欧洲核能研究所捕获到反物质原子
文章来源:未知 文章作者:meng 发布时间:2010-11-19 02:05 字体: [ ]  进入论坛
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Geneva, 17 November 2011. The ALPHA experiment at CERN has taken an important step forward in developing techniques to understand one of the Universe's open questions: is there a difference between matter and antimatter? In a paper published in Nature today, the collaboration1 shows that it has successfully produced and trapped atoms of antihydrogen(反氢) . This development opens the path to new ways of making detailed2 measurements of antihydrogen, which will in turn allow scientists to compare matter and antimatter.

Antimatter – or the lack of it – remains3 one of the biggest mysteries of science. Matter and its counterpart are identical except for opposite charge, and they annihilate4(消灭,灭绝) when they meet. At the Big Bang, matter and antimatter should have been produced in equal amounts. However, we know that our world is made up of matter: antimatter seems to have disappeared. To find out what has happened to it, scientists employ a range of methods to investigate whether a tiny difference in the properties of matter and antimatter could point towards an explanation.

One of these methods is to take one of the best-known systems in physics, the hydrogen atom, which is made of one proton and one electron, and check whether its antimatter counterpart, antihydrogen, consisting of an antiproton(反质子) and a positron(正电子) , behaves in the same way. CERN is the only laboratory in the world with a dedicated5 low-energy antiproton facility where this research can be carried out.

The antihydrogen programme goes back a long way. In 1995, the first nine atoms of man-made antihydrogen were produced at CERN. Then, in 2002, the ATHENA and ATRAP experiments showed that it was possible to produce antihydrogen in large quantities, opening up the possibility of conducting detailed studies. The new result from ALPHA is the latest step in this journey.

Antihydrogen atoms are produced in a vacuum at CERN, but are nevertheless surrounded by normal matter. Because matter and antimatter annihilate when they meet, the antihydrogen atoms have a very short life expectancy6. This can be extended, however, by using strong and complex magnetic fields to trap them and thus prevent them from coming into contact with matter. The ALPHA experiment has shown that it is possible to hold on to atoms of antihydrogen in this way for about a tenth of a second: easily long enough to study them. Of the many thousands of antiatoms the experiment has created, ALPHA's latest paper reports that 38 have been trapped for long enough to study.

"For reasons that no one yet understands, nature ruled out antimatter. It is thus very rewarding, and a bit overwhelming, to look at the ALPHA device and know that it contains stable, neutral atoms of antimatter," said Jeffrey Hangst of Aarhus University, Denmark, spokesman of the ALPHA collaboration. "This inspires us to work that much harder to see if antimatter holds some secret."

In another recent development in CERN's antimatter programme, the ASACUSA experiment has demonstrated a new technique for producing antihydrogen atoms. In a paper soon to appear in Physical Review Letters, the collaboration reports success in producing antihydrogen in a so-called Cusp trap, an essential precursor7 to making a beam. ASACUSA plans to develop this technique to the point at which beams of sufficient intensity8 will survive for long enough to be studied.

"With two alternative methods of producing and eventually studying antihydrogen, antimatter will not be able to hide its properties from us much longer," said Yasunori Yamazaki of Japan's RIKEN research centre and a member of the ASACUSA collaboration. "There's still some way to go, but we're very happy to see how well this technique works."

"These are significant steps in antimatter research," said CERN Director General Rolf Heuer, "and an important part of the very broad research programme at CERN."



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1 collaboration bW7yD     
n.合作,协作;勾结
参考例句:
  • The two companies are working in close collaboration each other.这两家公司密切合作。
  • He was shot for collaboration with the enemy.他因通敌而被枪毙了。
2 detailed xuNzms     
adj.详细的,详尽的,极注意细节的,完全的
参考例句:
  • He had made a detailed study of the terrain.他对地形作了缜密的研究。
  • A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。
3 remains 1kMzTy     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • The remains of the meal were fed to the dog.残羹剩饭喂狗了。
4 annihilate Peryn     
v.使无效;毁灭;取消
参考例句:
  • Archer crumpled up the yellow sheet as if the gesture could annihilate the news it contained.阿切尔把这张黄纸揉皱,好象用这个动作就会抹掉里面的消息似的。
  • We should bear in mind that we have to annihilate the enemy.我们要把歼敌的重任时刻记在心上。
5 dedicated duHzy2     
adj.一心一意的;献身的;热诚的
参考例句:
  • He dedicated his life to the cause of education.他献身于教育事业。
  • His whole energies are dedicated to improve the design.他的全部精力都放在改进这项设计上了。
6 expectancy tlMys     
n.期望,预期,(根据概率统计求得)预期数额
参考例句:
  • Japanese people have a very high life expectancy.日本人的平均寿命非常长。
  • The atomosphere of tense expectancy sobered everyone.这种期望的紧张气氛使每个人变得严肃起来。
7 precursor rPOx1     
n.先驱者;前辈;前任;预兆;先兆
参考例句:
  • Error is often the precursor of what is correct.错误常常是正确的先导。
  • He said that the deal should not be seen as a precursor to a merger.他说该笔交易不应该被看作是合并的前兆。
8 intensity 45Ixd     
n.强烈,剧烈;强度;烈度
参考例句:
  • I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
  • The strike is growing in intensity.罢工日益加剧。
TAG标签: matter atoms antimatter
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