The doping of the NaI crystal with thallium
improves the scintillation efficiency by improving the light emission
due to the improved recombination by light emission of electrons and holes at the dopant site.
Why the NaI crystal is activated with thallium Tl when used as a scintillator?
Sodium Iodide crystals
have a very high luminescence (scintillation) efficiency
and are available in a wide variety of sizes and geometries that makes it the most widely used scintillator. Thallium-doped Sodium Iodide produces one of the highest signals in a PMT per amount of radiation absorbed.
Why activator is used in scintillation detector?
The electron drops into the impurity site, creates a neutral impurity configuration with its own set of excited states. De-excitation occurs quickly with a high probability of photon emission. The activator is
chosen so that the photon is visible
.
What is the role of TL in NaI TL detector?
Photomultiplier tubes (PMTs) are a photon detection device that
uses the photoelectric effect combined with secondary emission to convert light into an electrical signal
. A photomultiplier absorbs light emitted by the scintillator and re-emit it in the form of electrons via the photoelectric effect.
How does NaI detector work?
NaI(Tl) detectors
The thallium-activated sodium iodide detector, or NaI(Tl) detector,
responds to the gamma ray by producing a small flash of light, or a scintillation
. The scintillation occurs when scintillator electrons, excited by the energy of the photon, return to their ground state.
Can gamma rays be detected?
Gamma rays are
detected by observing the effects they have on matter
. A gamma ray can collide with an electron and bounce off it like a billiard ball (Compton scatter) or it can push an electron to a higher energy level (photoelectric ionization).
What is BGO detector?
Bismuth germanium oxide
is used in detectors in particle physics, aerospace physics, nuclear medicine, geology exploration, and other industries. Bismuth germanate arrays are used for gamma pulse spectroscopy. BGO crystals are also used in positron emission tomography detectors. … Large crystals can be obtained.
What is the basic principle of scintillation detector?
The basic principle is the same for every scintillation-type detector:
when radiation strikes the scintillator it causes it to give off photons of visible light
(that’s the scintillation part).
Which gas is filled in GM counter?
A Geiger counter (Geiger-Muller tube) is a device used for the detection and measurement of all types of radiation: alpha, beta and gamma radiation. Basically it consists of a pair of electrodes surrounded by a gas. The electrodes have a high voltage across them. The gas used is usually
Helium or Argon
.
What are the two most widely used scintillation phosphor?
Inorganic Scintillation Phosphors
They include lithium iodide (LiI), sodium iodide (NaI), cesium iodide (CsI), and zinc sulfide (ZnS). The most widely used scintillation material is
NaI(Tl) (thallium-doped sodium iodide)
.
Which detector is useful for V ray spectroscopy?
Common detector materials include
sodium iodide (NaI) scintillation counters
and high-purity germanium detectors. To accurately determine the energy of the gamma ray, it is advantageous if the photoelectric effect occurs, as it absorbs all of the energy of the incident ray.
Which detector has very good resolution and efficiency?
High purity germanium detector
has better resolution compared to the scintillation type of detector, Sodium iodide (NaI). The HPGe detector offers the advantage of resolving two closely located energy points and has the ability to detect a mixture of nuclear material.
How does a high purity germanium detector work?
Ionizing radiation enters the sensitive volume (germanium crystal) of the detector and interacts with the semiconductor material. High
-energy photon passing through the detector ionizes the atoms of semiconductor
, producing the electron-hole pairs.
What is a germanium detector?
Germanium detectors are
semiconductor diodes having a p-i-n structure in which the intrinsic (i) region is sensitive to ionizing radiation
, particularly x rays and gamma rays. … The detector is mounted in a vacuum chamber which is attached to or inserted into an LN
2
Dewar.
Why is photomultiplier tube used in a scintillation detector?
Two main types of device are used to do this; the photomultiplier tube and the photodiode. Photomultiplier tubes
are extremely good at converting light into an electrical signal
; electrical pulses can be obtained from a few hundred visible photons.
Is gamma radiation a wave or a particle?
Gamma radiation is
electromagnetic radiation
that is emitted by an unstable nucleus of an atom during radioactive decay. A nucleus in an unstable state may fall to a more stable state by the emission of energy as gamma radiation. The radiation has a dual nature, that of a wave and a particle with zero mass at rest.
