PbSeTe-based quantum dot superlattice structures grown by molecular beam epitaxy have been investigated for applications in thermoelectrics. We demonstrate improved cooling values relative to the ...conventional bulk$(Bi,Sb)_{2}(Se,Te)_{3}$thermoelectric materials using a n-type film in a one-leg thermoelectric device test setup, which cooled the cold junction 43.7 K below the room temperature hot junction temperature of 299.7 K. The typical device consists of a substrate-free, bulk-like (typically 0.1 millimeter in thickness, 10 millimeters in width, and 5 millimeters in length) slab of nanostructured PbSeTe/PbTe as the n-type leg and a metal wire as the p-type leg.
Nanostructured thermoelectric materials HARMAN, T. C; WALSH, M. P; LAFORGE, B. E ...
Journal of electronic materials,
05/2005, Letnik:
34, Številka:
5
Journal Article
Recenzirano
High values of thermoelectric figures of merit ZT, ranging from ZT = 1.6 at 300 K to ZT = 3 at 550 K, are reported for Bi-doped n-type PbSeTe/PbTe quantum-dot superlattice (QDSL) samples grown by ...molecular beam epitaxy (MBE). These ZT values were determined by directly measuring Seebeck coefficients and electrical conductivities and using the low lattice thermal conductivity value (~3.3 mW/cm-K) determined experimentally from measurements of a one-legged thermoelectric cooler. Initial experiments have also shown that high values of ZT (~1.1 at 300 K) are achievable for complementary Na-doped p-type PbSeTe/PbTe QDSL samples, in which the conduction and valence bands mirror those in the Bi-doped Pb chalcogenides. PUBLICATION ABSTRACT
Single-cell analysis allows biologists to gain huge insight into cell differentiation and tissue structuration. Randomness of differentiation, both in vitro and in vivo, of pluripotent (multipotent) ...stem cells is now demonstrated to be mainly based on stochastic gene expression. Nevertheless, it remains necessary to incorporate this inherent stochasticity of developmental processes within a coherent scheme. We argue here that the theory called ontophylogenesis is more relevant and better fits with experimental data than alternative theories which have been suggested based on the notions of self-organization and attractor states. The ontophylogenesis theory considers the generation of a differentiated state as a constrained random process: randomness is provided by the stochastic dynamics of biochemical reactions while the environmental constraints, including cell inner structures and cell-cell interactions, drive the system toward a stabilized state of equilibrium. In this conception, biological organization during development can be seen as the result of multiscale constraints produced by the dynamical organization of the biological system which retroacts on the stochastic dynamics at lower scales. This scheme makes it possible to really understand how the generation of reproducible structures at higher organization levels can be fully compatible with probabilistic behavior at the lower levels. It is compatible with the second law of thermodynamics but allows the overtaking of the limitations exhibited by models only based on entropy exchanges which cannot cope with the description nor the dynamics of the mesoscopic and macroscopic organization of biological systems.
The ATLAS detector has been designed for operation at CERN's Large Hadron Collider. ATLAS includes a complex system of liquid argon calorimeters. The electronics for amplifying, shaping, sampling, ...pipelining, and digitizing the calorimeter signals is implemented on the Front End Boards (FEBs). This paper describes the design, implementation and production of the FEBs and presents measurement results from testing performed at several stages during the production process.
Calorimeters play an important role in high-energy physics experiments. Their design includes electronic instrumentation, signal processing chain, computing infrastructure, and also a good ...understanding of their response to particle showers produced by the interaction of incoming particles. This is usually supported by full simulation frameworks developed for specific experiments so that their access is restricted to the collaboration members only. Such restrictions limit the general-purpose developments that aim to propose innovative approaches to signal processing, which may include machine learning and advanced stochastic signal processing models. This work presents the Lorenzetti Showers, a general-purpose framework that mainly targets supporting novel signal reconstruction and triggering strategies using segmented calorimeter information. This framework fully incorporates developments down to the signal processing chain level (signal shaping, energy estimation, and noise mitigation techniques) to allow advanced signal processing approaches in modern calorimetry and triggering systems. The developed framework is flexible enough to be extended in different directions. For instance, it can become a tool for the phenomenology community to go beyond the usual detector design and physics process generation approaches.
Program Title: Lorenzetti Showers
CPC Library link to program files:https://doi.org/10.17632/sy64367452.1
Developer's repository link:https://github.com/lorenzetti-hep/lorenzetti
Licensing provisions: GPLv3
Programming language: Python, C++.
Nature of problem: In experimental high-energy physics, simulation is essential for experiment preparation, design and interpretations of ongoing acquisitions. Especially for calorimeters, an accurate simulation that can describe detector geometry, behavior to different physics processes and signal generation close to the readout electronics and data acquisition levels is required to properly develop signal processing and computational methods. Such detectors may face very challenging demands arising from the new designs, such as pileup mitigation and noise reduction tasks under unprecedented levels. In this sense, simulation requirements continuously increase in complexity and performance, because new physics searches require large datasets and accurate modeling to experimental effects.
Solution method: The Lorenzetti Showers is an integrated software framework that provides complete calorimeter information close enough to the electronic readout chain. Thus, the proposed framework allows users to access cell readout values, configurable sensor pulse-shapes, crosstalk modeling, and different energy estimation methods. It aims at supporting designs that target low or high pileup operation conditions in an easy-to-use modular structure. The developed framework is based on Pythia 8 (particle generation) and Geant4 (interactions with the calorimeter technique under analysis). An efficient data recording structure was used to allow full access to the Lorenzetti Showers outputs. In summary, the Lorenzetti Showers tool provides to the scientific community a user-friendly, flexible, user-oriented, and low-level calorimeter simulation framework.
Additional comments including restrictions and unusual features: The framework current version provides the implementation of a generic segmented calorimeter (electromagnetic and hadronic sections), which may be modified by the user, if desired. It allows the generation of particles interactions using Pythia 8 (native) or any generator compatible with the HepMC format (which may be integrated using an external input file) and propagation through a user-configurable calorimeter using Geant4.
Grand unified theories (GUTs) and extra dimensions are potential ingredients of the new physics that may resolve various outstanding problems of the Standard Model. If the inverse size of (one of) ...the extra dimension(s) is smaller than the GUT scale and standard gauge bosons are allowed to propagate in the bulk then, among other consequences, the evolution of the gauge couplings deviates from the usual logarithmic running somewhat below and between these two scales. In this Letter we show that if the compactification scale is the order of 10 TeV, then this modified running may be observable at the CERN large hadron collider in the dijet invariant mass distribution. We also demonstrate that dijets are highly sensitive to the renormalization effects of the extra dimensions, and are potential tools for determining the number of dimensions and the value of the compactification scale.
The ATLAS detector has been built to study the reactions produced by the Large Hadron Collider (LHC). ATLAS includes a system of liquid argon calorimeters for energy measurements. The electronics for ...amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on a set of front-end electronic boards. The front-end boards are installed in crates mounted between the calorimeters, where they will be subjected to significant levels of radiation during LHC operation. As a result, all components used on the front-end boards had to be subjected to an extensive set of radiation qualification tests. This paper describes radiationtolerant designs, radiation testing, and radiation qualification of the front-end readout system for the ATLAS liquid argon calorimeters.
This paper presents the status of a serial protocol developed in the framework of ATLAS (A Toroidal LHC ApparatuS), a high energy physics experiment that will be installed at the Large Hadron ...Collider (LHC) based at CERN. This link will be used to control the front-end electronics of the liquid argon calorimeters, located in an irradiated environment. After a technical description of the communication system architecture, we detail the features and performances of the designed components. This protocol could be applied in other contexts (nuclear physics, industry) where a fast, reliable and radhard serial communication is needed.
The ATLAS liquid argon calorimeter read-out system Bazan, A.; Bellachia, F.; Blondel, A. ...
IEEE Transactions on Nuclear Science,
06/2006, Letnik:
53, Številka:
3
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The Liquid Argon calorimeters play a central role in the ATLAS experiment. The environment at the LHC collider imposes challenging tasks to their read-out system. To achieve measurements of particles ...and trigger signals at high precision, the detector signals are processed at various stages before reaching the Data Acquisition system (DAQ). Signals from the calorimeter cells are received by front-end boards, which digitize and sample the incoming pulse. Read-out Driver (ROD) boards further process the data at a trigger rate of up to 75 kHz. An optimal filtering procedure is applied to optimize the signal-to-noise ratio. The ROD boards calculate precise energy, time and quality of the detector pulse, which are then sent to the DAQ. In addition, the RODs perform a monitoring of the data. The architecture of the ATLAS Liquid Argon detector read-out is discussed, in particular the design and functionality of the ROD board. Performance results obtained with ROD prototypes as well as experience from complete test setups with final production boards are reported.
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