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
2025-04-08
22
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 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. [br] 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:http://tihaiku.com/zcyy/4031880.html
相关试题推荐
Thejoysoftravel,havinglong_______thedisabled,areopeninguptovirtually
(81)Realestate,inbroaddefinition,islandandeverythingmadepermanentl
(81)Realestate,inbroaddefinition,islandandeverythingmadepermanentl
(81)Realestate,inbroaddefinition,islandandeverythingmadepermanentl
Manyobjectsindailyusehaveclearlybeeninfluencedbyscience,buttheir
Manyobjectsindailyusehaveclearlybeeninfluencedbyscience,buttheir
Inthecaseofmobilephones,changeiseverything.Recentresearchindicate
Inthecaseofmobilephones,changeiseverything.Recentresearchindicate
Asasalesman,heworksona_____basis,taking10%ofeverythinghesells.A、reve
Hewas______bythenoiseoutsideyesterdayeveningandcouldnotconcentrateo
随机试题
CriticsofaproposeddepartmentstoreinWintertown’shistoricaldistricth
Morethan2millionfilmslanguishinvaults(地窖)aroundtheworld,someofth
弓形虫的终宿主是A.人 B.牛 C.猫 D.犬 E.猪
男性,34岁,腹部砸伤4小时,查体见四肢湿冷,腹肌紧张,全腹压痛反跳痛,有移动性
心与肉作用不同,须分别入药的是A.莲子 B.远志 C.巴戟天 D.
β-胡萝卜素是哪种维生素原A:维生素K B:维生素C C:维生素H D:维
2020年5月,国家发改委、国家粮食和物资储备局等五部委发布关于切实做好20
根据《关于进一步改革完善药品生产流通使用政策的若干意见》,下列属于药品流通环节改
下列不属于金融风险的特征的是()。A.可测性 B.确定性 C.可控性
投资项目决策分析与评价的基本要求包括贯彻落实科学发展观、资料数据准确可靠和()
最新回复
(
0
)