Our group contributes to the upgrade work of the CMS experiment for the High Luminosity LHC. In the second phase of the LHC physics program, the accelerator will provide to CMS an additional integrated luminosity of about 2500 fb^–1 over 10 years of operation, starting in 2025. This will substantially enlarge the mass reach in the search for new particles and will also greatly extend the potential to study the properties of the Higgs boson discovered at the LHC in 2012. In order to meet the experimental challenges of unprecedented p-p luminosity, the CMS collaboration will need to address the aging of the present detector and to improve the ability of the apparatus to isolate and precisely measure the products of the most interesting collisions.

Major revisions to the machine or the experiments require access to the accelerator tunnels and the experimental areas that can only be accomplished efficiently during long shutdown periods. The current plan calls for a series of long periods of data-taking, referred to as Run-I, Run-II, etc. interleaved with long shutdowns, designated LS1, LS2, LS3. Run-I is the name given to the completed data-taking period in 2011 and 2012. During the first long shutdown, LS1, which started in 2013 and ended at the beginning of 2015, modifications were made to the LHC to enable it to run at the center-of-mass energy of 13 TeV. The energy will be raised closer to the design energy of 14 TeV over time. Run-II is just beginning. It is expected that the bunch spacing will be reduced to 25 ns from 50 ns. The original performance goal for the LHC, to operate at an instantaneous luminosity of 10³⁴ cm^–2 s^–1 with 25 ns bunch spacing, is likely to be achieved relatively soon after the startup. Under these conditions, early in Run-II, CMS will experience an average of about 25 inelastic interactions per bunch crossing, referred to as event pileup (PU). This is the operating scenario for which the CMS experiment was designed.

HCAL Upgrade

The CMS hadron calorimeter system consists of a brass/scintillator sampling hadron calorimeter (HCAL) with coverage up to eta <  3.0, followed by the iron/quartz-fiber Hadron Forward (HF) calorimeter with coverage 3.0 < jeta <  5.0, comprising 9528 readout channels in total. The Barrel Hadron calorimeter (HB) is 9 meters long, one meter thick and 6 meters in the outer diameter, consisting of two half barrels of 18 identical 20⁰ wedges in , each made of flat brass alloy absorber plates with wavelength shifting fiber (WLS) readout, parallel to the z-axis in CMS coordinate frame. The two End Caps (HE) covering the geometrical region 1.305 < eta < 3.0, are also made of brass and scintillator, with a diameter of 0.8 to 6.0 m. and a thickness of 1.8 meters. HB and HE are inside the 4-tesla solenoid coil. The two forward calorimeters (HF) are made of quarts fibers embedded in iron. Cherenkov light generated in the fibers is transmitted to the photo tubes (PMT). The central shower containment in the region eta < 1.26 is improved with an array of scintillators located outside the magnet in the outer barrel hadronic calorimeter (HO). The design plan was that the optical signal from the HCAL towers, except HF, is detected with hybrid photo diodes (HPD) mounted at the ends of the barrel and so was at the first period of data taking.

In order to refine the performance of their calorimetric system, HCAL collaboration made the plans for replacing the photomultipliers with Silicon Photomultipliers (SiPM) already in 2008 and R&D of the project took place around 2011 followed by production, testing and the final state installation. Our group has been actively participated to this work. Another upgrade activity that ITU participated is the replacement of the HE scintillators. During 2015-2016, we have run RADDAM analysis on various scintillators produced by the University of Iowa, University of Maryland, Fermi lab and Dubna. Those RADDAM analysis were done in collaboration of the Iowa group. At present, there is technical shutdown phase at CERN untill middle of March, 2017, and researchers from ITU will be participating to perform various upgrade efforts in HCAL

Also, we plan to participate the upgrade efforts of the HCAL back-end electronics during long shutdown. In the future shutdowns of LHC, the HCAL front end electronics of the is planned to be upgraded. With this upgrade, the detector will be able to send the timing information to the muon detector, which will be very crucial to tag the muon from LHC collision or from other sources.

Phase II Tracker Upgrade

Our group contributed CMS Tracker and Vertexing Technical Design Report. Pre11-Pre12 validation plots between different releases and different PU scenarios are presented for RelVal samples can be seen from http://cmsdoc.cern.ch/cms/Physics/tracking/validation/MC/