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원자 및 핵물리의 기초Basic Atomic and Nuclear Physics 2013.04.01

양산부산대학교병원 방사선종양학과전호상

hjeon316@gmail.com

[방사선 공학 개론]

4/01 Basic Atomic and Nuclear Physics

4/08 Radioactivity

4/15 Radiation Interaction with Matter

4/22 Mid-exam

Plan

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Chap 1. Fundamental Concepts

1.1 Modern Unit

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1.1.1 Special Nuclear Unit

1V

-

C 1mol = 12g612

1.2.3 Atomic and Nuclear Nomenclature

+

n

-

+

-

+ +

+++

++

nn

nnn

n n

-

-

-

-

--

-

H2O

H O1116

8

• X : chemical symbol• Z : number of protons• N : number of neutrons• A (mass number) = Z + N

+

-

n

protonelectronneutron

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1.2.3 Atomic and Nuclear Nomenclature

n+

-

+ +

+++

++

nn

nnn

n n

-

-

-

-

--

-

+

-

n

protonelectronneutron

• Nuclide (핵종) : 특정 Z와 A 및 에너지 상태를 가진 원자 또는 원자핵• Nucleus (핵) : 양성자와 중성자로 이루어진 원자의 중심 (복수: Nuclei)• Nucleon (핵자) : 핵을 구성하는 양성자와 중성자의 통칭

1.2.3 Atomic and Nuclear Nomenclature

+

-

nn+

-

Tritium Hydrogen

H11 H3

1

• Status of nuclide

Stable RadioactiveRadiation

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1.2.3 Atomic and Nuclear Nomenclature

+

-

n

protonelectronneutron

• 무엇이 원소의 종류를 결정하는가?

+

-

+nn

-

-

-

n++ +

+++

++

nn

nnn

n n-

-

-

-

-

-

1.2.3 Atomic and Nuclear Nomenclature

• Radioactive Isotope (방사성 동위원소)

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1.2.4 Atomic and Molecular Weights

• Atomic weight

1.2.4 Atomic and Molecular Weights

• Atomic weight

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1.2.4 Atomic and Molecular Weights

• Molecular weight

(Na=6.022 x 1023)

1.2.8 Size of an Atom

1 Å = 10-8 cm

• Angstrom

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1.2.10 Nuclear Dimensions

Nucleus : 1cm ball in PNU campus !

+

-

1.2.10 Nuclear Dimensions

Fe56

U238

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Chap 2. Modern Physics Concepts

2.2 Radiation as Waves and Particles

• As Waves

• As Particles

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2.2.1 The Photoelectric Effect

• Hertz (1887) and Thomson (1898)

• If light were a wave…

2.2.1 The Photoelectric Effect

• But experimental results were…

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2.2.1 The Photoelectric Effect

• Einstein’s prediction : “particle model”

2.2.1 The Photoelectric Effect

• Hughes (1912) and Milliken (1916)

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2.2.1 The Photoelectric Effect

2.2.2 Compton Scattering

• Scattered radiation was changed in wavelength !

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2.2.2 Compton Scattering

• Governing equation

2.2.2 Compton Scattering

• Governing equation

• If angle = 0, no collision

• If angle = 180, reflection

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2.2.2 Compton Scattering

2.2.2 Compton Scattering

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2.2.5 Wave-Particle Duality

• De Broglie wavelength

Chap 3. Atomic/Nuclear Models

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3.1.1 Discovery of Radioactivity

• Becquerel (1896) and Curies (1898)

• α : Helium ion (He2+)• β : electron• γ : electromagnetic wave

-

-

++nn He2

4

3.1.2 The Plum Pudding Model

• Becquerel’s discovery of radioactivity (1896)• Thomson’s discovery of electron (1898)

• “The atom as a sphere full of an electrically positive substance mixed with negative electron”

10-10 m

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3.1.3 The Rutherford Atomic Model

• Geiger and Marsden : alpha particle scatter with thin gold foil

10-14 m

10-10 m

• Rutherford (1911) : discovery of the nucleus!• “The electron moves around nucleus like planets around Sun”

3.1.4 The Bohr Atomic Model

• Rutherford’s deficiencies : Electrons fall into the nucleus? No!

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3.1.4 The Bohr Atomic Model

• Rutherford’s deficiencies : Electrons fall into the nucleus? No!

3.1.4 The Bohr Atomic Model

• Bohr postulated…

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3.1.4 The Bohr Atomic Model

• Bohr orbits

3.1.6 The Quantum Mechanical Model of Atom

• Description of the spectrum of complicated atoms• Electrons are not point particles in atoms in QM

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3.2.3 The Proton-Electron Model

• Momentums of protons and electrons did not agree with experiments!

• Description of nucleus

Na2311Atomic charge : 11

Mass number : 23

-

+-

2312

11

3.1.6 The Quantum Mechanical Model of Atom

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3.2.3 The Proton-Neutron Model

• Discovery of neutrons (Chadwick, 1932)• Nucleus with protons and neutrons (Heisenberg, 1932)

• Well verified by experiments• Consistent with radioactivity (ex. β- decay)

proton

neutron

• How the protons are held together ?

3.2.3 The Proton-Neutron Model

• Discovery of neutrons (Chadwick, 1932)• Nucleus with protons and neutrons (Heisenberg, 1932)

• Well verified by experiments• Consistent with radioactivity (ex. β- decay)

• How the protons are held together ?proton

neutron

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3.2.4 Stability of Nuclei

• 3200 known nuclides• Solid point : 266 stable nuclides

• N=Z at light stable nuclides• N>Z at heavy nuclides

for additional nuclear force

• Z>83(Bismuth) : radioactive

3.2.4 Stability of Nuclei

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3.2.4 Stability of Nuclei

Homework

• Chap 1

• Chap 2

• Chap 3

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