暗物质

nullDark Matter ——暗物质Dark Matter ——暗物质Some conception about dark matterSome conception about dark matterThe latest progress about dark matterThe latest progress about dark matterApril 3th,2013, Samuel Chao Chung Ting (丁肇中) reported the first batch of the physical results of AMS02(阿尔法磁谱仪 ) in CERN (European Organisation for Nuclear Research欧洲核子研究组织) :the results of 0.5 - 350 GeV Positron (正电子). AMS02 was sent to the International Space Station (ISS) by the space shuttle in May 2011 .It has obtained more than 300 billion cosmic ray examples, including 6.8 million positron and electron. Published results is the measured curve of the positron pair electron-positron with the energy change. The CAS scientists involved in the AMS experiment and make a significant contribution.The latest progress about dark matterThe latest progress about dark matterCosmic ray particles’（宇宙线粒子） collision can produce positrons（正电子）. Through the analysis of cosmic ray energy spectrum（宇宙线能谱） and its ingredients, we can more accurately predict the curve that positron’s proportion of the electron-positron which changes with energy. The latest progress about dark matterThe latest progress about dark matterHowever, the annihilation of dark matter particles in the universe will also generate additional positron. Therefore, the curve that positron’s proportion of the electron-positron which changes with energy is very sensitive to the presence of dark matter articles . It becomes a hotspot of international particle physics community（国际粒子物理界） and the universe academic study. The latest progress about dark matterThe latest progress about dark matterAMS is the first particle physics detector of space（粒子物理探测器）. It can accurately measure the energy spectrum of electrons（电子的能谱） and distinguish between protons and positrons. And the misjudgment rate is less than one millionth. The published statistical errors and systematic errors of the measured results are less than 1%. The latest progress about dark matterThe latest progress about dark matterThe latest progress about dark matterThe latest progress about dark matterAMS measured the proportion of positron within the range of 0.5-350 billion eV. (That the proportion of the sum of the number of electronic and positron).   From 0.5 billion to 10 billion eV, this proportion decreases with the increase of energy. From 10 billion to 250 billion eV, the ratio increases with the increase of energy. From 200 billion electron volts of energy, the increasing rate gradually decreases by an order of magnitude.nullIn more than 250 billion eV, the energy spectrum of the positron proportion looks flat.” But this requires more data to study. The reported data is based on about one-tenth of the total expected data of AMS. The energy spectrum of the positron proportion didn’t show its changed by structure or time.The latest progress about dark matterThe latest progress about dark matterThe excess physical analysis of the published positron may have two sources: First, the positive and negative particles of dark matter annihilation change into electron-positron. Second, the positron produced by Pulsar. The AMS02’s positron proportion of the energy range is not enough to distinguish between these two explanations. Estimated to take several years to accumulate the data, it may be concluded.nullChinese Academy of Sciences has made ​​a significant contribution to AMS. The most critical large permanent magnet of AMS was designed and developed by the Institute of Electrical Engineering(电工研究所) of the Chinese Academy of Sciences, High Energy Physics and the China Academy of Launch Vehicle Technology in Beijing in 1995-1997 .