波士顿大学学者发现新式微中子振荡
文章来源:未知 文章作者:enread 发布时间:2011-06-17 03:05 字体: [ ]  进入论坛
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The international T2K collaboration1 announced today that they have observed an indication(指示) of a new type of neutrino(微中子) transformation2 or oscillation from a muon neutrino to an electron neutrino. Boston University Professor of Physics Edward Kearns is among the team of researchers responsible for this discovery. Evidence of this new type of neutrino oscillation may lead the way to new studies of a matter/ anti-matter asymmetry3(不对称) called charge-parity (CP) violation4. This phenomenon has been observed in quarks (for which Nobel prizes were awarded in 1980 and 2008), but never in neutrinos. CP violation in the early universe may be the reason that the observable universe today is dominated by matter and no significant anti-matter. If the T2K result does indicate this third oscillation, then a search for CP violation in neutrinos will be a major scientific quest in the coming years.

"Even though we have studied neutrino oscillations for years, there is still a great thrill in seeing these six events. The neutrino beam technique that we use is working beautifully and the interpretation5 is simple and direct. I can hardly wait to collect more data. It has been a privilege(特权,优待) for all of us at Boston University to participate in this series of experiments in Japan, and we greatly appreciate the efforts at J-PARC and KEK to restart the T2K beam," says Kearns.

Neutrinos come in three types, or "flavors"; electron, muon, and tau. In the T2K experiment in Japan, a muon neutrino beam was produced in the Japan Proton Accelerator Research Complex, called J-PARC, located in Tokai village, Ibaraki prefecture(县,辖区) , on the east coast of Japan, and was aimed at the gigantic Super-Kamiokande underground detector6 in Kamioka, near the west coast of Japan, 295 km (185 miles) away from Tokai. An analysis of the detected neutrino-induced events in the Super-Kamiokande detector indicates that a very small number of muon neutrinos traveling from Tokai to Kamioka (T2K) transformed themselves into electron neutrinos.

Further steps towards this goal will continue to require global scientific collaborations, like T2K, to overcome the significant technical challenges in this search. The T2K experiment utilizes7 the J-PARC complex that accelerates protons onto a target to produce an intense secondary particle beam that is focused by special magnets called neutrino horns. The focused particle beam decays into a beam of neutrinos, which is monitored by a neutrino detector 280 meters from the target. This beam of neutrinos travels 295 km underground to be detected in the Super-Kamiokande detector.

The work of the T2K experiment is located in Japan and primarily supported by the Japanese Ministry8 of Education, Culture, Sports, Science and Technology. However, the experiment was constructed and is operated by an international collaboration, which consists of about 500 physicists9 from 59 institutions in 12 countries [Japan, US, UK, Italy, Canada, Korea, Switzerland, Spain, Germany, France, Poland, and Russia]. The data collected by the experiment is also analyzed10 by the collaboration. The US T2K collaborating11 team of approximately 70 members [Boston University, Brookhaven National Lab, UC Irvine, University of Colorado, Colorado State University, Duke University, Louisiana State University, Stony13 Brook12 University, University of Pittsburgh, University of Rochester, and University of Washington (Seattle)] is funded by the US Department of Energy, Office of Science. The US groups have built superconducting corrector magnets(磁体) , proton beam monitor electronics, the second neutrino horn and a GPS time synchronization14 system for the T2K neutrino beamline; and a pi-zero detector and a side muon range detector (partial detector) in the T2K near detector complex.

They are also part of the team that built, upgraded and operates the Super-Kamiokande detector.

The March 2011 earthquake in eastern Japan caused damage to the accelerator complex at JPARC, and the data-taking run of the T2K experiment was abruptly15 discontinued. Fortunately, however, no scientists working on T2K or technical staff supporting their work were injured in the earthquake or its aftermath. The T2K experiment will be ready to take data when J-PARC resumes its operation, which is planned to occur at the end of 2011.



点击收听单词发音收听单词发音  

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 transformation SnFwO     
n.变化;改造;转变
参考例句:
  • Going to college brought about a dramatic transformation in her outlook.上大学使她的观念发生了巨大的变化。
  • He was struggling to make the transformation from single man to responsible husband.他正在努力使自己由单身汉变为可靠的丈夫。
3 asymmetry zyIzlK     
n.不对称;adj.不对称的,不对等的
参考例句:
  • These bands must introduce longitudinal asymmetry in the planetary albedo.这些云带必定引起行星反照率的经向不对称性。
  • In any event the asymmetry is clear enough.总之,不对称是非常明显的。
4 violation lLBzJ     
n.违反(行为),违背(行为),侵犯
参考例句:
  • He roared that was a violation of the rules.他大声说,那是违反规则的。
  • He was fined 200 dollars for violation of traffic regulation.他因违反交通规则被罚款200美元。
5 interpretation P5jxQ     
n.解释,说明,描述;艺术处理
参考例句:
  • His statement admits of one interpretation only.他的话只有一种解释。
  • Analysis and interpretation is a very personal thing.分析与说明是个很主观的事情。
6 detector svnxk     
n.发觉者,探测器
参考例句:
  • The detector is housed in a streamlined cylindrical container.探测器安装在流线型圆柱形容器内。
  • Please walk through the metal detector.请走过金属检测器。
7 utilizes 557861a39a30cf55cdbbf728aa4de1b8     
v.利用,使用( utilize的第三人称单数 )
参考例句:
  • One highly successful approach utilizes a triplet aspheric lens array. 一种很成功的方法是利用一个三合非球面透镜阵列。 来自辞典例句
  • The first utilizes a blend of finely ground ceramic powders. 第一种用的是一种磨细的陶瓷粉末混合物。 来自辞典例句
8 ministry kD5x2     
n.(政府的)部;牧师
参考例句:
  • They sent a deputation to the ministry to complain.他们派了一个代表团到部里投诉。
  • We probed the Air Ministry statements.我们调查了空军部的记录。
9 physicists 18316b43c980524885c1a898ed1528b1     
物理学家( physicist的名词复数 )
参考例句:
  • For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说,这是受挫折的一年。 来自英汉非文学 - 科技
  • Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。
10 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
11 collaborating bd93aed5558c4b146fa553d822f7c432     
合作( collaborate的现在分词 ); 勾结叛国
参考例句:
  • Joe is collaborating on the work with a friend. 乔正与一位朋友合作做那件工作。
  • He was not only learning from but also collaborating with Joseph Thomson. 他不仅是在跟约瑟福?汤姆逊学习,而且也是在和他合作。
12 brook PSIyg     
n.小河,溪;v.忍受,容让
参考例句:
  • In our room we could hear the murmur of a distant brook.在我们房间能听到远处小溪汩汩的流水声。
  • The brook trickled through the valley.小溪涓涓流过峡谷。
13 stony qu1wX     
adj.石头的,多石头的,冷酷的,无情的
参考例句:
  • The ground is too dry and stony.这块地太干,而且布满了石头。
  • He listened to her story with a stony expression.他带着冷漠的表情听她讲经历。
14 synchronization DgDzwV     
n.同一时刻;同步;使时间互相一致;同时性
参考例句:
  • Communication record: the function supports synchronization record during the communication process. 通话录音:支持通话过程的同步录音。 来自互联网
  • Synchronization is an important problem of digital audio watermarking. 同步性是数字音频水印的一个重要问题。 来自互联网
15 abruptly iINyJ     
adv.突然地,出其不意地
参考例句:
  • He gestured abruptly for Virginia to get in the car.他粗鲁地示意弗吉尼亚上车。
  • I was abruptly notified that a half-hour speech was expected of me.我突然被通知要讲半个小时的话。
TAG标签: matter electron neutrino
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