Name________________________________________
The Particle Adventure
1. Go to the website: www.particleadventure.org
2. Click on the “Go!” button in the image titled “The Standard Model.”
3. On the left, you will see a table of contents. At the top right is a set of
navigation buttons with a HOME button, forward and back buttons, and a
button to open a glossary of terms. Click the forward button to move through
the pages of the particle adventure tour. You can keep track of your progress
in the table of contents on the left side of the page. Read through all of the
pages under the “What is Fundamental?”, “What is the World Made of?”,
“What holds it together?”, and “Particle Decays and Annihilations” tabs.
Answer the questions below as you go along.
What is Fundamental?
4. Why is the term “atom” a misnomer?
5. Atoms are composed of electrons surrounding a nucleus of protons and
neutrons. Are protons and neutrons fundamental particles, or are they made
of smaller particles?
6. Are quarks fundamental particles, or are they made of even smaller
particles?
7. Are electrons fundamental particles, or are they made of even smaller
particles?
8. What is The Standard Model?
What is the World Made Of?
9. What is anti-matter? What is similar about a particle and its antiparticle
partner? What is different?
10. According to the tutorial, when a particle and its corresponding anti-particle
collide they annihilate one another. What is meant by “annihilation?” The
Glossary may help you clarify this.
11. According to the tutorial, why is there so much more matter in the Universe
than anti-matter?
12. How many quarks are there (not including anti-quarks)? What are their
names? When was the sixth (and last) quark discovered?
13. Have we ever experimentally seen a single quark by itself? In what two ways
do quarks (and/or anti-quarks) clump together?
14. What fundamental particles (number and type) is a proton made of?
15. What fundamental particles (number and type) is a neutron made of?
16. How many leptons are there (not including anti-leptons)? What are their
names.
17. Why do we not typically see heavy leptons like the tau and muon in ordinary
matter?
18. In terms of subatomic particles, what is meant by the term “decay”? The
Glossary may provide clarification. Give an example of a decay.
19. A neutrino can pass all the way through the Earth without ever interacting
with a single atom in it. Why is this?
What Holds it Together?
20. When we use the term “interaction”, we don’t just mean “force.” What other
types of processes are meant by the term interaction?
21. How many fundamental interactions are there in the Universe? What are
they?
22. When discussing light, we talked about how electrically charged particles
exert forces on each other by creating electric fields around them
everywhere in space. It is the electric field that exerts the force on the
charges. In this tutorial, they describe a different model for explaining how
matter particles interact without “touching”. Describe this model in the
space below.
23. What is the carrier particle of the electromagnetic interaction?
24. A nucleus contains protons confined to a very small space. However, these
protons all have + electric charge and repel each other very strongly. What
overcomes this electric repulsion and keeps the nucleus together?
25. What is the carrier particle of the strong interaction?
26. What special type of charge do quarks have that allow them to exchange
gluons (**Note, this is different from electric charge)?
27. Why does all of the stable matter in the Universe appear to only be made of
the lightest quarks and leptons (i.e. up/down quarks, electrons, and
neutrinos)?
28. What interaction is responsible for heavier quarks and leptons decaying into
lighter quarks and leptons? What are the carrier particles of this interaction
(note there are more than one)?
29. What is the hypothesized carrier particle of the gravitational interaction?
Have we ever observed it?
30. At this point, take a moment to fill in the table below. It summarizes the
Standard Model, which describes the Universe in terms of matter particles
(quarks and leptons) and force carrier particles that mediate the four
fundamental forces.
The Standard Model
Matter Particles
(Fermions)
Quarks
Leptons
Force Carrier Particles
(Bosons)
Interaction
Electromagnetic
Strong
Weak
Gravity
Carrier(s)
31. What does the term “quantum” mean? Give four examples of properties that
are quantized.
32. What does the Pauli Exclusion Principle state? Which particles obey this
principle and which do not?
33. What single quantum property distinguishes a fermion from a boson?
Particle Decays and Annihilations
34. Describe what is meant by the term “nuclear decay.” What happens during
this process?
35. What happens when a fundamental particle decays? How is this different
from the process of nuclear decay?
36. What is radioactivity?
37. What is meant by the term “radiation”? What are three different types of
radiation? Give their names and describe what they are.
38. Representing particles (like protons and neutrons) as solid little balls is
somewhat misleading. Why is this, and in what way can they be drawn to
more accurately reflect their true nature?
39. Alpha decay is an example of
quantum tunneling. An alpha
particle (which is actually a group of
two protons and two neutrons stuck
together) has a high probability of
being bound to the other protons
and neutrons inside a nucleus.
Classically speaking, it does not
have the energy needed to escape
the residual strong force binding it
to the rest of the nucleus.
Nonetheless, because of its wavelike nature, there is a very small
probability that this alpha particle
will find itself outside the nucleus.
This is depicted with the small, slightly fuzzy region outside the dashed line
in the figure. Although this is not highly probable, and although we cannot
predict exactly when it will happen, every once in a while it does happen.
This is the phenomenon of radioactivity.
40. The tutorial describes the process of uranium decaying into an atom of
thorium and an alpha particle. The strange thing about this is that if you add
the mass of the thorium atom and the mass of the alpha particle together, it is
less than the mass of the original uranium atom. It appears that some mass is
missing after the decay. Where does this missing mass go?
41. How does a fundamental particle decay (or transform) into other particles?
Describe the process in detail and give an example.
42. What is a virtual particle?
43. How are virtual particles involved in particle-antiparticle annihilations?
44. One type of radioactivity is neutron beta decay. In this process, one of the
neutrons inside a nucleus turns into a proton, and an electron and an
antineutrino are emitted as radiation. The essential steps in this process are
shown below. Describe what is happening in each step.
45. The tutorial describes the process of an electron and an antielectron (i.e.
positron) annihilating and producing a D+ and D- meson. Previously, we said
that when a particle and antiparticle collide, they turn into pure energy. This
is pretty vague. What form does this energy take just after the collision?
46. After a very short time, what happens to this “pure energy”?