Question 1

A virtual Z particle is emitted in a weak interaction.The range of the interaction is

Accepted Answer

A) 1 * 10-14 m. 
B) 4 * 10-15 m. 
C) 5 * 10-16 m. 
D) 2 * 10-18 m. 
A) 1 * 10-14 m. 
B) 4 * 10-15 m. 
C) 5 * 10-16 m. 
D) 2 * 10-18 m. D

Question 2

A 5.00 MeV alpha particle is incident on a lead nucleus.Because of the Coulomb force between them,the alpha particle will only approach the nucleus to a minimum distance,rmin.Determine rmin.

Accepted Answer

A) 32.5 fm 
B) 47.2 fm 
C) 51.0 fm 
D) 60.3 fm 
A) 32.5 fm 
B) 47.2 fm 
C) 51.0 fm 
D) 60.3 fm B

Question 3

What is the wavelength of a photon that has the minimum energy necessary to produce an electron-positron pair?

Accepted Answer

A) 1.2 pm 
B) 2.4 pm 
C) 7.6 pm 
D) 91 nm 
E) 120 nm 
A) 1.2 pm 
B) 2.4 pm 
C) 7.6 pm 
D) 91 nm 
E) 120 nm A

Question 4

Suppose an eta meson (rest mass 547 MeV/c2)decays at rest into two photons.What is the wavelength of one of the photons?

Accepted Answer

A) 2.3 fm 
B) 2.3 pm 
C) 4.5 fm 
D) 4.5 pm 
E) More information is needed. 
A) 2.3 fm 
B) 2.3 pm 
C) 4.5 fm 
D) 4.5 pm 
E) More information is needed.

Question 5

A particle composed of two down quarks and one strange quark dds is a baryon with strangeness -1.Its total charge is

Accepted Answer

A) -3e. 
B) -2e. 
C) -1e. 
D) +1e. 
A) -3e. 
B) -2e. 
C) -1e. 
D) +1e.

Question 6

Which Feynman diagram shows an electron-proton scattering,e- + p $\rarr$ e- + p mediated by a photon exchange?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 7

In the Standard Model of elementary particle physics,how many fermions are there? Include both particles and anti-particles.

Accepted Answer

A) 3 
B) 4 
C) 12 
D) 24 
A) 3 
B) 4 
C) 12 
D) 24

Question 8

Of the fundamental bosons,which has the greatest mass?

Accepted Answer

A) W boson 
B) Z boson 
C) Higgs Boson 
D) gluon 
A) W boson 
B) Z boson 
C) Higgs Boson 
D) gluon

Question 9

The differential scattering cross section for particles to scatter by 60S1U1P1$\circ$S1S1P0 off a 1 mm2 area target is 1.5 * 10-18 m2/sr.A detector with an area of 2.0 cm2 is placed 1.0 m away from the target in order to detect particles that have been scattered at 60S1U1P1$\circ$S1S1P0.If 2 * 1018 particles hit the target every second,how many will strike the detector every second?

Accepted Answer

A) 100 
B) 300 
C) 600 
D) 1000 
E) 2000 
A) 100 
B) 300 
C) 600 
D) 1000 
E) 2000

Question 10

The closest distance,rmin to a gold nucleus an alpha particle can get is 38.9 fm.The kinetic energy of the alpha particle is

Accepted Answer

A) 5.85 MeV. 
B) 12.1 MeV. 
C) 7.24 MeV. 
D) 16.8 MeV. 
E) 0 MeV. 
A) 5.85 MeV. 
B) 12.1 MeV. 
C) 7.24 MeV. 
D) 16.8 MeV. 
E) 0 MeV.

Question 11

A 5.00 MeV alpha particle is incident on a lead nucleus.Because of the Coulomb force between them,the alpha particle will only approach the nucleus to a minimum distance,   .If the kinetic energy of the alpha particle is decreased,will the particle's distance of approach increase,or remain the same?

Accepted Answer

A) increase 
B) decrease 
C) remain the same 
A) increase 
B) decrease 
C) remain the same

Question 12

An alpha particle is incident on a lead nucleus.Because of the Coulomb force between them,the alpha particle will only approach the nucleus to a minimum distance of 32.5 fm.Determine the kinetic energy initial kinetic energy of the alpha particle.

Accepted Answer

A) 8.66 MeV 
B) 7.27 MeV 
C) 5.00 MeV 
D) 9.18 MeV 
A) 8.66 MeV 
B) 7.27 MeV 
C) 5.00 MeV 
D) 9.18 MeV

Question 13

Which of the following formed latest in the universe?

Accepted Answer

A) quarks 
B) protons and neutrons 
C) hydrogen atoms 
D) helium nuclei 
E) gluons 
A) quarks 
B) protons and neutrons 
C) hydrogen atoms 
D) helium nuclei 
E) gluons

Question 14

In the Feynman diagram for proton-neutron scattering shown in the figure,what is the virtual particle?

Accepted Answer

A) W+ 
B) KS1U1P1$\circ$S1S1P0 
C) g 
D) $\pi$- 
E) $\pi$+ 
A) W+ 
B) KS1U1P1$\circ$S1S1P0 
C) g 
D) $\pi$- 
E) $\pi$+

Question 15

In a scattering experiment,an alpha particle initially with 8.00 MeV of kinetic energy can approach the nucleus of an unknown element to within 20.0 fm.If the only force between the alpha particle and the nucleus of the unknown element is the electric force,then how close would it approach if its initial kinetic energy was 4.00 MeV instead?

Accepted Answer

A) 10.0 fm 
B) 20.0 fm 
C) 40.0 fm 
D) 80.0 fm 
A) 10.0 fm 
B) 20.0 fm 
C) 40.0 fm 
D) 80.0 fm

Question 16

Which particles are always comprised of some number of quarks greater than one?

Accepted Answer

A) fermions 
B) bosons 
C) hadrons 
D) gravitons 
A) fermions 
B) bosons 
C) hadrons 
D) gravitons

Question 17

What is the correct expression for the Planck mass?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 18

An electron-positron pair traveling towards each other with a speed of 0.95 c with respect to their center of mass,collide and annihilate according to e- + e+ $\rarr$ $\gamma$ + $\gamma$.Assuming the observer is at rest with respect to the center of mass of the electron-positron pair,what is the frequency of the photons?

Accepted Answer

A) 9.89 * 1019 Hz 
B) 9.02 * 1018 Hz 
C) 5.13 * 1020 Hz 
D) 7.25 * 1019 Hz 
E) 3.95 * 1020 Hz 
A) 9.89 * 1019 Hz 
B) 9.02 * 1018 Hz 
C) 5.13 * 1020 Hz 
D) 7.25 * 1019 Hz 
E) 3.95 * 1020 Hz

Question 19

The order of magnitude of the background radiation intensity at the end of the radiation-dominated era was 1011 W/m2.How long after the big bang did the radiation dominant era end?

Accepted Answer

A) 1010 s 
B) 1012 s 
C) 109 s 
D) 1011 s 
E) 1013 s 
A) 1010 s 
B) 1012 s 
C) 109 s 
D) 1011 s 
E) 1013 s

Question 20

As the early universe began to cool,what was the neutron/proton ratio at a temperature of 20 billion Kelvin?

Accepted Answer

A) 0.14 
B) 0.5 
C) 1.1 
D) 2.1 
E) 10.4 
A) 0.14 
B) 0.5 
C) 1.1 
D) 2.1 
E) 10.4

Exam 39: Elementary Particle Physics

A virtual Z particle is emitted in a weak interaction.The range of the interaction is

A 5.00 MeV alpha particle is incident on a lead nucleus.Because of the Coulomb force between them,the alpha particle will only approach the nucleus to a minimum distance,rmin.Determine rmin.

What is the wavelength of a photon that has the minimum energy necessary to produce an electron-positron pair?

Suppose an eta meson (rest mass 547 MeV/c2)decays at rest into two photons.What is the wavelength of one of the photons?

A particle composed of two down quarks and one strange quark dds is a baryon with strangeness -1.Its total charge is

Which Feynman diagram shows an electron-proton scattering,e- + p →\rarr→ e- + p mediated by a photon exchange?

In the Standard Model of elementary particle physics,how many fermions are there? Include both particles and anti-particles.

Of the fundamental bosons,which has the greatest mass?

The closest distance,rmin to a gold nucleus an alpha particle can get is 38.9 fm.The kinetic energy of the alpha particle is

A 5.00 MeV alpha particle is incident on a lead nucleus.Because of the Coulomb force between them,the alpha particle will only approach the nucleus to a minimum distance, .If the kinetic energy of the alpha particle is decreased,will the particle's distance of approach increase,or remain the same?

An alpha particle is incident on a lead nucleus.Because of the Coulomb force between them,the alpha particle will only approach the nucleus to a minimum distance of 32.5 fm.Determine the kinetic energy initial kinetic energy of the alpha particle.

Which of the following formed latest in the universe?

In the Feynman diagram for proton-neutron scattering shown in the figure,what is the virtual particle?

Which particles are always comprised of some number of quarks greater than one?

What is the correct expression for the Planck mass?

The order of magnitude of the background radiation intensity at the end of the radiation-dominated era was 1011 W/m2.How long after the big bang did the radiation dominant era end?

As the early universe began to cool,what was the neutron/proton ratio at a temperature of 20 billion Kelvin?

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A 5.00 MeV alpha particle is incident on a lead nucleus.Because of the Coulomb force between them,the alpha particle will only approach the nucleus to a minimum distance,r_min.Determine r_min.

Suppose an eta meson (rest mass 547 MeV/c²)decays at rest into two photons.What is the wavelength of one of the photons?

Which Feynman diagram shows an electron-proton scattering,e^- + p $\rarr$ e^- + p mediated by a photon exchange?

The closest distance,r_min to a gold nucleus an alpha particle can get is 38.9 fm.The kinetic energy of the alpha particle is

The order of magnitude of the background radiation intensity at the end of the radiation-dominated era was 10¹¹ W/m².How long after the big bang did the radiation dominant era end?