Nuclear Detectors and Accelerators, 20 mcqs on it with explained answers
Here are 20 MCQs on Nuclear Detectors and Accelerators with explained answers:
1. Which type of radiation can a Geiger-Muller counter detect?
a) Only alpha
b) Only beta
c) Only gamma
d) Alpha, beta, and gamma
**Answer:** d) Alpha, beta, and gamma. Geiger-Muller counters detect all three types by ionization of gas inside the tube [1].
2. What is the primary function of a cloud chamber?
a) Absorb radiation
b) Detect charged particles by visual tracks
c) Measure radiation energy
d) Filter neutrons
**Answer:** b) Detect charged particles by visual tracks. Vapor condenses along ionized particle paths making tracks visible [1].
3. Which of the following is the main component of a Geiger-Muller counter?
a) Photomultiplier tube
b) Geiger-Muller tube
c) Cloud chamber
d) Scintillation crystal
**Answer:** b) Geiger-Muller tube; it is a gas-filled tube that detects ionizing radiation [1].
4. What does a scintillation counter detect?
a) Only beta particles
b) Only gamma rays
c) Alpha, beta, and gamma particles
d) Only neutrons
**Answer:** c) Alpha, beta, and gamma particles by converting radiation to light pulses [1].
5. Which accelerator type uses magnetic fields to bend particle paths into circles?
a) Linear accelerator (LINAC)
b) Cyclotron
c) Van de Graaff generator
d) Electrostatic accelerator
**Answer:** b) Cyclotron; it uses magnetic fields to keep particles on a spiral path [2].
6. Why are LINAC tube lengths progressively longer along the accelerator?
a) To keep frequency constant
b) To reduce energy loss
c) To increase particle time in tube
d) Due to weakening electric fields
**Answer:** a) The frequency of alternating voltage can be constant because particles gain speed and longer tubes keep timing correct [3].
7. What is the fundamental principle behind particle accelerators?
a) Electrostatic attraction
b) Utilizing gravitational forces
c) Using electromagnetic fields to accelerate charged particles
d) Nuclear fission reactions
**Answer:** c) Electromagnetic fields propel charged particles to high speeds [2].
8. The Large Hadron Collider primarily accelerates:
a) Electrons
b) Protons
c) Neutrons
d) Positrons
**Answer:** b) Protons; it uses proton-proton collisions for physics experiments [3].
9. What characteristic of a particle does a cloud chamber visualize?
a) Its energy
b) Its mass
c) Its trail or path
d) Its charge
**Answer:** c) The track left as vapor condenses along ionized paths [1].
10. Which detector measures energy by converting radiation to light then to electrical signal?
a) Ionization chamber
b) Proportional counter
c) Scintillation counter
d) Geiger counter
**Answer:** c) Scintillation counter; uses scintillator and photomultiplier tube [1].
11. What kind of particles are accelerated in a cyclotron?
a) Neutral particles
b) Charged particles
c) Photons only
d) Neutrons
**Answer:** b) Charged particles, as cyclotrons use electromagnetic fields [3].
12. Which detector is most sensitive to low-energy beta and gamma radiation?
a) Ion chamber and scintillation
b) Geiger-Muller and ion chamber
c) Proportional counter and cloud chamber
d) Scintillation and cloud chamber
**Answer:** a) Ion chamber and scintillation counters are sensitive to low-energy beta/gamma [4].
13. What happens to the particle path in a synchrotron?
a) Straight line
b) Circular with increasing radius
c) Circular with fixed radius
d) Zigzag path
**Answer:** c) Circular with fixed radius due to increasing magnetic field to keep particles on track [2].
14. The output of a Geiger counter is typically:
a) Electrical pulse
b) Visual light spot
c) Mechanical dial reading
d) Audio clicks or counts
**Answer:** d) Audio clicks or counts indicating radiation events [1].
15. What is the role of the photomultiplier tube in a scintillation counter?
a) Detects particles directly
b) Converts light photons to electrical signals
c) Amplifies charged particles
d) Produces scintillation light
**Answer:** b) Converts light flashes from scintillator to electrical signals [1].
16. What is one advantage of particle accelerators?
a) They reduce atomic mass
b) Create new particles by high-energy collisions
c) They generate electrical power
d) Filter neutral particles
**Answer:** b) High energies allow creation of particles not normally found [2].
17. The ionization chamber functions by:
a) Collecting electrons produced by ionization of gas
b) Creating visual tracks
c) Producing light flashes
d) Focusing particle beams
**Answer:** a) It collects ionization electrons to produce a measurable current [4].
18. What is the basic working principle of a proportional counter?
a) Counting ions only
b) Producing proportional electrical pulses with particle energy
c) Visualizing particle tracks
d) Absorbing radiation
**Answer:** b) It gives electrical pulses proportional to energy deposited by radiation [4].
19. Solid state detectors detect radiation by:
a) Ionizing gas
b) Electron-hole pair creation in semiconductor
c) Producing vapor tracks
d) Emitting photons
**Answer:** b) Radiation creates electron-hole pairs that are collected as current [5].
20. What is the main role of magnetic fields in circular accelerators?
a) To accelerate particles in a straight line
b) To bend particle paths, keeping them in a circular orbit
c) To focus laser beams
d) To detect particles
**Answer:** b) Magnetic fields bend charged particles to keep them in circular orbits [2].
20 more
Here are 20 more MCQs on Nuclear Detectors and Accelerators with explained answers:
1. What is dead time in a Geiger-Muller counter?
a) Time when device is off
b) Time after each event when it cannot detect new events
c) Time before detection starts
d) Time between feeding power
**Answer:** b) Dead time is the period after detecting a particle during which the counter cannot detect another [1].
2. Which accelerator component is responsible for focusing the particle beam?
a) Dipole magnets
b) Quadrupole magnets
c) RF cavities
d) Ion pumps
**Answer:** b) Quadrupole magnets focus the beam, while dipole magnets bend it [2].
3. Which detector uses high purity germanium crystals?
a) Scintillation detector
b) Semiconductor detector
c) Ionization chamber
d) Geiger counter
**Answer:** b) Semiconductor detectors use germanium crystals for precise energy resolution [3].
4. The range of alpha particles in air is typically:
a) A few millimeters
b) Several centimeters
c) Several meters
d) Unlimited
**Answer:** b) Several centimeters; alpha particles have short range due to large mass and charge [4].
5. The power source of a linear accelerator is:
a) DC voltage
b) RF electromagnetic waves
c) Magnetic fields
d) Steam turbines
**Answer:** b) Oscillating RF waves accelerate particles in the LINAC [5].
6. What is the primary process generating gamma rays in nuclear reactors?
a) Alpha decay
b) Nuclear fission and subsequent de-excitation
c) Beta decay only
d) Photoelectric effect
**Answer:** b) Gamma rays arise from de-excitation of nuclei after fission [1].
7. What is the typical pressure inside a Geiger-Muller tube?
a) Atmosphere
b) Lower than atmospheric, a few torr
c) High pressure multiple atmospheres
d) Vacuum
**Answer:** b) Low pressure inert gas, typically a few torr, for proper ionization [1].
8. Synchrotron radiation is emitted when particles:
a) Tunneling
b) Accelerate in a magnetic field
c) Collide
d) Decay
**Answer:** b) Charged particles emit radiation when accelerated in curved paths by magnetic fields [2].
9. An ionization chamber operating in the saturation region means:
a) Maximum number of ion pairs collected
b) No ions collected
c) Unstable readings
d) Low voltage operation
**Answer:** a) All ion pairs produced by radiation are collected, giving current proportional to radiation intensity [6].
10. What limits the sensitivity of a photomultiplier tube?
a) Number of dynodes
b) Supply voltage stability
c) Photon wavelength matching
d) Dark current noise
**Answer:** d) Dark current and noise limit sensitivity by producing false signals [6].
11. Which of the following accelerators can achieve the highest energies?
a) Cyclotron
b) Synchrotron
c) Van de Graaff generator
d) Linear accelerator (LINAC)
**Answer:** b) Synchrotrons, especially with very large circumference (e.g., LHC) [2].
12. The first artificial nuclear reaction was discovered using:
a) Van de Graaff generator
b) Cyclotron
c) Linear accelerator
d) Cloud chamber
**Answer:** b) Cyclotron; Ernest Lawrence’s cyclotron observed artificial nuclear reactions [2].
13. The material inside a scintillator is usually:
a) Gas
b) Organic or inorganic crystal or liquid
c) Metal
d) Semiconductor
**Answer:** b) Scintillators can be organic liquids, plastics, or inorganic crystals like NaI [6].
14. Which of these shields gamma radiation most effectively?
a) Paper
b) Lead
c) Aluminum
d) Plastic
**Answer:** b) Lead, due to high density and atomic number, effectively absorbs gamma rays [1].
15. The inefficiency of detecting particles due to dead time in a GM counter causes:
a) Underestimation of count rate at high radiation levels
b) Overestimation of radiation intensity
c) Accurate counts always
d) Random counts
**Answer:** a) Dead time causes missed events, underestimating count rate especially at high intensity [1].
16. The magnetic rigidity of a particle beam is defined as:
a) Charge times velocity
b) Momentum to charge ratio
c) Diameter of beam
d) Energy squared
**Answer:** b) Magnetic rigidity is momentum divided by charge, determines bending radius in magnetic field [2].
17. What type of collisions occur inside particle colliders?
a) Nuclear fusion
b) Electromagnetic scattering
c) High-energy particle collisions to study fundamental particles
d) Chemical reactions
**Answer:** c) They create conditions for particle interactions revealing fundamental physics [2].
18. Particle beams are often extracted from accelerators and focused using:
a) Lasers
b) Quadrupole magnets
c) Cyclotrons
d) Ion pumps
**Answer:** b) Quadrupole magnets concentrate beams to tight spots for experiments [5].
19. The term "bremsstrahlung" refers to:
a) Radiation caused by deceleration of charged particles
b) Nuclear decay
c) Ionization losses
d) Particle collisions
**Answer:** a) It is emitted when charged particles slow down in matter, common in electron accelerators [3].
20. Which is true about detectors used in high-energy physics experiments?
a) Use multiple technologies combined for particle identification
b) Only use cloud chambers
c) None can detect neutrinos
d) Only measure energy, not direction
**Answer:** a) Multiple detectors like calorimeters, trackers, and time-of-flight systems work together [6].
