全球能量最高强子对撞机发生爆炸

http://www.sina.com.cn 2007年04月10日14:50 北京晚报

　　设计阶段的“低级失误”导致全球能量最高的大型强子对撞机日前发生爆炸。英国媒体9日报道，这次爆炸可能让对撞机无法按原计划于今年11月启动运行，人类探知宇宙大爆炸奥秘的征程可能也将因此被迫推迟数月。

　　现场20吨磁体被掀下基座

　　发生爆炸的大型强子对撞机位于瑞士和法国边境地区，由欧洲核子研究中心所有，是目前世界上在建能量最高的粒子对撞机，原计划今年11月启动。但在不久前，放置对撞机的地下隧道内发生爆炸，一块重达20吨的磁体被掀下基座，长达27公里的环形隧道内则充满氦气，工作人员全部紧急疏散。

　　《泰晤士报》9日援引欧洲核子研究中心负责对撞机建设的林恩·埃文斯博士的话说:“爆炸十分巨大，放置仪器的隧道充满氦气和尘土，我们被迫叫来消防队，紧急疏散所有人员。”他说，尽管在对撞机项目工作的所有人都被吓了一大跳，但在场人员全部安全撤离，无人受伤。

　　原因“低级失误”导致爆炸

　　爆炸后的初步调查显示，对撞机设计阶段的“低级失误”导致了爆炸。出现计算错误的是美国费米实验室，他们负责建设对撞机的磁体及放置磁体的基座。

　　由于设计有问题，大型强子对撞机的24块磁体都必须拆下修理或升级，这一工程可能让对撞机原定今年11月的启动日期推迟数月，要拖到明年春天才能启动。

　　对撞机主要由粒子加速器和探测器组成。在高能物理实验中，粒子加速器和探测器是常用设备。加速器利用超导磁体推动粒子在隧道内以稍低于光速的高速运行，在隧道内的四个对撞点让反方向运行的粒子相撞；探测器则在这些对撞点侦测碰撞产生的微小粒子，记录粒子能量、质量等信息，尤其是尚未被证实存在的“希格斯玻色子”。这些粒子可以帮助解释为什么物质有质量等基础物理难题。

　　要让粒子达到高速，就要使用巨型磁体，还要用液态氦让这些磁体的温度低于零下268摄氏度，以实现磁体的超导状态。除此之外，粒子还必须聚集成比头发丝还细的束，因此除了推动其运行的磁体外，还需要另一组磁体让其“聚焦”，正是在测试这一组磁体时发生了爆炸。

　　调查

　　设计者从中受益？

　　巧合的是，除了为大型强子对撞机制造磁体外，费米实验室的Tevatron加速器也在寻找“希格斯玻色子”。Tevatron是当前世界最强大的加速器，研究人员正一刻不停地工作，希望能在能量更高的大型强子对撞机启动前找到神秘的“希格斯玻色子”。

　　《泰晤士报》援引一名在大型强子对撞机项目工作的研究人员的话说:“真讽刺，这次推迟可能正好是他们所需要的东西。”不过费米实验室对这起事故仍十分恼火。实验室负责人皮尔·奥多内说:“我们很震惊，我们疏忽了一些最简单的力学平衡因素。不仅仅在设计的时候疏忽了，而且在开始建设磁体前的1998年至2002年间进行的4次设计审查中都疏忽了。”

　　小知识

　　大型强子对撞机是目前世界上在建最大的粒子对撞机，其长达27公里的环形隧道用来加速粒子，使其相撞，模拟出与宇宙大爆炸万亿分之一秒时类似状态。它有潜力帮助回答一些涉及自然和物质本质的基本问题，例如物质为什么有质量、各种作用力的统一、暗物质的本性、是否存在其他维度等等。

　　王丰丰(新华社专稿)

"The Large Hadron Collider at the CERN has suffered a big explosion deep inside that has caused a leak of hellium gas and the quick evacuation of everyone working there. The reason: a mathematical mistake that affected the design of the giant superconductive magnets made by Fermilab. Now the company will have to repair and upgrade the 24 magnets that are installed on the 27 km. circunference of one of the most important research centers on Earth."

From The Sunday Times (April 8, 2007)

Big Bang at the atomic lab after scientists get their maths wrong

Jonathan Leake, Science Editor

A £2 billion project to answer some of the biggest mysteries of the universe has been delayed by months after scientists building it made basic errors in their mathematical calculations.

The mistakes led to an explosion deep in the tunnel at the Cern particle accelerator complex near Geneva in Switzerland. It lifted a 20-ton magnet off its mountings, filling a tunnel with helium gas and forcing an evacuation.

It means that 24 magnets located all around the 17-mile circular accelerator must now be stripped down and repaired or upgraded. The failure is a huge embarrassment for Fermilab, the American national physics laboratory that built the magnets and the anchor system that secured them to the machine.

It appears Fermilab made elementary mistakes in the design of the magnets and their anchors that made them insecure once the system was operational.
Last week an apparently furious and embarrassed Pier Oddone, director of Fermilab, wrote to his staff saying they had caused “a pratfall on the world stage”. He said: “We are dumb-founded that we missed some very simple balance of forces. Not only was it missed in the engineering design but also in the four engineering reviews carried out between 1998 and 2002 before launching the construction of the magnets.”

The machine, the Large Hadron Collider (LHC), aims to recreate the conditions of the Big Bang, when the universe is thought to have exploded into existence about 14 billion years ago. However, the November start-up may now have to be delayed until next spring.

Dr Lyn Evans, who leads the accelerator construction project at Cern, the European organisation for nuclear research, said the explosion had been potentially very dangerous.

“There was a hell of a bang, the tunnel housing the machine filled with helium and dust and we had to call in the fire brigade to evacuate the place,” he said. “The people working on the test were frightened to death but they were all in a safe place so no-one was hurt.” An investigation by Cern researchers found “fundamental” flaws that caused the explosion, close to the CMS detector, one of the LHC’s most important experiments.

The accelerator is designed to smash together protons, a kind of sub-atomic particle, at near light speed. The hope is that such collisions will generate exotic new particles — especially the so-called Higgs boson which, theorists predict, could help explain key properties of matter, such as how it acquires mass and, hence, weight.

The LHC itself comprises two pipes, each containing a beam of protons travelling at near-light speed that are steered around the circular tunnel by powerful magnets. Such magnets are “superconducting” meaning they and the whole LHC are cooled to below -268C, using pipes filled with liquid helium.

The two proton beams travel in opposite directions but, at various points around the ring, their pipes merge, allowing the protons in each beam to collide.

However, since the thickness of each beam is less than that of a human hair, they have to be focused. This is the task of a second set of magnets, and it is these that were under test at the time of the explosion.

Coincidentally, Fermilab stands to gain most from delays at Cern. Its researchers also operate a rival but less powerful particle accelerator, the Tevatron.

Fermilab staff are pushing the Tevatron to ever-higher energies hoping that they might find the Higgs boson before the LHC switches on. An LHC researcher said: “Ironically, this delay could be all they need.”

例如物质为什么有质量、各种作用力的统一、暗物质的本性、是否存在其他维度等等。
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14Tev就可以研究各种力的统一，好像有点离谱啊

14Tev就可以研究各种力的统一，好像有点离谱啊

I will leave this as your homework to find out what is behind this claim.

太不可思义了,我认为这是阴谋.

I will leave this as your homework to find out what is behind this claim.
=========================================================================
If we only consider the electroweak and strong force,the GUT scale is larger than
14Tev,E(GUT)/E(EW)~0^(13), the E(EW)=O(100GeV).This is the so call hirachy problem,and it is the dominant motivation to introcuce SUSY.
if we contain the gtavity,we have to consider the Planck scale.

我的第一感觉也与ymytm兄一样 “太不可思义了,我认为这是阴谋.”在看“The Elegant Universe”那部电影时，曾听到费米实验室的科学家说过 要加紧实验以期在LHC前 “找到”“希格斯玻色子”。
如果按照精神分析的观点来看费米实验室的这种“低级失误”后的“潜意识”就是以期在LHC前 “找到”“希格斯玻色子”。如果让弗洛伊德来作“法官”费米实验室肯定死定了，呵呵。
(最近对精神分析很感兴趣，所以有点神经过敏了，呵呵！)

A magnet for the Large Hadron Collider (LHC) failed during a key test at the European particle physics laboratory CERN last week. Physicists and engineers will have to repair the damaged magnet and retrofit others to correct the underlying design flaw, which could delay the start-up of the mammoth subterranean machine near Geneva, Switzerland, from November until the spring of 2008. That would eliminate a 1-month "engineering run" with which physicists had hoped to shake the bugs out of the machine before shutting down for the winter, when power becomes prohibitively expensive.

Laboratory officials aren't giving up hope just yet, however. "We are pretty well along on finding a fix that can be implemented in the tunnel without having to bring [the magnets] up to the surface," says CERN's Lyndon Evans, who leads the construction of the accelerator. Only the damaged magnet will have to come out of the tunnel, he says.

The faulty magnets are designed to focus the LHC's beams of protons just before they collide. The beams will run through three such quadrupoles on either side of each of four collision points spaced around the 27-kilometer ring. The LHC's four massive particle detectors will sit at the collision points.

Designed and built at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, the magnet failed when researchers tried to pressurize its cylindrical casing to 25 times atmospheric pressure. The test was supposed to simulate the buildup of helium gas during a "quench," an event in which the superconducting wire in the magnet temporarily loses its superconducting properties and starts acting like a giant heating coil, boiling the liquid helium coolant that fills the volume between magnet and casing. The pressure pushed the innards of the magnet through the cylindrical container like a piston as a key support broke. The support was not designed to take a lengthwise push, says Stephen Holmes, an accelerator physicist at Fermilab.
"It's better to catch it now than a year from now when the LHC has its first quench," Holmes says. But, he adds, "we should have caught this before we got this far." Researchers at Fermilab and CERN already have ideas for modifying the magnets and will meet at CERN at the end of the month to finalize the plan and start the fix.

The schedule for starting the LHC in November was already extremely tight. Workers have lowered all but a handful of the LHC's 1624 main magnets into the tunnel and are busy connecting the equipment. Even so, they are currently about 5 weeks behind schedule and pushing to catch up, Evans says. "If it goes into 2008, then there is no question of having an engineering run and 3-month shutdown," Evans says. "We'll have to do without it."

If we only consider the electroweak and strong force,the GUT scale is larger than
14Tev,E(GUT)/E(EW)~0^(13), the E(EW)=O(100GeV).This is the so call hirachy problem,and it is the dominant motivation to introcuce SUSY.
if we contain the gtavity,we have to consider the Planck scale.

---------------------------------------------------------------

Well, you still have not answered my question. Why do people think LHC, running at 14 TeV, could test unification?

如此复杂的大型仪器，发生故障甚至灾难的可能性很大。简单的枪支还可能卡住或者走火呢。

I don't know their motivation to claim that they can test unification via the LHC.It is impossible to test unification in such low energy.

美国想阻碍欧洲发展，阴过它不止一次的。有前车之鉴，为阻止“伽利略”系统对GPS构成威胁，美国人把“伽利略”的密码给解了，让他以后赚不到一分钱，够黑。

The good news is that only a limited number of the magnets have this flaw. Work is
underway to develop a fix that can be done without removing the magnets from the tunnel.
It is not clear yet whether the schedule will be delayed a few months. Initial
indications are that the schedule can be preserved, but it is too soon to say for sure.

To read more, see

http://www.fnal.gov/pub/today/20070329_page01.html

按科幻小说风格，也可能是外星人 / 未来人的阴谋啊，哈哈。