Nuclear Physics

Question 1

E = mc^2

Answer 1

E = energy (J)
m = change of mass (kg)
c = speed of light in free space (3x10^8)

Question 2

What happens during annihilation?

Answer 2

• a particle and its corresponding antiparticle meet
• 2 gamma photons are produced
• each of energy (mc^2) - mass is of the particle

Question 3

What happens in pair production?

Answer 3

• a single gamma photon of energy in excess of 2mc^2
• produces particle and antiparticle
• each of mass, m

Question 4

The energy released formula

Answer 4

Q =mc^2

Question 5

Alpha decay energy change

Answer 5

• nucleus recoil when alpha particle is emitted so the energy released is shared between the alpha and nucleus
  the energy released is shared between the alpha particle and nucleus in inverse proportion to their masses

Question 6

Beta decay energy change reactions

Answer 6

• energy released in variable proportions between the beta particle, nucleus, neutrino or antineutrino released in decay
• when beta particle has maximum kinetic energy - the neutrino or antineutrino has negligible kinetic energy
• maximum kinetic energy of the beta particle is very slightly less than the energy released in the decay because of the nucleus recoil

Question 7

Electron capture energy changes

Answer 7

• nucleus emits a neutrino which carries away the energy released in the decay
• the atom also emits an X-ray photon when the inner shell vacancy due to the electron capture is filled

Question 8

How do you calculate the energy released in MeV

Answer 8

• calculate the difference between the total initial mass and total final mass in u
• multiply by 931.3 to give energy in MeV

Question 9

Define: binding energy of the nucleus

Answer 9

the work that must be done to separate a nucleus into its constituent neutrons and protons

Question 10

Define: mass defect of a nucleus

Answer 10

the difference between the mass of the separated nucleons and the mass of the nucleus

Question 11

formula for ass defect of a nucleus

Answer 11

m = Zmp + (A-Z)mn - Mnuc
- Z = proton number
- A = nucleon number
- mp = mass of a proton (kg)
- mn = mass of a neutron (kg)
- mtotal = measured mass of the nucleus (kg)

Question 12

nuclear stability - to what mass number is it fusion

Answer 12

1 to 50

Question 13

What mass number is it fission

Answer 13

50 and above

Question 14

Nuclear fission

Answer 14

• the process in which a large unstable nucleus splits into two fragments which are more stable than the original nucleus
• the binding energy per nucleon increases

Question 15

nuclear fusion

Answer 15

• the process of making smaller nuclei fuse together to form a larger nucleus
• product has more binding energy per nucleon than the smaller nuclei
• binding energy per nucleon also increases - provided that the nucleon number of the produce isn’t greater than about 50