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
2024-01-13
50
管理
问题
Virtually everything astronomers known about objects outside the solar system is based on the detection of photons-quanta of electromagnetic radia- tion. 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 substantialaggregations 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: there- fore, 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 par- ticle 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 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. [br] According to the passage, the interaction of a neutrino with other matter can produce
选项
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.
答案
D
解析
中微子和其他物质反应可产生:A.中性的,大量粒子。无。B.能穿越宇宙的辐射形式。无。C.关于地区周边环境的不正确信息。无。D.带电粒子和光。正确。见原文L56—59。E.能阻碍光和其他电磁辐射的环境。无。
转载请注明原文地址:https://tihaiku.com/zcyy/3359274.html
相关试题推荐
Itwouldbeamistaketo______thislawtosituationswhichareoutsidethisrang
这所大学提供了他所期望的一切。Theuniversityhasofferedeverythingheexpected.
JardenZinc(锌)Products,alargezincplantafewmilesoutsideGreeneville
JardenZinc(锌)Products,alargezincplantafewmilesoutsideGreeneville
JardenZinc(锌)Products,alargezincplantafewmilesoutsideGreeneville
Bytheendofnextmonthhe______everythinginschool.A、willfinishB、wouldhave
Itwouldbeamistaketo______thislawtosituationswhichareoutsidethisra
Don’tworryifyoucan’tunderstandeverything.Theteacherwill________thema
Lyinginhospital,thepatient_________theoutsideworldbywatchingnewsprog
SpeakerA;Howiseverythinggoingwithyou?SpeakerB:________A、Thesametoyou
随机试题
【B1】[br]【B7】A、toB、byC、forCforyou为你
ThePacificislandnationofPalauhasbecomehometothesixthlargestmarin
[originaltext]Peoplewithbiggerbrainstendtoscorehigheronstandardte
天沟排水有关溢流口的叙述,以下哪条错误?()A.可不设溢流口 B.应在女儿
下列不属于农药污染食品主要途径的是A.喷洒作物 B.植物根部吸收 C.空中随
《巴塞尔协议Ⅲ》首次提出两个流动性监管量化标准:一是流动性覆盖率;二是净稳定资金
重型病毒性肝炎患者,出血最主要的原因是A、维生素K吸收障碍 B、凝血因子合成障
(2017年真题)信托型股权投资基金的清算小组由()负责组织,并由基金管理
B
丹毒是A.急性蜂窝织炎 B.急性淋巴结炎,扩散至周围组织 C.急性管状淋巴管
最新回复
(
0
)