University of California at Santa Barbara

The UC Santa Barbara Experimental High Energy Physics Group and the LHC

Ten physicists in front of cylindrical structure with wires radiating out
This shows a bunch of US people with the tracker when it was being built. Four of the 10 people shown are UCSB. Image courtesy of UCSB

UCSB physicists view the LHC as an unparalleled opportunity to search for new clues to the underlying structure of our universe -- namely its forces and its fundamental building blocks. The energy ranges that will be accessed by the proton-proton collisions at the LHC correspond to a realm where there is good reason to expect important new particles and interactions to appear. The data from the LHC program will help us to answer basic questions about the origin of mass, explain why the universe is made up predominantly of matter while anti-matter is nearly absent, and perhaps even assist theoretical physicists in their quest to reconcile the theory of gravity with quantum mechanics.  Although there are many models and speculations of what will be seen at the LHC, nobody knows for sure what will appear. UCSB physicists are particularly excited about the potential to explore the unexpected.

The experimental high energy physics group at UCSB involves faculty members Claudio Campagnari, Joe Incandela, Jeff Richman, David Stuart and Mike Witherell. The group also includes 3 engineers, 7 post-doctoral research associates and 9 graduate students.  They are part of the Compact Muon Solenoid (CMS) experiment at the CERN LHC. More than 2.5 million channels of high-precision particle position tracking elements used in the CMS semiconductor-based tracking system were assembled and tested at UCSB. UCSB personnel also participated in the final assembly of the tracking system at CERN and will help to operate and maintain the detector.

Activities of UCSB faculty in the CMS experiment

Eight people around a clean room table
This shows a part of our clean room crew working around the module assembly robot at UCSB during the major production effort period in 2006. Image courtesy of UCSB

Claudio Campagnari is co-leader of the CMS top quark physics group in the period 2008-2009. This group is focused on understanding the production and decay properties of top quarks in proton-proton collisions at the LHC primarily to help to separate these events from events resulting from new particles and processes. He has also been involved in preparatory studies of top quark pair production and decay to electrons and muons.

Joe Incandela is the deputy physics coordinator for the CMS experiment in the period 2007-2008. The CMS physics program in this period is focused on preparations for potential discoveries in early data. In addition, Incandela has led the US CMS tracking group since 1998. The US CMS tracking group involves faculty, scientists, engineers, technicians, and students from 8 US institutions and played a large role in the construction of the CMS tracking system. His own research is focused on understanding events with missing energy (due to undetected particles) which includes known processes, such as top quark decays, and unknown processes that could include dark matter.

Jeff Richman and members of his group are working on projects related to the CMS High Level Trigger (HLT), muons, tracking, and searches for supersymmetric particles and other types of new physics. The HLT is the last stage in determining which events are recorded for detailed study. We must be highly selective because we can record only a tiny fraction of events based on event features that canbe rapidly analyzed. Our group focuses on the algorithms that look for muons, which can signal either interesting new physics processes or known processes that can be used for calibration purposes. We are also studying processes with muons to search for new kinds of matter, including the predicted supersymmetric partners of known particles.

David Stuart is leading an effort in analysis of early commissioning of the tracker using cosmic rays. This has helped us understand the functioning and precision alignment of the detector components. We are preparing to further this commissioning with beam particles, including electron-positron pairs from photon conversions. His group is also developing an algorithm to use some of the well-known properties of the Z boson's particle production to measure other aspects that are theoretically difficult to calculate. Circumventing these theoretical uncertainties should allow more rapid sensitivity to new phenomena.