Professor Mark Lancaster has been elected as co-spokesperson of Fermilab’s Muon g-2 experiment

UCL Physics & Astronomy’s Professor Mark Lancaster has been elected as co-spokesperson of Fermilab’s Muon g-2 experiment, which examines muons — short-lived particles that could open a window on possible sources of new physics. 

Professor Lancaster instigated UCL and the UK’s involvement in the Muon g-2 experiment five years ago and has since has helped lead the design and construction of one of the Fermilab experiment’s two particle detector systems. He now takes the helm to co-lead the experiment itself, along with current Muon g-2 co-spokesperson and Fermilab scientist [title] Chris Polly.

“Mark has played a vital role in building up the international collaboration,” [title] Polly said. “As he takes on this leadership role, he’ll help bring a fresh, independent perspective at a time when the experiment has to be at its most introspective, moving towards our first physics result.”

Muon g-2 scientists are measuring a property of the muon — a heavy cousin of the electron — called its magnetic moment. Departures from the predicted value of this property could point to new physics, including the existence of undiscovered particles or new forces, and pave the way for future experiments.

“At the moment, Muon g-2 is entering a very exciting time — we’ve just started our first major data collection period here at Fermilab,” Professor Lancaster said.

At Muon g-2, muons travel through a large, 50-foot-wide particle storage ring with a strong magnetic field. As the beam of muons circles around the ring, they act like tiny, spinning magnets. Within the ring, the muon’s spin direction rotates around its axis — like a gyroscope — in response to the magnetic field.

The muons subsequently decay, producing particles whose direction of travel is directly related to the muon’s magnetic moment. The magnetic moment can also be affected by previously undiscovered particles popping in and out of the vacuum, so any disagreement with the prediction is a clear sign of a new discovery.

The Fermilab experiment, a collaboration of over 25 institutions and almost 200 physicists and engineers, recently began the first of three year-long data-taking runs. It picks up where the Brookhaven National Laboratory Muon g-2 experiment left off. 

In 2001, Brookhaven first reported a discrepancy between the predicted and measured values of the magnetic moment – a hint of a possible new discovery. 

The storage ring was relocated to Fermilab in 2013. Now that the experiment has begun taking data, the goal at Fermilab is to collect 20 times the amount of data with four times the precision compared to Brookhaven.

“We’re currently seeking to measure the muon’s magnetic moment with a far greater precision than previously achieved,” Professor Lancaster said. “By taking more data and reducing the systematic uncertainties in the measurement, we hope to conclusively confirm or refute the Brookhaven measurement.”

The benefit of leading such  significant and potentially groundbreaking research for Muon g-2 is the opportunity to work with a diverse range of scientists and engineers.

“What I look forward to most is working with all of the young people on the experiment who will have smart, new ideas for the way we analyze the data,” Professor Lancaster said. “New approaches for analyzing the data will be invaluable in achieving our goal to solve the longstanding puzzle of the muon’s magnetic moment.”

Links

• UCL Physics & Astronomy
• Muon g-2 experiment