Atomic Physics Flashcards
Nuclear fusion
- fusing two smaller nuclei together
- produces more energy than fission
- sun and stars
- need high pressure and temp
Nuclear fission
- split nucleus in half
- need neutron
- releases atleast 1 neutron
- can become chain reaction
Radioactive decay
Final amount=(1/2)^number decays(starting amount)
Alpha decay
-helium nucleus
-4
He
-2
Alpha decay properties
- highly ionisiing
- weakly penetrating
- stopped sheet of paper
- slightly deflected by electric and magnetic fields
Beta decay equation
-electron produced
A. A. 0
X ———-> Y. E
Z. Z+1. -1
Beta radiation properties
- moderately ionising
- moderately penetrating
- stopped thin sheet aluminium
- greatly deflected by electric and magnetic fields
Gamma radiation property
- lowly ionising
- highly penetrating
- stopped many cm of lead
- not deflected magnetic and electric field
Where does background radiation come from
- radioactivity of naturally occuring unstablee isotopes- air, food, building material, rocks
- radiation from space
- sun, cosmic rays, earths atmoosphere protects us from most of this
- human activity- fallout nucleur explosions, nuclear weapons- v small amount of background radiation
How to measure background radiation
-count rate when no radioactive sample is present using geiger-muller tube and counter
What must be ensured when calculating the count rate of radioactive sample
Minus background radiation
Smoke detectors
-long half lide alpha emitters used
-alpha particles cause current in the alarm
0if smoke enters detector, some of alpha particles are absorbed and current drops- triggering the alarm
Thickness monitoring
- long half life beta emmitters can be used for thickness monitoring of metal sheets
- source and reciever placed either side of sheet during production
- if drop or rise in no beta particles detected -thckness of sheet has been changed and need to be adjusted
Sterilisation of equipment
- gamma emmitters
- kill pathogens on equipment so safe for operations
Diagnosis and treatment
- short half life gamma emmitters used as traces in medicine as concentrate in certain parts of body
- half life must be long enough for diagnostic procedures to be performed
- but short enough that the sample does not remain radiioactive for too long
