The ATLAS detector as installed in its experimental cavern at point 1 at CERN is described in this paper. A brief overview of the expected performance of the detector when the Large Hadron Collider begins operation is also presented.

The ATLAS Experiment at the CERN Large Hadron Collider

This paper describes the ATLAS experiment as installed in i ts experimental cavern at point 1 at CERN. It also presents a brief overview of the expec ted performance of the detector.

http://absimage.aps.org/image/SES08/MWS_SES08-2008-020010.pdf

During the shutdown of the CERN Large Hadron Collider in 2013-2014, an additional pixel layer was installed between the existing Pixel detector of the ATLAS experiment and a new, smaller radius beam pipe. The motivation for this new pixel layer, the Insertable B-Layer (IBL), was to maintain or improve the robustness and performance of the ATLAS tracking system, given the higher instantaneous and integrated luminosities realised following the shutdown. Because of the extreme radiation and collision rate environment, several new radiation-tolerant sensor and electronic technologies were utilised for this layer. This paper reports on the IBL construction and integration prior to its operation in the ATLAS detector.

Production and integration of the ATLAS Insertable B-Layer

We present a comprehensive review of the properties of the epitaxial 4H silicon carbide polytype (4H–SiC). Particular emphasis is placed on those aspects of this material related to room, high-temperature and harsh environment ionizing radiation detector operation. A review of the characterization methods and electrical contacting issues and how these are related to detector performance is presented. The most recent data on charge transport parameters across the Schottky barrier and how these are related to radiation spectrometer performance are presented. Experimental results on pixel detectors having equivalent noise energies of 144 eV FWHM (7.8 electrons rms) and 196 eV FWHM at +27 °C and +100 °C, respectively, are reported. Results of studying the radiation resistance of 4H–SiC are analysed. The data on the ionization energies, capture cross section, deep-level centre concentrations and their plausible structures formed in SiC as a result of irradiation with various particles are reviewed. The emphasis is placed on the study of the 1 MeV neutron irradiation, since these thermal particles seem to play the main role in the detector degradation. An accurate electrical characterization of the induced deep-level centres by means of PICTS technique has allowed one to identify which play the main role in the detector degradation.

https://iopscience.iop.org/article/10.1088/0957-0233/19/10/102001/pdf

Silicon carbide and its use as a radiation detector material

The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1 +/- 0.9 mu m and a relative momentum resolution sigma (p) /p=(4.83 +/- 0.16)x10(-4) GeV(-1)xp (T) have been measured for high momentum tracks.

/pdf/the-atlas-inner-detector-commissioning-and-calibration-26rz42duea.pdf

The ATLAS Inner Detector commissioning and calibration

Abstract Background Empirical data in proton therapy indicate that relative biological effectiveness (RBE) is not constant, and it is directly related to the linear energy transfer (LET). The experimental assessment of LET with high resolution would be a powerful tool for minimizing the LET hot spots in intensity‐modulated proton therapy, RBE‐ or LET‐guided evaluation and optimization to achieve biologically optimized proton plans, verifying the theoretical predictions of variable proton RBE models, and so on. This could impact clinical outcomes by reducing toxicities in organs at risk. Purpose The present work shows the first 2D LET maps obtained at a proton therapy facility using the double scattering delivery mode in clinical conditions by means of new silicon 3D‐cylindrical microdetectors. Methods The device consists of a matrix of 121 independent silicon‐based detectors that have 3D‐cylindrical electrodes of 25‐µm diameter and 20‐µm depth, resulting each one of them in a well‐defined micrometric radiation sensitive volume etched inside the silicon. They have been specifically designed for a hadron therapy, improving the performance of current silicon‐based microdosimeters. Microdosimetry spectra were obtained at different positions of the Bragg curve by using a water‐equivalent phantom along an 89‐MeV pristine proton beam generated in the Y1 proton passive scattering beamline of the Orsay Proton Therapy Centre (Institut Curie, France). Results Microdosimetry 2D‐maps showing the variation of the lineal energy with depth in the three dimensions were obtained in situ during irradiation at clinical fluence rates (∼108 s−1 cm−2) for the first time with a spatial resolution of 200 µm, the highest achieved in the transverse plane so far. The experimental results were cross‐checked with Monte Carlo simulations and a good agreement between the spectra shapes was found. The experimental frequency‐mean lineal energy values in silicon were 1.858 ± 0.019 keV µm−1 at the entrance, 2.61 ± 0.03 keV µm−1 at the proximal distance, 4.97 ± 0.05 keV µm−1 close to the Bragg peak, and 8.6 ± 0.1 keV µm−1 at the distal edge. They are in good agreement with the expected trends in the literature in clinical proton beams. Conclusions We present the first 2D microdosimetry maps obtained in situ during irradiation at clinical fluence rates in proton therapy. Our results show that the arrays of 3D‐cylindrical microdetectors are a reliable microdosimeter to evaluate LET maps not only in the longitudinal axis of the beam, but also in the transverse plane allowing for LET characterization in three dimensions. This work is a proof of principle showing the capacity of our system to deliver LET 2D maps. This kind of experimental data is needed to validate variable proton RBE models and to optimize LET‐guided plans.

First experimental measurements of 2D microdosimetry maps in proton therapy

The projected luminosity upgrade of the large hadron collider (LHC), the sLHC, will constitute a challenging radiation environment for tracking detectors. Massive improvements in radiation hardness are required with respect to the LHC. In the layout for the new ATLAS tracker, silicon strip detectors (SSDs) with short strips cover the region from 28 to 60 cm distance to the beam. These SSDs will be exposed to fluences up to 10 15 N eq / cm 2 , hence radiation resistance is the major concern. It is advantageous to fuse the superior radiation hardness of the 3D design originally conceived for pixel-style applications with the benefits of the well-known planar technology for strip detectors. This is achieved by ganging rows of 3D columns together to form strips. Several prototype sLHC detector modules using 3D SSD with short strips, processed on p-type silicon, and LHC-speed front-end electronics from the present ATLAS semi-conductor tracker (SCT) were built. The modules were tested before and after irradiation to fluences of 10 15 N eq / cm 2 . The tests were performed with three systems: a highly focused IR-laser with 5 μ m spot size to make position-resolved scans of the charge collection efficiency (CCE), a Sr 90 β -source set-up to measure the signal levels for a minimum ionizing particles (MIPs), and a beam test with 180 GeV pions at CERN. This article gives a brief overview of the performance of these 3D modules, and draws conclusions about options for using 3D strip sensors as tracking detectors at the sLHC.

Silicon microstrip detectors in 3D technology for the sLHC

Interconnection between detectors and electronics in modern High Energy Physics has become an issue of difficult solution due to the need to integrate both parts in the same module and the need for a low mass, simple connection. The Endcap section of the Semiconductor Tracker (SCT) of the ATLAS experiment at CERN has adopted the solution of using interface devices called pitch adaptors or fan-ins that, mounted on the modules, and using automatic wire bonding, connect the detector's multiple channels to the front-end electronics, adapting their different designs (pad pitch, dimensions, position). This paper describes the characteristics of these devices, the qualification tests that they have been submitted to, and the final results of their fabrication including quality assurance procedures.

Pitch adaptors of the ATLAS-SCT Endcap detector modules

For the ATLAS Phase II Upgrade, new silicon microstrip sensors located in the End-cap part of the Inner detector, will bring new issues related to their complex design In order to investigate the End-cap Upgrade specific problems, the petalet prototype was defined as a small End-cap prototype The software tools developed in this work for the automatic generation of microelectronic sensor layouts are very helpful for these developments and allow us to face these design difficulties New layout and technological solutions have been designed and implemented Sensors have been fabricated and first test results are presented

http://ieeexplore.ieee.org/iel7/6531926/6551044/06551302.pdf

Design and fabrication of sensor prototypes for the end-cap tracker of the ATLAS upgrade

3D solid state detectors have very promising characteristics for particle trackers in harsh radiation environments such as the expected after the proposed luminosity upgrade of the large hadron collider at CERN. Different 3D technologies, including single- and double- type column and full 3D detectors, are being evaluated by the CERN RD50 collaboration. In this review the most recent work will be presented and discussed.

Celeste Fleta

Papers

First experimental measurements of 2D microdosimetry maps in proton therapy

Silicon microstrip detectors in 3D technology for the sLHC

Pitch adaptors of the ATLAS-SCT Endcap detector modules

Design and fabrication of sensor prototypes for the end-cap tracker of the ATLAS upgrade

Development of 3D detectors for very high luminosity colliders