TOTEM Upgrade Proposal

During the first LHC running period 2009 -- 2012 TOTEM collected a wealth of data at sqrt(s)= 7 and 8 TeV, mostly in special runs at reduced luminosity, allowing a comprehensive scrutiny of large cross-section processes. After the first Long Shutdown, TOTEM will join forces with its partner experiment CMS, creating a combined apparatus with the largest rapidity coverage and with the most performing two-arm proton spectrometer ever built at a collider. Focussing on the process of central diffraction opens unique opportunities for exploring QCD in new phase space regions and for the search for new physics. First studies of central diffraction and, in particular, diffractive dijet production in special runs in 2012 together with CMS have provided the proof of concept, but demonstrate that even at moderate luminosities a key issue to be overcome in physics with leading protons is the pileup of several events per bunch crossing. This document outlines the TOTEM strategy for increasing the reachable integrated luminosity and rendering its apparatus capable of resolving event pileup and multiple tracks in the proton detectors. In addition to the already approved consolidation programme including the relocation of the old Roman Pot station RP147 to the region between the quadrupole Q5 and the Roman Pot station RP220, TOTEM proposes the installation of two new Roman Pots designed to accomodate timing detectors for reconstructing the longitudinal vertex position of the leading protons in central diffractive events. Thus the protons can be assigned to the appropriate central vertex reconstructed by the CMS tracking detectors. Furthermore, the present silicon strip detectors are foreseen to be replaced by radiation-hard pixel detectors with better tracking capability.