博客李淼

Seed杂志有一段Luis Alvarez-Gaume和Ulrich Fuchs的录音，介绍LHC：

录音

好久没有听到Alvarez-Gaume的西班牙口音的英语了，他本来答应夏天参加弦论班的，结果太忙没来。现在做了CERN理论组的头，也开始玩起政治来了。

这个录音的一些照片很漂亮，等一会转几张过来。

从以下的图片介绍我们得知，LHC的目标不仅仅是发现新物理，同时还要研究“老”物理中的新现象，ALICE探测器的设计就是为了研究夸克-胶子等离子体。所以，即使万一LHC不能发现新物理，我们至少还能研究夸克-胶子等离子体。现在，许多人用弦论中的AdS/CFT来研究夸克-胶子等离子体的一些问题，所以我们可以说，LHC也和弦论有关。希望学习弦论的人记住这一点，在别人攻击你的时候你将这个摆出来。当然，你最好知道什么是AdS/CFT，如果你仅仅知道cohomology或者homotopy，拜托，就不要提弦论了

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在看严肃的东西之前，稍事休息。在三表那里看到的关于意大利人和欧洲人的区别。意大利人几乎完全和中国人一样，只有一样不一样，就是咖啡。中国的咖啡是全世界最难喝的，常见的是速溶加三合一 。

“Europe and Italy”

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CERN俯视图：

Delphi，老的LEP加速器上的探测器，正在被拆卸：

LHC上一共将安装四个探测器，即CMS，ATLAS，ALICE，LHC-B。对于那些不太了解实验的人，应该解释一下，通常一个探测器对应于一个研究小组。

ATLAS探测器。下面是一段介绍ATLAS的话：

ATLAS (A Toroidal LHC ApparatuS) is a general purpose particle detector and one of four experiments planned for the LHC. The LHC design imposes heavy demands on these detectors. Proton bunches, travelling in opposite direction around the machine, will pass through each other every 25 nanoseconds; in each of these bunch crossings, five to ten interactions will occur; each interactions will produce hundreds of neutral and charge particles. Only a fraction of these events will contain interesting physics.

The ATLAS detector will be housed in Point 1 of the LEP/LHC tunnel. Point 1 is a large underground cavern, surrounded by smaller caverns housing electronics, cryogenic equipment, etc. The ATLAS detector will be 42 m long, 22 m wide and 22 m high ( about the same volume as the Physics building) and weigh 7000 tonnes. The detector has been designed with specific physics goals in mind.

ATLAS探测器的内部。

CMS探测器。

The CMS detector is designed to exploit the full range of physics at the LHC up to the highest luminosities. The detector tracking and calorimetry components are to be built within a high-field (4T) superconducting solenoid, leading to a compact design for the muon spectrometer. Identification of muons, photons and electrons and precise measurement of these particles, with an energy resolution of 1%over a large momentum range, are emphasized in the design considerations.

CMS探测器真空箱的外壳：

ALICE探测器的早期阶段。

The aim of the ALICE collaboration is to build a dedicated heavy-ion detector to exploit the unique physics potential of nucleus-nucleus interactions at LHC energies. Our aim is to study the physics of strongly interacting matter at extreme densities where the formation of a new phase of matter, the quark-gluon plasma, is expected. The existence of such a phase of matter and the study of its properties are crucial for understanding QCD and in particular chiral symmetry restoration. For this we propose to perform a comprehensive study of hadrons, electrons, muons and photons in the collisions of heavy ion nuclei.

ALICE探测器用到的time projection chamber。

Wikipedia：

In physics, a time projection chamber is a particle detector consisting of a gas-filled cylindrical chamber with multiwire proportional chambers (MWPC) as endplates. Along its length, the chamber is divided into halves by means of a central high voltage electrode disc, which establishes an electric field between the center and the endplates. Furthermore, a magnetic field is applied along the length of the cylinder, parallel to the electric field, in order to minimize the diffusion of the electrons coming from the ionization of the gas. On passing through the detector gas a particle will produce primary ionization along its track. The z-coordinate, the coordinate along the cylinder axis, is determined by measuring the drift time from the ionization event to the MWPC at the end. This is done using the usual technique of a drift chamber. The MWPC at the end is arranged with the anode wires in the azimuthal direction, θ, which provides information on the radial coordinate, r. To obtain the azimuthal direction, each cathode plane is divided into strips along the radial direction.

这篇文章发表于 2006年7月28日, 星期五 17:38:21，属于分类 理论物理。 你可以查看 HTML打印版 或通过 新闻聚合(RSS) 来追踪这篇文章的最新评论。 在文章后 发表评论。