Fsika Internasional Nuclear Physics by Tiara Indah Rainy 09330124

7/31/2019 Fsika Internasional Nuclear Physics by Tiara Indah Rainy 09330124

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By:

Name: Tiara Indah Rainy09330124 /5C


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The atoms of all elements are made up of threeparticles called protons, neutrons, and electrons.

The protons and neutrons are at the centre or nucleus

of the atom. The electrons orbit the nucleus. The protons and neutrons both have a mass of about

one atomic mass unit

By comparison, the mass of an electron is very small

about of 1 u.

kgxu 1027

66,11

20001


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Atoms and ions

Atoms are uncharge because they contain equalnumbers of protons and electrons.

An atom loses one or more electrons so that it does notcontain an equal number of protons and electrons , itbecomes charged is called an ion.

Proton number and nucleon number The Proton number is the number of protons in the

nucleus of an atom (atomic number Z)

The nucleon number is the number of protons together

with the number of neutrons in the nucleus (massnumber A )


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Nuclear representation

The nucleus of one form of sodium contains 11 protons

and 12 neutrons. Therefore the proton number Z is 11 + 12 = 23

A nucleus can be represented as

Where X is the chemical symbol.

Isotopes

Isotopes are different forms of the same element (thatis, with the same proton number ) but with a differentnucleon number.

Xnumbernucleon

numberproton

_

_


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Radioactive is the unstable nuclei emit particlesand/or electromagnetic radiation , to become morestable.

And the emission is called radioactivity. The emissions are of three different types. These are

particles, particles, and radiation.

All three emissions organate from the nucleus.


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An particle is the identical to the helium nucleus (two

protons + two neutrons) It can pass through very thin paper, but is unable to

penetrate a thin card.

Its range in air is few centimetres. Because particles

are charged, they can be deflected by electric andmagnetic fields.

The original nuclide is called the parent nuclide, andthe new one the daughter nuclide.

emission reduces the nucleon number of the parentnucleus by 4 , and reduces the proton number by 2.

energyHeThU 4

2

230

90

234

92


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particles are fast moving electrons, have speed in

excess of 99% of the speed of light. These particles have half the charge and very much

less mass than particles .

They can penetrate the card and sheets of aluminium

up to a few milimetres thick. The differences between behaviour ofand

particles, particles carry a negative charge , and particles carry a positive charge.

emission causes no change to the nucleon numberof the parent nucleus , and increases the protonnumber by 1.

energyepn

0

1

230

90

1

0


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radiation is part of the electromagnetic spectrum

with wavelengths between m and m Since radiation has no charge , its ionising power is

much less than that of either or particles.

In emission no particles are emitted and there is

therefore no change to the proton number or nucleonnumber of the parent nuclide.

example :

10

11

10

13

234

90

234

90 Th

0

0

234

90

234

90 ThTh


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Radioactive decay series is spontaneous , randomprocess. The series ends when a stable nuclide is reached.

If we investigate the decay of sample of radioactivematerial we find that the greater the number ofradioactive nuclei in the sample the greater the rate ofdecay. This can be describe mathematically:

N is the number of undecayed atoms in the sample.

dN/dt is the rate at which the number of nuclei in thesample is changing or the rate of the decay.

is defined as the probability per unit time that a nucleus

will undergo decay.

Ndt

dN

teNN

0

the radioactive decayequations :


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For any radioactive nuclide , the number of undecayed

nuclei after one-halflife is ,by the definition of halflife , equal to , where is the original number ofundecayed nuclei. Using the radioactive decayequations :

We have at time become And dividing each side of the equation by

or taking natural logaritms of

both sides So that or

20

N0

N

teNN

0

21tt 2

1

0

t

eNN

0N

2

1

2

1

0

te

N

N

2

12

te

2

12ln t

2ln

2

1t

693,0

2

1 t


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One atomic mass unit (1 u) is defined as being to one-twelfth of the mass of carbon -12 atom .

Proton mass mp= 1.007276

Proton mass mn= 1.008665

Electron mass me= 0.000549

The differences between the expected mass and theactual mass of a nucleon is called the mass defect ofthe nucleus.

In the case the mass of helium -4 nucleus , the messdefect is 4.031882-4.001508 = 0.030374 u

271066,11 xu


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In 1905, Albert Einstein proposed that there is an

equivalence between massand energy E and mass m is:

Where , c is the speed of light(m/s)

E is energy (joule), m is mass (kg)

If mass is measured in u and energy in MeV

1 u is the equivalent of 931 MeV

2mcE

Cxisechelectronthe19

1060,1arg

619 1000,11060,11 xJxxMeV

JxMeVor 131060,11

Fsika Internasional Nuclear Physics by Tiara Indah Rainy 09330124

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