Title: Computational Physicist Office: CERN, 8-1-005 Email: David.Lange@cern.ch

David Lange is an experimental particle physicist whose area of expertise is in the design, development and operation of robust reconstruction, simulation and analysis algorithms in high-energy physics experiments. These applications run at massive scale to allow modern particle physics experiments produce scientific results across a huge range of research topics.

Lange's current research at Princeton University (and previously at Lawrence Livermore National Laboratory) is as a member of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) located at the European Laboratory for Particle Physics (CERN). The LHC is a discovery class facility designed to probe the most fundamental particle interactions at high energy. The LHC interaction points are surrounded by high-precision detectors (including CMS) designed to capture the products of these interactions for analysis by experts. Lange is the current offline software and computing coordinator in CMS. The hundreds of developers currently contribute to CMS software monthly and its applications are run across a worldwide distributed computing system. Typically more than 200,000 processing cores are in use across CERN and other laboratory facilities, university computing centers and cloud facilities. 

Effective use of these facilities is critical to the success of the CMS physics program. An important research focus is on how the detector and software and computing for high-energy physics will evolve over the next 10 to 20 years. Lange organized CMS software for the recent Technical Proposal describing a CMS detector concept for the high luminosity LHC phase (HL-LHC). The complex events foreseen in HL-LHC due to possible 200 interactions occurring every 25 ns present a major detector and computing challenge. 

Prior to joining the CMS experiment, Lange worked on the BABAR experiment at the SLAC National Accelerator Laboratory and the CLEO-II experiment at Cornell University Laboratory for Elementary Particle Physics. Lange’s thesis research was in semileptonic B meson decays, operation of the CLEO-II.V silicon vertex detector and the design of physics event generators for B-meson decays. Lange co-authored  EvtGen, one of the first wave of first physics event generators written in C++.

Lange worked on several facets of the BABAR analysis that first observed charge-parity (CP) violation in B-meson decays. These include the identification of long-lived Kaon particles in the BABAR calorimeter and muon system and efficient techniques for multivariate minimization.