Passage 8 (8/63)-T9

27/4,问题解决型，读文章花时5分21秒

第一段：新老观点，新观点的优点

第二段：新观点的困难

第三段：新观点的解决

第四段：新观点的前景

Virtually everything astronomers known about objects outside the solar system is based on the detection of photons—quanta of electromagnetic radiation.(老观点：探测宇宙用P) Yet there is another form of radiation that permeates the universe: neutrinos.（新观点：用N） With (as its name implies) no electric charge, and negligible mass, the neutrino interacts with other particles so rarely that a neutrino can cross the entire universe, even traversing substantial aggregations of matter, without being absorbed or even deflected. Neutrinos can thus escape from regions of space where light and other kinds of electromagnetic radiation are blocked by matter. Furthermore, neutrinos carry with them information about the site and circumstances of their production: therefore, the detection of cosmic neutrinos could provide new information about a wide variety of cosmic phenomena and about the history of the universe.（N的优点：1。与其他物质接触少，所以不受干扰 2。带着环境的信息）

But how can scientists detect a particle that interacts so infrequently with other matter? Twenty-five years passed between Pauli’s hypothesis that the neutrino existed and its actual detection: since then virtually all research with neutrinos has been with neutrinos created artificially in large particle accelerators and studied under neutrino microscopes. But a neutrino telescope, capable of detecting cosmic neutrinos, is difficult to construct. No apparatus can detect neutrinos unless it is extremely massive, because great mass is synonymous with huge numbers of nucleons (neutrons and protons), and the more massive the detector, the greater the probability of one of its nucleon’s reacting with a neutrino. In addition, the apparatus must be sufficiently shielded from the interfering effects of other particles.（问题：N与其他物质接触少，难测试。详细解释：要建N的望远镜，要极大还要避免与其他物质的接触，不可能）

Fortunately, a group of astrophysicists has proposed a means of detecting cosmic neutrinos by harnessing the mass of the ocean.（解决：用海洋的物质） Named DUMAND, for Deep Underwater Muon (muon: n. μ介子) and Neutrino Detector, the project calls for placing an array of light sensors at a depth of five kilometers under the ocean surface. The detecting medium is the seawater itself: when a neutrino interacts with a particle in an atom of seawater, the result is a cascade of electrically charged particles and a flash of light that can be detected by the sensors. The five kilometers of seawater above the sensors will shield them from the interfering effects of other high-energy particles raining down through the atmosphere.（N的反应可用感应器接受，也可避免其他物质的干扰）解决的办法：用海水

The strongest motivation for the DUMAND project is that it will exploit an important source of information about the universe. （办法的优点：能够探测宇宙的信息）The extension of astronomy from visible light to radio waves to x-rays and gamma rays never failed to lead to the discovery of unusual objects such as radio galaxies, quasars, and pulsars. Each of these discoveries came as a surprise. Neutrino astronomy will doubtless bring its own share of surprises.（N必将带来新的发现）