Technical proposal for the upgrade of the CMS detector through 2020

The Large Hadron Collider at CERN has begun operations at 7 TeV center of mass energy. CERN plans to run at this energy until the end of 2012 with the goal of providing an integrated luminosity of a few fb $^{-1}$ to the CMS and ATLAS experiments.The LHC will then shut down for 1.5 to 2 years to make the revisions necessary to run at $sim$14 TeV. Operation resumes in 2014. In 2017/18, there will be another long shutdown to prepare the LHC to operate at and eventually above the design luminosity of 10$^ ext{34}$percms. Operation will then resume with the luminosity rising gradually during this period to 2$ imes$ 10$^ ext{34}$percms. The two long shutdowns provide CMS an opportunity to carry out improvements to make the experiment more efficient, to repair problems that have been uncovered during early operations, and to upgrade the detector to cope with the ultimate luminosity that will be achieved during this period. The detector work involves the hadron calorimeters, the muon detectors, the pixel detector, the beam radiation monitoring and luminosity measurement system, the trigger, the data acquistion system, and the CMS infrastructure and facilities. The purpose of this report is to explain the need for these improvements, repairs and upgrades and the plans for carrying them out and installing them in the two long shutdowns forseen in 2013/14 and 2017/18.