Virtually everything astronomers known about objects outside the solar system is based on the detection of photons—quanta of electromagnetic radiation. Yet there is another form of radiation that permeates the universe: neutrinos. 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.
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.
Fortunately, a group of astrophysicists has proposed a means of detecting cosmic neutrinos by harnessing the mass of the ocean. 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.
The strongest motivation for the DUMAND project is that it will exploit an important source of information about the universe. 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.
1. Which of the following titles best summarizes the passage as a whole?
(A) At the Threshold of Neutrino Astronomy
(B) Neutrinos and the History of the Universe
(C) The Creation and Study of Neutrinos
(D) The DUMAND System and How It Works
(E) The Properties of the Neutrino
2. With which of the following statements regarding neutrino astronomy would the author be most likely to agree?
(A) Neutrino astronomy will supersede all present forms of astronomy.
(B) Neutrino astronomy will be abandoned if the DUMAND project fails.
(C) Neutrino astronomy can be expected to lead to major breakthroughs in astronomy.
(D) Neutrino astronomy will disclose phenomena that will be more surprising than past discoveries.
(E) Neutrino astronomy will always be characterized by a large time lag between hypothesis and experimental confirmation.
3. In the last paragraph, the author describes the development of astronomy in order to
(A) suggest that the potential findings of neutrino astronomy can be seen as part of a series of astronomical successes
(B) illustrate the role of surprise in scientific discovery
(C) demonstrate the effectiveness of the DUMAND apparatus in detecting neutrinos
(D) name some cosmic phenomena that neutrino astronomy will illuminate
(E) contrast the motivation of earlier astronomers with that of the astrophysicists working on the DUMAND project
4. According to the passage, one advantage that neutrinos have for studies in astronomy is that they
(A) have been detected for the last twenty-five years
(B) possess a variable electric charge
(C) are usually extremely massive
(D) carry information about their history with them
(E) are very similar to other electromagnetic particles
5. According to the passage, the primary use of the apparatus mentioned in lines 24-32 would be to
(A) increase the mass of a neutrino
(B) interpret the information neutrinos carry with them
(C) study the internal structure of a neutrino
(D) see neutrinos in distant regions of space
(E) detect the presence of cosmic neutrinos
6. The passage states that interactions between neutrinos and other matter are
(A) rare
(B) artificial
(C) undetectable
(D) unpredictable
(E) hazardous
7. The passage mentions which of the following as a reason that neutrinos are hard to detect?
(A) Their pervasiveness in the universe
(B) Their ability to escape from different regions of space
(C) Their inability to penetrate dense matter
(D) The similarity of their structure to that of nucleons
(E) The infrequency of their interaction with other matter
8. According to the passage, the interaction of a neutrino with other matter can produce
(A) particles that are neutral and massive
(B) a form of radiation that permeates the universe
(C) inaccurate information about the site and circumstances of the neutrino’s production
(D) charged particles and light
(E) a situation in which light and other forms of electromagnetic radiation are blocked
9. According to the passage, one of the methods used to establish the properties of neutrinos was
(A) detection of photons
(B) observation of the interaction of neutrinos with gamma rays
(C) observation of neutrinos that were artificially created
(D) measurement of neutrinos that interacted with particles of seawater
(E) experiments with electromagnetic radiation
参考答案:ACAD EAEDC
拼了!巴西将动用"核辐射"绝育技术灭蚊抗寨卡
2013年3月剑桥商务英语考试(BEC中级)各考点报名时间汇总
商务英语就业方向及前景分析
时事资讯:英首相夫人写博客 爆"G8夫人峰会"内幕
时事资讯:"老妈裤"时尚风波 奥巴马笑称自己老土
大连外国语学院旅顺校区2013年3月BEC中级报名时间
暨南大学珠海校区2013年3月剑桥BEC中级报考通知
G20将邀请穷国参与国际税务谈判
时事资讯:花旗将与联邦存款保险签署秘密协议
伊朗提高追杀英国小说家拉什迪的赏金
时事资讯:奥巴马获赠巴西队球衣 面露尴尬
时事资讯:09年奥巴马独立纪念日献词
2011年BEC商务英语中级考试大纲:阅读
2013年上半年剑桥商务英语考试BEC报名时间汇总
云南大学2013年BEC上半年报名时间
时事资讯:美国新泽西州三市长涉嫌腐败被捕
时事资讯:世卫建议先给医护人员接种甲流疫苗
河南科技大学2013年BEC中级报名时间
2013年BEC考试时间公布:纸笔考试7场、机考4场
湖南大学外国语学院2013年3月BEC中级考试报名通知
剑桥BEC高级考试等级评定说明
2011年上半年全国国际商务英语(一级)考试报名时间
2011年下半年商务英语考试报名截止时间
北京外国语大学网络教育学院2013上半年BEC考试报名时间
天津大学研究生院2013年BEC中级报名时间
四川外语学院2013年3月BEC中级考试报名通知
时事资讯:伊朗客机坠毁 168人罹难
联合国一官员称中美就制裁朝鲜达成一致
2011下半年全国国际商务英语二级考试报名时间
特朗普轻松赢得内华达州初选
| 不限 |
| 英语教案 |
| 英语课件 |
| 英语试题 |
| 不限 |
| 不限 |
| 上册 |
| 下册 |
| 不限 |