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
2023-11-13
83
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] In the last paragraph, the author describes the development of astronomy in order to
选项
A、suggest the potential discovery of celestial bodies by means of neutrino astronomy.
B、illustrate the importance of surprises in making astronomic discoveries.
C、demonstrate the effectiveness of the DUMAND apparatus in detecting neutrinos.
D、name some cosmic phenomena that neutrino astronomy will illuminate.
答案
A
解析
推断题。末段末句中的its own share of surprises及该句时态表明中微子天文学也将像该段第2句提到的天文学发展那样为天体的发现做出贡献,因此本题答案应为选项A。
转载请注明原文地址:https://tihaiku.com/zcyy/3183383.html
相关试题推荐
Although,somestudentsgraduatefromhighschool,theyarevirtuallyilliterate
Shehurtmyfeelings______ratherthanbyaccident.A、virtuallyB、literallyC、deli
Iaminchargeofwelcomingthe______.A、visitorsfromoutside-of-townB、out-of-t
Themanstopstotakehisdogoutsidetodoexercisebecause[br][originaltext
Themanstopstotakehisdogoutsidetodoexercisebecause[originaltext]M:Th
Themandidn’tputhisluggageoutsidethedoorontimebecause______.[br][o
Themandidn’tputhisluggageoutsidethedoorontimebecause______.[br][o
Themandidn’tputhisluggageoutsidethedoorontimebecause______.[origina
Annawasreadingapieceofsciencefiction,completely______totheoutsidewo
Noonewouldhavetimetoreadorlistentoanaccountofeverything______goin
随机试题
业主方的项目管理工作涉及项目施工阶段的全过程,即在()。A.设计前的准备阶段
“社会上一旦有技术的需要,则这种需要会比十所大学更能把科学推向前进。”这说明的是
材料的年度计划是企业控制成本,编制资金计划和考核物资部门全年工作的主要依据。(
一般情况下,可控串补投入时,先投入可控部分、后投入()部分。(A)固定(
如果无法估计被测电压或电流的大小,应先把数字万用表拨到最高量程测量一次
A.杠杆仍能平衡 B.杠杆不能平衡,右端下沉 C.杠杆不能平衡,左端下沉
根据下列图、表,回答问题: 2009年,平均每个表演团体机构赴农村
配筋砌块抗震墙的竖向和水平方向分布钢筋,下列各项中哪一项不符合规范要求(
甲、乙签订一份水泥买卖合同,双方约定由甲向乙供货,交货地点在乙单位工地。在交易前
下列各项关于财务管理两大核心概念的说法中,错误的是()。A.货币具有时间价
最新回复
(
0
)