Quality Assurance and Performance Tests of Silicon Detector Modules for the CMS/Tracker

After providing a short overview of the LHC accelerator, the CMS experiment and it’s various detector systems, we will have an in-depth look on silicon semiconductor particle detectors. Various important aspects like theoretical principles, radiation damage and actual design considerations are discussed and the quality assurance scheme for the sensor and module production is introduced. A strong emphasis is made on the ARC module teststand which was set up and operated be the author. Another important aspect in establishing a good quality assurance scheme is flexibility and keeping an eye on the unexpected. At one such occasion, the author had to gather custom made test equipment, to investigate certain effects in silicon sensors manufactured by ST Microelectronics. Conclusions from these measurement could only be drawn very cautiously, as the manufacturing process and many of its subtle changes, remained a well kept secret of the company. Nevertheless, the investigations proofed to be useful and ST Microelectronics was able to remedy the problems. A manufacturing, assembly and quality assurance process can only be declared successful, when the final product in the end is working within the specifications. To prove that this is true for the CMS tracker detector modules, the author joined a collaboration of young physicists to examine the performance of a selection of modules in a testbeam at the DESY research facility in Hamb urg, Germany. As a novelty, fully irradiated CMS detector modules where put into a testbeam for the very first time. It will be shown, that module types used in this testbeam are capable of working well within specs even after experiencing the full 10 years of LHC lifetime

Razvoj laboratorijskog sistema za merenje karakteristika fotonaponskotermičkog panela

The emissions of harmful gases into the atmosphere, air pollution and global warming can be greatly reduced by increasing the use of renewable energy sources such as solar energy to heat domestic hot water, space heating and generating electricity. This paper describes the systems of combined (hybrid) PV/T panels that can simultaneously generate both heat and electricity, as well as the characteristics of the PV/T panel. A prototype of the laboratory setting for the examination of these systems along with the used components is also shown. The temperature, fluid flow rate values, obtained heat and electric gain are also presented. Deficiencies and proposed changes in the laboratory setup and used equipment were laid out, in order to improve the accuracy of the measurements.Publishe

Laboratorijska elektro-pneumatski upravljana postavka

Studying the dynamic behaviour of objects or systems in response to conditions cannot always be easily or safely applied in real life. Computer simulations in engineering are very important as it solves real-world problems safely and efficiently. It provides an important method of analysis which is easily verified, communicated, and understood. Across industries and disciplines, simulation modelling provides valuable solutions by giving clear insights into complex systems. A system presented in this paper is a pneumatic sheet metal bending laboratory setup. An electro-pneumatic motion control of this system is modelled and simulated in FluidSim software. This system is also physically built using main pneumatic and electrical components with PLC. Described laboratory setup in this paper was used in the education of students and significant enchantment in the understanding of how similar systems work was noticed.Publishe

Integrisan proces proizvodnje abrazivnih reznih elemenata bagera u rudarskoj industriji

The paper presents an integrated production process for excavator cutting elements in the mining industry based on modern software systems for the optimization and management of casting process parameters through simulations. The concept involves the virtual manufacture, practical implementation of the established technological process and quality control of final castings i.e. excavator cutting elements. The presented production methodology reduces the time required to develop and manufacture the new product compared to the traditional methods of prototype testing.Publishe

Search for signatures of extra dimensions in the diphoton mass spectrum at the Large Hadron Collider

A search for signatures of extra dimensions in the diphoton invariant-mass spectrum has been performed with the CMS detector at the LHC. No excess of events above the standard model expectation is observed using a data sample collected in proton-proton collisions at {radical}s = 7 TeV corresponding to an integrated luminosity of 2.2 fb{sup -1}. In the context of the large-extra-dimensions model, lower limits are set on the effective Planck scale in the range of 2.3-3.8 TeV at the 95% confidence level. These limits are the most restrictive bounds on virtual-graviton exchange to date. The most restrictive lower limits to date are also set on the mass of the first graviton excitation in the Randall-Sundrum model in the range of 0.86-1.84 TeV, for values of the associated coupling parameter between 0.01 and 0.10

Integration of the End Cap TEC+ of the CMS Silicon Strip Tracker

The silicon strip tracker of the CMS experiment has been completed and inserted into the CMS detector in late 2007. The largest sub-system of the tracker is its end cap system, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted into the TEC support structures. Each end cap consists of 144 petals, and the insertion of these petals into the end cap structure is referred to as TEC integration. The two end caps were integrated independently in Aachen (TEC+) and at CERN (TEC--). This note deals with the integration of TEC+, describing procedures for end cap integration and for quality control during testing of integrated sections of the end cap and presenting results from the testing

Reception Test of Petals for the End Cap TEC+ of the CMS Silicon Strip Tracker

The silicon strip tracker of the CMS experiment has been completed and was inserted into the CMS detector in late 2007. The largest sub system of the tracker are its end caps, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted onto the TEC support structures. Each end cap consists of 144 such petals, which were built and fully qualified by several institutes across Europe. Fro

Measurement of differential cross sections for top quark pair production using the lepton plus jets final state in proton-proton collisions at 13 TeV

National Science Foundation (U.S.

Particle-flow reconstruction and global event description with the CMS detector

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions

Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV

Many measurements and searches for physics beyond the standard model at the LHC rely on the efficient identification of heavy-flavour jets, i.e. jets originating from bottom or charm quarks. In this paper, the discriminating variables and the algorithms used for heavy-flavour jet identification during the first years of operation of the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, are presented. Heavy-flavour jet identification algorithms have been improved compared to those used previously at centre-of-mass energies of 7 and 8 TeV. For jets with transverse momenta in the range expected in simulated $\mathrm{t}\overline{\mathrm{t}}$ events, these new developments result in an efficiency of 68% for the correct identification of a b jet for a probability of 1% of misidentifying a light-flavour jet. The improvement in relative efficiency at this misidentification probability is about 15%, compared to previous CMS algorithms. In addition, for the first time algorithms have been developed to identify jets containing two b hadrons in Lorentz-boosted event topologies, as well as to tag c jets. The large data sample recorded in 2016 at a centre-of-mass energy of 13 TeV has also allowed the development of new methods to measure the efficiency and misidentification probability of heavy-flavour jet identification algorithms. The heavy-flavour jet identification efficiency is measured with a precision of a few per cent at moderate jet transverse momenta (between 30 and 300 GeV) and about 5% at the highest jet transverse momenta (between 500 and 1000 GeV)