Particles and nuclear structure

Question 1

Describe quarks

Answer 1

Relatively high mass, either ‘up’ or ‘down’ type, affected by strong force.

Question 2

Describe leptons

Answer 2

Lightweight particles, two types- electron and electron neutrino, affected by weak forces.

Question 3

What are the characteristics of an antiparticle?

Answer 3

They have the same mass but opposite charge, lepton number and baryon number.

Question 4

What happens when a particle and its corresponding antiparticle collide?

Answer 4

Annihilation occurs. They cease to be and their mass is converted into a pair of photons.

Question 5

What is charge (e)?

Answer 5

The magnitude of the charge of a proton.

Question 6

What is the charge of an up quark?

Answer 6

+2/3.

Question 7

What is the charge of a down quark?

Answer 7

-1/3.

Question 8

What are hadrons?

Answer 8

Composite particles made of quarks.

Question 9

What are the three types of hadron?

Answer 9

Baryon (combination of three quarks)
Antibaryon (combination of three antiquarks)
Meson (quark and antiquark pair)

Question 10

What is the quark composition of a proton?

Answer 10

uud
Charge: +1

Question 11

What is the quark composition of a neutron?

Answer 11

udd
Charge: 0

Question 12

What is the quark composition of a delta plus plus baryon?

Answer 12

uuu
Charge: +2

Question 13

What is the quark composition of a delta minus baryon?

Answer 13

ddd,
Charge: -1

Question 14

What is the quark compostions of a pi plus meson?

Answer 14

uḋ
Charge: +1

Question 15

What is the quark composition of a pi minus meson?

Answer 15

ūd
Charge: -1

Question 16

What is the quark composition of a pi zero meson?

Answer 16

uū or dḋ
Charge: 0

Question 17

What is the charge and lepton number of an electron?

Answer 17

Charge: -1
Lepton number: +1

Question 18

What is the charge and lepton number of an electron neutrino?

Answer 18

Charge: 0
Lepton number: +1

Question 19

What is the conservation of momentum?

Answer 19

In any interaction between particles in a system, the total momentum must stay constant.

Question 20

What is the conservation of mass-energy?

Answer 20

In any interaction between particles in a system, mass energy should neither be created or destroyed.

Question 21

What is the conservation of charge?

Answer 21

In any interaction between particles in a system, the total charge in the system must not change.

Question 22

What is the conservation of baryon number?

Answer 22

In any interaction between particles in a system, the total baryon number in the system must not change.

Question 23

What is the conservation of lepton number?

Answer 23

In any interaction between particles in a system, the total lepton number of the system must not change.

Question 24

Describe gravitational force

Answer 24

Experienced by: all particles
Range: infinite
• Not applicable to the interactions of sub-atomic particles

Question 25

Describe weak force

Answer 25

Experienced by: all particles
Range: very short
• Neutrino or antineutrino involved • Change of quark flavour • Long time (10^-12s)

Question 26

Describe electromagnetic force

Answer 26

Experienced by: charged particles
Range: infinite
• Photons involved • Particles interacting have charge • Typical time is 10^-17s

Question 27

Describe strong force

Answer 27

Experienced by: quarks
Range: short
• Only hadrons involved • No change of quark flavour • Takes very little time(10^-23s)