The atomic nucleus

What lies within?

The atomic nucleus

What lies within?

The internal structure of Nucleons

Radioactivity & Nuclear Reactions

The variety of Nuclei

The atomic nucleus

What lies within?

Nucleons & their structure

Atomic Nucleus

      Nucleons & their structure

           Rutherford

Once upon a time ...

Atomic Nucleus

      Nucleons & their structure

           Discovery of the neutron (1932)

James Chadwick

Chadwick suggested the radiation was a neutral particle

of about the same mass as a proton.

Atomic Nucleus

           Size of the nucleus 

Atomic nuclei are bound states of protons + neutrons

Probability density for the presence of neutrons and protons predicted for the neon-20 nucleus. It can be seen that this is not homogeneous: the neutrons and protons are distributed in clusters. © Jean-Paul Ebran/CEA

      Nucleons & their structure

The spatial extension of a typical nucleus is ~ fm

The comparative spatial extension of the atomic nucleus to the spatial extension of the electronic cloud in an atom is of the same order as the ratio of the size of your thumb compared to the size of UCF campus.

Atomic Nucleus

           Underlying structure

Atomic nuclei are bound states of protons + neutrons

Probability density for the presence of neutrons and protons predicted for the neon-20 nucleus. It can be seen that this is not homogeneous: the neutrons and protons are distributed in clusters. © Jean-Paul Ebran/CEA

protons & neutrons

have internal structure

      Nucleons & their structure

proton

neutron

Atomic Nucleus

           Underlying structure

The Standard Model

of Elementary Particles

      Nucleons & their structure

The atomic nucleus

What lies within?

The variety of nuclei

Atomic Nucleus

      The variety of nuclei

           Definitions

Isotope:

Atoms with same Z but different A

Nuclide:

A nuclear species with a given Z, N, and A

Isotone:

Atoms with same N but different A

Isobar:

Atoms with same A but different combination of Z and N

Atomic Nucleus

           Chart of the nuclides

      The variety of nuclei

Atomic Nucleus

           Chart of the nuclides

      The variety of nuclei

Atomic Nucleus

           Chart of the nuclides

      The variety of nuclei

Atomic Nucleus

           Binding energy

B(^A_ZX)=[Nm_n+ZM(^1H)-M(^A_ZX)]c^2

Naively, we might think that the mass of each nucleus is the sum of the masses of the constituents:

M(^A_ZX)= Nm_n+ZM(^1H)

The difference is known as the binding energy

M(^A_ZX)\ne Nm_n+ZM(^1H)

But when the masses are measured, we find a discrepancy (~ 0.1%)

      The variety of nuclei

Atomic Nucleus

           3D chart of the nuclides

      The variety of nuclei

The atomic nucleus

What lies within?

Radioactivity & other Nuclear Reactions

Atomic Nucleus

      Radioactivity & other Nuclear Reactions

           Radioactive decay

Alpha-decay

^A_ZX \rightarrow \ ^{A-4}_{Z-2}D +\alpha

Beta-decay

^A_ZX \rightarrow \ ^{A}_{Z+1}D +\beta^-+\bar{\nu}

Gamma-decay

^A_ZX^* \rightarrow \ ^A_ZX

Atomic Nucleus

           Beta decay

Beta-decay

^A_ZX \rightarrow \ ^{A}_{Z+1}D +\beta^-+\bar{\nu}

      Radioactivity & other Nuclear Reactions

Atomic Nucleus

      Radioactivity & other Nuclear Reactions

           Radioactive decay chains

...

...

Atomic Nucleus

           Nuclear Fission

      Radioactivity & other Nuclear Reactions

Atomic Nucleus

           Nuclear Fission

      Radioactivity & other Nuclear Reactions

Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei.

 

The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.

 

The fission process can be either induced by a collision, or spontaneous.

Induced fission of Uranium 235

Atomic Nucleus

           Nuclear Fission

^1_0 \text{n} + ^{235}_{92}\text{U} \rightarrow \ ^{141}_{56}\text{Ba} + ^{92}_{36}\text{Kr} + 3\ ^1_0 \text{n}

      Radioactivity & other Nuclear Reactions

Atomic Nucleus

           Fusion

      Radioactivity & other Nuclear Reactions

Triple-alpha process

Nuclear fusion is a reaction in which two or more atomic nuclei, combine to form one or more different atomic nuclei and subatomic particles (neutrons or protons).

 

The difference in mass between the reactants and products is manifested as either the release or absorption of energy. 

 

A nuclear fusion process that produces atomic nuclei lighter than iron-56 or nickel-62 will generally release energy. 

Atomic Nucleus

           The origin story

      Radioactivity & other Nuclear Reactions

per 10,000 atoms in the universe

Atomic Nucleus

           The origin story

^A_ZX \rightarrow \ ^{A}_{Z+1}D +\beta^-+\bar{\nu}

      Radioactivity & other Nuclear Reactions

Learn more about Stellar Nucleosynthesis

Atomic Nucleus

           Origin Story

      Radioactivity & other Nuclear Reactions

Utterly captivating! One of the best presentations on the topic!

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