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
54
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 primary use of the apparatus mentioned in lines 33 — 45 would be to
选项
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.
答案
E
解析
L33—45的仪器的主要用途是:见原文L33—45,所说即neutrino telescope。A.提高中微子质量。无。B.解读中微子携带的信息。无。C.研究中微子内容结构。无。D.观察遥远的中微子。易错,原文指出其功能是detect。E.探测宇宙中微子。正确。L34—35的标准改写。
转载请注明原文地址:https://tihaiku.com/zcyy/3359271.html
相关试题推荐
Mavis:Howiseverything,Ruth?Ruth:______A、Nottoobad.B、Well,thankyou.C、
TherewassuchalongqueueoutsidetheChinaPavilionthatwe______gaveup.A、un
Experimentsinthephotographyofmovingobjects______inboththeUnitedState
Whathesaidwasquite______,therefore,Iwoulddoeverythingtohelphim.A、val
Everythingcomeswitha______,thatis,there’snosuchthingasafreelunch
______,everythingwouldhavebeenallright.A、HehadbeenthereB、Herehehadb
外面太嘈杂了,我无法集中精力。ItissonoisyoutsidethatIcan’tconcentrate.
JardenZincProducts,alargezincplantafewmilesoutsideGreeneville,Ten
JardenZincProducts,alargezincplantafewmilesoutsideGreeneville,Ten
JardenZincProducts,alargezincplantafewmilesoutsideGreeneville,Ten
随机试题
HowtoSucceedinYourLiteratureClassCollegeliteratu
Allvisitorsarerequestedto______withtheregulationsdrawnupmonthsago.A、c
Since2007,theAmericanPsychologicalAssociation(APA)hasconductedasurve
“容器是一个构件,构件不一定是容器;一个容器可以包含一个或多个构件,一个构件只能
下列关于证券公司违反规定委托他人代为买卖证券的处理处罚办法正确的有( )。
2011年全年,我国棉花产量660万吨,比上年增产10.7%。油料产量3279
洪某与张某发生纠纷,在开庭审理时,洪某作为原告提交了下列证据,哪项能作为单独认定
甲乙两国均为WTO成员,甲国纳税居民马克是甲国保险公司的大股东,马克从该保险公司
继电保护整定计算时,以下配合原则中()是不正确的。 A.上下级保护之间,除有特
近亲结婚的坏处主要是( )。A.唐氏综合征儿出生率高 B.影响小儿大脑及智力
最新回复
(
0
)