Search

10th International “Hiroshima” Symposium on the Development and Application of Semiconductor Tracking Detectors, HSTD10, Xian, China, 25 Sep 2015 - 29 Sep 2015 ; Nuclear instruments & methods in physics research / A 831, 207 - 212(2016). doi:10.1016/j.nima.2016.04.044, The upgrade to the High-Luminosity LHC foreseen in about ten years represents a great challenge for the ATLAS inner tracker and the silicon strip sensors in the forward region. Several strip sensor designs were developed by the ATLAS collaboration and fabricated by Hamamatsu in order to maintain enough performance in terms of charge collection efficiency and its uniformity throughout the active region. Of particular attention, in the case of a stereo-strip sensor, is the area near the sensor edge where shorter strips were ganged to the complete ones. In this work the electrical and charge collection test results on irradiated miniature sensors with forward geometry are presented. Results from charge collection efficiency measurements show that at the maximum expected fluence, the collected charge is roughly halved with respect to the one obtained prior to irradiation. Laser measurements show a good signal uniformity over the sensor. Ganged strips have a similar efficiency as standard strips., Published by Elsevier, Amsterdam

The ATLAS group has evaluated the charge collection in silicon microstrip sensors irradiated up to a fluence of 1×1016 n eq /cm 2 , exceeding the maximum of 1.6×1015 n eq /cm 2 expected for the strip tracker during the high luminosity LHC (HL-LHC) period including a safety factor of 2. The ATLAS12, n + -on-p type sensor, which is fabricated by Hamamatsu Photonics (HPK) on float zone (FZ) substrates, is the latest barrel sensor prototype. The charge collection from the irradiated 1×1 cm 2 barrel test sensors has been evaluated systematically using penetrating β-rays and an Alibava readout system. The data obtained at different measurement sites are compared with each other and with the results obtained from the previous ATLAS07 design. The results are very consistent, in particular, when the deposit charge is normalized by the sensor's active thickness derived from the edge transient current technique (edge-TCT) measurements. The measurements obtained using β-rays are verified to be consistent with the measurements using an electron beam. The edge-TCT is also effective for evaluating the field profiles across the depth. The differences between the irradiated ATLAS07 and ATLAS12 samples have been examined along with the differences among the samples irradiated with different radiation sources: neutrons, protons, and pions. The studies of the bulk properties of the devices show that the devices can yield a sufficiently large signal for the expected fluence range in the HL-LHC, thereby acting as precision tracking sensors.

A radiation hard n+-in-p micro-strip sensor for the use in the Upgrade of the strip tracker of the ATLAS experiment at the High Luminosity Large Hadron Collider (HL-LHC) has been developed by the “ATLAS ITk Strip Sensor collaboration” and produced by Hamamatsu Photonics. Surface properties of different types of end-cap and barrel miniature sensors of the latest sensor design ATLAS12 have been studied before and after irradiation. The tested barrel sensors vary in “punch-through protection” (PTP) structure, and the end-cap sensors, whose stereo-strips differ in fan geometry, in strip pitch and in edge strip ganging options. Sensors have been irradiated with proton fluences of up to 1×1016 neq/cm2, by reactor neutron fluence of 1×1015 neq/cm2 and by gamma rays from 60Co up to dose of 1 MGy. The main goal of the present study is to characterize the leakage current for micro-discharge breakdown voltage estimation, the inter-strip resistance and capacitance, the bias resistance and the effectiveness of PTP structures as a function of bias voltage and fluence. It has been verified that the ATLAS12 sensors have high breakdown voltage well above the operational voltage which implies that different geometries of sensors do not influence their stability. The inter-strip isolation is a strong function of irradiation fluence, however the sensor performance is acceptable in the expected range for HL-LHC. New gated PTP structure exhibits low PTP onset voltage and sharp cut-off of effective resistance even at the highest tested radiation fluence. The inter-strip capacitance complies with the technical specification required before irradiation and no radiation-induced degradation was observed. A summary of ATLAS12 sensors tests is presented including a comparison of results from different irradiation sites. The measured characteristics are compared with the previous prototype of the sensor design, ATLAS07.

Journal of Instrumentation 12(05), P05015 - P05015 (2017). doi:10.1088/1748-0221/12/05/P05015, For the High-Luminosity upgrade of the Large Hadron Collider an increased instantaneous luminosity of up to 7.5 ⋅ 10$^{34}$ cm$^{−2}$ s$^{−1}$, leading to a total integrated luminosity of up to 3000 fb$^{−1}$, is foreseen. The current silicon and transition radiation tracking detectors of the ATLAS experiment will be unable to cope with the increased track densities and radiation levels, and will need to be replaced. The new tracking detector will consist entirely of silicon pixel and strip detectors. In this paper, results on the development and tests of prototype components for the new silicon strip detector in the forward regions (end-caps) of the ATLAS detector are presented. Flex-printed readout boards with fast readout chips, referred to as hybrids, and silicon detector modules are investigated. The modules consist of a hybrid glued onto a silicon strip sensor. The channels on both are connected via wire-bonds for readout and powering. Measurements of important performance parameters and a comparison of two possible readout schemes are presented. In addition, the assembly procedure is described and recommendations for further prototyping are derived., Published by Inst. of Physics, London

In the year 2022 an upgrade of the Large Hadron Collider (LHC) is planned to increase the luminosity such that an integrated luminosity of L int ∼ 3000 fb − 1 can be accumulated by 2030 [1] . The radiation damage of the present inner tracker at this date and the high track density of the High Luminosity LHC (HL-LHC) require an upgrade of the inner tracker of the ATLAS (A Toroidal LHC ApparatuS) experiment. A new integration concept will be used: the readout electronics is directly glued on the strip surface of the silicon sensors and the sensors are glued to a support structure. For the barrel region this structure is referred to as a Stave and for the end-cap region it is referred to as a Petal. For tests a smaller version, the Petalet, will be build with two design concepts. In this article the construction method is explained and first hybrid test results for one Petalet sensor are presented.

Nuclear instruments & methods in physics research / A 833, 226 - 232(2016). doi:10.1016/j.nima.2016.07.023, The new silicon microstrip sensors of the End-cap part of the HL-LHC ATLAS Inner Tracker (ITk) present a number of challenges due to their complex design features such as the multiple different sensor shapes, the varying strip pitch, or the built-in stereo angle. In order to investigate these specific problems, the “petalet” prototype was defined as a small End-cap prototype. The sensors for the petalet prototype include several new layout and technological solutions to investigate the issues, they have been tested in detail by the collaboration. The sensor description and detailed test results are presented in this paper. New software tools have been developed for the automatic layout generation of the complex designs. The sensors have been fabricated, characterized and delivered to the institutes in the collaboration for their assembly on petalet prototypes. This paper describes the lessons learnt from the design and tests of the new solutions implemented on these sensors, which are being used for the full petal sensor development. This has resulted in the ITk strip community acquiring the necessary expertise to develop the full End-cap structure, the petal., Published by North-Holland Publ. Co., Amsterdam

Nuclear instruments & methods in physics research / A 831, 221 - 228(2016). doi:10.1016/j.nima.2016.04.019, A proposal to fabricate large area strip sensors with integrated, or embedded, pitch adapters is presentedfor the End-cap part of the Inner Tracker in the ATLAS experiment. To implement the embedded pitchadapters, a second metal layer is used in the sensor fabrication, for signal routing to the ASICs. Sensorswith different embedded pitch adapters have been fabricated in order to optimize the design andtechnology. Inter-strip capacitance, noise, pick-up, cross-talk, signal efficiency, and fabrication yield havebeen taken into account in their design and fabrication. Inter-strip capacitance tests taking into accountall channel neighbors reveal the important differences between the various designs considered. Thesetests have been correlated with noisefigures obtained in full assembled modules, showing that the testsperformed on the bare sensors are a valid tool to estimate thefinal noise in the full module. The fullmodules have been subjected to test beam experiments in order to evaluate the incidence of cross-talk,pick-up, and signal loss. The detailed analysis shows no indication of cross-talk or pick-up as no addi-tional hits can be observed in any channel not being hit by the beam above 170 mV threshold, and thesignal in those channels is always below 1% of the signal recorded in the channel being hit, above 100 mVthreshold. First results on irradiated mini-sensors with embedded pitch adapters do not show anychange in the interstrip capacitance measurements with only thefirst neighbors connected., Published by North-Holland Publ. Co., Amsterdam

Nuclear instruments & methods in physics research / A 831, 167 - 173(2016). doi:10.1016/j.nima.2016.03.042, The “ATLAS ITk Strip Sensor Collaboration” R&D group has developed a second iteration of single-sided n+-in-p type micro-strip sensors for use in the tracker upgrade of the ATLAS experiment at the High-Luminosity (HL) LHC. The full size sensors measure approximately 97×97 mm$^2$ and are designed for tolerance against the 1.1×10$^{15}$n$_{eq}$/cm$^2$ fluence expected at the HL-LHC. Each sensor has 4 columns of 1280 individual 23.9mm long channels, arranged at 74.5μm pitch. Four batches comprising 120 sensors produced by Hamamatsu Photonics were evaluated for their mechanical, and electrical bulk and strip characteristics. Optical microscopy measurements were performed to obtain the sensor surface profile. Leakage current and bulk capacitance properties were measured for each individual sensor. For sample strips across the sensor batches, the inter-strip capacitance and resistance as well as properties of the punch-through protection structure were measured. A multi-channel probecard was used to measure leakage current, coupling capacitance and bias resistance for each individual channel of 100 sensors in three batches. The compiled results for 120 unirradiated sensors are presented in this paper, including summary results for almost 500,000 strips probed. Results on the reverse bias voltage dependence of various parameters and frequency dependence of tested capacitances are included for validation of the experimental methods used. Comparing results with specified values, almost all sensors fall well within specification., Published by North-Holland Publ. Co., Amsterdam

Journal of Instrumentation 13(03), T03004 (2018). doi:10.1088/1748-0221/13/03/T03004, In the high luminosity era of the Large Hadron Collider, the instantaneous luminosity is expected to reach unprecedented values, resulting in about 200 proton-proton interactions in a typical bunch crossing. To cope with the resultant increase in occupancy, bandwidth and radiation damage, the ATLAS Inner Detector will be replaced by an all-silicon system, the Inner Tracker (ITk). The ITk consists of a silicon pixel and a strip detector and exploits the concept of modularity. Prototyping and testing of various strip detector components has been carried out. This paper presents the developments and results obtained with reduced-size structures equivalent to those foreseen to be used in the forward region of the silicon strip detector. Referred to as petalets, these structures are built around a composite sandwich with embedded cooling pipes and electrical tapes for routing the signals and power. Detector modules built using electronic flex boards and silicon strip sensors are glued on both the front and back side surfaces of the carbon structure. Details are given on the assembly, testing and evaluation of several petalets. Measurement results of both mechanical and electrical quantities are shown. Moreover, an outlook is given for improved prototyping plans for large structures., Published by Inst. of Physics, London

A detailed description of the integration structures for the barrel region of the silicon strips tracker of the ATLAS Phase-II upgrade for the upgrade of the Large Hadron Collider, the so-called High Luminosity LHC (HL-LHC), is presented. This paper focuses on one of the latest demonstrator prototypes recently assembled, with numerous unique features. It consists of a shortened, shield-less, and double sided stave, with two candidate power distributions implemented. Thermal and electrical performances of the prototype are presented, as well as a description of the assembly procedures and tools.

The ATLAS experiment is a general purpose detector aiming to fully exploit the discovery potential of the Large Hadron Collider (LHC) at CERN. It is foreseen that after several years of successful data-taking, the LHC physics programme will be extended in the so-called High-Luminosity LHC, where the instantaneous luminosity will be increased up to 5 x 10(34) cm(-2) s(-1). For ATLAS, an upgrade scenario will imply the complete replacement of its internal tracker, as the existing detector will not provide the required performance due to the cumulated radiation damage and the increase in the detector occupancy. The current baseline layout for the new ATLAS tracker is an all-silicon-based detector, with pixel sensors in the inner layers and silicon micro-strip detectors at intermediate and outer radii. The super-module is an integration concept proposed for the strip region of the future ATLAS tracker, where double-sided stereo silicon micro-strip modules are assembled into a low-mass local support structure. An electrical super-module prototype for eight double-sided strip modules has been constructed. The aim is to exercise the multi-module readout chain and to investigate the noise performance of such a system. In this paper, the main components of the current super-module prototype are described and its electrical performance is presented in detail.

The ATLAS experiment is preparing for the planned luminosity upgrade of the LHC (the super-luminous LHC or sLHC) with a programme of development for tracking able to withstand an order of greater magnitude radiation fluence and much greater hit occupancy rates than the current detector. This has led to the concept of an all-silicon tracker with an enhanced performance pixel-based inner region and short-strips for much of the higher radii. Both sub-systems employ many common technologies, including the proposed "stave" concept for integrated cooling and support. For the short-strip region, use of this integrated stave concept requires single-sided modules mounted on either side of a thin central lightweight support.Each sensor is divided into four rows of 23.82 mm length strips; within each row, there are 1280 strips of 74.5μm pitch. Well over a hundred prototype sensors are being delivered by Hamamatsu Photonics (HPK) to Japan, Europe and the US.We present results of the first 20 chip ABCN25 ASIC hybrids for these sensors, results of the first prototype 5120 strip module built with 40 ABCN25 read-out ASICs, and the status of the hybrids and modules being developed for the ATLAS tracker upgrade stave programme.

Background Road crashes are a leading cause of death for Mexicans aged 15-34 years. This population is one of the targets for drinking and driving (DWI) related campaigns and interventions instituted as part of a large road safety intervention programme. Aims/Objectives/Purpose To evaluate the reach of DWI reduction interventions in a random sample of high school and university students from Guadalajara-Zapopan and Leon by assessing their knowledge related to DWI, their awareness of various interventions and campaigns, and their self-reported behaviour change as a result. Methods A close-ended questionnaire was applied in-person to a random sample of students at both public and private institutions in October-December 2011. Results/Outcome A total of 5114 students were surveyed: 2478 in Guadalajara-Zapopan, and 2636 in Leon. Only 17.3% and 14.3%, respectively, correctly identified a maximum number of alcoholic beverages one can ingest before driving. In the two cities, ∼40% reported exposure to a wide-spread campaign; accurate knowledge of campaign phrases ranged from 1-60% and 45% reported resulting attitude/behaviour change. 30-35% had experienced individualised intervention, and 50% reported attitude/behaviour change as a result. Significance/Contribution to the Field Students self-reported having had exposure to various targeted road safety interventions in both cities; ∼50% of those noted resulting attitude/behaviour changes as a result of these exposures. There was a marked knowledge deficit regarding the number of alcoholic drinks one could consume prior to driving safely. This study highlights an opportunity both for targeted education and continued intense interventions in order to reduce DWI in Mexican youth. This is an abstract of a presentation at Safety 2012, the 11th World Conference on Injury Prevention and Safety Promotion, 1-4 October 2012, Michael Fowler Center, Wellington, New Zealand. Full text does not seem to be available for this abstract.