Particle Accelerators-
A particle accelerator is a machine for increasing the kinetic energy of electrically charged particles.
Types of particle accelerators-
There are three types of accelerators
i.
Static Accelerator
ii.
Linear Accelerator
iii.
Circular Accelerator
Here our attention is focused on only
Circular accelerator.
Circular Accelerator-
There are seven types of circular accelerators-
1. Cyclotron (Fixed Frequency Cyclotron)
It is used for
acceleration of positive charge particles like protons, deutrons, alpha
particles etc.
It based on the principle of Magnetic Resonance.
2. Synchro-Cyclotron (Frequency Modulated Cyclotron)
3. Betatron
It is used for
acceleration of electrons (beta particles).
It employed no electric
field.
It employed changing magnetic field which produce an induced e.m.f. which is responsible for the acceleration of electrons.
4. Electron Cyclotron
5. Proton Cyclotron
6. Alternating Gradient Cyclotron
7. Omnitron
Geiger-Muller Counter-
It based on the principle that gases
becomes electrical conductors due to ionization produced by their exposure to
radioactive or nuclear radiation.
MCQS
1: The angular frequency of a cyclotron is
independent of
(a) Speed
(b) Mass
(c) Magnetic field
(d) Charge
Answer: (a)
2: The maximum kinetic energy of the
positive ion in the cyclotron is
(a) qBR2/2m
(b) q2B2R2/2m
(c) q2B2R2/m
(d) qBR/m
Answer: (b)
3: Cyclotron cannot accelerate
(a) Electrons
(b) Neutrons
(c) Positive ions
(d) Both
(a) and (b)
Answer: (d) Both (a) and (b)
4: The cyclotron frequency of an electron
grating in a magnetic field of 1 T is approximately
(a) 28 MHz
(b) 280 MHz
(c) 2.8 GHz
(d) 28 GHz
Answer: (d)
5: Suppose a cyclotron is operated at an
oscillator frequency of 12 MHz and a dee radius of 53cm. What is the resulting
kinetic energy of the deuterons?
(a) 16.6 MeV
(b) 12 MeV
(c) 15 MeV
(d) 14 MeV
Answer: (a)
6: Cyclotron can be used in
(a)
Particle therapy to treat cancer
(b)
Source of high energy beam for a nuclear physics experiment
(c)
Produce short-lived positron-emitting isotopes for PET imaging
(d)
All the above
Answer: (d)
7: A proton of energy 100 eV is moving
perpendicular to a magnetic field
(a) 2.80 x 106
(a) 9.6
x 103
(c) 5.6 x 106
(d) 1.76
x 106
Answer: (b)
8: A cyclotron can accelerate
(a) β particles
(b) α
particles
(c) High-velocity gamma rays
(d) High-velocity X-rays
Answer: (b)
9: Which of the following is preferred for
accelerating electrons?
(a) Betatron
(b) Cyclotron
(c) Synchrotron
(d) None of above
Answer: (b)
10: How much pressure is in metal chamber
of Geiger Muller Counter?
(a) 100 atm
(b) 0.1 atm
(c) 10 atm
(d) 1 atm
Answer: b
11: Which of the following is cyclic
accelerator?
(a) betatron
(b) synchrocyclotron
(c) synchrotron
(d) all of these
Answer: d
12: Which of the following accelerate the
particles in cyclotron?
(a) Electric field
(b)
Magnetic field
(c) Both (a) and (b)
(d) None of
these
Answer: a
13: Which of the following deflects the
particle in cyclotron?
(a) Electric field
(b) Magnetic field
(c) None of these
(d) Both (a) and (b)
Answer: b
14: Betatron works on the principle of
(a) Superposition
(b)
Ampere’s law
(c) electromagnetic induction
(d) self-induction
Answer: c
15: In betatron, the electron moves in
orbit
(a) of constant radius
(b) of variables
radius
(c) of radius as r2
(d) of radius
as
Answer: a
16: In Betatron, the electrons are
injected during
(a) decreasing magnetic field
(b) peak magnetic field
(c) increasing magnetic field
(d) zero magnetic field
Answer: c
17: The vacuum chamber are coated with
silver to
(a) avoid any insulation
(b) avoid eddy
currents
(c) increase the conductivity
(d) none of these
Answer: b
18: For proton acceleration up to 30 GeV, which of the following is used?
(a) Cyclotron
(b) Betatron
(c) Betatron
(d)
Cosmotron
Answer: d
19: In synchrocyclotron, the frequency is
(a) varied
(b)
kept constant
(c) varies as q 2
(d)
varies as r 2
Answer: a
20: ‘When nuclear radiations pass through
the counter, gas ionization is produced.’ This is the principle of which of the
following detectors?
(a) Proportional counter
(b) Flow counter
(c) Geiger Muller counter
(d) Scintillation counter
Answer: c
Explanation: ‘When
nuclear radiations pass through, gas ionization is produced.’ This is the
principle of which of Geiger Muller counter. It is used to measure the intensity
of radioactive radiation.
21: Which of the following acts as
quenching gas in G.M. counter?
(a) Alcohol
(b)
Argon gas
(c) Krypton
(d) Hydrogen
Answer: a
Explanation: Alcohol acts
as quenching gas in G.M. counter. It is present in a gas tight envelope along
with the electrodes.
22: Which of the following acts as
ionising gas in Geiger Muller (G.M.) counter?
(a) Alcohol
(b)
Argon gas
(c) Krypton
(d) Hydrogen
Answer: b
Explanation: Argon gas acts as an ionising
gas in G.M. counter. It is present in a gas type envelope along with the
electrodes.
23: Geiger counter is a device to detect
(a) Mass
(b) Momentum
(c) Charge
(d) Radiation
Answer: d
24: Normally G. M. counter uses potential
different of
(a) 10 Volt
(b) 100 Volt
(c) 1000Volt
(d) 5000Volt
Answer: c
25: Giger- Muller counter detects
(a) Photons
(b) Neutrons
(c) Alpha Particles
(d) All the above
Answer: c
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