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
2016-01-30
32
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/MmGO777K
0
考博英语
相关试题推荐
______studentsshouldbemotivatedbyakeeninterestintheatreandshouldhavesomefamiliaritywithplaysinproduction.
(清华大学2008年试题)ThechangesingloballyaveragedtemperaturethathaveoccurredattheEarth’ssurfaceoverthepastcenturya
Theobjectiveofthispopularconsultationistodetermine,______,thefinalpoliticalstatusoftheregion,whethertoremaino
(浙江大学2008年试题)Theenergycrisis,whichisbeingfeltaroundtheworld,hasdramatizedhowthecarelessuseoftheearth’sre
(四川大学2010年试题)Youprobablyknowthatit’sbetterforbothyouandtheenvironmentifyoubuyanorganictomatoinsteadofon
Asawisemanoncesaid,weareallultimatelyalone.ButanincreasingnumberofEuropeansarechoosingtobesoataneverear
Inspiteofthe______economicforecast,manufacturingoutputhasrisenslightly.
Melissaisacomputer______thatdestroyedfilesincomputersandfrustratedthousandsofusersaroundtheworld.
Thewaypeopleholdtothebeliefthatafunfilled,painfreelifeequalshappinessactuallyreducestheirchancesofeverattai
Famedfortheirhigh-elevationforests,theAppalachianMountainssweepsouthfromQuebectoAlabama.HighestinNewEnglandand
随机试题
室内吊灯及日光灯的内部连接导线其截面积应不小于________mm2。
A.寒化B.热化C.燥化D.湿化气虚湿盛体质者,受邪后多从
下列哪一项决定了医生对患者的特殊责任和信托义务
蛋白质具有重要的生理功能,但下列对其描述并非全部正确,其中错误的是
钢筋外表有()、麻坑等缺陷时,应予剔除,不得使用。
某医院由多幢大楼(门诊楼、急诊楼、住院楼和综合楼等)组成,安装公司承包了该医院的机电工程,机电工程内容有建筑给排水,建筑电气、通风空调、智能化等工程。工程合同约定为固定总价5000万元,每幢大楼完工后立即进入竣工验收。工程的设备、材料均由业主指定品牌,由安
竣工验收前建设单位应请()对施工技术资料进行预验收。
具有一定格式,约定由债务人按期无条件支付一定金额,并能够转让流通的债权、债务证书是()。
下列关于道德与法律关系的说法中,正确的是()。
小金从网站上查到了最近一次全国人口普查的数据表格,他准备将这份表格中的数据引用到Excel中以便进一步分析,最优的操作方法是()。
最新回复
(
0
)