A framework for Fast Simulation of particle interactions in the CMS detector (FastSim) has been developed and implemented in the overall simulation, reconstruction and analysis framework of CMS. It produces data samples in the same format as the one used by the Geant4-based (henceforth Full) Simulation and Reconstruction chain; the output of the Fast Simulation of CMS can therefore be used in the analysis in the same way as data and Full Simulation samples. FastSim is used in several physics analyses in CMS, in particular those requiring a generation of many samples to scan an extended parameter space of the physics model (e.g. SUSY) or for the purpose of estimating systematic uncertainties. It is also used by several groups to design future sub-detectors for the Phase-II CMS upgrades.
Related activities at UCL include the integration with the Full Simulation in the simulation of the electronic read-out ("digitization") and of the pileup of events from other proton-proton collisions, both in-time and out-of-time; the performance monitoring; and the overall maintenance and upgrade of the tracking-related code. Matthias Komm is current L3 convener of Tracking in FastSim, and Andrea Giammanco has been main responsible of the FastSim project from 2011 to 2013.
GasToF (Gas Time-of-Flight) detector is a Cherenkov detector developed for very precise (with ~10 ps resolution) flight time measurements of very forward protons at the LHC. Such an excellent time resolution allows, using z-by-timing technique, for precise measurements of the event vertex z-coordinate and the background reduction. This detector is essential for selecting exclusive and semi-exclusive processes at the LHC, and can also be applied for the particle ID at future experiments.
External collaborators: CMS PPS project, M. Albrow (Fermilab), M. Khakzad (Tehran), J. Varela (Lisbon), and E. Schnys (Photonis) and J. Howorth (Photek Ltd).
High-energy photon-photon and photon-proton interactions at the LHC offer interesting possibilities for the study of the electroweak sector up to TeV scale and the search for processes beyond the Standard Model. After in-depth exploratory studies, we performed using the CMS data first measurement of two-photon muon pair production as well as first ever observation of W boson pairs produced by photon fusion. Now our group is leading unique investigations of quartic couplings between photons and W and Z bosons.
External collaborators: CMS FSQ analysis group and the group of A. Szczurek (Krakow).