文章来源:未知 文章作者:meng 发布时间:2010-12-01 03:53 字体: [ ]  进入论坛

Seeking to detect mysterious, ultra-high-energy neutrinos(中微子) from distant regions of space, a team of astronomers1 used the Moon as part of an innovative2 telescope system for the search. Their work gave new insight on the possible origin of the elusive3(难懂的,易忘的) subatomic particles and points the way to opening a new view of the Universe in the future. The team used special-purpose electronic equipment brought to the National Science Foundation's Very Large Array (VLA) radio telescope, and took advantage of new, more-sensitive radio receivers installed as part of the Expanded VLA (EVLA) project. Prior to their observations, they tested their system by flying a small, specialized5 transmitter over the VLA in a helium balloon.

In 200 hours of observations, Ted4 Jaeger of the University of Iowa and the Naval6 Research Laboratory, and Robert Mutel and Kenneth Gayley of the University of Iowa did not detect any of the ultra-high-energy neutrinos they sought. This lack of detection placed a new limit on the amount of such particles arriving from space, and cast doubt on some theoretical models for how those neutrinos are produced.

Neutrinos are fast-moving subatomic particles with no electrical charge that readily pass unimpeded(畅通无阻的) through ordinary matter. Though plentiful7 in the Universe, they are notoriously difficult to detect. Experiments to detect neutrinos from the Sun and supernova explosions have used large volumes of material such as water or chlorine to capture the rare interactions of the particles with ordinary matter.

The ultra-high-energy neutrinos the astronomers sought are postulated8 to be produced by the energetic, black-hole-powered cores of distant galaxies9; massive stellar explosions; annihilation(灭绝,消灭) of dark matter; cosmic-ray particles interacting with photons of the Cosmic Microwave Background; tears in the fabric10 of space-time; and collisions of the ultra-high-energy neutrinos with lower-energy neutrinos left over from the Big Bang.

Radio telescopes can't detect neutrinos, but the scientists pointed11 sets of VLA antennas12 around the edge of the Moon in hopes of seeing brief bursts of radio waves emitted when the neutrinos they sought passed through the Moon and interacted with lunar material. Such interactions, they calculated, should send the radio bursts toward Earth. This technique was first used in 1995 and has been used several times since then, with no detections recorded. The latest VLA observations have been the most sensitive yet done.

"Our observations have set a new upper limit -- the lowest yet -- for the amount of the type of neutrinos we sought," Mutel said. "This limit eliminates some models that proposed bursts of these neutrinos coming from the halo(光环) of the Milky13 Way Galaxy," he added. To test other models, the scientists said, will require observations with more sensitivity.

"Some of the techniques we developed for these observations can be adapted to the next generation of radio telescopes and assist in more-sensitive searches later," Mutel said. "When we develop the ability to detect these particles, we will open a new window for observing the Universe and advancing our understanding of basic astrophysics(天体物理学) ," he said.


1 astronomers 569155f16962e086bd7de77deceefcbd     
n.天文学者,天文学家( astronomer的名词复数 )
  • Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
  • Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪,为什么只有土星有光环。 来自《简明英汉词典》
2 innovative D6Vxq     
  • Discover an innovative way of marketing.发现一个创新的营销方式。
  • He was one of the most creative and innovative engineers of his generation.他是他那代人当中最富创造性与革新精神的工程师之一。
3 elusive d8vyH     
  • Try to catch the elusive charm of the original in translation.翻译时设法把握住原文中难以捉摸的风韵。
  • Interpol have searched all the corners of the earth for the elusive hijackers.国际刑警组织已在世界各地搜查在逃的飞机劫持者。
4 ted 9gazhs     
  • The invaders gut ted the village.侵略者把村中财物洗劫一空。
  • She often teds the corn when it's sunny.天好的时候她就翻晒玉米。
5 specialized Chuzwe     
  • There are many specialized agencies in the United Nations.联合国有许多专门机构。
  • These tools are very specialized.这些是专用工具。
6 naval h1lyU     
  • He took part in a great naval battle.他参加了一次大海战。
  • The harbour is an important naval base.该港是一个重要的海军基地。
7 plentiful r2izH     
  • Their family has a plentiful harvest this year.他们家今年又丰收了。
  • Rainfall is plentiful in the area.这个地区雨量充足。
8 postulated 28ea70fa3a37cd78c20423a907408aaa     
v.假定,假设( postulate的过去式和过去分词 )
  • They postulated a 500-year lifespan for a plastic container. 他们假定塑料容器的寿命为500年。
  • Freud postulated that we all have a death instinct as well as a life instinct. 弗洛伊德曾假定我们所有人都有生存本能和死亡本能。 来自辞典例句
9 galaxies fa8833b92b82bcb88ee3b3d7644caf77     
星系( galaxy的名词复数 ); 银河系; 一群(杰出或著名的人物)
  • Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
  • We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。
10 fabric 3hezG     
  • The fabric will spot easily.这种织品很容易玷污。
  • I don't like the pattern on the fabric.我不喜欢那块布料上的图案。
11 pointed Il8zB4     
  • He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
  • She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。
12 antennas 69d2181fbb4566604480c825f4e01d29     
[生] 触角,触须(antenna的复数形式)
  • Marconi tied several antennas to kites. 马可尼在风筝上系了几根天线。 来自超越目标英语 第3册
  • Radio astronomy today is armed with the largest antennas in the world. 射电天文学拥有世界上最大的天线。
13 milky JD0xg     
  • 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。
TAG标签: energy moon space telescope