Nuclear Detectors and Accelerators, 40 mcqs with explained answers
Here are 40 multiple-choice questions (MCQs) on Nuclear Detectors and Accelerators with explained answers for your competitive exam preparation:
1. Which detector is commonly used for detecting alpha particles?
- A) Geiger-Müller counter
- B) Scintillation detector
- C) Cloud chamber
- D) Semiconductor detector
Answer: C) Cloud chamber
Explanation: Cloud chambers visualize the tracks of charged particles like alpha particles.
2. What is the main principle behind a Geiger-Müller counter?
- A) Scintillation
- B) Ionization in gas
- C) Semiconductor junction
- D) Nuclear reaction
Answer: B) Ionization in gas
Explanation: GM counter detects ionizing radiation by gas ionization and avalanche multiplication.
3. Scintillation detectors convert radiation into:
- A) Heat
- B) Electric current
- C) Light photons
- D) Magnetic field
Answer: C) Light photons
Explanation: Scintillators emit light when struck by ionizing radiation.
4. Which particle accelerator achieves the highest energies in fundamental physics?
- A) Cyclotron
- B) Linear accelerator
- C) Synchrotron
- D) Betatron
Answer: C) Synchrotron
Explanation: Synchrotrons accelerate particles to very high energies by synchronizing the magnetic field.
5. The Betatron is mainly used to accelerate:
- A) Protons
- B) Electrons
- C) Neutrons
- D) Alpha particles
Answer: B) Electrons
Explanation: Betatron accelerates electrons using changing magnetic fields.
6. Which accelerator type uses a constant magnetic field and variable RF frequency?
- A) Cyclotron
- B) Synchrotron
- C) Linear accelerator
- D) Betatron
Answer: B) Synchrotron
Explanation: Synchrotrons adjust RF and magnetic fields to keep particles in stable orbits.
7. Semiconductor detectors operate based on:
- A) Ionization in gas
- B) Light emission
- C) Electron-hole pair generation
- D) Heat conduction
Answer: C) Electron-hole pair generation
Explanation: Radiation produces charge carriers in semiconductor materials.
8. Which detector provides excellent energy resolution?
- A) Geiger-Müller counter
- B) Semiconductor detector
- C) Cloud chamber
- D) Scintillation detector
Answer: B) Semiconductor detector
Explanation: Semiconductor detectors have superior energy resolution to identify particles.
9. The time-of-flight method in accelerators is used to measure:
- A) Particle energy
- B) Particle velocity
- C) Particle charge
- D) Particle mass
Answer: B) Particle velocity
Explanation: Time-of-flight measures particle velocity by timing travel between two points.
10. Cyclotrons cannot accelerate particles beyond:
- A) Speed of light
- B) Non-relativistic speeds accurately
- C) Thermal speeds
- D) Speed of sound
Answer: B) Non-relativistic speeds accurately
Explanation: As particles approach relativistic speeds, cyclotron frequency changes preventing synchronization.
11. What is the main advantage of a Linear Accelerator (LINAC)?
- A) Compact size
- B) Simple construction
- C) No relativistic limit on particle energy
- D) Continuous acceleration path
Answer: C) No relativistic limit on particle energy
Explanation: LINACs can accelerate particles to relativistic speeds straightforwardly.
12. Ionization chambers measure:
- A) Total radiation dose
- B) Particle tracks
- C) Particle speed
- D) Number of photons
Answer: A) Total radiation dose
Explanation: Ionization chambers integrate ion pairs to measure ionizing radiation dose.
13. Which device is used to study nuclear reactions by accelerating ions into targets?
- A) Cyclotron
- B) Cloud chamber
- C) Geiger counter
- D) Magnetron
Answer: A) Cyclotron
Explanation: Cyclotrons accelerate ions to induce nuclear reactions in targets.
14. What is the working gas commonly used in Geiger-Müller counters?
- A) Helium
- B) Argon
- C) Neon
- D) Xenon
Answer: B) Argon
Explanation: Argon is ionized easily and commonly used in GM tubes.
15. Which accelerator uses RF cavities to accelerate charged particles?
- A) Cyclotron
- B) Synchrotron
- C) Betatron
- D) LINAC
Answer: D) LINAC
Explanation: LINACs use radio frequency cavities to accelerate particles in a straight line.
16. The damage caused by radiation in semiconductor detectors mainly affects:
- A) Scintillation efficiency
- B) Energy resolution
- C) Charge collection
- D) Ionization rate
Answer: C) Charge collection
Explanation: Radiation damage creates defects that trap charge carriers reducing efficiency.
17. In accelerator physics, beam focusing is achieved using:
- A) Electric fields only
- B) Magnetic fields only
- C) Magnetic quadrupole lenses
- D) RF cavities
Answer: C) Magnetic quadrupole lenses
Explanation: Quadrupole magnets focus beams by shaping magnetic fields.
18. Which particle is commonly accelerated in cyclotrons?
- A) Electrons
- B) Protons
- C) Neutrons
- D) Photons
Answer: B) Protons
Explanation: Protons and other ions are suited for acceleration in cyclotrons.
19. Scintillation counters often use which material as scintillator?
- A) Sodium iodide (NaI)
- B) Silicon
- C) Argon gas
- D) Lead
Answer: A) Sodium iodide (NaI)
Explanation: NaI crystals emit visible light efficiently under radiation.
20. Which detector type allows visualization of particle tracks?
- A) Geiger-Müller counter
- B) Cloud chamber
- C) Semiconductor detector
- D) Ionization chamber
Answer: B) Cloud chamber
Explanation: Cloud chambers show condensation trails from charged particles.
21. The maximum energy attainable in a cyclotron is limited by:
- A) Magnetic field strength and radius
- B) RF frequency only
- C) Particle charge only
- D) Vacuum quality
Answer: A) Magnetic field strength and radius
Explanation: Maximum energy depends on the magnetic field and the cyclotron’s size.
22. The relativistic effect causes frequency in a cyclotron to:
- A) Increase
- B) Decrease
- C) Remain constant
- D) Vary randomly
Answer: B) Decrease
Explanation: As particles approach light speed, their mass appears to increase, lowering frequency.
23. In a scintillation detector, the photomultiplier tube (PMT) converts:
- A) Light photons to electrical signals
- B) Electrical signals to light
- C) Heat to light photons
- D) Magnetic signals to electrical signals
Answer: A) Light photons to electrical signals
Explanation: PMTs amplify the light emitted by scintillator into electrical pulses.
24. A cloud chamber operates by:
- A) Ionization of gas producing light
- B) Super-saturated vapor condensing on ions
- C) Electric discharge
- D) Magnetic deflection
Answer: B) Super-saturated vapor condensing on ions
Explanation: Charged particles create ions, which act as nuclei for vapor condensation, leaving visible tracks.
25. The synchrotron radiation is produced by:
- A) Accelerating charged particles
- B) Decelerating charged particles
- C) Moving neutral particles
- D) Nuclear fission
Answer: A) Accelerating charged particles
Explanation: Charged particles emit electromagnetic radiation when accelerated in curved paths.
26. The energy resolution of detectors depends primarily on:
- A) Noise and signal strength
- B) Particle mass
- C) Detector size only
- D) Magnetic field
Answer: A) Noise and signal strength
Explanation: Better signal-to-noise ratio leads to improved energy resolution.
27. The first nuclear accelerator was:
- A) Betatron
- B) Cyclotron
- C) Synchrotron
- D) LINAC
Answer: B) Cyclotron
Explanation: Cyclotron was the earliest type of particle accelerator.
28. The function of an ionization chamber is to:
- A) Detect neutrons only
- B) Measure ionizing radiation dose
- C) Visualize particle tracks
- D) Accelerate particles
Answer: B) Measure ionizing radiation dose
Explanation: Ionization chambers collect charge from ion-created pairs for dose measurement.
29. In a LINAC, the acceleration of particles is achieved by:
- A) Magnetic fields around the path
- B) Electric fields in RF cavities
- C) Electrostatic fields
- D) Chemical reactions
Answer: B) Electric fields in RF cavities
Explanation: LINAC uses oscillating electric fields to accelerate charged particles.
30. Cherenkov radiation occurs when:
- A) Particles exceed speed of light in vacuum
- B) Particles exceed speed of light in a medium
- C) Particles slow down in vacuum
- D) Nuclear reactions occur
Answer: B) Particles exceed speed of light in a medium
Explanation: Cherenkov radiation is produced by charged particles moving faster than light speed in a dielectric medium.
31. A Geiger-Müller tube cannot:
- A) Measure energy of radiation accurately
- B) Detect alpha particles
- C) Detect gamma rays
- D) Operate in a magnetic field
Answer: A) Measure energy of radiation accurately
Explanation: GM counters provide count rate but poor energy resolution.
32. Beam collimation in accelerators is used to:
- A) Increase particle energy
- B) Keep beam tightly focused
- C) Increase beam divergence
- D) Decrease beam intensity
Answer: B) Keep beam tightly focused
Explanation: Collimators restrict beam spread for precision.
33. The Alvarez LINAC uses which material for its drift tubes?
- A) Aluminum
- B) Copper
- C) Steel
- D) Tungsten
Answer: B) Copper
Explanation: Copper is used due to good conductivity and machining properties.
34. Which of the following detectors is best suited for neutron detection?
- A) Geiger-Müller counter with boron trifluoride
- B) Scintillator made from NaI
- C) Silicon semiconductor detector
- D) Cloud chamber
Answer: A) Geiger-Müller counter with boron trifluoride
Explanation: BF3 gas reacts with neutrons to produce charged particles detected by GM counter.
35. To increase the voltage in a Van de Graaff generator, the charge is carried by:
- A) Electrons in a wire
- B) Charged belt
- C) Magnetic field
- D) Neutrons
Answer: B) Charged belt
Explanation: A moving belt carries charge to the dome generating high voltage.
36. The main difference between linear and circular accelerators is:
- A) Particle types accelerated
- B) Path shape and acceleration method
- C) Detector used
- D) Power source
Answer: B) Path shape and acceleration method
Explanation: LINACs accelerate particles in straight path; circular accelerators use circular tracks.
37. Which accelerator uses alternating electric fields to accelerate particles in gaps?
- A) Cyclotron
- B) LINAC
- C) Betatron
- D) Synchrotron
Answer: B) LINAC
Explanation: Particles gain energy crossing gaps where RF fields alternate.
38. Magnetic rigidity in accelerators is:
- A) Magnetic field strength
- B) Momentum to charge ratio $$ \left(\frac{p}{q}\right) $$
- C) Field gradient
- D) Radius of curvature
Answer: B) Momentum to charge ratio $$ \left(\frac{p}{q}\right) $$
Explanation: Magnetic rigidity reflects how difficult it is to bend particle path using magnetic fields.
39. Which characteristic negatively affects the performance of a semiconductor detector?
- A) Low temperature operation
- B) Radiation damage
- C) Clean contacts
- D) Good resolution
Answer: B) Radiation damage
Explanation: Damage creates defects trapping carriers reducing detector efficiency.
40. Which radiation detector provides both spatial and temporal information about radiation?
- A) Geiger counter
- B) Scintillation detector with PMT arrays
- C) Ionization chamber
- D) None
Answer: B) Scintillation detector with PMT arrays
Explanation: Arrays give location (spatial) and timing of photon detection.
