1. Experimental Nuclear physics
Course Instructor: Dr. Waseem Ahmad
Presentation On: Coulomb Barrier
presented by: Mehak Tariq
Ghazi University DG Khan
2. Coulomb Barrier
The barrier between two atomic nuclei, due to coulomb repulsion that has to be overcome for
nuclear fusion to proceed
This is given by coulomb potential
Where
Z & z` are atomic numbers of two nuclei
3. Coulomb Barrier
R & R` are their effective radii
The quantity ( R+R`) therefore classically the distance of closest approach.
Previous study as we know that
R= 1.2 A⅓ fm
4. Coulomb Barrier
This is relatively small amount of energy to supply by simply colliding two accelerated beams of
light nuclei but in practice nearly all the particles would be elastically scattered
The only particle way is to heat a confined mixture of the nuclei to supply enough thermal
energy to overcome the coulomb barrier
The temperature estimated from the relation
E= kT
Where Kb is Boltzmann’s constant given by kB = 8.6× 𝟏𝟎−𝟓
eVK`
5. Coulomb Barrier
Fusion actually occurs at low temperature than this estimate due to a combination of two
reasons
First & most important is the phenomenon of quantum tunneling, which means that the full
height of the coulomb barrier does not have to be overcome.
Second reason that fusion occurs at low temperature then expected is that a collection of nuclei
at a given mean temperature.
