首页
登录
职称英语
Virtually everything astronomers known about objects outside the solar syste
Virtually everything astronomers known about objects outside the solar syste
游客
2023-11-13
115
管理
问题
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 (中微子). 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 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 wilt 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 (类星体), and pulsars (脉冲星). Each of these discoveries came as a surprise. Neutrino astronomy will doubtless bring its own share of surprises. [br] In the last paragraph, the author describes the development of astronomy in order to
选项
A、suggest the potential discovery of celestial bodies by means of neutrino astronomy.
B、illustrate the importance of surprises in making astronomic discoveries.
C、demonstrate the effectiveness of the DUMAND apparatus in detecting neutrinos.
D、name some cosmic phenomena that neutrino astronomy will illuminate.
答案
A
解析
推断题。末段末句中的its own share of surprises及该句时态表明中微子天文学也将像该段第2句提到的天文学发展那样为天体的发现做出贡献,因此本题答案应为选项A。
转载请注明原文地址:https://tihaiku.com/zcyy/3183383.html
相关试题推荐
Although,somestudentsgraduatefromhighschool,theyarevirtuallyilliterate
Shehurtmyfeelings______ratherthanbyaccident.A、virtuallyB、literallyC、deli
Iaminchargeofwelcomingthe______.A、visitorsfromoutside-of-townB、out-of-t
Themanstopstotakehisdogoutsidetodoexercisebecause[br][originaltext
Themanstopstotakehisdogoutsidetodoexercisebecause[originaltext]M:Th
Themandidn’tputhisluggageoutsidethedoorontimebecause______.[br][o
Themandidn’tputhisluggageoutsidethedoorontimebecause______.[br][o
Themandidn’tputhisluggageoutsidethedoorontimebecause______.[origina
Annawasreadingapieceofsciencefiction,completely______totheoutsidewo
Noonewouldhavetimetoreadorlistentoanaccountofeverything______goin
随机试题
AccordingtoWorldHealthOrganization,howmanypeoplearekilledbyoutdoorai
ABritishstudyhasfoundthatBvitaminscanreducebrainshrinkageinolde
Yourweightaffectshowlongyoulive—b
AudienceAwarenessofWritingI.Introduction—contents,【T1】______andstylesd
蛋白质的特征紫外吸收峰280nm,主要是由于含有()。A.色氨酸 B.赖氨
经济较不发达阶段,政府往往更强调产业布局的()。A.公平性 B.竞争性 C
辛伐他汀的服药时间为A.早餐后 B.睡前 C.晚餐或晚餐后 D.饭前 E
根据下列资料回答问题。 《河北省2010年国民经济和社会发展统计公报》显示:河
根据《商业银行代理保险业务管理办法》,商业银行的每个网点在同一会计年度内不得与超
某钢筋混凝土结构分项工程,某月份的计划单价和计划工程量分别为350元/m3和30
最新回复
(
0
)