fizika nuclear radiation. fizika 2 radioactivity dr. seres istván [email protected] helium...

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Nuclear radiation

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Radioactivity

Dr. Seres István [email protected]

Helium nucleus: 2 proton + 2 neutron

neutrons protons of umerlntotanumber mass -A 4Aprotons ofnumber number atomic - Z2ZHe

42He

Components of the nucleus:

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Radioactivity


Components of the nucleus:

Isotopes: same atomic number, dfferent mass number

Eg. hydrogen isotopes: - normal hydrogen isotope

- deuterium

- tricium 31

21

11

H

H

H

126CEg. carbon: stabil isotope, radioactive isotope14

6C

23592UEg. uranium: , radioactive isotopes238

92U

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Radioactivity


Helium nucleus ( particle): 2 protons + 2 neutrons

Mass - defects:

m = 6,6447·10-27 kg,mp = 1,6727·10-27 kg,mn = 1,6749·10-27 kg,

Nuclear binding energy

)m2m2(mm np

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Mass-defect:

)m2m2(mm np

Einstein principle on matter and energy:

Binding energy:

= mc2 = -5·10-29·(3·108)2

= 4,5·10-12 J = 2,8·107 eV = 28 MeV·(1 eV = 1,6·10-19 J)

The mass is converted to energy

= -5·10-29 kg

Nuclear binding energy

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Nuclear physics

Nuclear binding energy:

2npX

2 c)m)ZA(mZ(mcm

AZX

Specific binding energy :A

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Nuclear physics

A

Radioactive decay, fissionfusi

on

Spe

cific

bin

ding

ene

rgy

(MeV

)Mass number (A)

-1-2-3-4-5-6-7-8-9

0 20 40 60 80 100 120 140 160 180 200 220 240

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Radioactivity


Radioactive decay

N~dt

dN

T

t

0 2N)t(N

Law of radioactivityN

N0

N0/2

T 2T

N0/4T – half period

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Radioactivity


Radioactivity

•Radiocarbon dating (C14)

Examination of metabolism of plants, animals

http://c14.arch.ox.ac.uk/calibration.php

Pharaos, Shroud of Turin

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Aktivity

Number of radioactive decay per seconds.

SI Unit Bq (Becquerel).

s

decayBq

NT

2lnA

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Dozimetry

Absorbed dose: (D) (the absorbed radiative energy by a unit mass) SI unit Gray =J/kg

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Radioactivity


alfa radiation (helium nucleus)

beta radiation (electron / pozitron)

gamma radiation (elektromagnetic)

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Dozimetry Dose equivalent (biological dose) H=D·RBE, where RBE= radiobiological equivalent SI unit: Sievert

Type and Energy Range Radiation Weighting Factors

X and Gamma rays 1

Electrons 1

Neutrons (energy dependent) 5-20

Protons 5

Alpha Particles 20

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Radioactivity


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)

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Radioactivity


Dozimetry Background radiation

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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 : LD50/30 = 4 – 5 Sv

(50% of the people dies without treatment within 30 days

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DozimetryBackground radiationradon

Fresh air 8 Bq/m3

Flats in tropic areas 20 Bq/m3

Drafty room 30 Bq/m3

Flat (worlds average) 40 Bq/m3

Room without ventilation 100 Bq/m3

Hungarian village house 130 Bq/m3

Cellar 250 Bq/m3

Flat in radon areas 1000 Bq/m3

Mine (in vulcanic areas) 30 000 Bq/m3

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DozimetryUSA 37 Bq/m3

Finland 90 Bq/m3

France 62 Bq/m3

Indonesia 12 Bq/m3

Japan 29 Bq/m3

Hungary 55 Bq/m3

Germany 49 Bq/m3

Sveden 108 Bq/m3

Siria 20 Bq/m3

40 Bq/m3 activity concentartion is equivalent to about 1mSv/year dose.

Background radiationradon

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Detecting of nuclear radiation Cloud chamber

http://www.ejf.hu/oktkut/kiallitas/Oldalak/Kodkamra/Kodkamra.htm

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Radioactivity


Cloud chamber (Paks, Nuclear Power Plant, Visitor Centre)

http://www.tar.hu/fizfoto/fizfoto7.html

Detecting of nuclear radiation

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Radioactivity


Filmdozimeter (staff – doctors, Y-Ray staff)

www.sulinet.hu/.../Rab/0/11448/radioakt.htm

http://www.euronuclear.org/info/encyclopedia/f/filmdosimeter.htm


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Radioactivity


Geiger Müller counter (GM tube)

http://zope.reaktor.fh-furtwangen.de/portal/human_sciences/alchemie/portal/lectures/gesamttour/geiger/f3.html


fizika nuclear radiation. fizika 2 radioactivity dr. seres istván [email protected] helium...

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