Narrow Results

The CMS silicon strip tracker is the largest device of its kind ever built, and is the first instance of a large collider detector relying exclusively on this all-silicon technology for tracking. With an instrumented surface of over 200 m², and over nine million readout channels, it is two orders of magnitude larger than the silicon vertex detectors of the LEP experiments, and 30–40 times larger than the silicon inner detectors of the CDF and D0 experiments at the Tevatron. It makes use of microelectronics technology, but deploys it at the macroscale.

The photograph below shows the completed CMS silicon tracker, ready for installation in the experiment, side by side with the silicon strip vertex detector of the OPAL experiment at LEP. Approximately a decade and more than two orders of magnitude in scale separate these two silicon strip detectors.

In the following we motivate the choice of an all-silicon tracker for the CMS experiment, and discuss the reasons for the major design choices that define the system.

The CMS silicon microstrip tracker readout system is unprecedented in size, with over nine million channels. It is an analogue readout system, implemented using CMOS ASICs and linear, semiconductor laser transmitters which send pulse height data off-detector for digitisation and the first level of data processing. The basic components which define the architecture originated in R&D projects in the early 1990s and were crucial in allowing this system to be realised. The availability of several key technologies was critical to achieving the design preferences, and the components and technologies were utilised also to build the control and monitoring system and, later, to implement critical elements of other CMS sub-detector systems. The background to the technology choices and early development of the system is described and an attempt is made to draw some lessons which could be relevant for the future.

The journey in search for the Higgs boson with the ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN started more than two decades ago. But the first discussions motivating the LHC project dream date back even further into the 1980s. This article will recall some of these early historical considerations, mention some of the LHC machine milestones and achievements, focus as an example of a technological challenge on the unique ATLAS superconducting magnet system, and then give an account of the physics results so far, leading to, and featuring particularly, the Higgs boson results, and sketching finally prospects for the future. With its emphasis on the ATLAS experiment it is complementary to the preceding article by Tejinder S. Virdee which focused on the CMS experiment.

Since 2010 there has been a rich harvest of results on standard model physics by the ATLAS and CMS experiments operating on the Large Hadron Collider. In the summer of 2012, a spectacular discovery was made by these experiments of a new, heavy particle. All the subsequently analysed data point strongly to the properties of this particle as those expected for the Higgs boson associated with the Brout–Englert–Higgs mechanism postulated to explain the spontaneous symmetry breaking in the electroweak sector, thereby explaining how elementary particles acquire mass. This article focuses on the CMS experiment, the technological challenges encountered in its construction, describing some of the physics results obtained so far, including the discovery of the Higgs boson, and searches for the widely anticipated new physics beyond the standard model, and peer into the future involving the high-luminosity phase of the LHC. This article is complementary to the one by Peter Jenni⁴ that focuses on the ATLAS experiment.

Since 2010 there has been a rich harvest of results on standard model physics by the ATLAS and CMS experiments operating on the Large Hadron Collider. In the summer of 2012, a spectacular discovery was made by these experiments of a new, heavy particle. All the subsequently analysed data point strongly to the properties of this particle as those expected for the Higgs boson associated with the Brout–Englert–Higgs mechanism postulated to explain the spontaneous symmetry breaking in the electroweak sector, thereby explaining how elementary particles acquire mass. This article focuses on the CMS experiment, the technological challenges encountered in its construction, describing some of the physics results obtained so far, including the discovery of the Higgs boson, and searches for the widely anticipated new physics beyond the standard model, and peer into the future involving the high-luminosity phase of the LHC. This article is complementary to the one by Peter Jenni that focuses on the ATLAS experiment.

The journey in search for the Higgs boson with the ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN started more than two decades ago. But the first discussions motivating the LHC project dream date back even further into the 1980s. This article will recall some of these early historical considerations, mention some of the LHC machine milestones and achievements, focus as an example of a technological challenge on the unique ATLAS superconducting magnet system, and then give an account of the physics results so far, leading to, and featuring particularly, the Higgs boson results, and sketching finally prospects for the future. With its emphasis on the ATLAS experiment it is complementary to the preceding article by Tejinder S. Virdee which focused on the CMS experiment.