The Journey Inward

1. If a pion (mass = 139.6 MeV) were the only exchange particle for the strong force, what would be the range of the strong force? What fraction of the diameter of a proton is this? If the W particle (mass = 80.5 GeV) were the only exchange particle for the weak force, what would be the range of the weak force? What fraction of the diameter of a proton is this?
Resources:

Exchange forces

Range of forces

Nuclear sizes

2. If quarks are what all the heavy particles like protons and neutrons are made of, why haven't we seen one?
Resources:

Quarks

Confinement of quarks

Bag model

3. What is a neutrino and how can you detect one?
Resources:

Neutrinos

Detection of neutrinos

Cowan & Reines

Super Kamiokande

4. How can you say that the electromagnetic and weak forces are "unified" when they seem so different?
Resources:

Exchange forces

Electroweak unification

Spontaneous symmetry breaking

5. Almost all the heavy particles are unstable, even the neutron. But the proton is stable - no one has ever seen the decay of a proton. Why? Resources:

   Proton

   Conservation laws

   Conservation of baryon number

6. Why is it necessary to have high energies to investigate small things? Assume that the wavelength necessary to see an object is equal to the size of the object, and that the wavelength is given by the deBroglie wavelength relationship. What energy electron would be necessary to see an atom (size 0.3 nm)? a carbon nucleus (5.8 fm)? a proton (2.4 fm)? to probe to the current limit of resolution of 0.001 fm? Resources:

   Why high energies?

   DeBroglie wavelength

   DeBroglie calculation