The new radiation-hard optical links for the ATLAS pixel detector

The ATLAS detector is currently being upgraded with a new layer of pixel based charged particle tracking and a new arrangement of the services for the pixel detector. These upgrades require the replacement of the opto-boards previously used by the pixel detector. In this report we give details on the design and production of the new opto-boards.Comment: Presentation at the DPF 2013 Meeting of the American Physical Society Division of Particles and Fields, Santa Cruz, California, August 13-17, 201

Numerical Study of Wave Propagation in Uniaxially Anisotropic Lorentzian Backward Wave Slabs

The propagation and refraction of a cylindrical wave created by a line current through a slab of backward wave medium, also called left-handed medium, is numerically studied with FDTD. The slab is assumed to be uniaxially anisotropic. Several sets of constitutive parameters are considered and comparisons with theoretical results are made. Electric field distributions are studied inside and behind the slab. It is found that the shape of the wavefronts and the regions of real and complex wave vectors are in agreement with theoretical results.Comment: 6 pages, figure

Convolutional neural networks for the shape design of a magnetic core for material testing: Forward and inverse approaches

In this paper CNNs are used for solving an optimization problem with two different approaches: CNN is used as a surrogate model of the forward problem, inserted in an optimization loop governed by a genetic algorithm, in the first approach, while a CNN is trained for solving directly the inverse problem in the second approach. The case study is the shape design of a magnetic core used for material testing

Radiation-hard ASICs for optical data transmission in the ATLAS pixel detector

We have developed two radiation-hard ASICs for optical data transmission in the ATLAS pixel detector at the LHC at CERN: a driver chip for a Vertical Cavity Surface Emitting Laser (VCSEL) diode for 80 Mbit/s data transmission from the detector, and a Bi-Phase Mark decoder chip to recover the control data and 40 MHz clock received optically by a PIN diode. We have successfully implemented both ASICs in 0.25 um CMOS technology using enclosed layout transistors and guard rings for increased radiation hardness. We present results from prototype circuits and from irradiation studies with 24 GeV protons up to 57 Mrad (1.9 x 10e15 p/cm2).Comment: 8th Tropical Seminar on Innovative Particle and Radiation Detectors, Siena, Italy (2002

Anisotropic permittivity of ultra-thin crystalline Au films: Impacts on the plasmonic response of metasurfaces

It has been determined by density functional theory (DFT) simulations that the extracted permittivities of ultra-thin crystalline gold (Au) films exhibit large anisotropies which are not predicted by classical models or previous experimental determinations of the dielectric function. The optical scattering characteristics of a periodic array of Au discs are simulated with the DFT extracted permittivity and contrasted against those obtained with several commonly used Au permittivity models. It is demonstrated that the DFT-based transmittance spectra for these plasmonic metasurfaces lead to significantly redshifted results when compared to those predicted by standard Drude and Johnson-Christy permittivity models. © 2013 AIP Publishing LLC