US media reported on February 20 that the project's chief scientist Ding Zhaozhong revealed that the analysis report of the first batch of AMS data will be published in a few weeks. According to general expectations, the results will help to understand the composition of dark matter.

In response to this news, a reporter from the Science and Technology Daily interviewed Chen Guoming, a researcher at the Institute of High Energy Physics, Chinese Academy of Sciences. Some researchers from the Institute of High Energy Physics including him participated in the AMS project. Chen Guoming said that the paper is indeed about to be published, and Chinese scientists play a key role in the analysis of AMS data.

The AMS project was proposed by Ding Zhaozhong in the mid-1990s. In 2011, AMS, which cost more than US $ 2 billion and weighed 7 tons, was placed on the International Space Station. The permanent magnet developed by the Institute of Electrical Engineering of the Chinese Academy of Sciences will bend the orbit of the charged particles. By measuring the degree of bending, combined with the mass and momentum of the particles measured by other instruments, you can know which particles have been captured. AMS collected 25 billion particle events in the first 18 months.

An important task of AMS is to verify what particles dark matter consists of. According to the current mainstream speculation, dark matter is composed of weakly interacting protons (WIMP), and WIMP collision annihilation will emit positrons that are difficult to see in daily life. Therefore, measuring a high percentage of positrons will be a support for WIMP dark matter theory.

Chen Guoming told reporters that the analysis of the first batch of AMS data showed that the ratio curve of positrons and negative electrons began to rise in the range of 30-40 GeV (note: eV is the electron volt, which is the unit of particle energy), up to 300GeV. This is an indication that the proportion of positrons is high.

The data of AMS is analyzed by six teams around the world, and they "pick the wrong" with each other to reach an agreement. Chen Guoming said that the results of the analysis by the Chinese team became a key part of the paper. According to reports, when the positron momentum is high, the determination of positive and negative charges becomes difficult; on the other hand, positrons and protons are also easily confused because they have the same charge. The Institute of High Energy, Chinese Academy of Sciences has been studying this for several years, and the data analysis is quite accurate.

Chen Guoming also pointed out that this staged result cannot confirm the composition of dark matter. Because in theory, the higher proportion of positrons may also be caused by a celestial phenomenon near the earth; the possibility of other unrecognized physical phenomena cannot be ruled out.

Zhang Xinmin, an expert in dark matter theory and a researcher at the Institute of High Energy Physics of the Chinese Academy of Sciences, told reporters that in the past few years, the PAMELA detector in Europe and Russia and the Fermi ray detector in the United States have also found a high proportion of positrons. Many people believe that dark matter is the source of this anomaly ;

This time, AMS measured this anomaly again, with higher accuracy and wider energy range.

Zhang Xinmin believes that AMS is an important data source for dark matter measurement, but it cannot be the only source. If there is a decisive conclusion in the future, it must be confirmed by the data of different instruments.

"In the next 10 years, dark matter research is likely to produce results." Zhang Xinmin said, "Now according to the theoretical model of WIMP, everyone has designed various experiments, and many devices have done this, including LHC (European Large Hadron Collider). Hope to get WIMP particles. "According to him, many domestic projects are focused on detecting dark matter, such as the" deepest laboratory under rocks "in Jinping, Sichuan; and LAMOST and FAST telescopes can measure the cosmic distribution of dark matter. Help to interpret the measurement results of AMS and other instruments.

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