The TileCal Demonstrator is a prototype for the future upgrade of the ATLAS hadron calorimeter when the Large Hadron Collider increases luminosity in year 2023 (HL-LHC). It will be used for ...functionality and performance tests. The Demonstrator has 48 channels of upgraded readout and digitizing electronics and a new digital trigger capability, but is backwards-compatible with the present detector system insofar as it also provides analog trigger signals and can communicate as the present system. The on-detector part of the Demonstrator is comprised of 4 identical mechanical mini-drawers, each equipped with up to 12 photomultipliers (PMTs). The on-detector electronics includes 45 Analog Front-End Boards, each serving an individual PMT; 4 Main Boards, each to control and digitize up to 12 PMT signals, and 4 corresponding high-speed Daughter Boards serving as data hubs between on-detector and off-detector electronics. It is fully compatible with the present system, accepting ATLAS triggers, timing and slow control commands for the data acquisition, detector control, and detector operation monitoring. We plan to insert one fully functional Demonstrator module into the present ATLAS TileCal detector for the LHC RUN 2 in Christmas shutdown in 2015 or 2016.
A non-transferred plasma torch is a device used to generate a steady thermal plasma jet. Plasma torches have the potential to replace fossil fuel burners used as heat sources in the process industry. ...Today, however, the available plasma torches are of small scale compared to the power used in the burners in the process industry. In order to understand the effects of large scales on the plasma flow dynamics, it is essential to understand the operation of the plasma torch under different operating conditions and for different geometries. In this study, the analysis of a non-transferred plasma torch has been carried out using both computational and experimental methods. Computationally, the magnetohydrodynamic (MHD) equations are solved using a single-fluid model on a 2D axisymmetric torch geometry. The experiments are performed using emission spectroscopy to measure the plasma jet temperature at the outlet. This paper explains the changes in the arc formation, temperature, and velocity for different working gases and power inputs. Furthermore, the possibilities and disadvantages of the MHD approach, considering a local thermal equilibrium, are discussed. It was found that in general, the computational temperature obtained is supported by the experimental and equilibrium data. The computational temperatures agree by within 10% with the experimental ones at the center of the plasma torch. The paper concludes by explaining the significant impact of input properties like working gas and power input on the output properties like velocity and temperature of plasma jet.
The paper presents a study of the deposition of submicron charged spherical particles caused by convection, Brownian and turbulent diffusion in a pipe with a smooth wall and with a cartilaginous ring ...wall structure. The model is supposed to describe deposition of charged particles in generation 0 (trachea) of the human respiratory airways. The flow is modeled with a SST-turbulence model combined with a convective-diffusion equation including electric field migration for the particles, and Poisson’s equation for the determination of the electrostatic potential in terms of the space-charge density of the particles. An approximate analytical solution is derived for the case of a smooth pipe which is used to verify the numerical solutions obtained from using the commercial software Comsol Multiphysics. Numerical results of deposition rates are also provided for the case of a pipe with a cartilaginous ring wall structure.
An improvement of an existing three-dimensional analytical model describing the solar wind flow near a reconnection site at the dayside magnetopause is reported. Introducing an arbitrary orientation ...of the reconnection line, general solutions for the plasma velocity and magnetic field during the transition of the magnetopause are presented, together with the development of the magnetopause transition layer away from the reconnection site.
A potential upgrade for the front-end electronics, signal digitization, and data acquisition system of the ATLAS central hadron calorimeter for the High Luminosity Large Hadron Collider (HL-LHC) is ...described. A Demonstrator is being built to readout a slice of the TileCal detector with this system. The on-detector electronics includes up to 48 analog Front-end Boards for processing the PMT signals, 4 Main Boards for data digitization and slow controls, 4 Daughter Boards with high speed optical links to interface the on-detector and off-detector electronics. Two new ReadOut Driver Boards are used for off-detector data acquisition and preprocessing the digital trigger signals.
During 2014, upgraded-demonstrator electronics will be installed in a Tile calorimeter drawer to obtain long term experience with the redundant electronics proposed for a full upgrade scheduled for ...2022.The new, FPGA-based system uses dense programmable logic, which must be proven to be sufficiently radiation tolerant. It must also be protected against radiation induced single event upsets that can corrupt memory and logic Radiation induced errors need to be detected and compensated for in time to minimize data loss, and also to avoid permanent damage. Strategies for detecting and correcting radiation induced errors in the Kintex-7 FPGAs on the Demonstrator electronics are evaluated and discussed.
The stand-alone test-bench deployed in the past for the verification of the Tile Calorimeter (TileCal) front-end electronics is reaching the end of its life cycle. A new version of the test-bench has ...been designed and built with the aim of improving the portability and exploring new technologies for future versions of the TileCal read-out electronics. An FPGA-based motherboard with an embedded hardware processor and a few dedicated daughter-boards are used to implement all the functionalities needed to interface with the front-end electronics (TTC, G-Link, CANbus) and to verify the functionalities using electronic signals and LED pulses. The new device is portable and performs well, allowing validation of the data transmission under realistic conditions. We discuss the system implementation and all the tests required to gain full confidence in the operation of the front-end electronics of the TileCal in the ATLAS detector.
The initial solidification problem of a two-dimensional liquid metal film flow over a heat extracting moving boundary is studied. Analytical solutions in the limit of large Peclet numbers are found. ...It is shown that the point of initial solidification depends on the Peclet number, the Biot number and the superheat. The initial growth of the solidified phase is found to have a quadratic dependence of the distance from the point of initial solidification. The results are applicable to continuous strip casters.
An asymptotic approach is considered for the transport and deposition of nanofibres in pipe flow. Convection and Brownian diffusion are included, and Brownian diffusion is assumed to be the dominant ...mechanism. The fibre position and orientation are modelled with a probability density function for which the governing equation is a Fokker–Planck equation. The focus is set on dilute fibres concentrations implying that interaction between individual fibres is neglected. At the entrance of the pipe, a fully developed velocity profile is set and it is assumed that the fibres enter the pipe with a completely random orientation and position. A small parameter
is introduced, where
l
is the fibre half-length and
a
is the pipe radius. The probability density function is expanded for small
and the solution turns out to be multi-structured with three areas, consisting of one outer solution and two boundary layers. For the deposition of fibres on the wall, it is found that for parabolic flow, and for the lowest order, the deposition can be obtained with a simplified angle averaged convective-diffusion equation. It is suggested that this simplification is valid also for more complex flows like when the inflow boundary condition yields a developing velocity profile and flows within more intricate geometries than here studied. With the model fibre, deposition rates in human respiratory airways are derived. The results obtained compare relatively well with those obtained with a previously published model.
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