How to detect extremely high -energy neutrinos?

01

Extremely high -energy neutrin

Neutrinos are one of the basic micro -particles that constitute the material world. In 1930, it was proposed by the famous physicist Wolfgang. The neutron has a tiny but non -zero quality, without charging, and the interaction with material is weak. It is transmitted along the line in the universe space to easily penetrate the celestial body and even the entire universe. messenger. At present, neutrinos are still popular topics in the field of physics and astronomy.

This article will introduce extremely high -energy neutrinos -energy from PEV (1 PEV = 1015EV) to 100 EEV (1 EEV = 1018EV). The problem is closely related.

Different experiments have a high -energy cosmic line energy spectrum, and interesting "knee" structure and "ankle" structure appeared in the high -energy section. Source: Wikipedia Encyclopedia

02

Radio detection

The high -energy segment of the high -energy segment is extremely low. According to the measurement result of the energy spectrum of the charging cosmic line energy of the ankle section (1018 ~ 1019EV), the ground can only be collected by a cosmic meter with an average of a square kilometer area! The case rate of extremely high -energy neutrinos is lower, and its detection efficiency is lower, so a large area of ​​detection array is required to collect cases.

子 Traditional method: particle detection

At present, the cosmic line detection experiment is mainly divided into direct detection (based on satellite or high air balloon), and indirect detection on the ground. These two methods have their own focus and complement each other. In recent years, some good progress has been made. The detection methods used by indirect detection on the ground mainly include particle counting detectors (including flash body detectors, gas detectors and water Chellenkov detectors), atmospheric fluorescent telescope, atmospheric Chellenkov imaging telescope, etc. These types of experiments mainly detect the secondary particles and fluorescence, and Chelv photons produced by air firing, which can be regarded as particle -type experiments.

The general cost of particle -type detectors is generally high, and the single scale of the latter two types of detectors is generally large, so that it cannot be laid out in large volumes and large areas (the area of ​​thousands of square meters and larger areas). The detection of the child has a short board.

Basic configuration of traditional ground air clustering experiments 丨 Source: Wikipedia Encyclopedia

0 new method: radio detection

For ground experiments, the clustering process after the high -energy universe line enters the atmosphere is fully developed in the earth's atmospheric layers like an avalanche effect. When reaching the ground, it may cover the area area near the square. The positive and negative charging -level particles generated by the atmospheric cluster process are extremely easy to be deflected by the magnetic field of the earth. The positive and negative particles naturally separate the electric field separately in the local magnetic field. This electric field changes with the evolution of the cluster, which produces electromagnetic radiation! This electromagnetic wave is about tens of to 100 mega -Hverz short -wave bands (~ 100 MHz, wavelength is about 3 meters), which provides a physical basis for the radio detection of cosmic rays.

In the case of scientific goals, a small number of auxiliary particles detectors can also be placed in the radio detection antenna array to truly achieve the collaborative measurement of "wave" and "particles". In fact, in the 1960s, scientists have detected electromagnetic radiation generated by this extremely high -energy universe line, but due to the rapid development of technical reasons and the direction of particle detectors, based on radio radiation detection extremely high -energy universe lines in decades in decades Slow progress.

After entering this century, thanks to the rapid development of human beings in semiconductor devices, integrated circuits, etc., the rapid digital reading plan has become feasible, making it possible to detect radio radiation generated by high -energy cosmic lines. Starting from sexual principles, the physical process of radio radiation is better understood by the atmospheric cluster, and the verification of several pathors is obtained.

Extremely high -energy cosmic line accompanied by radio radio radiation schematic images 丨 Source: Wikipedia Encyclopedia

的 The advantages of radio power detection

Why is the radio exploration scheme obtained and favored? the reason is:

Compared with a large -scale layout particle detector, at the same experimental scale, the cost of radio detection antenna is very cheap, which is particularly suitable for mass production, and it is conducive to a larger -scale layout;

Compared with ground detection experiments (atmospheric fluorescent telescope) with the same scientific goals (atmospheric fluorescent telescope), it is necessary to observe on the sunny night, radio detection can achieve close to all -weather observations, and more extremely high -energy cosmic line cases can be collected in the same time;

From a physical principle, radio radiation mainly comes from positive and negative electrons generated during the atmospheric cluster. Different from the interaction of Qiangzi, the electromagnetic cluster is the most profound and clear at present. Therefore, it is equivalent to the use of the clearest physical process to detect extremely high -energy neutrinos, and naturally you can get better measurement results;

At the same time, the absorption and scattering of the radio signals from tens of trillion to 100 mezzhz are very weak in the atmosphere. It can well recall the nature of the original incident particles, which is very conducive to studying the important high -energy cosmic line composition, origin and acceleration and other important. Scientific question.

高 Radio -detection high -energy neutrinos

At present, some large ground experimental arrays have made some significant progress in the field of high -energy cosmic line detection, but the detection of extremely high -energy neutron cosmic lines is still a major problem in the scientific community. With the help of radio detection methods, the ground antennas can be detected through large -scale layout, which can detect those large -angle incidents or neutrinos that pass through the mountain.

As a phased goal in the early stage, the radio detection of the extremely high -energy charging cosmic line is easier to achieve, and the messenger cosmic line merit can also answer very important scientific questions. A challenging topic is to identify the ingredients (that is, the quality of the quality) of the extremely high -energy cosmic line, which is very important for understanding the origin and spread of the extremely high -energy cosmic line, and the radio detection is expected to obtain the current best measurement result. However, it should be noted that because the Galaxy has a radio power background, the energy threshold of the cosmic line that can be detected is about dozens of PEV (1016EV), and the radio signal generated by lower energy particles will be drowned in the Galactic radio background and it is difficult to be identified come out.

Grand experiment extremely high -energy cosmic line radio detection schematic diagram ▏ Source: Garnd science white paper

03

Pathfinder of China

Relying on the "first rays of dawn detection" research project in the Tianshan area of ​​Xinjiang before, an international team composed of Chinese and French scientists conducted a radio detection in the cosmic line in the Tianshan area. The trigger method makes the large -scale layout of radio antennas for high -energy cosmic line detection. This route is more solid! The full name of the experiment The Tianshan Radio Experiment for Neutrino Detection (referred to as Trend).

Due to the inaccessible person and the high mountains around the experimental site, the local radio environment is very clean, and the antenna is very sensitive to the low -frequency radio signal. It is triggered by multiple antennas to be triggered in a short period of time. TR

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