Particle Detector

Define?

The presence and characteristics of subatomic particles like electrons, protons, neutrons, and other elementary particles are detected and measured using a particle detector, a piece of equipment used in science. Particle, nuclear, astro, and high energy physics are just a few of the scientific disciplines that employ particle detectors. Its main job is to recognize and quantify the properties of individual particles, including their charge, energy, momentum, mass, and decay products. These are needed to study the fundamental nature of matter, unravel the mysteries of the universe and test theoretical models.

Main Types:

The classifications that follow can be used to classify the various types:

Ionization Detectors:

These instruments detect the ionization that charged particles cause as they move through a medium. These include:

a) Gas ionization detectors (e.g. Geiger-Muller counters, proportional counters, drift chambers).
b) Solid-state ionization detectors (e.g. silicon band detectors, silicon drift detectors).

Scintillation Detectors:

These detectors use shimmering materials that emit light when particles interact with them. These include:

a) Inorganic scintillators (e.g. sodium iodide, cesium iodide).
b) Organic scintillators (e.g. liquid scintillators, plastic).

Cherenkov Detectors:

These use Cherenkov radiation, which occurs when charged particles pass through a medium faster than the speed of light in that medium. These include:

a) Cherenkov water sensors (for example, Super-Kamiokande).
b) Airgel Cherenkov detectors.

Time-of-flight detectors:

These detectors determine how long it takes a particle to traverse a specific distance, enabling the identification of them and the calculation of their velocity.

Neutrino Detectors:

These are specifically designed to detect neutrinos, which are weakly interacting particles. These include:

a) Liquid scintillation detectors (e.g. Minerva, NOvA).
b) Cherenkov water sensors (for example, Super-Kamiokande).

Types of Sub-Detectors:

The apparatus used in particle physics nowadays is made up of layers of sub-detectors, each of which is tailored to a specific kind of particle or feature. There are 3 main types of sub-detectors:

1)Tracking Device: Detects and displays the path of the particle
2)Calorimeter: Stops, absorbs, and measures the energy of a particle.
3)Particle Identification Detector: Determines the type of particles using various methods.

The detector typically includes a magnetic field to aid in identifying particles created by collisions. The particle usually moves in a straight line, but in the presence of a magnetic field, its trajectory bends into a curve. From the curvature of the trajectory, physicists can calculate the particle's momentum, which helps determine its type. Extremely high momentum particles travel in nearly straight lines, whereas low momentum particles travel in tightly wound spirals.

1)Tracking device:

Tracking equipment detects the paths of electrically charged particles by following the trails they leave behind. There are similar everyday effects: high-flying planes seem invisible, but under certain circumstances, you can see the trails they leave behind. Similarly, when particles pass through suitable substances, the interaction of the passing particle with atoms of the substance itself can be detected.

Most modern tracking devices do not allow you to see particle trails directly. Instead, they produce small electrical signals that can be recorded as computer data. The computer program then reconstructs the traces recorded by the detector and displays them on the screen. They can record the curvature of a particle's trajectory (created in the presence of a magnetic field), from which the particle's momentum can be calculated. This is useful for particle identification. Muon cameras are tracking devices used to detect muons. These particles have little interaction with matter and can travel long distances through meters of dense material. Muons can traverse successively detectable layers like a ghost moving through a wall. 

2)Calorimeters:

The calorimeter measures the energy lost by a particle passing through it. It is usually designed to completely stop or "absorb" most of the particles resulting from a collision, giving them all of their energy into the detector. Calorimeters typically consist of layers of a high-density "passive" or "absorbent" material (such as lead) alternating with layers of an "active" medium such as solid lead-glass or liquid argon. The energy of light particles, including electrons and photons, as they interact with electrically charged particles in matter is measured using electromagnetic calorimeters. Hadrons, which are quark-containing particles like protons and neutrons, interact with atomic nuclei to produce energy, which is measured using hadron calorimeters. Except for muons and neutrinos, most known particles can be stopped by thermometers.

3)Particle Identification Detectors:

By monitoring the radiation that charged particles emit, two identification techniques are possible:

1. Cherenkov radiation:

When a charged particle moves through a particular medium more quickly than light, Cherenkov radiation is the light that results. The light comes out at a certain angle, depending on the speed of the particle. In combination with measuring the momentum of the particle, the velocity can be used to determine the mass and thus identify the particle.

     2. Transition Radiation:

This radiation is produced by a rapidly charged particle when it crosses a boundary between two electrical insulators of different resistance to electrical current. This phenomenon is related to the energy of the particle and distinguishes between different types of particles.

How the Detector Works:

Its job is to record and display particle explosions resulting from collisions at accelerators. Physics researchers can identify the type of particle by learning about its speed, mass, and electrical charge. The task of particle physicists to identify a particle that has passed through a detector is similar to examining animal footprints in mud or snow. In animal footprints, factors such as the size and shape of the markings, stride length, general pattern, direction, and depth of impressions can reveal the type of animal that passed first. The particles leave clues in detectors in a similar way that physicists can decipher.

Applications:

They have a wide variety of applications in various scientific disciplines. Some of the main applications are:

Particle Physics: It experiments to study the fundamental building blocks of matter, the forces they control, and the properties of particles. They are used to identify and measure particles, study particle interactions and test theoretical models. They have played an important role in major discoveries such as the Higgs boson at the Large Hadron Collider (LHC).

Nuclear Physics: It experiments to study the structure and properties of atomic nuclei. They help identify and measure the particles emitted during nuclear reactions, providing insights into nuclear structure, decay processes, and nuclear reactions.

Medical Imaging: They are used in medical imaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT). These detectors detect the radiation emitted by radioactive tracers in the body, allowing the visualization and diagnosis of various diseases and conditions.

Radiation Control and Security: They are used for radiation control and security. They are used in environments where radiation is present, such as nuclear power plants, research centers, and medical facilities. These detectors help measure and monitor radiation levels, keeping workers and the environment safe.

Astrophysics and Cosmology: They are used in astrophysics and cosmology to study cosmic rays, high-energy particles that come from space. They help identify and measure the energy and properties of cosmic rays, providing valuable insights into the composition of the universe, high-energy phenomena, and the nature of dark matter.

Environmental Control: They are used in environmental studies to measure and monitor various types of particles, including air pollutants, radioactive particles, and aerosols. They provide valuable data to understand the impact of human activities on the environment and assess air quality.

Archeology and Geology: These are used in archeology and geology for radiocarbon dating and studying the composition of geological samples. They help determine the age of artifacts and provide insight into geological processes and the history of the Earth.

Materials Science: They are used in materials science to study the interaction of particles with different materials. They help characterize the properties and behavior of materials under different conditions, facilitating the development of new materials and technologies.