The US and ALICE

Simulation of a lead-lead collision in the ALICE detector. Image © CERN

About 53 physicists, engineers, and students from 12 U.S. institutions participate in the ALICE experiment. The ALICE experiment will study the hot quark-gluon plasma that existed several microseconds after the Big Bang by analyzing the collisions of lead nuclei at the LHC.

The ALICE-USA collaboration, funded primarily by the Division of Nuclear Physics of the US Department of Energy Office of Science, collaborates with institutions in France and Italy to construct an electromagnetic calorimeter (EMCal) for ALICE. The EMCal, which will be installed over the next three years, is a lead-scintillator sampling calorimeter consisting of approximately 13,000 towers. The EMCal will give ALICE the ability to trigger on and measure high energy jets, clusters of elementary particles created from fast-moving quarks and gluons. Such fast quarks and gluons are formed in the initial stage of the collisions of lead nuclei and are used to investigate properties of the quark-gluon plasma.

Since their initial involvement in ALICE 10 years ago, scientists and students from three US institutions – Creighton University, Ohio State University and the Ohio Supercomputing Center – have made many critical contributions to the construction of ALICE. Members of these institutions developed the control systems for ALICE that allow control and monitoring of more than 100,000 pieces of information from the running detector, such as voltages, pressures and temperatures. US scientists have also developed and tested silicon drift detectors for the ALICE Inner Tracking System (ITS), contributed software for the ITS, developed hardware and controls for the ALICE detector laser-alignment system, and completed various computer simulations on the anticipated signals and physics from ALICE. Two supercomputer centers in the US have supplied ALICE with state-of-the-art cluster computing and helped port the ALICE computing framework and environment to US-based computing platforms.

Additional support for the US participation in ALICE comes from the National Science Foundation and the State of Ohio.