The ABC130 barrel module prototyping programme for the ATLAS strip tracker

For the Phase-II Upgrade of the ATLAS Detector, its Inner Detector, consisting of silicon pixel, silicon strip and transition radiation sub-detectors, will be replaced with an all new 100 % silicon tracker, composed of a pixel tracker at inner radii and a strip tracker at outer radii. The future ATLAS strip tracker will include 11,000 silicon sensor modules in the central region (barrel) and 7,000 modules in the forward region (end-caps), which are foreseen to be constructed over a period of 3.5 years. The construction of each module consists of a series of assembly and quality control steps, which were engineered to be identical for all production sites. In order to develop the tooling and procedures for assembly and testing of these modules, two series of major prototyping programs were conducted: an early program using readout chips designed using a 250 nm fabrication process (ABCN-25) and a subsequent program using a follow-up chip set made using 130 nm processing (ABC130 and HCC130 chips). This second generation of readout chips was used for an extensive prototyping program that produced around 100 barrel-type modules and contributed significantly to the development of the final module layout. This paper gives an overview of the components used in ABC130 barrel modules, their assembly procedure and findings resulting from their tests.Comment: 82 pages, 66 figure

Modules and Front-End Electronics Developments for the ATLAS ITk Strips Upgrade

The ATLAS experiment is currently preparing for an upgrade of the tracking system in the course of the High Luminosity LHC, scheduled for 2024. The existing Inner Detector will be replaced by an all-silicon Inner Tracker (ITk) with a pixel detector surrounded by a strip detector. The ITk strip detector consists of a four layer barrel and a forward region composed of six discs on each side of the barrel. The basic unit of the detector is the silicon-strip module, consisting of a sensor and one or more hybrid circuits that hold the read-out electronics. The geometries of the barrel and end-cap modules take into account the regions that they have to cover. In the central region, the detectors are rectangular with straight strips, whereas on the forward region the modules require wedge shaped sensors with varying strip length and pitch. The current prototyping phase has resulted in the ITk Strip Detector Technical Design Report (TDR), which kicks-off the pre-production readiness phase at the involved institutes. In this contribution we present the current status of R&D of the ITk Strip Detector modules and read-out electronics

The ATLAS ITk Strip Detector. Status of R&D

While the LHC at CERN is ramping up luminosity after the discovery of the Higgs Boson in the ATLAS and CMS experiments in 2012, upgrades to the LHC and experiments are planned. The major upgrade is foreseen for 2024, with a roughly tenfold increase in luminosity, resulting in corresponding increases in particle rates and radiation doses. In ATLAS the entire Inner Detector will be replaced for Phase-2 running with an all-silicon system. This paper concentrates on the strip part. Its layout foresees low-mass and modular yet highly integrated double-sided structures for the barrel and forward region. The design features conceptually simple modules made from electronic hybrids glued directly onto the silicon. Modules will then be assembled on both sides of large carbon-core structures with integrated cooling and electrical services

Assembly and Electrical Tests of the First Full-size Forward Module for the ATLAS ITk Strip Detector

The ATLAS experiment will replace the existing Inner Detector by an all-silicon detector named the Inner Tracker (ITk) for the High Luminosity LHC upgrades. In the outer region of the Inner Tracker is the strip detector, which consists of a four layer barrel and six discs to each side of the barrel, with silicon-strip modules as basic units. Each module is composed of a sensor and one or more flex circuits that hold the read-out electronics. In the experiment, the modules are mounted on support structures with integrated power and cooling. The modules are designed with geometries that accommodate the central and forward regions, with rectangular sensors in the barrels and wedge shaped sensors in the end-caps. The strips lengths and pitch sizes vary according to the occupancy of the region. In this contribution, we present the construction and the results of the electrical tests of the first full-size module of the innermost forward region, named Ring 0 in the ATLAS ITk strip detector nomenclature. This module uses a sensor with stereo annulus geometry, having four segments of strips of different lengths and pitch. The read-out of the strips is achieved through dedicated ASICs mounted on two hybrid boards, with 8 and 9 chips. The two innermost strips segments are read out through 8 chips, for a total of 2048 strips, while the two outermost segments are read out through 9 chips, for a total of 2304 strips. We introduce the assembly procedure that lead to the construction of the module as well as the testing during the intermediate steps

Staves and Petals: Multi-module Local Support Structures of the ATLAS ITk Strips Upgrade

The ATLAS Inner Tracker (ITk) is an all-silicon tracker that will replace the existing inner detector at the Phase-II Upgrade of ATLAS. The outermost part of the tracker consists of the strips tracker, in which the sensors elements consist of silicon micro-strip sensors with strip lengths varying from 1.7 to up to 10 cm. The current design, at the moment under internal review in the Strips part of the Technical Design Report (TDR), envisions a four-layer barrel and two six-disk endcap regions. The sensor and readout units (“modules”) are directly glued onto multi-module, low-mass, high thermal performance carbon fiber structures, called “staves” for the barrel and “petals” for the endcap. They provide cooling, power, data and control lines to the modules with a minimal amount of external services. An extensive prototyping program was put in place over the last years to fully characterize these structures mechanically, thermally, and electrically. Thermo-mechanical stave and petal prototypes have recently been built and are currently under intensive study. This contribution will focus on describing the stave and petal structures and the prototyping work carried out so far. In addition, some details of the work carried out on the global supports which will hold the staves and petals in place will also be presented

Staves and Petals: Multi-module Local Support Structures of the ATLAS ITk Strips Upgrade

The ATLAS Inner Tracker (ITk) is an all-silicon tracker that will replace the existing inner detector at the Phase-II Upgrade of ATLAS. The outermost part of the tracker consists of the strips tracker, in which the sensor elements consist of silicon micro-strip sensors with strip lengths varying from 1.7 to up to 10 cm. The current design is part of the ATLAS ITk Strip Detector Technical Design Report (TDR) and envisions a four-layer barrel and two six-disk end-cap regions. The sensor and readout units (``modules'') are directly glued onto multi-module, low-mass, high thermal performance carbon fibre structures, called “staves” for the barrel and ``petals'' for the end-cap. They provide cooling, power, data and control lines to the modules with a minimal amount of external services. An extensive prototyping program was put in place over the last years to fully characterise these structures mechanically, thermally, and electrically. Thermo-mechanical stave and petal prototypes have recently been built and are currently under intensive study. This contribution will focus on describing the stave and petal structures and the prototyping work carried out so far. In addition, some details of the work carried out on the global supports which will hold the staves and petals in place will also be presented

Front-end Electronics of the Forward Strip Detector for the ATLAS HL-LHC Upgrade

The ATLAS Experiment will upgrade its central tracking detector with an all-silicon Inner Tracker(ITk) for the HL-LHC, comprising pixel and strip detectors. The strip detector is based on siliconstrip sensors, which are read out by low mass, radiation hard circuits carrying custom designedradiation hard ASICs in 130 nm technology. The circuits are made from flexible PCB multi-layercopper polyimide constructions. The ASICs are glued onto the flex and connections are madeby wire-bonding. This contribution discusses the evolution and electrical performance of varioushybrid prototypes necessary to equip the forward region of the detector, as well as their finaldevelopment

First Double-Sided End-Cap Strip Module for the ATLAS High-Luminosity Upgrade

The ATLAS Experiment will upgrade its inner tracking system for the High-Luminosity-LHCwith an all-silicon system. The strip part will be based on individual modules, constructed bygluing the front-end hybrids directly onto the strip side of the sensors. These modules will thenbe glued onto a low-mass carbon-fibre based local support structure with integrated services.This paper presents the first double-sided module made from full-size end-cap sensors by gluing modules onto a reduced-size core. A summary on the experience gained in the prototyping process and results obtained from running this module, with emphasis on signal integrity and noise performance will be given

The sROD Module for the ATLAS Tile Calorimeter Upgrade Demonstrator

This work presents the first prototype of the super Read-Out Driver (sROD) demonstrator board for the Tile Calorimeter Demonstrator project. This project aims to test the new readout electronics architecture for the Phase 2 Upgrade of the ATLAS Tile Calorimeter, replacing the front-end electronics of one complete drawer with the new electronics during the shutdown at the end of 2015, in order to evaluate its performance. The sROD demonstrator board will receive and process data from a complete module sending it to the present RODs to keep compatibility with the current DAQ system. Moreover the sROD demonstrator board will transmit Timing, Trigger and control information (TTC) and Detector Control System (DCS) commands to the front-end. A detailed description of the sROD board design, firmware and control and data acquisition software is presented

First bulk and surface results for the ATLAS ITk stereo annulus sensors

A novel microstrip sensor geometry, the “stereo annulus”, has been developed for use in the end-cap of the ATLAS experiment’s strip tracker upgrade at the High-Luminosity Large Hadron Collider (HL- LHC). The radiation-hard, single-sided, ac-coupled, n + -in-p microstrip sensors are designed by the ITk Strip Sensor Collaboration and produced by Hamamatsu Photonics. The stereo annulus design has the potential to revolutionize the layout of end-cap microstrip trackers promising better tracking performance and more complete coverage than the contemporary configurations. These advantages are achieved by the union of equal length, radially oriented strips with a small stereo angle implemented directly into the sensor surface. The first-ever results for the stereo annulus geometry have been collected across several sites world- wide and are presented here. A number of full-size, unirradiated sensors were evaluated for their mechanical, bulk, and surface properties. The new device, the ATLAS12EC, is compared against its conventionally shaped predecessors, the ATLAS07 and ATLAS12, for realistic evaluation of the sensor design. The bulk character of the unirradiated sensors has been determined from IV curve, CV curve, and metrology studies. The leakage current and full depletion voltage characteristics have been obtained and compared with the strict specifications required by the next-generation tracker. Interstrip capacitance and resistance in the four segments of strips, each with equal length constituents and a constant angular pitch, have also been ascertained and are compared to expectations. Long-term leakage current stability tests under various humidity conditions have been conducted to investigate more closely the surface and edge processing. These also allow the determination of any high electric field gradients in the synthesis of stereo radial strips with a tracking coverage enhancing slim edge- width. The impact of the novel stereo annulus sensor geometry on the operation of the detector has been evaluated in these studies. The suitability of the optimized sensor shape for the ATLAS HL-LHC upgrade and future end-cap microstrip trackers will be discussed