首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Virtually everything astronomers known about objects outside the solar system is based on the detection of photons—quanta of ele
Virtually everything astronomers known about objects outside the solar system is based on the detection of photons—quanta of ele
admin
2015-04-24
40
问题
Virtually everything astronomers known about objects outside the solar system is based on the detection of photons—quanta of electromagnetic radiation. Yet mere 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 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.
The neutrinos are hard to detect most probably because of______.
选项
A、their ability to escape from different regions of space
B、their inability to penetrate dense matter
C、the similarity of their structure to that of nucleons
D、the infrequency of their interaction with other matter
答案
D
解析
细节推断题。原文虽然没有直接提到中微子难以探测的原因,但是首段第三句的定语从句暗示了中微子难以探测与它so rarely(极少)和别的物质起反应密切相关。接着定位到第二段首句,提到了研究中微子的探测问题,detect…interacts so infrequently with other matter与选项D重现,这是最可能造成中微子难以探测的原因。
转载请注明原文地址:https://kaotiyun.com/show/GfLO777K
0
考博英语
相关试题推荐
TestshaveconfirmedthatfourpeopleinWisconsincontractedthemonkeypoxvirusaftercomingintoclosecontactwithpetprair
TestshaveconfirmedthatfourpeopleinWisconsincontractedthemonkeypoxvirusaftercomingintoclosecontactwithpetprair
TestshaveconfirmedthatfourpeopleinWisconsincontractedthemonkeypoxvirusaftercomingintoclosecontactwithpetprair
Thereisanewtypeofsmalladvertisementbecomingincreasinglycommoninnewspaperclassifiedcolumns.Itissometimesplaced
Kaganmaintainsthataninfant’sreactionstoitsfirststressfulexperiencesarepartofanaturalprocessofdevelopment,not
Priortothe20thcentury,manylanguageswithsmallnumbersofspeakerssurvivedforcenturies.Theincreasinglyinterconnected
Somepoliticiansarescurryingaboutwithmuchzestandanticipation.It’stime,theirpollsinformthem,tofindthequickfix
IhaveneverseenMrs.Clarkbefore,butIknowfromhermedicalchartandthereportIreceivedfromtheprecedingshiftthatt
IhaveneverseenMrs.Clarkbefore,butIknowfromhermedicalchartandthereportIreceivedfromtheprecedingshiftthatt
Wateristhegiverand,atthesametime,thetakeroflife.Itcoversmostofthesurfaceoftheplanetweliveonandfeatures
随机试题
液压系统由哪些部分组成?
"ShallIhelpyouwiththewashingup?""Don’t______—I’lldoitlater."
治疗丹毒以何经为主( )
鸡胸的特征是
基底压力直线分布的假设适用于:
关于消防安全管理人及其职责的说法,错误的是()。
除国库券外,其他证券投资或多或少都存在一定的违约风险。()
一位海关检查员认为,他在特殊工作经历中培养了一种特殊的技能,即能够准确地判定一个人是否在欺骗他。他的根据是,在海关通道执行公务时,短短的几句对话就能使他确定对方是否可疑;而在他认为可疑的人身上,无一例外地都查出了违禁物品。以下哪项如果为真,能削弱上述海关检
党的十八大首次提出要积极培育和践行社会主义核心价值观。这与中国特色社会主义发展要求相契合,与中华优秀传统文化和人类文明优秀成果相承接,是党凝聚全党全社会共识作出的重要论断。社会主义核心价值观“三个倡导”中从个人行为层面对社会主义核心价值观基本理念的凝练的是
DearSir/Madam,IampleasedtowritealetterofrecommendationonbehalfofSandRiveranditsCEO,Mrs.JaneKing.Iamv
最新回复
(
0
)