the phenomenon of natural radioactive decay.

NATURAL RADIOACTIVE DECAY: A random and spontaneous process in which an unstable nucleus emits a particle (disintegration). The element of the nucleus changes. The emission of an alpha or beta particle or a gamma ray are the three possible processes. ALPHA PARTICLE: Consists of two protons and two neutrons (= helium nucleus). Has approximately 5 MeV kinetic energy. Travels at approx 5% speed of light. BETA MINUS PARTICLE: Consists of one electron, often travelling at close to the speed of light. They have a range of speeds and kinetic energies depending on the element and the anti-neutrino. BETA MINUS DECAY: In the nucleus, a neutron changes into a proton and an electron (which is emitted as a beta minus particle). ANTI-NEUTRINO: Particle emitted with beta minus particle.Carries away some of the kinetic energy. GAMMA RAY: High energy (also frequency) electromagnetic radiation emitted by nucleus following alpha and beta decay (which left the nucleus in an excited state).

ACTIVITY: See the general equations below. Write the alpha and beta decays here in a similar form. See example. Example:
 * [[image:Alpha decay 1.gif]] || [[image:beta 5.gif]] ||
 * [[image:alpha 3.gif]] || [[image:beta_decay 2.jpg width="329" height="164"]] ||
 * [[image:alpha_decay 4.gif]] || [[image:beta-minus_decay 1.gif]] ||
 * [[image:nothingnerdy/Alpha 2.gif width="294" height="209"]] || [[image:beta 3.gif width="313" height="279"]] ||
 * [[image:apha general equation.JPG width="241" height="231" caption="Alpha decay general equation"]] || [[image:beta minus general equation.gif width="344" height="91" caption="Beta minus decay general equation"]] ||

The inclusion of the anti-neutrino in β − decay is required.

7.2.2 Describe the properties of alpha (α) and beta (β) particles and gamma (γ) radiation. 7.2.3 Describe the ionizing properties of alpha (α) and beta (β) particles and gamma (γ) radiation IONISATION: Ionisation can be thought of as 'damage' to the medium the radiation is passing through. The greater the ionisation, the less the penetration into the medium, since the radiation more rapidly loses energy. Thus the most ionisation is by alpha and the least (almost none) by gamma.
 * || **KINETIC ENERGY** || **IONISING POWER** || **PENETRATION** ||
 * **ALPHA** || approx 5 MeV, the highest, so || it ionises 10 000 pairs in 1 cm of air || but is slowed down rapidly ||
 * **BETA** || typically 1 MeV || 100 pairs per cm of air || is slowed down less rapidly ||
 * **GAMMA** || no mass, so no KE || very little ionisation || very difficult to stop. ||

7.2 B - RADIOACTIVITY EFFECTS, STABILITY AND HALF-LIFE