Experimental results for the world's largest dark matter particles were found traces | | dark matter _ Shanghai Jiao Tong University news

Shanghai scientists leading dark matter research on international level

Morning news reporter Dong Chuanfeng

Shanghai traffic University hongwen told seats Professor, and China Jinping underground laboratory Pan-daX (Panda plans) experiment head Ji Xiangdong Dr July 21 in United Kingdom held of two years once of international dark material Assembly Shang official announced has PandaX two period 500 kg level liquid Xenon dark material detector run of first a physical results, in 33,000 kg/days of exposure volume Xia, not found dark material particles trail, on May of dark material candidate object obtained has latest of limit.

　　"Passive" detection of dark matter

PandaX dark matter experiment is led by the Shanghai Jiao Tong University, China in cooperation with Beijing University, Shandong University, Shanghai Institute of applied physics, Chinese Academy of science, Sun Yat-sen University, China University of science and technology, China Institute of Atomic Energy and the Yalong River hydropower development company will take part in the first major underground liquid Xenon dark matter direct detection experiments. United States University of Maryland, and scientists at the University of Michigan also participated in this experiment.

PandaX Xenon atoms as probe targets used in the experiment, take the "Bull" way, detection of dispersion in the hundreds of billions of dark matter particles around Earth possible collision to a weak signal that occurs on the Xenon atom. Collision will recoil into the Xenon atoms, glows in the detector, power generation. Sensitive photocell optical and electrical signals to pass through as the "incidents" recorded. PandaX was first used in the experimental 110 new three-inch photomultiplier tubes for recording. Latest equivalent of 33,000 kilograms of Xenon atoms in one day without a collision occurred and these dark matter particles, or one in 33,000 kilograms of Xenon atoms, there has not been a crash. Experiments on dark matter particles may make an unprecedented restrictions.

　Detection levels of the world's leading

Responsible for the analysis of experimental data of Shanghai Jiao Tong University Professor Liu Jianglai, PandaX experiment is like weaving a dense "networks", getting denser, more likely to find dark matter. "We use this experiment unprecedented accuracy to identify dark matter signal and background ' noise '. PandaX 500 kg detector is used by independent research and development of the PandaX cooperation group, Shanghai Jiao Tong University Laboratory construction, can be sensitive detecting one photon or one electron. In running the world's largest dark matter Detector sensitivity is high. ”

Former Director, academician of Chinese Academy of Sciences, Institute of high energy Physics Department of science and technology "Thirteen-Five" major projects group leader Chen hesheng, PandaX phase II tests the latest results show that deep dark matter detection experiments, China has been in the international leading level.

　[Link]

"Ghost"-like dark matter

Represents the universe, about 85% content

According to the latest study of astronomy and Cosmology, dark matter represents about 85% of the matter content of the universe. If there is no dark matter won't form galaxies, stars and planets, however, because no direct electromagnetic interactions with ordinary matter, dark matter does not glow, similar to the "ghost", could not be seen in the usual way. But it can interfere with stars made of light or gravity, its existence can be clearly felt.

Editors: in Yang SN185

Article keywords:
Dark matter, Shanghai Jiao Tong University

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世界最大暗物质实验首结果公布 未发现粒子踪迹|暗物质|上海交通大学_新闻资讯

上海科学家暗物质研究领先国际水平

　　晨报记者　董川峰

　　上海交通大学鸿文讲席教授、中国锦屏地下实验室　Pan-daX（熊猫计划）实验负责人季向东博士7月21日在英 国举行的两年一度的国际暗物质大会上正式公布了PandaX二期500公斤级液氙暗物质探测器运行的第一个物理结果，在3.3万公斤/天的曝光量下，未发 现暗物质粒子踪迹，对可能的暗物质候选对象得出了最新的限制。

　　“守株待兔”探测暗物质

　　PandaX 暗物质实 验是由上海交通大学牵头，国内多个合作单位包括北京大学、山东大学、中科院上海应用物理研究所、中山大学、中国科学技术大学、中国原子能科学研究院和雅砻 江流域水电开发有限公司等参与的首个大型液氙暗物质地下直接探测实验。美国马里兰大学和密西根大学的科学家也参加了这个实验。

　　PandaX实 验用氙原子作为探测靶子，采取“守株待兔”的方式，探测弥散在地球周围的成千上万亿的暗物质粒子可能碰撞到氙原子上而发生的微弱信号。碰撞会转化为氙原子 的反冲能，在探测器中发光、发电。光和电信号都可以通过灵敏的光电管作为“事件”记录下来。PandaX实验首次采用了110个新型三英吋的光电倍增管来 进行记录。最新结果相当于3.3万公斤的氙原子在一天时间内没有和这些暗物质粒子发生过一次碰撞，或者一公斤的氙原子在3.3万天里没有发生过一次碰撞。 这对可能的暗物质粒子作出前所未有的实验限制。

　　探测实验水平国际领先

　　负责实验数据分析的上海交通大学特聘教授刘 江来表示，PandaX实验就像是在织一个密不透风的“网”，织得越密，越有可能找到暗物质。“这次实验我们用前所未有的精度来甄别暗物质信号和背景‘噪 声’。PandaX 所用的500公斤级探测器是PandaX合作组自主研发的，在上海交通大学实验室里建造，可以对一个光子或一个电子进行灵敏探测。 这是全世界运行中最大的暗物质探测器，灵敏度也最高。”

　　中国科学院院士、中国科学院高能物理研究所原所长、科技部“十三五”重大项目组组长陈和生表示，PandaX二期实验的最新结果表明，中国深地暗物质探测实验已经处于国际领先水平。

　　[链接]

　　“幽灵”般的暗物质

　　代表宇宙中约85%物质含量

　　根据最新天文学和宇宙学的研究，暗物质代表了宇宙中约85%的物质含量。如果没有暗物质就不会形成星系、恒星和行星，但是，由于与普通物质没有直接电磁 相互作用，所以暗物质不发光，类似于“幽灵”，无法用通常的办法看到。但它却能干扰星体发出的光波或引力，其存在能被明显地感受到。

责任编辑：于越杨 SN185

文章关键词：
暗物质 上海交通大学

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