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Neutrino Mass Upper Limit Estimated by Galactic Distribution
利用銀河系分布估計(jì)出中微子質(zhì)量上限

"Six thousand billion of them are going through your body every second." That's physicist Lawrence Krauss on neutrinos, on the June 15th weekly Science Talk podcast. "Neutrinos are the lightest elementary particles we know of. The name comes from the fact that they had to be neutral because we couldn't see them in detectors. But they had to be light. So Enrico Fermi called them "a little neutron," in Italian is neutrino. So they were baby neutrons, which were the only other neutral particles at the time that were known."
“每秒鐘有6萬億個(gè)這種物質(zhì)穿過你的身體?！边@是物理學(xué)家勞倫斯?克勞斯在6月15 日的每周《科學(xué)講座》播客上對(duì)中微子的描述。他說：“中微子是我們所知的基本粒子當(dāng)中最輕的一個(gè)。之所以叫它中微子是源于它的中性特質(zhì)，因?yàn)槲覀冊(cè)跈z測(cè)器里無法觀測(cè)到它們。而毫無疑問，它們必然很輕。因此，恩里科?費(fèi)米把它們叫做‘小中子’，在意大利語中就是中微子的意思。綜上，中微子就是極小的中子，是它被發(fā)現(xiàn)以來除中子外唯一的中性粒子?！?/div>

Now astrophysicists have put a best-guess upper limit on the mass of the neutrino. The research is being reported this week at the Weizmann U.K. conference at University College London and will appear in an upcoming issue of Physical Review Letters.
現(xiàn)在，天天物理學(xué)家對(duì)中微子的質(zhì)量上限作出了一個(gè)最佳測(cè)定。研究結(jié)果將于本周在魏茨曼英國(guó)倫敦大學(xué)會(huì)議上作出報(bào)道，并發(fā)表于即將出版的《物理評(píng)論通訊》上。

The work took advantage of the huge 3-D galaxy map called Mega Z. Because there are so many neutrinos, their tiny masses add up to influence the overall distribution of galaxies. And the researchers say the galactic map depends on a neutrino's mass being no more than 0.28 electron volts, less than a billionth of the mass of an atom of hydrogen, the lightest element. "These are the most interesting particles in nature."
這項(xiàng)研究利用了Mega Z這個(gè)巨大的三維星圖。原因在于，星系中有眾多的中微子，而當(dāng)這些微不足道的質(zhì)量加在一起時(shí)，其總和就會(huì)影響整個(gè)星系的分布。研究人員還說，銀河系的構(gòu)成取決于中微子的質(zhì)量，由此推斷出中微子質(zhì)量的最小上限：不超過0.28電子伏特，該數(shù)值還不到一個(gè)氫原子質(zhì)量的十億分之一?！斑@可真是一種最有意思的粒子！”

—Steve Mirsky

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