LHCb particle identification upgrade technical design report

The LHCb upgrade will take place in the second long shutdown of the LHC, currently scheduled to begin in 2018. The upgrade will enable the experiment to run at luminosities of 2 x 10^33cm^-2s^-1 and will read out data at a rate of 40MHz into a flexible software-based trigger. All sub-detectors of LHCb will be re-designed to comply with these new operating conditions. This Technical Design Report presents the upgrade plans of the Ring Imaging Cherenkov (RICH) system, the calorimeter system and the muon system, which together provide the particle identification capabilities of the experiment

LHCb tracker upgrade technical design report

The upgrade of the LHCb detector will extend the physics reach of the experiment by allowing it to run at higher luminosity, Linst = 2 x 1033 cm\uf02d2 s\uf02d1, with increased trigger e_ciency for a wide range of decay channels. This is facilitated by the implementation of new front-end electronics, designed such that complete events can be read out and sent to the LHCb data acquisition farm for selection by a full software trigger, every 25 ns. The upgraded LHCb detector is conceived to take physics data for an integrated luminosity of at least 50 fb bc0 c001. This Technical Design Report describes in detail the upgrade of the two tracking subsystems, located just before and just after the LHCb dipole magnet. The tracking detector before the magnet (the Upstream Tracker) will be composed of new, high-granularity silicon micro-strip planes with an improved coverage of the LHCb acceptance. Behind the magnet, a Scintillating Fibre Tracker will be built, which is composed of 2.5m long _bres read out by silicon photomultipliers at the edge of the acceptance. The performance of the two tracking detectors and of the LHCb tracking software are presented, as well as the cost, schedule and task sharing

LHCb VELO upgrade technical design report

The upgraded LHCb VELO silicon vertex detector is a lightweight hybrid pixel detector capable of 40 MHz readout at a luminosity of 2 x 10^33 cm^-2 s^-1. The track reconstruction speed and precision is enhanced relative to the current VELO detector even at the high occupancy conditions of the upgrade, due to the pixel geometry and a closest distance of approach to the LHC beams of just 5.1 mm for the first sensitive pixel. Cooling is provided by evaporative CO2 circulating in microchannel cooling substrates. The detector contains 41 million 55 um x 55 um pixels, read out by the custom developed VeloPix front end ASIC. The detector will start operation together with the rest of the upgraded LHCb experiment after the LHC LS2 shutdown, currently scheduled to end in 2019. This Technical Design Report describes the upgraded VELO system, planned construction and installation, and gives an overview of the expected detector performance

Description and performance of track and primary-vertex reconstruction with the CMS tracker

A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For t (t) over bar events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of p(T) > 0.9GeV is 94% for pseudorapidities of vertical bar eta vertical bar < 0.9 and 85% for 0.9 < vertical bar eta vertical bar < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p(T) = 100GeV emitted at vertical bar eta vertical bar < 1.4, the resolutions are approximately 2.8% in p(T), and respectively, 10 m m and 30 mu m in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10-12 mu m in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung

Measurement of the cross section ratio sigma(t(t)over-barb(b)over-bar)/sigma(t(t)over-barjj) in pp collisions at root s=8 TeV

The first measurement of the cross section ratio sigma(t (t) over barb (b) over bar)/sigma(t (t) over bar jj) is presented using a data sample corresponding to an integrated luminosity of 19.6 fb(-1) collected in pp collisions at root s = 8 TeV with the CMS detector at the LHC. Events with two leptons (e or mu) and four reconstructed jets, including two identified as b quark jets, in the final state are selected. The ratio is determined for a minimum jet transverse momentum p(T) of both 20 and 40 GeV/c. The measured ratio is 0.022 +/- 0.003 (stat) +/- 0.005 (syst) for p(T) > 20GeV/c. The absolute cross sections sigma(t (t) over barb (b) over bar) and sigma(t (t) over bar jj) are also measured. The measured ratio for p(T) > 40 GeV/c is compatible with a theoretical quantum chromodynamics calculation at next-to-leading order. (C) 2015 CERN for the benefit of the CMS Collaboration