Basic of Nuclear Physics

History of nuclear physics

@ The history of nuclear physics
The discipline distinct from atomic physics starts with the discovery of radioactivity by Henri Becquerel in 1896,while investigating phosphorescence in uranium salts. The discovery of the electron by J. J. Thomson a year later was an indication that the atom had internal structure.
At the turn of the 20th century the accepted model of the atom was J. J. Thomson's "plum pudding" model in which the atom was a large positively charged ball with small negatively charged electrons embedded inside of it. By the turn of the century physicists had also discovered three types of radiation coming from atoms, which they named alpha, beta, and gamma radiation. Experiments in 1911 by Lise Meitner and Otto Hahn, and by James Chadwick in 1914 discovered that the beta decay spectrum was continuous rather than discrete.

@ There are the best things that we must know about the nuclear physics.
Nuclear physics is the field of  
-atomic nuclei
-nuclear power
-nuclear weapons
-nuclear medicine
-magnetic resonance imaging
-material engineering
-ion implatation
-archaeology
-radiocarbon dating 

For this reason, has been included under the same term in earlier times.

@ The atoms of which every element of matter is composed have a nucleus at the center and electrons whirling about this nucleus that can be visualized as planets circling around a sun, though it is impossible to locate them precisely within the atom. 
@ The nuclei of atoms are composed of protons, which have a positive electrical charge, and neutrons, which are electrically neutral. Electrons are electrically negative and have a charge equal in magnitude to that of a proton. 

What is the Nuclear (fission) energy:

• Commercially established since 1956 

  Calder Hall, gas-cooled Magnox NPP at Sellafield (UK), 50 MW (later 200 MW)

• Today: ~16% of world’s electricity generation (18% hydro, 66% fossil)

• Switzerland: ~40% (nearly all the rest: hydro)

This is about the structure of the atom (Rutherford’s model):

• Mass concentrated in the nucleus (mH/me ~ 1837)

• Nuclear charge: +Ze (Z: atomic number, e ~ 1.6.10-19 coulomb)

• Quantum mechanical basis for atomic, nuclear structure

• “Classical dimensions”: nucleus ~ 10-13 cm, atom ~ 10-8 cm

Energy units (1eV ~ 1.6.10-19 J)is the :

- Binding energy of outermost electrons ~ order of eV

– Energy involved in chemical reactions ~ same order

- Binding energy of nucleons (constituents of nucleus) ~ order of  MeV !

– Energy in nuclear reactions ~ x 106 times greater than in chemical

This is the Often encountered in nuclear engineering:

- Nuclear fuel, activation of materials, fission products, wastes

- Fundamental law: (λ : decay constant)

- Units of (radio)activity:

- Historical.. 1 curie (Ci) = 3.7 x 1010 dis/s (activity of 1 gm of Ra226)

- Actual.. 1 becquerel (Bq) = 1 dis/s

- For example: 1 mCi = 10-3 Ci = 3.7 x 107 Bq = 37 MBq