Physics Reviews (A level)

Rutherford scattering  discovered alpha, beta, gamma. They put the 3 radiations through a magnetic field, and because α and β are oppositely charged they curved in separate directions. Gamma was unaffected (uncharged).

Thomson Plum pudding, nucleus Rutherford gold leaf.

αβγ properties.

tests.

γ intensity over range decreases by inverse square law.

I=k/x²

x is distance away from source

k=nhf/4π

intensity is radiation energy per sec/area

Ionising radiation is dangerous 😱

-damages cells, DNA, affects cell division

-Monitor dose (energy per mass)

-film badge monitors dose- has strips of material, shows radiation exposure

Background radiation

-radon

-medical

-rocks

-food

-cosmic rays

Storage

-locked lead-lined boxes, reduces radiation

-sealed containers, can't be breathed in

Usage

-don't touch skin

-far from body as poss (tongs, gloves)

-lower exposure

Decay

half-life- time for a source mass to half

Activity- num of nuclei to decay per sec, Bq

λ- prob of nucleus decaying per sec

T=ln2/λ. This comes from the decay equation, as -ln(½)=ln2

A=λN

N=num of nuclei

Dating

Carbon has long half life

Tracers

Nuclear instability

A daughter nucleus can form in an excited state, this is short-lived, moves to lower energy state, emits photon. Metastable- stays in excited state for longer, then emits gamma.

Fission, large unstable nucleus splits after collision with thermal, slow neutron.

Moderator- slows down neutrons (moderates them)

Control rods- absorbs spare neutrons (controls the fission reaction). Can be lowered or risen to absorb more or less neutrons.

Coolant- absorbs excess heat energy, controls fission

Concrete, kept away,