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
2024-10-12
0
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 there is another form of radiation that permeates the universe: neutrinos (中微子). 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 wilt 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 (类星体), and pulsars (脉冲星). Each of these discoveries came as a surprise. Neutrino astronomy will doubtless bring its own share of surprises. [br] The ocean may be used to detect neutrinos for the following reasons EXCEPT that
选项
A、it can provide massive nucleons.
B、it is like a huge detecting apparatus.
C、it enables neutrinos to move more actively.
D、it can keep away the interference of other particles.
答案
C
解析
推断题。第2段最后两句说明制造中微子探测器的要求,第3段首句提到天体物理学家们想到利用海洋来探测宇宙中微子,由此可推断,海洋应具有第2段末提到的中微子探测器的要求,将四个选项与第2段末对比,即可发现只有选项C没有提及。
转载请注明原文地址:https://tihaiku.com/zcyy/3797946.html
相关试题推荐
AstronomersattheUniversityofCaliforniadiscoveredoneofthemostdistant_
Hisbrotherfoundfault______everythingthedoctorsaid.A、inB、atC、withD、of
TheDiscoveryofAstronomersThediscoveryofplanetsar
TheDiscoveryofAstronomersThediscoveryofplanetsar
TheDiscoveryofAstronomersThediscoveryofplanetsar
Whatkindofweatherwillitbewhendistantobjectssuchashillsandtalltree
Whatkindofweatherwillitbewhendistantobjectssuchashillsandtalltree
Hewassuchageniusthathealmost______everythinghedid.A、excelledinB、exce
Everythingisready,______?A、isn’titB、aren’ttheyC、isitD、aretheyA此题考查反意疑
Theenvironmentiseverythingthatsurroundsus:plants,animals,buildings
随机试题
[originaltext]Yourteamwonthefootballgame.Congratulations![/originaltext]
Whichofthefollowingisnotcontainedinthegeneticallymodifiedmaize?[orig
Whatkindofaccommodationdoesthewomanneed?[originaltext]M:Goodmorning.C
1948年在香港成立的三联书店,由( )等合并组成。A.生活书店 B.良友图
患者女性,28岁。近两周工作忙,经常加班,睡眠少,就餐时间不保证,三天前来月经。
Thechangeinthatvillagewasmiraculou
下列哪种情况的体温升高处于发热A.妇女月经前期 B.妇女妊娠期 C.剧烈运动
A.硫喷妥 B.三唑仑 C.地西泮 D.水合氯醛 E.苯巴比妥癫痫持续状
患者,男,25岁,腹部被人扎伤后,有少量肠管脱出,现场处理原则是A.立即送回腹腔
物业经营管理的常规工作中,影响建筑物全寿命周期中的维修成本的因素包括()A:管理
最新回复
(
0
)