3.4 Probing Nucleons Flashcards
When electrons collide with atoms a collision can…?
Be elastic
Be inelastic
Liberate an electron.
How can a collision be elastic?
After the collision the total kinetic energy of the electron and the recoiling atom is equal to the kinetic energy of the incident electron.
How can a collision be inelastic?
There is a loss of kinetic energy which is caused by electrons in the atom becoming excited.
How can a collision liberate an electron?
Kinetic energy is lost in ionising the atom.
What does it suggest if a particle new to science could be knocked out of a nucleon?
The nucleon is made of even smaller particles.
What does it suggest if an inelastic collision of an electron with a nucleon occurs?
An internal substructure for the nucleon.
Why did the size of the experiments that need to probe deeper have to become bigger?
The particles being looked for have become smaller and smaller so to produce higher energies the accelerators have to become larger, as have the detectors.
What led to the confirmation of the existence of quarks?
Physicists bombarded protons with very high energy electrons which gave the first evidence of nucleon substructure.
What are Quarks?
Quarks are believed to be the basic building blocks of protons, neutrons and a wide variety of other, heavier particles, collectively called hadrons. Just as atoms are primarily composed of different combinations of protons, neutrons and electrons, hadrons are believed to be composed of different combinations of quarks. Quarks are usually thought of as elementary particles, i.e. particles that cannot be further broken down into other particles by any known means.
What enables the probing of protons?
The very high energies and therefore short wavelengths of electrons.
What experiment showed that there were particles within the proton?
Electrons probed into protons.
Low energies- proportion of electrons scattered at any angle just as predicted assuming proton fundamental particle.
As energy increased, proportion scattered at large angles increases.
Incident electrons appeared to be undergoing collision with charged point like particles inside the proton.
What are the charges of quarks?
+ 2/3 and -1/3.
Explain what is meant by deep inelastic scattering.
The collision of an electron with a nucleon where there is a loss of energy- it can be used to find out the internal substructure for the nucleon.
Suggest pieces of scientific information that can be gained by bombarding matter with particles such as alpha particles.
Substructure of atom
Size of nucleus
Charge on nucleus
Atoms mostly empty space
