探寻宇宙射线的起源
文章来源:未知 文章作者:enread 发布时间:2013-09-02 07:23 字体: [ ]  进入论坛
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The origin of cosmic rays in the universe has confounded scientists for decades. But a study by researchers using data from the IceCube Neutrino Observatory1 at the South Pole reveals new information that may help unravel2 the longstanding mystery of exactly how and where these "rays" (they are actually high-energy particles) are produced. Cosmic rays can damage electronics on Earth, as well as human DNA3, putting astronauts in space especially at risk.
 
The research, which draws on data collected by IceTop, the IceCube Observatory's surface array of detectors4, is published online in Physical Review D, a leading journal in elementary particle physics.
 
University of Delaware physicist5 Bakhtiyar Ruzybayev is the study's corresponding author. UD scientists were the lead group for the construction of IceTop with support from the National Science Foundation and coordination6 by the project office at the University of Wisconsin, Madison.
 
The more scientists learn about the energy spectrum7 and chemical composition of cosmic rays, the closer humanity will come to uncovering where these energetic particles originate.
 
Cosmic rays are known to reach energies above 100 billion giga-electron volts8 (1011 GeV). The data reported in this latest paper cover the energy range from 1.6 times 106 GeV to 109 GeV.
 
Researchers are particularly interested in identifying cosmic rays in this interval9 because the transition from cosmic rays produced in the Milky10 Way Galaxy11 to "extragalactic" cosmic rays, produced outside our galaxy, is expected to occur in this energy range.
 
Exploding stars called supernovae are among the sources of cosmic rays here in the Milky Way, while distant objects such as collapsing12 massive stars and active galactic nuclei13 far from the Milky Way are believed to produce the highest energy particles in nature.
 
As Ruzybayev points out, the cosmic-ray energy spectrum does not follow a simple power law between the "knee" around 4 PeV (peta-electron volts) and the "ankle" around 4 EeV (exa-electron volts), as previously14 thought, but exhibits features like hardening around 20 PeV and steepening around 130 PeV.
 
"The spectrum steepens at the 'knee,' which is generally interpreted as the beginning of the end of the galactic population. Below the knee, cosmic rays are galactic in origin, while above that energy, particles from more distant regions in our universe become more and more likely," Ruzybayev explained. "These measurements provide new constraints15 that must be satisfied by any models that try to explain the acceleration16 and propagation(传播,繁殖) of cosmic rays."

 



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1 observatory hRgzP     
n.天文台,气象台,瞭望台,观测台
参考例句:
  • Guy's house was close to the observatory.盖伊的房子离天文台很近。
  • Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。
2 unravel Ajzwo     
v.弄清楚(秘密);拆开,解开,松开
参考例句:
  • He was good with his hands and could unravel a knot or untangle yarn that others wouldn't even attempt.他的手很灵巧,其他人甚至都不敢尝试的一些难解的绳结或缠在一起的纱线,他都能解开。
  • This is the attitude that led him to unravel a mystery that long puzzled Chinese historians.正是这种态度使他解决了长期以来使中国历史学家们大惑不解的谜。
3 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
4 detectors bff80b364ed19e1821aa038fae38df83     
探测器( detector的名词复数 )
参考例句:
  • The report advocated that all buildings be fitted with smoke detectors. 报告主张所有的建筑物都应安装烟火探测器。
  • This is heady wine for experimenters using these neutrino detectors. 对于使用中微子探测器的实验工作者,这是令人兴奋的美酒。 来自英汉非文学 - 科技
5 physicist oNqx4     
n.物理学家,研究物理学的人
参考例句:
  • He is a physicist of the first rank.他是一流的物理学家。
  • The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。
6 coordination Ho8zt     
n.协调,协作
参考例句:
  • Gymnastics is a sport that requires a considerable level of coordination.体操是一项需要高协调性的运动。
  • The perfect coordination of the dancers and singers added a rhythmic charm to the performance.舞蹈演员和歌手们配合得很好,使演出更具魅力。
7 spectrum Trhy6     
n.谱,光谱,频谱;范围,幅度,系列
参考例句:
  • This is a kind of atomic spectrum.这是一种原子光谱。
  • We have known much of the constitution of the solar spectrum.关于太阳光谱的构成,我们已了解不少。
8 volts 98e8d837b26722c4cf6887fd4ebf60e8     
n.(电压单位)伏特( volt的名词复数 )
参考例句:
  • The floating potential, Vf is usually only a few volts below ground. 浮置电势Vf通常只低于接地电位几伏。 来自辞典例句
  • If gamma particles are present, potential differences of several thousand volts can be generated. 如果存在γ粒子,可能产生几千伏的电位差。 来自辞典例句
9 interval 85kxY     
n.间隔,间距;幕间休息,中场休息
参考例句:
  • The interval between the two trees measures 40 feet.这两棵树的间隔是40英尺。
  • There was a long interval before he anwsered the telephone.隔了好久他才回了电话。
10 milky JD0xg     
adj.牛奶的,多奶的;乳白色的
参考例句:
  • Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
  • I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。
11 galaxy OhoxB     
n.星系;银河系;一群(杰出或著名的人物)
参考例句:
  • The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
  • The company has a galaxy of talent.该公司拥有一批优秀的人才。
12 collapsing 6becc10b3eacfd79485e188c6ac90cb2     
压扁[平],毁坏,断裂
参考例句:
  • Rescuers used props to stop the roof of the tunnel collapsing. 救援人员用支柱防止隧道顶塌陷。
  • The rocks were folded by collapsing into the center of the trough. 岩石由于坍陷进入凹槽的中心而发生褶皱。
13 nuclei tHCxF     
n.核
参考例句:
  • To free electrons, something has to make them whirl fast enough to break away from their nuclei. 为了释放电子,必须使电子高速旋转而足以摆脱原子核的束缚。
  • Energy is released by the fission of atomic nuclei. 能量是由原子核分裂释放出来的。
14 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
15 constraints d178923285d63e9968956a0a4758267e     
强制( constraint的名词复数 ); 限制; 约束
参考例句:
  • Data and constraints can easily be changed to test theories. 信息库中的数据和限制条件可以轻易地改变以检验假设。 来自英汉非文学 - 科学史
  • What are the constraints that each of these imply for any design? 这每种产品的要求和约束对于设计意味着什么? 来自About Face 3交互设计精髓
16 acceleration ff8ya     
n.加速,加速度
参考例句:
  • All spacemen must be able to bear acceleration.所有太空人都应能承受加速度。
  • He has also called for an acceleration of political reforms.他同时呼吁加快政治改革的步伐。
TAG标签: energy cosmic rays
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