Theory of Fission and Spontaneous Fission.pptx

Theory of Fission and Spontaneous Fission

1. Theory of Fission and Spontaneous Fission Submitted To: Dr. Naveed Ahmad Submitted By: Usama Yousaf BS Physics (VIII)Eve BSF1800372 University of Education , Township Lahore

2. Introduction ⇨ Nuclear fission is a reaction in which the nucleus of a heavy nuclide splits into smaller nuclides, a few new neutrons are created and a significant amount of energy is released. ⇨ S pontaneous fission is a type of radioactive decay in which certain unstable nuclei of heavier elements split into two nearly equal fragments and liberate a large amount of energy.   ⇨  In nuclear physics, nuclear fission is  either a nuclear reaction or a radioactive decay process . The case of decay process is called  spontaneous fission  and it is very rare process.

3. theory of fission Here we will discuss about Bohr Wheeler theory of Fission. Bohr and wheeler in 1939 gave a successful explanation of fission phenomenon . ⇨ The short range nuclear attractive forces produce surface tension and maintain the spherical shape of the nucleus by overcoming the coloumb force of repulsion between protons . ⇨ When a heavy nucleus is imparted with some energy by thermal neutrons , it forms a compound nucleus and surface oscillations are set up in the nucleus and distorting it spherical shape to ellipsoidal .

4. ⇨ The strong nuclear forces want to return the nucleus in the spherical shape whereas the repulsive force wants to distort its shape . ⇨ If the excitation energy is high then the coloumb force overcome the nuclear forces and compound nucleus is now like a dumb-bell shape . ⇨ Excitation energy produces oscillations which splits two parts of dum -bell because of p-p repulsion And consequently , two fission fragments , some neutrons and high amount of energy is obtained.

5. Spontaneous Fission ⇨ In 1940, Flarov and Petrzhak explained that without external bombardment of nuclear particles on uranium and heavy nucleus, nuclei itself undergo fission which is called spontaneous fission.

6. Symmetric fission: ⇨ The fission reaction which spontaneously splits into two equal mass fragments having mass no. A/2 and Z/2 , this type of fission is called symmetric fission . Energy Released in symmetric fission:  

7. ⇨ is exact mass of nuclei ⇨ is exact mass of fission product . By putting these values in equation we will get energy release equation Where ,  

8. Applications