A recent experiment sent a beam of neutrinos produced in a particle accelerator…
PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation
Problem
A recent experiment sent a beam of neutrinos produced in a particle accelerator toward a solid lead wall that is 1.0 m thick. Even though more than 1012 neutrinos struck each square centimeter of the wall every second, virtually none were absorbed or scattered, while a comparable beam of electrons was completely stopped within a few millimeters.
Answer the following about the behavior of the two particle beams as they interact with matter.
(a) Describe the fundamental properties (electric charge, rest mass, and relevant fundamental interactions) of neutrinos, antineutrinos, and electrons.
(b) Explain qualitatively why the 1.0 m thickness of lead is sufficient to stop electrons but has almost no effect on the neutrino beam.
(c) The weak interaction governing neutrino scattering is roughly 106 times weaker than the electromagnetic interaction at typical nuclear energies. Discuss how this difference in interaction strength accounts for both the long mean free path of neutrinos in matter and the experimental difficulty of detecting them.