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FIZIKA Nuclear radiation. FIZIKA 2 Radioactivity Dr. Seres István Helium nucleus: 2 proton + 2 neutron Components of the nucleus:

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Presentation on theme: "FIZIKA Nuclear radiation. FIZIKA 2 Radioactivity Dr. Seres István Helium nucleus: 2 proton + 2 neutron Components of the nucleus:"— Presentation transcript:

1 FIZIKA Nuclear radiation

2 FIZIKA 2 Radioactivity Dr. Seres István Helium nucleus: 2 proton + 2 neutron Components of the nucleus:

3 FIZIKA 3 Radioactivity Dr. Seres István Components of the nucleus: Isotopes: same atomic number, dfferent mass number Eg. hydrogen isotopes: - normal hydrogen isotope - deuterium - tricium Eg. carbon: stabil isotope, radioactive isotope Eg. uranium:, radioactive isotopes

4 FIZIKA 4 Radioactivity Dr. Seres István Helium nucleus (  particle): 2 protons + 2 neutrons Mass - defects: m  = 6,6447· kg, m p = 1,6727· kg, m n = 1,6749· kg, Nuclear binding energy

5 FIZIKA 5 Radioactivity Dr. Seres István Mass-defect: Einstein principle on matter and energy: Binding energy:  = mc 2 = -5· ·(3·10 8 ) 2  = 4,5· J = 2,8·10 7 eV = 28 MeV· (1 eV = 1,6· J) The mass is converted to energy = -5· kg Nuclear binding energy

6 FIZIKA 6 Radioactivity Dr. Seres István Nuclear physics Nuclear binding energy: Specific binding energy :

7 FIZIKA 7 Radioactivity Dr. Seres István Nuclear physics Radioactive decay, fission fusion Specific binding energy (MeV) Mass number (A)

8 FIZIKA 8 Radioactivity Dr. Seres István Radioactive decay Law of radioactivity N N0N0 N 0 /2 T 2T N 0 /4 T – half period

9 FIZIKA 9 Radioactivity Dr. Seres István Radioactivity Radiocarbon dating (C 14 ) Examination of metabolism of plants, animals Pharaos, Shroud of Turin

10 FIZIKA 10 Radioactivity Dr. Seres István Aktivity Number of radioactive decay per seconds. SI Unit Bq (Becquerel).

11 FIZIKA 11 Radioactivity Dr. Seres István Dozimetry  Absorbed dose: (D) (the absorbed radiative energy by a unit mass) SI unit Gray =J/kg

12 FIZIKA 12 Radioactivity Dr. Seres István  alfa radiation (helium nucleus)  beta radiation (electron / pozitron)  gamma radiation (elektromagnetic)

13 FIZIKA 13 Radioactivity Dr. Seres István Dozimetry  Dose equivalent (biological dose) H=D·RBE, where RBE= radiobiological equivalent SI unit: Sievert Type and Energy RangeRadiation Weighting Factors X and Gamma rays1 Electrons1 Neutrons (energy dependent)5-20 Protons5 Alpha Particles20

14 FIZIKA 14 Radioactivity Dr. Seres István Dozimetry Background radiation The average natural backround radiation is about 1.8 mSv/year + artificial components, - mainly medical imaging (X-ray) and therapy – an average of 0.4 mSv/year, alltogether maximum about 2,5 mSv/year. The miain components of the background radiation: radon in closed buildings (about 0.5 mSv/year), raditaions from the buildings (about 0.4 mSv/year), cosmical radiation (about 0.3 mSv/year), Calium from our own body (about 0.2 mSv/year)

15 FIZIKA 15 Radioactivity Dr. Seres István Dozimetry Background radiation

16 FIZIKA 16 Radioactivity Dr. Seres István Dozimetry Background Radiation For the professionals working with isotopes (doctors, researchers, etc.) the limit is 25 times bigger than the average background radiation (maximum 50 mSv/year), this is called as dose limit. The dose limit for the population is the double of the average background radiation, such as maximum 5 mSv/year. Lethal Dose : LD 50/30 = 4 – 5 Sv (50% of the people dies without treatment within 30 days

17 FIZIKA 17 Radioactivity Dr. Seres István Dozimetry Background radiation radon Fresh air8 Bq/m 3Bq Flats in tropic areas20 Bq/m 3 Drafty room30 Bq/m 3 Flat (worlds average)40 Bq/m 3 Room without ventilation100 Bq/m 3 Hungarian village house130 Bq/m 3 Cellar250 Bq/m 3 Flat in radon areas1000 Bq/m 3 Mine (in vulcanic areas) Bq/m 3

18 FIZIKA 18 Radioactivity Dr. Seres István Dozimetry USA37 Bq/m 3Bq Finland90 Bq/m 3 France62 Bq/m 3 Indonesia12 Bq/m 3 Japan29 Bq/m 3 Hungary55 Bq/m 3 Germany49 Bq/m 3 Sveden108 Bq/m 3 Siria20 Bq/m 3 40 Bq/m 3 activity concentartion is equivalent to about 1mSv/year dose. Background radiation radon

19 FIZIKA 19 Radioactivity Dr. Seres István Detecting of nuclear radiation  Cloud chamber

20 FIZIKA 20 Radioactivity Dr. Seres István  Cloud chamber (Paks, Nuclear Power Plant, Visitor Centre) Detecting of nuclear radiation

21 FIZIKA 21 Radioactivity Dr. Seres István Filmdozimeter (staff – doctors, Y-Ray staff) Detecting of nuclear radiation

22 FIZIKA 22 Radioactivity Dr. Seres István Geiger Müller counter (GM tube) Detecting of nuclear radiation


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