applications of nuclear physics chp 43.5 – 43.7. biological effects of radiation applications to...

Applications of Nuclear Physics

Chp 43.5 – 43.7

• Biological Effects of Radiation• Applications to Astrophysics• Nuclear Power

Medical Applications of Nuclear Energy

The Strange Tale of Alexander Litvenenko• Former KGB agent and

political “whistle blower” became suddenly ill on November 1, 2006 following a restaurant meeting with a Russian “agent”

• Died three weeks later. He is believed to be the first confirmed case of deliberate 210Po radiation poisoning

• It has been suggested that as little as 10 g of Polonium was put in his tea – this would be a fatal dose!

Alexander Litvenenko (1962-2006)

The “perfect assassin”

• Po is readily available and essentially un-regulated in small amounts

• Po half-life is 138.4 d; EK = 5.41 MeV

• Is an alpha-emitter: Easy to transport safely and lethal if ingested

• Does NOT emit gamma rays!• Completely tasteless in quantities that would be lethal• It is estimate that 1 g of Po introduced to an urban water

supply could poison 20 million people with 10 million fatalities.

“Back of the envelope…”• Assume it concentrates in the liver

– Calculate the radiation exposure this represents

• Ideas we need:– Units of radiation exposure:

• Activity = Bq• Absorbed dose = Gray = Gy = 1.00

J/kg (=100 rad)• Relative biological effectiveness =

RBE• REM = rad X RBE• Dose equivalent = absorbed dose

X RBE in Sieverts = Sv (an older unit is the REM = 0.010 Sv)

Dose (REM)

Effect

> 1000 Death in a few days

100 - 1000 Death in a few weeks

50 High probability of cancer in next 30 years

Type RBE

10-20

1-2

1

Older terms

• The Roentgen = amount of ionizing radiation producing 0.3 nC in 1 cc of air

• 1 rad = amount of radiation which would deposit 0.01J/kg in any material

• SI unit is the GRAY = 100 rad• When considering biological effects the REM is

often used = rad X RBE

Fukushima

• Major radio nuclides being released are 137Cs (t1/2 = 30 a) and 131I (t1/2 = 8 d)

• A core breach exposes fuel rods

• Iodine concentrates in thyroid, Cs concentrates in muscle throughout body

Positron Emission Tomography

• fluorodeoxyglucose (FDG), C6H11FO5 is a sugar that is commonly used in nuclear medicine

• The fluorine atom is labeled – instead of “normal” F, it is

• This decays via a + process – write the equation for this and predict the final product

• The positron emitted doesn’t get far!

18

9F

Conservation Laws make this all possible!

Stellar Structure and Evolution

• Hydrogen fusion in Solar Mass stars – the proton-proton cycle– 4 1H 4He

• CNO cycle in higher mass stars

(link to astronomy notes)

Back of the envelope…

• Sun emits 3.99 x 1026 J/s• PP-chain fusion reaction releases about 25

MeV• Solar Mass is 1.99 x 1030 kg

• From this we can estimate the life expectancy of the Sun!

Supernovae and Nucleosynthesis

• Recall the binding energy curve…

Eb(MeV) per Nucleon

7.000

7.100

7.200

7.300

7.400

7.500

7.600

7.700

7.800

7.900

8.000

70 75 80 85 90 95

Z

Eb

(M

eV)

(link to astronomy notes)

• Questions to work on…

• You are 1m from a 1 kg lump of pure radium!– What kind of radiation are you likely going to be

exposed to?– Estimate the exposure you will receive in REM

over 1 hour– What is your “prognosis”?