Deck 9: A Universe of Particles

Question 1

What is the minimum energy required to produced a proton-antiproton pair? A proton has a rest mass of 938 MeV/c².

A) 1876 MeV
B) 938 MeV
C) 3752 MeV
D) 2814 MeV

Answer 1

1876 MeV

Question 2

What is the speed of a proton with kinetic energy of 2 GeV?

A) 0.86 c
B) 0.88 c
C) 0.92 c
D) 0.95 c

Answer 2

0.95 c

Question 3

What is the speed of a 2-MeV electron?

A) 0.98 c
B) 0.95 c
C) 0.93 c
D) 0.90 c

Answer 3

0.98 c

Question 4

What is the temperature corresponding to a thermal energy of 50 GeV, the particle energy in the accelerator at SLAC?

A) 3.9 × 10¹¹ K
B) 3.9 × 10¹⁴ K
C) 7.8 × 10¹¹ K
D) 7.8 × 10¹⁴ K

Question 5

How far is the galaxy from the Earth if it recedes from Earth at a speed v = 0.5 c ?
(Use H₀ = 0.022 m/s · lightyear for Hubble's constant.)

A) 22.7 lightyears
B) 7.2 × 10⁸ lightyears
C) 6.8 × 10⁹ lightyears
D) 1.3 × 10⁷ lightyears

Question 6

A certain galaxy is 2.7 x 10⁹ lightyears from the Earth. How fast is it receding from us?
(Use H₀ = 0.022 m/s · lightyear for Hubble's constant.)

A) 0.5 c
B) 0.4 c
C) 0.3 c
D) 0.2 c

Question 7

How much energy is available when a 30 GeV electron strikes a stationary proton?

A) 7.6 GeV
B) 8.2 GeV
C) 8.6 GeV
D) 9.2 GeV)

Question 8

How much energy is available when two 30-GeV electrons collide head-on?

A) 30 GeV
B) 60 GeV
C) 90 GeV
D) cannot be determined from the information given

Question 9

What is the minimum energy required to produced an electron-position pair? A electron has a rest mass of 0.511 MeV/c².

A) 0.511 MeV
B) 1.022 MeV
C) 2.044 MeV
D) 3.066 MeV

Question 10

The rest energy of ? meson is about 140 MeV. What is the range of strong force?
(h = 6.63 × 10^-34 J·s)

A) 0.7 × 10^-15 m
B) 1.8 × 10^-15 m
C) 1.4 × 10^-15 m
D) 2.5 × 10^-15 m

Question 11

The rest energy of a Z⁰ boson is 91 GeV. Using the uncertainty principle, what is the approximate interaction time when it mediates weak interaction? (h = 6.63 × 10^-34 J·s)

A) 7.2 × 10^-27 s
B) 6.7 × 10^-26 s
C) 8.5 × 10^-29 s
D) 2.6 × 10^-27 s

Question 12

A ?⁺ and ?^- at rest annihilate to produce two gamma rays that fly in the opposite directions. What is the wavelength of each gamma ray? The rest energy of a muon is 106 MeV and
H = 6.63 × 10^-34 J·s.

A) 1.17 × 10^-14 m
B) 5.85 × 10^-15 m
C) 2.92 × 10^-15 m
D) 1.46 × 10^-15 m

Question 13

The rest energy of W⁺ boson is about 80 GeV. What is the range of weak interaction?
(h = 6.63 × 10^-34 J·s)

A) 2.5 × 10^-15 m
B) 2.5 × 10^-18 m
C) 2.5 × 10^-17 m
D) 2.5 × 10^-19 m

Question 14

Protons are baryons made up of three quarks.

Question 15

The reaction p + p ? p + ?⁺ + ? is allowed.

Question 16

The reaction e⁺ + ?⁰ ? p + v_e is not allowed.

Question 17

The K^- meson, with quark composition ${s }\overline{u}$ , has strangeness number S = +1.

Question 18

The D⁺ meson, with quark composition C = +1.
$c \bar{d}$ , has charm number

Question 19

Scientists were led to postulate the existence of the neutrino in order to

A) maintain the conservation of energy and of momentum in beta decay.
B) provide a mechanism for quark production.
C) account for alpha decay.
D) explain the intense radiation emitted by quasars.

Question 20

Which one of the following particles can interact with all 4 of the known forces?

A) muon
B) anti-proton
C) electron
D) neutrino
E) graviton

Question 21

What effect does an increase in the mass of the virtual exchange particle have on the range of the force it mediates?

A) decreases it
B) increases it
C) has no appreciable effect
D) decreases charged particle interactions and increases neutral particle interactions

Question 22

Which of the following is not considered a fundamental particle?

A) alpha particle
B) beta particle
C) muon
D) neutrino

Question 23

A distinctive feature of quarks is that they

A) are always observed singly, since they do not readily interact with other particles.
B) have zero charge.
C) have zero rest mass.
D) have fractional electric charge.