Rice particle physicist to lead major US contribution at CERN

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Rice particle physicist to lead major US contribution at CERN
Padley to direct $40M muon detector effort at large hadron collider

Rice University physicist B. Paul Padley has been chosen to lead the scientific operations for the $40 million Endcap Muon System of particle detectors at the European Organization for Nuclear Research’s (CERN) Large Hadron Collider (LHC).

Scheduled to begin operations next year, LHC is poised to become the most powerful particle accelerator in the world. Housed in a sprawling 27-kilometer ring of subterranean tunnels on the border between France and Switzerland, LHC will smash together beams of protons traveling near light speed in order to recreate high-energy conditions that existed during the universe’s infancy.

“The LHC is one of the preeminent international research efforts of our day, and Dr. Padley’s selection to lead a major U.S. contribution to this program there is indicative both of his expertise and of Rice’s stature in the international subatomic physics community,” said Kathleen Matthews, dean of Rice’s Wiess School of Natural Sciences. “Scientists from Rice’s T.W. Bonner Nuclear Laboratory have participated in every major international particle accelerator project for the past 40 years, and Dr. Padley is continuing that tradition of excellence.”

Padley, associate professor of physics and astronomy, has been chosen to lead the scientific operations of the CMS Endcap Muon System, one of the major subsystems of the massive 13,000-ton Compact Muon Solenoid (CMS). CMS is housed in an underground chamber in Cessy, France, just across the border from Geneva, Switzerland. The physical scale of the CMS project is matched by its human scale: the project team boasts 2,300 people from 159 scientific institutions.

Like most particle physics detectors, the heart of CMS is a powerful electromagnet. As subatomic particles fly away from the collisions inside the accelerator, they follow a curved track and pass through the detector’s magnetic field. Based on the tracks the particles follow, scientists can distinguish the various particles based on their charge-to-mass ratios.

A goal of CMS is to detect the rapid stream of muons that will be created in the LHC. Muons are short-lived particles that act much like electrons but are far more massive. Detection of muons is crucial at the LHC because muons will play a key role in unveiling the physics of the Higgs field and of supersymmetry, two of the collider’s primary goals.

“Precise and reliable detection of muons is a notoriously difficult task at hadron colliders, but we must solve this problem at LHC if we are to adequately reconstruct the decay products of the Higgs particle,” Padley said. “Most exciting of all, we may be able to shed light on the mysterious dark matter that pervades the universe.”

The CMS Endcap Muon System consists of some 6,000 square meters of muon detectors and about 400,000 electronic readout channels. Scientists have to design systems that can sift through the massive stream of data flowing from the detectors in order to reconstruct the chain of events that occurs during each particle collision. For example, the path of each muon must be calculated to within one millimeter’s accuracy in space and to within four nanoseconds accuracy in time.

“Some of the best minds in physics are working to ensure that the Endcap Muon System provides the best possible physics, and I count it as a rare honor to be able to take part,” Padley said.