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
41
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
Suchcrimesmaybesocomplexthatmonthsoryearsgobybeforeanyone______th
你的青春就是一场远行,一场离自己的童年,离自己的少年,越来越远的远行。你会发现这个世界跟你想象的一点都不一样,你甚至会觉得很孤独,你会受到很多的排挤。度假和
在第3-5腰椎高度的椎管内不含有:()A.尾神经根 B.骶神经根 C.
()是目前我国股权投资基金最主要的投资资金来源。A.工商企业 B.社会保障基
青蒿抗疟的有效成分是A.青蒿素B.青蒿内酯C.青蒿酸D.青蒿醇E.挥发油
直流系统充电装置型式应选用特高频开关电源模块型充电装置。
既能治疗湿热黄疸,又能治疗大便秘结的药物是A.大黄 B.蔊菜 C.马兜铃
视杆系统( )。A.对光敏感度高,有色觉,分辨力弱 B.对光敏感度低,有色觉
某男,65岁。久咳不已,短气乏力,痰多清稀,食纳减少,腹胀便溏,足面浮肿,苔白舌
A.异种抗原 B.同种异型抗原 C.自身抗原 D.异嗜性抗原 E.肿瘤相
最新回复
(
0
)