Steve Nahn takes over US CMS detector upgrade project

Steve Nahn

This fall, Steve Nahn begins work as project manager of the US CMS phase I detector upgrade project. Nahn comes to Fermilab as a guest scientist and will be in charge of upgrading equipment that is vital to the CMS experiment at CERN.

CMS is designed to study the products of collisions from two counter-circulating proton beams, and in the next few years the rate of these collisions is expected to increase. The experiment’s detector will need to be upgraded in order to handle the additional particles that will be produced.

In fact, the project will replace all or part of three different systems: the forward pixel detector, which tracks charged particles very close to the beam; the electronics of the hadron calorimeter, which measures the energy of particles after they go through the tracking system; and the trigger, which selects the most interesting particle interactions to record for further study.

Nahn’s responsibility with US CMS at Fermilab will be the overall oversight of the project’s construction to ensure that the upgraded components are available for installation in two LHC shutdown periods, one in early 2017 and one in 2018. Until each upgrade is installed, CMS will continue to operate according to schedule using its current detectors and trigger system.

“Steve understands CMS and US CMS, and he’s very good technically, so he’s going to do a great job on managing this project,” said Joel Butler, head of the US CMS Operations Program. Butler was running the project on an interim basis up until Nahn was hired in August, during which time the project passed two DOE reviews.

Nahn is no stranger to Fermilab, since, as an associate research scientist with Yale, he worked on CDF for eight years. More recently, Nahn worked on the CMS silicon strip tracker while continuing to work as an associate professor at MIT.

Butler calls Nahn one of the “real heroes” of preparing the silicon strip tracker for CMS. This involved commissioning the detector and fine-tuning it before the experiment began — an important task since, once underground, it would be much more difficult to solve problems.

Nahn looks forward to the additional responsibilities that come with his new position, which will entail communicating with 32 different institutions involved in the upgrade. After all is said and done, though, Nahn is a scientist at heart and cannot wait until the detector starts to come together, years down the road.

“The fun stuff is building it, making it work, installing it and seeing it produce physics,” Nahn said. “I’m a bit removed from that now, but I think I will get involved to some extent if I can.”

Sarah Witman