EXAM 2

Question 1

What is the maximum possible angle for neutron scattered from Hydrogen?

Answer 1

90 degree

Question 2

Why the scattering if neutrons by hydrogen is unique?

Answer 2

because the masses of the neutron and hydrogen nucleus (proton) are essentially equal.

Question 3

At high energy, a neutron’s lethargy is ______

Answer 3

low

Question 4

As neutrons slows down and neutron’s energy decreases, it’s lethargy _____

Answer 4

decreases

Question 5

For an inelastic scattering the incident neutron kinetic energy must exceed a certain threshold energy. (T/F)

Answer 5

True

Question 6

In elastic scattering:the kinetic energy of the scattered neutron is (smaller/larger) __ than the energy of the incident neutron by an amount equal to the energy acquired by the recoiling nucleus.

Answer 6

smaller

Question 7

The good moderator has low alpha (the collision parameter). (T/F)

Answer 7

True

Question 8

The disintegration process of a compound nucleus is dependent of the original mode of formation. (T/F)

Answer 8

False

Question 9

In general, interaction rate of neutrons does not depend on _____

Answer 9

the size of the nucleus

Question 10

What is the difference between Spontaneous disintegrations of nuclei and the neutron-nucleus collision events?

Answer 10

Spontaneous disintegration of nuclei is the radioactive decay of unstable fission products; this disintegration reactions depend only on the properties of an individual nucleus. The neutron-nucleus collision events are the fission. chain reaction and this reaction depend not only on the properties of the colliding particle but also the relative velocity with which the strike one another.

Question 11

MACROscopic:

Answer 11

the probability of neutron interaction in a chunk of material and undergo any type of reaction (1/cm)

Question 12

MICROscopic

Answer 12

Characterizes the probability of interaction with only a single nucleus. (barns)

Question 13

Mean Free Pass (m.f.p)

Answer 13

the average distance neutron goes without interaction (cm)

Question 14

The neutron interaction rate increases as the population density of atoms decreases (T/F)

Answer 14

False

Question 15

The neutron absorption cross section of thermal neutrons increases linearly with the neutron speed. (T/F)

Answer 15

False

Question 16

Microscopic neutron cross sections increase at resonance energies. (T/F)

Answer 16

True

Question 17

The neutron cross section always increases with the radius of the interacting nucleus. (T/F)

Answer 17

False

Question 18

4 He(p,e)

Answer 18

5Be4

Question 19

9 Be (a,n)

Answer 19

12C6

Question 20

14N(n,p)

Answer 20

14C6

Question 21

115In(d,p)

Answer 21

116In49

Question 22

207Pb(g,n)

Answer 22

207Pb(g,n)

Question 23

alpha-decay will undergo ____ decay

Answer 23

heavy nuclides

Question 24

gamma minus-decay will undergo ____ decay

Answer 24

neutron-rich nuclides

Question 25

gamma plus-decay will undergo ____ decay

Answer 25

neutron-pure nuclides

Question 26

What is the difference between X-ray and gamma photon?

Answer 26

A gamma photon is any photon emitted from a nucleus. X-rays are photon emitted when atomic electrons change their energy state.

Question 27

what fraction of a certain number of radioactive atoms will have decayed after three half-lives?

Answer 27

7/8

Question 28

the decay constants of two different isotopes are 0.01[1/h] for Isotope I and 0.01[1/d] for Isotope II. which one will decay faster?

Answer 28

Isotope I

Question 29

The electron that is emitted in gamma minus decay is one of the orbital electrons around the nucleus of the parent atom. (T/F)

Answer 29

False

Question 30

All Alpha particles emitted in the radioactive decay of a particular radioisotope have the same energy. (T/F)

Answer 30

True

Question 31

All Beta particles emitted in the radioactive decay of a particular radioisotope have the same energy. (T/F)

Answer 31

False

Question 32

Daughter isotopes of alpha and beta decays often de-excite by emitting gamma rays. (T/F)

Answer 32

True

Question 33

Electron-Positron annihilation results in the generation of 2 gamma rays of 0.511 MeV each (T/F).

Answer 33

True

Question 34

Alpha particles being heavy, positively charged ions of energy around 4-6 MeV,

Answer 34

travel in straight lines, typically will penetrate only of the order of a few micrometers in solid media, lose their energy mostly by ionization.

Question 35

Charge particles (direct/indirect)

Answer 35

directly ionizing

Question 36

neutral particles (direct/indirect)

Answer 36

indirectly ionizing

Question 37

transmutation

Answer 37

can occur through nuclear reactions, atoms of one element can be changed into atoms of another element, can occur through radioactive decay, the conversion of one chemical element or isotope into another.

Question 38

beta particles being light, charged particles lose energy by ?

Answer 38

electron excitation, ionization, emitting photons as they are delected around nuclei

Question 39

gamma rays may interact with matter through?

Answer 39

photoelectric absorption, compton scattering, pair production

Question 40

Pair production requires that the gamma ray have at least 0.511MeV energy. (T/F)

Answer 40

False

Question 41

A gamma ray gains enegry when it undergoes Compton scattering (T/F).

Answer 41

False

Question 42

Photoelectrons have the same kinetic energy as that of the gamma ray that produced them. (T/F)

Answer 42

False

Question 43

The higher the value of the linear attenuation coefficient, the smaller the average depth of penetration of gamma rays. (T/F)

Answer 43

True

Question 43

How do ionization chambers detect radiation

Answer 43

Radiation ionizes atoms of a gas. The ions and electrons are collected at electrodes held at a high potential, and the resulting current is measured.