LHC at CERN -- Recreation of the Big Bang

Today's accelerator such as LHC is capable of recreating the condition at the beginning of the Universe as early as 0.1 nano second after the Big Bang. At that time the horizon of universe was only 3 cm and the temperature of the Universe was 1E15 Kelvin (or 100 GeV). This is believed to be the critical epoch for particles to acquire their own mass. This is the first phase transition caused by the spontaneous symmetry breaking, described by so-called Higgs mechanism. At around the same time (or even before), the dark matter is believed to be created and freeze out from the thermal equilibrium. To study this incredible condition. two large experiments are running at LHC: ATLAS and CMS.

CMS and End-cap Muon System

UCLA is one of the major US institutes in the CMS collaboration. The UCLA CMS group includes all the UCLA high energy groups : Profs. David Cline, Robert Cousins, Jay Hauser, David Saltzberg and Katsushi Arisaka. Among these, Arisaka and Cline's group have contributed to the End-cap Muon Chambers from the initial construction to commissioning and operation. This efforts have been led by a research scientist, Misha Ignatenko for a decade.


The picture above is the 3D illustration of the CMS detector back in 1994 when it was initially designed. It took the next 10 years and ~2,000 people to construct it piece by piece at all over the world.


The construction of seventy pieces of the End-cap Muon Chambers were carried out at the STRB Building in Westwood village adjacent to the UCLA campus from 1995 until 2004. Then all the chambers were shipped to CERN in 2004 and installed in 2004 - 2006 as shown above. Each end-cap muon system was slowly lifted up and down into the cave, then reached to the CMS experimental hall 100 m under the ground.


Our CMS End-cap Muon Chamber was the cover picture of the European version of Newsweek issued on September 15, 2008. Please note the statement, "And It's European", after 15 years of our hard works at UCLA!

CMS 4 muons

The LHC accelerator and the CMS experiment have been running like a miracle for the last two years. On July 4 of 2012, we announced the discovery of the Higgs Particle with 125 GeV mass. The above picture shows one of the Higgs candidates decaying into four muons, where two muons hit the End-cap Muon Chambers constructed by Arisaka's group.

Publications by CMS

A complete list of the publications by the CMS can be found by InSPIRE => CMS. The discovery of the Higgs Particle has been published at

Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC.

By CMS Collaboration (Serguei Chatrchyan et al.).
[arXiv:1207.7235 [hep-ex]].
Phys.Lett. B716 (2012) 30-61.

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