1.5- PARTICLE INTERACTIONS

Question 1

What can we use to measure forces?

Answer 1

newton meters and force sensors

Question 2

What is the momentum of an object?

Answer 2

its mass multiplied by its velocity

Question 3

What is transferred through these forces?

Answer 3

momentum

Question 4

What are exchange particles?

Answer 4

particle that causes the force between two particles in a particle interaction.
They are virtual particles

Question 5

How long do exchange particles last?

Answer 5

Enough to transfer energy, momentum and other properties but overall a very short time

Question 6

What did Richard Feynman say about the electromagnetic force between two charge particles?

Answer 6

the electromagnetic force between two charged objects is due to the exchange of virtual photons causing electrostatic repulsion.

Question 7

Why did Richard describe them as virtual photons?

Answer 7

we can’t detect them directly

Question 8

Using what would be used to intercept the virtual photons and what would happen?

Answer 8

using a detector

would stop the force acting

Question 9

analogy for two like-charged particles

Answer 9

two people on ice skates:

Question 10

What does the ball analogy not work for?

Answer 10

for two oppositely charged particles

Question 11

What would the ball have to be changed to for two oppositely charged particles?

Answer 11

Question 12

What are the exchange particles involved in the four fundamental forces called?

Answer 12

Gauge Bosons

Question 13

What are the Gauge Bosons for strong nuclear force?

Answer 13

Pions (+,-,0)

Question 14

What particles are effected by strong force?

Answer 14

Hadrons only

Question 15

What is the Gauge Boson for electromagnetic force?

Answer 15

Virtual photon

Question 16

What particles are effected by electromagnetic force?

Answer 16

charged particles only

Question 17

What are the Gauge Bosons for weak force?

Answer 17

Bosons (W+, W-)

Question 18

What particles are effected by weak force?

Answer 18

all types

Question 19

What does the strong nuclear force do?

Answer 19

hold the neutrons and protons in the nucleus together

Question 20

What does the weak nuclear force do?

Answer 20

cause a neutron to changed into a proton in beta (-) decay or proton to change into neutron in beta (+) decay

Question 21

What determines the range of the force?

Answer 21

size of exchange particle

Question 22

Heavier exchange particle =

Answer 22

smaller range = smaller range of force

Question 23

How much more mass do W bosons have than protons

Answer 23

100 x more mass

Question 24

Why can’t W bosons travel far?

Answer 24

High mass = creating it uses so much energy that it can only last for a short amount of time and it can’t travel far.

Question 25

Why does electromagnetic force have infinite range?

Answer 25

It has no mass

Question 26

What do each of the lines on a Feynman's diagram represent?

Answer 26

Question 27

What are the rules for drawing particle interaction diagrams?

Answer 27

Question 28

What is something strange about the particle and antiparticle released in beta decay?

Answer 28

not a corresponding particle-antiparticle pair one is an electron or positron other is neutrino or antineutrino

Question 29

How often do neutrinos and antineutrinos interact?

Answer 29

hardly interact with each other

Question 30

Examples of neutrino and antineutrino interactions (2)

Answer 30

neutrino can interact with a neutron and make it change into a proton. beta(-) particle (electron) created and emitted as a result of change antineutrino can interact with a proton and make it change into a neutron. beta (+) particle (positron) created and emitted as a result of change

Question 31

What are the neutrino and antineutrino interactions due to?

Answer 31

the exchange of particles referred to as W bosons

Question 32

3 things about W bosons

Answer 32

have a non-zero rest mass have a very short range of no more than about 0.001fm positively charged or negatively charged

Question 33

How were W bosons first detected?

Answer 33

using the 2km diameter Super Proton Synchrotron at CERN in Geneva

Question 34

What happened during the experiment at CERN?

Answer 34

protons and antiprotons at very high energies were made to collide and annihilate each other at sufficiently high energies, annihilations produce W bosons as well as photons

Question 35

What role does W bosons play in beta decay?

Answer 35

W boson meets neutrino and changes it to a beta(-) particle (electron) W boson meets antineutrino and changes it to a beta(+) particle (positron)

Question 36

What happens to the W boson if no neutrino or antineutrino is present?

Answer 36

W(-) boson decays into a beta(-) particle and antineutrino | W(+) boson decays into a beta (+) particle and neutrino

Question 37

What does a beta minus decay look like in Feynman's?

Answer 37

Question 38

What does beta minus decay look like on Feynman's?

Answer 38

Question 39

What is electron capture?

Answer 39

sometimes a proton in a proton-rich nucleus turns into a neutron as a result of interacting through the weak interactions with an inner-shell electron from outside the nucleus.

Question 40

In electron capture, what is the "acting particle"? | Therefore, what is the boson and what direction is it?

Answer 40

W+

Question 41

What does electron capture look like on Feynman's?

Answer 41

Question 42

What does the W(+) boson change the electron to in electron capture?

Answer 42

a neutrino

Question 43

When can a similar change to that of electron capture happen?

Answer 43

when a proton and electron collide at very high speed

Question 44

For an electron with sufficient energy what can the overall change occur due to?

Answer 44

W(-) exchange from proton to proton

Question 45

What is electron proton collisions? What is the acting particle - which way is the boson? What does it look like on feynman's?

Answer 45

Question 46

What are the photon and W boson known as?

Answer 46

force carriers as they are exchanged when the electromagnetic force and weak nuclear force act representatively

Question 47

What is the exchange particle for EM repulsion?

Answer 47

Virtual photon

Question 48

What does EM repulsion look like?

Answer 48

Question 49

What is the pion known to be?

Answer 49

exchange particle of the strong nuclear force

Question 50

What do scientists think the carrier of the force of gravity is?

Answer 50

graviton- bit it has yet to be observed