32 Questions
What is the principle of operation of an ionization chamber (IC)?
Ion pairs are produced as energy deposited in the medium by ionizing radiation, and ion pairs are collected by charged electrodes placed in the medium.
What factor determines the drift velocity of ion pairs toward the charged electrodes in a gas-filled ionization chamber?
Type and pressure of gas
Why is the voltage (V) between electrodes increased in a gas-filled ionization chamber?
To collect all ion pairs produced by impinging radiation
What happens if the voltage (V) remains below that required to produce additional ion pairs in a gas-filled ionization chamber?
Only ion pairs resulting directly from interactions of ionizing radiation with gas are received by the collecting electrodes
Which type of detector produces ion pairs from energy deposited by ionizing radiation?
Ionization chamber
What is the function of charged electrodes in an ionization chamber?
To collect the ion pairs produced by ionizing radiation
In an ionization chamber, what happens when radiation enters the chamber?
Electrical current is produced due to the ion pairs collected by electrodes
What is the purpose of a coaxial ionization chamber?
To detect radiation from low activity radioactive sources
In a pulse type ionization chamber, why is only a portion of the reduction in voltage utilized in forming the voltage pulse?
To ensure rapid response
Why is the use of a direct current (dc) amplifier unsatisfactory for small currents from an ionization chamber?
It introduces instability and zero drift
What is the purpose of using an electrometer with an ionization chamber?
To measure small currents more accurately
Which method is used to measure the amplified alternating current in a current type ionization chamber?
V-drop method
What happens as positive ions approach the case (cathode) in a pulse type ionization chamber?
+ve charge on the electrode increases
Why are heavier positive ions mentioned to migrate more slowly toward the negative case (cathode) in a pulse type ionization chamber?
Due to their larger mass and size
What happens if the kinetic energy of an alpha particle is dissipated completely within the collecting volume of an ionization chamber?
Ion pairs are produced and collected by electrodes
In a parallel-plate ionization chamber, what does the central electrode consist of?
A straight wire or wire loop charged positively with respect to surrounding cylindrical case
Ion pairs in a gas-filled ionization chamber are collected by charged electrodes placed in the medium.
True
The drift velocity of ion pairs toward the charged electrodes in a gas-filled ionization chamber depends on the type and pressure of the gas, and the voltage and distance between electrodes.
True
The voltage between electrodes in a gas-filled ionization chamber is increased until all ion pairs produced by impinging radiation are collected.
True
The voltage (V) remains below that required to produce additional ion pairs in a gas-filled ionization chamber.
True
Ion pairs that result directly from interactions of ionizing radiation with gas in the chamber migrate to the collecting electrodes.
True
The cross section of a pulse ionization chamber consists of only one central electrode.
False
The pulse type ionization chamber utilizes the entire reduction in voltage to form the voltage pulse.
False
The heavier positive ions migrate more rapidly toward the negative case (cathode) in a pulse type ionization chamber.
False
When radiation enters the ionization chamber, it results in the production of electrical current or V pulses as ion pairs are collected by the electrodes.
True
If the voltage (V) remains below that required to produce additional ion pairs in a gas-filled ionization chamber, no electrical current will be produced.
True
If the kinetic energy of an alpha particle is dissipated completely within the collecting volume of an ionization chamber, a specific number of ion pairs are produced.
True
The voltage (V) between electrodes is increased in a gas-filled ionization chamber to facilitate the migration of positive ions toward the central electrode.
False
The charged electrodes in an ionization chamber serve to create an electric field that facilitates the collection of ion pairs by inducing an electrical current.
False
The principle of operation of an ionization chamber involves the production of alternating current by the collection of electrons at the anode.
False
The purpose of using an electrometer with an ionization chamber is to measure small currents accurately by converting the signal from the ionization chamber into direct current (dc).
False
A coaxial ionization chamber typically consists of a central electrode in the form of a straight wire or wire loop charged negatively with respect to the surrounding cylindrical case.
False
Test your knowledge on radiation detectors and quantitative measurements. Learn about the principles of operation and properties of different types of radiation detectors and image receptors used with ionizing radiation.
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