High energy particle detector is a device or device that detects high energy (energy above 109 electron volts) particles. Its principle is based on the interaction between particles and matter.High energy particle detectors are generally divided intoCounterAnd track room.
There are many potential wires and signal wires in the multi wire room, which are filled with gas. The working principle is similar to that of the proportional counter tubeparticleThe position, dE/dx and other information have good position resolution.The drift chamber uses the method of measuring the time when the electrons drift to the signal wire to locate, thus greatly reducing the number of wires and electronic circuits, and improving the position resolution (up to tens of microns).According to the structure and performance characteristics, drift chambers can be divided into three categories: multi wire drift chamber, uniform electric field drift chamber and adjustable electric field drift chamber.Emerging injection chambers andTime projection roomIt also plays an important role in high-energy particle physics experiments.NewMulti-step avalanche chamberTime expansion chamber, self quenching streamer chamber and so on have also received great attention.
Scintillation counter
Plastic is commonly usedScintillation counterAnd liquid scintillationCounter。It is characterized by easy fabrication of large area, close to 100% detection efficiency for charged particles, high allowable counting rate, good time resolution and easy measurement of flight time.The time resolution of the large area plastic scintillation counter has reached 0.2 nanoseconds.
Cerenkov counter
When charged particles move in a transparent medium, when their speed exceeds the transmission speed of light in the medium, they will produce weak visible light Cherenkov radiation light.Its radiation angle is related to the particle velocity, thus providing a method for measuring the velocity of charged particles.The working medium can be solid, liquid or gas.According to its structure and working mode, it can be divided into three types: threshold type, differential type and optical school formal type.The latter two have higher speed resolution.Cerenkov counter It is often used to identify particles with the same momentum but different masses.
Traversing radiation counter
High speed charged particles passing through the interface of two mediums will generate cross radiationradiationThe energy is proportional to the particle energy.When the particle velocity is very high and very close to the speed of light, neither the time of flight nor the Cherenkov counter can identify the particle through the resolution speed. The cross radiation counter provides a new method to identify high-energy particles in this energy region.
Electromagnetic calorimeter
High energy electrons or gamma photons will produce electromagnetic showers in the medium, and the total energy loss of the secondary particles is proportional to the total energy of the incident particles.Therefore, once the total energy loss is collected, the total energy of the particles can be determined.The electromagnetic calorimeter is divided into two types: full absorption type, such as sodium iodide (thallium), bismuth germanate, lead glass, and sampling type.The latter is formed by overlapping the sampling counter and the lead plate.The sampling counter can be a liquid argon ionization chamber, a plastic scintillation counter and a multi wire chamber.
Hadron calorimeter
High energy hadrons will produce hadrons in the mediumShower。The total energy of hadrons can be determined by collecting the total ionized charge, which is usually made by overlapping the iron (uranium) plate with a scintillation counter or a multi wire chamber.
Track chamber
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It is used to record and analyze track images generated by particles.The common ones are spark chamber, streamer chamber, cloud chamber and bubble chamber.
Spark chamber and streamer chamber
They are plenums and require a higher voltage.Ions are generated by movement in a strong electric field“avalanche”。During the development of "avalanche", streamers are generated first, and then sparks are generated.The time of streamer formation is very short (about 10 nanoseconds), so the streamer chamber has good time characteristics, and it and the spark chamber have good spatial resolution (about 200 μ m).They can not only display particle tracks by photography, but also record electric pulse signals.The time resolution of tens of picoseconds can be obtained by small gap planar spark chamber.
Cloud chamber and bubble chamber
The ion clusters generated by the incident particles along the track form the condensation center in the supersaturated steam and form droplets (cloud chambers);The vaporization center is formed in the superheated liquid and becomes bubbles (bubble chamber).Both of these track chambers are recorded by photography.The bubble chamber has good position resolution (up to several microns). It can be used as a vertex detector together with a counter to measure short-lived particles. The fast cycle bubble chamber can improve the efficiency of case recording.
