Introduction
Research significance
The development of nuclear radiation detectors is one of the markers of nuclear technology, and the development and production level of a national nuclear radiation detector, It is also one of the important signs of the high low technology level. The development of nuclear radiation detectors and the development of nuclear detection techniques have experienced the development history of counting, measuring, and image display. Erogens to the above process, the requirements for the development of the nuclear radiation detector are: fast time, high detectors, high (pulse amplitude, energy) resolution, and large volume, constituting arrays. In addition, under the premise of nuclear performance, the probe production process, the detector use environmental conditions and prices are also an important factor that leads to the more detector.
For more than ten years, successful development successfully has successfully developed a new nuclear radiation detector, some of which have been formed by the market; some detectors have been eliminated or gradually replaced; Some "old" detectors are reused.
Development History
It is no longer more than 100 kinds of radiation detectors that can give electrical signals. The most commonly used main gas ionizing detector, semiconductor detector and scintillation detector three categories. As early as 1908, the gas ionization detector has been published. But until the 1931 pulse counter appeared, the rapid count problem was solved. In 1947, the appearance of a scintillation counter increased the detection efficiency of the particles due to its density much greater than the gas. The most significant is the sodium iodide (铊) scintillator, which has a higher energy resolution for γ rays. In the early 1960s, the development of semiconductor detectors was successfully developed to make the spectral measurement technology. Modern type detection devices and devices for high energy physics, nuclear physics, and other science and technology are based on the above three types of detection devices have developed through continuous improvement of innovation.
principle
When particles pass a certain substance, such a substance is absorbed or excited to generate an ionization or excitation. If the particles are charged, its electromagnetic field is directly interacting with the track electrons in the substance. If it is a gamma ray or X-ray, first pass through some intermediate, generating photoelectric effect, Compton effect, or electronic pair, the energy part or all of the transferred orbit electrons, and then generate ionization or excitation. For neutral particles that do not charge, for example neutron, it is generated by a nuclear reaction to produce a charged particles, and then an ionization or excitation. The radiation detector is a suitable detection medium as a substance acting with the particles, and the ionization or excitation of the particles in the detection medium is converted into various forms of information directly or indirectly can be accepted.
Classification
The way the radiation detector gives the information, mainly divided into two categories: a class is that the particles are incident to the detector, and have been dedicated to people's senses. The information that can be accepted. For example, various particle track detectors, generally passing through phases, developing or chemical corrosion. There is also a thermal release detector, a photoluminescent detector, and a light output associated with the illuminated amount is given through heat or light excitation. This type of detector is basically not a research scope of nuclear power. When another type of detector receives incident particles, the corresponding electrical signal is immediately given, and the electronic line is enlarged, and the processing can be recorded and analyzed. This second class can be called an electrical detector. The electrical player is the most widely used radiation detector. The advent of this type of detector has led to the emergence and development of new branch disciplines in nuclear power.
Composition
A radiation detector for detecting spatial distribution of incident radiation, comprising: a radiation-sensitive semiconductor; a common electrode formed on a surface of the semiconductor, used The bias voltage is received; a plurality of segmented electrodes formed on another surface of the semiconductor are used to output charge generated by incident radiation within the semiconductor, as an electrical signal; and a light irradiation mechanism for at least Light is emitted during radiation detection.
Performance
The main performance of the radiation detector is the detection efficiency, resolution, linear response, particle differentiation. The radiation can be converted into a device for a measurable signal. The basic principle of the detector is that the particles in the radiation and the detection medium interact, all of the energy or partially transmitted to the medium, and cause a macroscopically measured reaction under certain external conditions. For optical band, radiation can be regarded as electron beam, and the energy of the photon is electronically transmitted to the medium, producing a so-called photonic event, and radiation can be converted into thermal energy (such as thermocouple), electrical energy (such as photocurrent and photoelectric voltage), chemical energy (photosensitive) Generation of silver particles in latex), or another wavelength of radiation (fluorescence effect). According to these energy and radiation, various different devices are designed to measure the radiant energy of the celestial body.
Exploration efficiency
The number of particles detected by the detector is incident on the number of particles number in the detector in the same time interval. It is related to the sensitive volume of the detector, geometric shape, and sensitivity to the incident particles. Generally, the detector is required to have high detection efficiency. However, in some special occasions, such as under extremely strong radiation fields, the detector is required to have lower sensitivity. Refers to the ratio of the photon event number and the number of incident photon numbers during the initial process of the photon and the detector. It describes the ability of the detector to receive and record information. The incident photon may penetrate the medium or reflected by the medium. Sometimes the medium should absorb several photons cause a primary photon event, sometimes the photon event produced is not detected, so the quantum efficiency of the general detector is less than 1.
Resolution
Energy resolve
Resolution of the ability of its energy very close to particles
Spatial resolution
(location resolution): Accurate the ability of particle incident position;
time resolution
The ability to accurately give the particles arrival time. These indicators generally use the half-high wide (FWTM) of the spectral line and a very high wide (FWTM).
Particle Differential Capability
A certain type of detector is only sensitive to certain types of incident particles, but is not sensitive to other particles, or will be given different from the type of particles. The form of information is different, so that it is convenient to selectively detect the required particles to exclude other unnecessary nuclear radiation interference.
Responsive
is also called sensitivity, equal to the ratio of detector output signals and incident radiation power. When the radiation power is increased, the output signal is also proportionally increased, and such a detector is referred to as linear, otherwise it is called nonlinear.
Spectrotic Response
is also known as a split sensitivity, refers to the sensitivity of the detector when monochrome radiation. It characterizes the response characteristics of the detector to different wavelength radiation. Split response should be varied as the wavelength change, referred to as selective, and vice versa is non-selective. A relative spectroscopic response is called a relative spectrophot in response to the response of the detector's most sensitive wavelength.
Linear Response
The information given within a certain range and the energy, intensity or position of the incident particles is generally referred to as energy linear, intensity linear or Line linear.
detection rate
is equal to the minimum radiation power of the detector to detect. Any detector has noise, and the signal smaller than the noise and the average value is not detected. The radiation power required to generate a large number of noise is called the minimum radiation power that detects the detector, or is called equivalent noise power. Sometimes the sensitivity of the detector is described using a detection rate.
generally also requires radiation detectors to have anti-radiation damage and adaptability to various environmental conditions, such as temperature, humidity, light, corrosion resistance, and mechanical vibration. It has an imaging function and is a characteristic of modern new detectors. Such detectors have been used in neutron photographed, gamma photograph, X diffraction, and electron microscopy. Therefore, its application has long been exceeding the field of nuclear science, and expanding to other discipline research and related national economic departments.
The study of China's radiation detector is carried out in the early 1950s, successively developed a successful nuclear latex, a cover leather count tube, sodium iodide (铊) scintillator. By the end of the 1950s, the research work of other scintillators, photomultiplier tubes and semiconductor detectors were launched. In the study of nuclear weapons, China has basically used various radiation detectors developed by their country.
Development trend
The development trend of nuclear radiation detectors is: 1 Research simultaneously gives a combined detector and detecting device for multiple information such as particle position, energy, time and other information. . 2 Take advantage of new achievements of electronic technology and computer technology, improve the information of the information provided by the detector, the accuracy, speed, and utilization of information. Microelectronics technology is promoting the emergence of miniaturization detectors. 3 Search for more ideal detection media and detection mechanisms to develop superconducting detectors.