Decay chains

(1)

Decay chains

relation of  _A and  _B ?

1

1/2, 1/2,

X Y

stable

X Y

X Y Z

T T



_



_

 ^ ^ 

 

 

  

,0  ^Y e ^X ^t e ^Y ^t

Y Y Y X

Y X

A N A

(2)

90 90 90

28a 64h

Sr 

^^–

Y 

^^–

Zr

1 2,X



1 2,Y

T T

T

_1/2,X

= 8·10

⁷

h

T

_1/2,Y

=0,8h

2

(3)

222Rn

86 234Th

90 ²³⁴Pa

234U

92

230Th

90

226Ra

88 ²²²₈₆Rn

238U

92

214Po

84 ²¹⁴₈₃Bi ²¹⁴₈₂Pb ²¹⁸₈₄Po ²²²₈₆Rn

radonnak a talajban maradó

része

rések, ahol a radon egy része kijut a talajból a légkörbe további hosszú felezési

idejű leányelemek

– –

AEROSZOLOK

FÖLDFELSZíN

ESŐCSEPPEK

csapadék ülepedés

légáramlás

3

226 222

86 82

88

Ra 

1620a^

Rn 

3,83 d^

 ... Pb

aerosol raindrops

Surface of the Earth

Further long T_1/2 daughters

precipitation sedimentation

air current

cracks where Rn can escape to the atmosphere

Rn remaining underground

(4)

4

210

Po is an  -emitter, that has a half-life of 138.4 days, E

_

= 5.3 MeV

When former Russian spy Alexander Litvinenko died from polonium-210 poisoning several years ago in London,

it triggered a murder investigation that developed like a thriller.

Po-210 generate much heat as the atoms decay - it was used in Russian lunar landers to keep the craft's

instruments warm at night.

.

(5)

Interaction of the radiation with the matter

5

(6)

Partners

1. Electromagnetic field 2. Electron

3. Field of the nucleus 4. Nucleus

A) Absorption I E_kin, E*

C) Incoherent scattering (also exchange of E) I, E

elastic (no excitation) E_kin

inelastic E_kin, E*

B) Coherent scattering (only the direction I - is altered))

Effect on

Mechanism radiation matter

Particles/photons

I. II. III.

a b

p e⁺ n 

 e^- X

6

(7)

1. Ionizing radiations

7

(8)

The first step of the ionizing radiation in the matter:

1. Neutral excitation

A + radiation  A* + radiation’

2. External ionization

A + radiation  A⁺ + e^- + radiation’

3. Internal ionization

A + radiation  A*⁺ + e^- + radiation’

A*⁺ A⁺ + X_char A*⁺ A²⁺ + e^-_Auger 4. Bremsstrahlung (breaking radiation)

A + radiation ^  A + X_b + radiation ^’

F

^UNDAMETALS ^OF ^DETECTION

8

(9)

Quantitative description of the interaction

    nx

_A

 dn   (E)n 

_A

dx

 



₀ ⁽^E) ^A^x

n n e



₀ ^x

I I e

linear absorption coefficient

9

0 0 0

m

x d

I I e x I e I e

  

 ^  ^ ^

   

mass absorption

coefficient cross section

 n

I t

(10)

 -radiation

With electrons: incoherent scattering ionisation and excitation (50-50 %)

E and direction of the alpha particles is modified With the nucleus: Rutherford-scattering

nuclear reaction (see later)

! Bremsstrahlung (continuous energy gamma radiation)!

Intensity

10

Heavy, charged, high energy

distance in air

(11)

 -radiation

With electron: incoherent scattering ionisation (external and internal) excitation

E and the direction of the radiation changes With the field of the nucleus: incoherent scattering

! Bremsstrahlung !

 

 

  

 

 

 

r

ion

dE

dx EZ

dE 800 dx

m

d x

0 0

I  I e ^  I e ^

Linear/mass absorption coefficient¹¹ Monoenerg

n et

tro ic elec

-rad

iation

Thickness

small, charged, limited energy

(12)

12

air

Linear energy transfer (LET)



²

dE / dx 1/ v

(13)

13

Calculate the activity of 1 kg KCl. 0.012 % of the K atoms is radioactive ⁴⁰K. The half life of ⁴⁰K is 1.1310⁹ years.

We prepared a ³⁵S labelled protein at 12:00, 10 September 2014. The half life of the pure ^- emitter is 88 days. This

sample was measured at noon on 26 September and the intensity was found 7000 imp/s. The overall effieciency of the

measurement was 22 %. Calculate the activity of the sample in the time of synthesis.

The linear absorption coefficient of gamma radiation of 660 keV in aluminum is 3,4 cm^-1. Calculate the half thickness. How

efficiently will attenuate this radiation an 10 cm aluminum wall ?

(14)

1. Compton-scattering Elastic collision of the photon with an electron

 -radiation

E’_ E_C

E_

where 

_C

= 

_s

+ 

_a

14

electromagnetic radiation

C A A

C ,m C C

N Z A

 

     

 

(15)

2. Photoelectric effect

n(E)=4 - 5

15

(16)

3. Pair production

16

(17)

17

( )

0 0

C f p

d

I  I e ^ ^ d  I e ^ ^ ^ ^ ^ ^

pair Compton

Photo Photo Pair

Germanium

(18)

2. Nuclear reactions

18

(19)

10B +  ¹⁰B + 

14N* ¹³C +p

12C + d  ¹³N+n

Transition state

1. (n,)

(n,f) ²³³U, ²³⁵U, ²³⁹Pu, ²⁴¹Pu

10B(n,)

6Li(n,)

2. (,n)

(n,2n) (n,) (p, ) (d, )

Cross section (~probability)

Tunnel effect ¹⁹ Conventional equation

(20)

* * a

dN N N

dt     

 

* *

1 exp

N  N

_

^     t ^ 

 

1 exp

A  A

_

^     t ^ 

Kinetics of the nuclear reactions

*

A

_

  N

_

 

a

N ^  ^    ^





 

 

      '

1 exp exp

_h

A N

A t t

activation decay 20

meas.

end of activation

(21)

21

We intend to obtain ⁶⁵Ni with neutron irradiation. Therefore, we

expose 1 g of Ni (with a ⁶⁴Ni content of 91 %) to neutrons with a flux

=10¹²1/cm²s. Thre cross section  of the

64Ni(n,)⁶⁵Ni

reaction is 1.55·10^-28 m². The half-life of ⁶⁵Ni is 2.52 h.

i) How long should the irradtiation last if we want to reach 80 % of the saturation activity?

ii) Estimate the ratio of the ⁶⁴Ni/⁶⁵Ni isotopes in the sample after being „cooled” for the same period as the activation lasted.

(22)

- elastic scattering

- inelastic scattering

Excited nucleus, h

- neutron capture

(absorption): (n,?)

Interaction of neutrons with the matter

22

relatively heavy, no charge, energy ?

(23)

1. Slow

a) cold E  0.025 eV

b) thermal 0.025 eV  E  0.44 eV c) resonance 0.44 eV  E  1000 eV

2. Medium 1 keV  E  500 keV

3. Fast 0.5 MeV  E  10 MeV

4. High energy 10 MeV  E  50 MeV

5. Super fast 50 MeV  E

Due to the strong E dependence,

23

(24)

113

Cd(n,)

¹¹⁴

Cd  =6,31·10

^-24

m

²

      ^

10 B n , 7 Li 3 10 25 m 2

135Xe(n,  )136Xe   2,7 10  ^ ²² m ² , 149Sm(n,  )150Sm   6,6 10  ^ ²⁴ m ² ^,

157Gd(n,  )158Gd   4,6 10  ^ ²³ m ² ,

 ⁿ ^,  

 ⁿ ^, ^ 

Examples of practical relevance

24

(25)

25

 n f ,  fission

(26)

Fission ( n,f )

 

 

 

^236U

 

235

U n 3 n

90

Kr+

143

Ba +200 MeV

50 ways, 300 isotopes 35 elements



^–



^–

90 90

33 s 2,7 min

Kr

^

Rb

^ ⁹⁰ ⁹⁰ ⁹⁰

28a 64h

Sr 

^^–

Y 

^^–

Zr

26

(27)

kinetic energy of fission products:  160 MeV kinetic energy of the neutrons:  5 MeV

energy of the -rays:  5 MeV

energy of the secondary radioactive decay:  20 MeV energy released at neutron capture:  10 MeV

Distribution 200 MeV

Self-sustaining chain reaction: control

27

(28)

Nuclear reactor

28

Fuel

Moderator

Cooling system Control

Decay chains

Decay chains

relation of  A and  B ?





   

 

 

 

  

,0  Y e X t e Y t

Y Y Y X

Y X

A N A

Sr 

Y 

Zr



T T

T

= 8·10

h

T

=0,8h

Ra 

Rn 

 ... Pb

Po is an  -emitter, that has a half-life of 138.4 days, E

= 5.3 MeV

When former Russian spy Alexander Litvinenko died from polonium-210 poisoning several years ago in London,

it triggered a murder investigation that developed like a thriller.

Po-210 generate much heat as the atoms decay - it was used in Russian lunar landers to keep the craft's

instruments warm at night.

Interaction of the radiation with the matter

1. Ionizing radiations

The first step of the ionizing radiation in the matter:

F

Quantitative description of the interaction

    nx

 dn   (E)n 

dx



n n e



I I e

0 0 0

x d

I I e x I e I e

  

    

   

 n

I t

 -radiation

Heavy, charged, high energy

 -radiation

 

 

  

 

 

 

dE

dx EZ

dE 800 dx

d x

0 0

I  I e   I e 

small, charged, limited energy

air

Linear energy transfer (LET)



dE / dx 1/ v

 -radiation

where 

= 

+ 

electromagnetic radiation

N Z A

 

relation of  _A and  _B ?

 ^ ^ 

,0  ^Y e ^X ^t e ^Y ^t

 ^  ^ ^

I  I e ^  I e ^

I  I e ^ ^ d  I e ^ ^ ^ ^ ^ ^

^     t ^ 

^     t ^ 

N ^  ^    ^

      ^

135Xe(n,  )136Xe   2,7 10  ^ ²² m ² , 149Sm(n,  )150Sm   6,6 10  ^ ²⁴ m ² ^,

157Gd(n,  )158Gd   4,6 10  ^ ²³ m ² ,

 ⁿ ^,  

 ⁿ ^, ^ 