Physics at the frontier of knowledge

Honorary doctorate recipient Prof. Peter Jenni

People behind the science

March 13, 2018
Source: 
WEIZMANN MAGAZINE VOL. 13
Credit: Frank Hommes

Credit: Frank Hommes

For most of his professional life, Prof. Peter Jenni has been at the center of a global scientific adventure: the search for missing pieces in the Standard Model of Particle Physics. A leader on a successful experiment conducted at CERN’s Large Hadron Collider (LHC), Prof. Jenni’s scientific leadership has paved the way to seminal discoveries about the fundamental building blocks of the universe. He was awarded a PhD honoris causa at the International Board meeting.

“Physics is all about collaboration, and Israelis were behind some of the LHC’s fundamental technologies,” he says. “The friendships I’ve built make it a special pleasure to come to Rehovot and receive this honor. I mean it when I say that I share this honor with my colleagues here on campus.”

For decades, Prof. Jenni has been associated with the LHC, a 27-km (19-mile) long circular accelerator, dug 100 m (328 feet) below ground on the border between France and Switzerland. The largest machine ever built, the LHC employs thousands of magnets to keep subatomic particles moving at nearly the speed of light along this circular race-track, and then smash them together to examine their components. Prof. Jenni served as the spokesperson (project leader) of ATLAS, a massive detector partially based on Weizmann research, which was involved in detecting a long-predicted particle called the Higgs Boson in 2012.

“One of the questions left unanswered by the Standard Model is how subatomic particles —the basic constituents of matter—acquire mass,” he explains. “The discovery of the Higgs Boson, based on collision data gathered by the ATLAS detector, helps explain this, which is why it generated so much excitement.”

Prof. Jenni says that steady advancement in accelerator technology makes discovery possible.

“Back in the 1980s, CERN’s Super Proton Synchrotron, a 6.7-kilometer accelerator, allowed us to identify fundamental particles known as the W and Z bosons. But to get to the Higgs, we needed to reach much higher energy levels. Our concept for the ATLAS experiment at the LHC was first submitted in a letter of intent in 1992, and five years later construction began. Today, the LHC accelerates particles to 99.9999991% of the speed of light at an energy level of 13 trillion electron volts. It recorded its first collisions in 2009.”

The Swiss-born scientist trained at the University of Bern and the Swiss Federal Institute of Technology in Zürich, and also worked at CERN during graduate school. But progress also relied heavily on Prof. Jenni’s natural talent for diplomacy, and for bringing the right people and resources together.

“The ATLAS team just got bigger and bigger,” he recalls. “It was difficult, in the sense that you really have to find a consensus, rather than ordering people to do one thing or another. It was also not an easy task to acquire the very expensive equipment. That’s how the LHC became a collaboration, not just between scientists, but between countries.”

And one of these countries, of course, was Israel.

“Scientists from the Weizmann Institute—as well as Tel Aviv University and the Technion— were involved in ATLAS from the beginning, but some CERN member states were reluctant to have Israel involved,” he recalls. “I wasn’t part of the council that makes these decisions, but I did find opportunities to improve the atmosphere, and eventually Israel came on board.”

Prof. Jenni still believes in the power of science to break down barriers. He points out that at CERN, scientists talk to each other even if the countries they represent do not. He is similarly proud of the fact that women scientists are increasingly taking charge of what was once an entirely male-dominated field. One is Fabiola Gianotti, an Italian particle physicist who did her PhD with Prof. Jenni and later worked with him on the ATLAS experiment, and who recently became first woman to be named CERN’s Director General.

Currently consulting on projects around the world, Prof. Jenni still sees the future as a wide-open scientific adventure.

“Look at it this way: our work at CERN’s LHC is a bit like figure skating. There’s the ‘short program’ where you know exactly what you’re aiming for. That was the Higgs. Now, I predict that for the next 15 to 20 years we’ll be doing the ‘free program’—exploratory science that has no limit on fantasy and creativity. While we still need the very best instruments to move forward, this is where the fun really begins.”

Prof. Peter Jenni

Prof. Peter Jenni