Chooz-ing Flavors: Drexel Faculty and Students Conduct Neutrino Research in France

By Maia Livengood

February 19, 2011 — Summer 2010 marked the completion of a major step in the Double Chooz project—a global collaboration project stationed in the French Ardennes. Among the research groups from Brazil, France, Germany, Japan, the United States, Russia, Spain, and the United Kingdom, were two Drexel professors, a post-doctoral researcher, and three notably accomplished physics students. The group, studying the transformations of neutrino species—highly specified particle physics—completed the construction of its on-site neutrino detector.

Lab Students Choozing FlavorsNeutrinos, associated with electrons, were initially created in the “big bang,” formed in the sun during the fission process. The neutrino particles change as they travel through space, creating a “flavor”—M or T flavors, to be exact. The research team aims to discover the probability of the independent flavors. They do so by using two neutrino detectors (the second is expected to launch in 2012) to measure the neutrinos created by a nuclear reactor. Oscillations, as measured by the detectors, describe the transformations of different neutrino species and the observation of this effect implies—for the first time—that neutrinos have mass.

Neutrinos are of scientific interest as a probe for environments that are typically concealed from traditional observation techniques, such as optical and radio detection. The first use of neutrinos was for observation of the core of the Sun; neutrinos are virtually unimpeded due to their minimal interaction with external matter. Their movements, though, were a major discovery in the late 1990s, beginning with the original Chooz collaboration (named for its host city in Chooz, France). In fact, so monumental were the discoveries that the corresponding findings were included in the 2002 Nobel Prize.

Dr. Charles Lane, professor of physics, worked on the original Chooz project, beginning in 1992 and running through 2000. The same location site was used, and many of the collaborators from the original project remained. Lane’s involvement largely dealt with the management of the experiment’s electronics: photomultiplier tubes (PMTs) require circuits to make them operate properly, and he was involved both in designing and building the circuit dividers. Most recently, in the Double Chooz collaboration, Lane has been working on front-end electronics, using PMT signals to amplify and process them to be readable by particular triggers.

As a returning collaborator, Lane was able to involve Dr. Jelena Maricic, assistant professor of physics, as well as Karim Zbiri, post-doctoral researcher, Erica Caden, doctoral candidate under Lane, Edward Damon, doctoral candidate under Maricic, and James Monahan, a physics undergraduate. Monahan was responsible for installing the PMTs in their “housings” and testing the housing units to ensure their readiness for the official testing in France.

CadenCaden, who was the recipient of the prestigious Lindau Award (a fellowship allowing graduate students to attend an annual meeting of Nobel Laureates in Lindau, Germany), worked extensively on the electronics associated with the project. Due to the sensitivity of the PMTs, she aided Lane in designing and building a technology that amplifies the pulses for digital signaling, allowing them to be read on hardware and later analyzed. As the detector was recently “turned on,” (essentially filling the nesting doll-like volumes with liquid, an organic scintillator), the pair now face an intense phase of identifying and fixing any problems that might arise.

“I always knew that I wanted to study particle physics,” Caden says. “I’m very much a hardware person, so I wanted something experimental. Dr. Lane was incredibly helpful by starting me off on smaller projects, later leading into more depth in electronics. In the spring of 2009, we went to help install 390 PMTs, which required cleaning, double-testing, and finally, mounting them to the detector walls. I had the opportunity to live in France for two months—which was truly an unparalleled experience.”

The pair’s signals will be processed in a data acquisition system, now ready to receive data over the course of the next five years. In a larger sense, due to the potential application and use of neutrinos in probing challenging space environments, the new detectors ensure that neutrino physics will remain one the most innovative areas in the field for years to come, with implications both in particle physics and cosmology.

Maia Livingood '12 is a Business Administration major with concentrations in Finance and Economics, as well as an English minor. Working for the College of Arts and Sciences, she has developed a strong interest in publication management and hopes to build upon the experience throughout her professional career.