The Silicon Ministrip Detector of the DELPHI Very Forward Tracker

The subject of this work is the design, test and construction of a new silicon tracking detector for the extreme forward region of the DELPHI experiment at LEP. I joined the Very Forward Tracker (VFT) Ministrip group in 1993, at a time when the upgrade of the DELPHI tracking system was proposed. My first task was to participate in the design of the ministrip detector for the VFT. This included the optimisation of the detector layout in simulations and the study of prototype detectors in the testbeam. In 1994 I became responsible for the tests and assembly' of the VFT ministrip detector at CERN. The main focus of my work was the study of the performance of a large variety of detectors in beam tests. This included the preparation of the test setup, the tests of different detectors and the analysis of the measurements. With these measurements it is possible to compare the advantages and disadvantages of various new layouts for large pitch silicon strip detectors. In particular the signal response and spatial resolution of the VFT ministrip detector was precisely measured and modelled. The results of this study form the central part of my thesis. During 1995, prior to the assembly of the VFT detector, my main task was the quality monitoring of the final VFT ministrip detectors in acceptance tests at CERN. The experience gained during these tests was subsequently used to optimise the control of the detector to assure reliable operation in DELPHI. In the following I will give a brief overview of the contents of this thesis: In chapter 1 an overview of the DELPHI detector and its components, in particular the silicon tracking detector, is presented. Chapter 2 is dedicated to the design of the DELPHI Very For- ward Tracker. The requirements for the VFT are given together with the considerations infiuencing the layout and capability of the detector. The chapter shows the complex environment in the extreme forward region of collider experiments. A new unconven- tional design with inclined detectors was necessary to optimise efficiency and acceptance area. The only way to cope with the tight space constraints in the forward region is to mount the readout electronics on top of the active detector surface. The advantages and technical problems of this solution are described. Chapter 3 presents the results of testbeam studies carried out on different large pitch strip detectors. The signal response and spatial resolution of well known and newly developed detectors was precisely measured. This study allows the comparison of many different layouts concerning their track reconstruction capability and intrinsic problems like insufficient charge measurement. The study provides useful information for the VFT ministrip layout and demonstrates the influence of layout parameters. It also provides necessary information for the design of similar detectors to be used in the future LHC (Large Hadron Collider) experiments. The tracking capability of the VFT ministrip detector is pre$ented in chapter 4. As the tracks in DELPHI will be inclined with respect to the detector surface, dedicated measurements at different track angles were carried out with the VFT ministrip detector. The measured signal response and spatial resolution could be modelled in a simulation, which proves excellent agreement with measurement data. Chapter 4 is concluded by an evaluation of the effects infiuencing the spatial resolution. In chapter 5 the production of the VFT ministrip detector is summarised. The chapter prescnts test results from the acceptance test of the full VFT ministrip detector prior to the installation in DELPHI. Extensive tests with the final configuration helped us to op- timise the operation parameters and insure reliable detector operation. Throughout the last three years I have been given the possibility to report on my work for this thesis. The considerations and results of the detector design are sumrnerisecl in Nucl.Phys.B(Proc.Supp.)44(1995)292-295, which I had the pleasure to present at the 4th Int. Conference on Aclvanced Technology and Particle Physics 1994. The predictions of the detector simulation for the final layout has been accomplished with testbeam meas- urements on VFT prototype detectors (NIM A349(1994)424-430, DELPHI internal note DELPHI 94-44 Track 78). I had also the pleasure to report the results of the testbeam analysis with different large pitch detectors to the CMS collaboration ( CMS collaboration meeting, Feb. 1996). Write-ups of the results presented in chapter 3 and 4 are currently in preparation and will be submitted for publication. I owe special thanks to Dr. M. Krammer, head of the serniconductor group of the lnstitute for High Energy Physics, for the motivating work in his group and the many hours of fruitful discussions. His attention, encouragement and knowledge was essential for this thesis. I would like to thank my thesis superviser, Prof. M. Regier, for his constant support and interest over many years. His advise and guidance was important for the analysis presentecl in this thesis. I want to express my gratefullness to Prof. W. Majerotto, director of the Institute for High Energy Physics, for financial support during this work. Furthermore I want to thank all my colleagues, in particular W. Adam, D. Rakoczy, N. Ncufelcl, V. Cindro, V. Rykalin and R. Turchetta. I also want to a.cknowlcclge the help of Prof. P. Weilhammer and Dr. W. Dulinski for their support during the test.bca.m rneasurements and the supply of many test detectors. Finally I want to thank my beloved girl-friend Bruna for all her patience and encour- agement throughout the years. I dedicate this thesis to Bruna

Simulations of CMOS pixel sensors with a small collection electrode, improved for a faster charge collection and increased radiation tolerance

CMOS pixel sensors with a small collection electrode combine the advantages of a small sensor capacitance with the advantages of a fully monolithic design. The small sensor capacitance results in a large ratio of signal-to-noise and a low analogue power consumption, while the monolithic design reduces the material budget, cost and production effort. However, the low electric field in the pixel corners of such sensors results in an increased charge collection time, that makes a fully efficient operation after irradiation and a timing resolution in the order of nanoseconds challenging for pixel sizes larger than approximately forty micrometers. This paper presents the development of concepts of CMOS sensors with a small collection electrode to overcome these limitations, using three-dimensional Technology Computer Aided Design simulations. The studied design uses a 0.18 micrometer process implemented on a high-resistivity epitaxial layer.Comment: Proceedings of the PIXEL 2018 Worksho

Innovating Advanced Radiation Instruments

STREAM is a 4-year multi-site training network that aims at career development of Early Stage Researchers (ESRs) on scientific design, construction manufacturing and of advanced radiation instrumentation. STREAM targets the development of innovative radiation-hard, smart CMOS sensor technologies for scientific and industrial applications. The platform technology developed within the project will be tested in the demanding conditions posed by the CERN LHC detectors' environment as well as European industry leaders in the field of CMOS imaging, electron microscopy and radiation sensors. This leveraging factor will allow to fine-tune the technology to meet the requirements of industrial application cases on demand such as electron microscopy and medical X-ray imaging, as well as pathway towards novel application fields such as satellite environments, industrial X-ray systems and near-infrared imaging. The project will train a new generation of creative, entrepreneurial and innovative early-stage researchers and widen their academic career and employment opportunities. The STREAM consortium is composed of 10 research organisations and 5 industrial partners; the network will provide training to 17 ESRs. STREAM structures the research and training in four scientific work-packages which span the whole value-chain from research to application: CMOS Technologies Assessment, Smart Sensor Design and Layout, Validation and Qualification, Technology Integration, and Valorization

Charge collection and efficiency measurements of the TJ-Monopix2 DMAPS in 180 \,nm CMOS technology

Monolithic CMOS pixel detectors have emerged as competitive contenders in the field of high-energy particle physics detectors. By utilizing commercial processes they offer high-volume production of such detectors. A series of prototypes has been designed in a 180$\,$nm Tower process with depletion of the sensor material and a column-drain readout architecture. The latest iteration, TJ-Monopix2, features a large 2$\,$cm x 2$\,$cm matrix consisting of 512 x 512 pixels with 33.04$\,$um pitch. A small collection electrode design aims at low power consumption and low noise while the radiation tolerance for high-energy particle detector applications needs extra attention. With a goal to reach radiation tolerance to levels of $10^{15}\,1\,$MeV n$_\text{eq}\,$cm$^{-2}$ of NIEL damage a modification of the standard process has been implemented by adding a low-dosed n-type silicon implant across the pixel in order to allow for homogeneous depletion of the sensor volume. Recent lab measurements and beam tests were conducted for unirradiated modules to study electrical characteristics and hit detection efficiency.Comment: Conference proceedings for PIXEL2022 conference, submitted to Po

Development of 3D-DDTC pixel detectors for the ATLAS upgrade

We report on the development of n-on-p, 3D Double-Side Double Type Column (3D-DDTC) pixel detectors fabricated at FBK-irst (Trento, Italy) and oriented to the ATLAS upgrade. The considered fabrication technology is simpler than that required for full 3D detectors with active edge, but the detector efficiency and radiation hardness critically depend on the columnar electrode overlap and should be carefully evaluated. The first assemblies of these sensors (featuring 2, 3, or 4 columns per pixel) with the ATLAS FEI3 read-out chip have been tested in laboratory. Selected results from the electrical and functional characterization with radioactive sources are here discussed.Comment: 20 pages, 14 figures, presented at 7th International "Hiroshima" Symposium on Development and Applications of Semiconductor Tracking Devices International Conference Center Hiroshima, Japan, Aug. 29-Sep.1, 200

The MERIT (nTOF-11) High Intensity Liquid Mercury Target Experiment at the CERN PS

The MERIT(nTOF-11) experiment is a proof-of-principle test of a target system for a high power proton beam to be used as front-end for a neutrino factory or a muon collider. The experiment took data in autumn 2007 with the fast-extracted beam from the CERN Proton Synchrotron (PS) to a maximum intensity of 30 x 10{sup 12} per pulse. The target system, based on a free mercury jet, is capable of intercepting a 4-MW proton beam inside a 15-T magnetic field required to capture the low energy secondary pions as the source for intense muon beams. Particle detectors installed around the target setup measure the secondary particle flux out of the target and can probe cavitation effects in the mercury jet when excited by an intense proton beam.Preliminary results of the data analysis will be presented here

Radiation hardness of MALTA2 monolithic CMOS imaging sensors on Czochralski substrates

MALTA2 is the latest full-scale prototype of the MALTA family of Depleted Monolithic Active Pixel Sensors (DMAPS) produced in Tower Semiconductor 180 nm CMOS sensor imaging technology. In order to comply with the requirements of high energy physics (HEP) experiments, various process modifications and front-end changes have been implemented to achieve low power consumption, reduce random telegraph signal (RTS) noise, and optimise the charge collection geometry. Compared to its predecessors, MALTA2 targets the use of a high-resistivity, thick Czochralski (Cz) substrates in order to demonstrate radiation hardness in terms of detection efficiency and timing resolution up to 3 × 1015 1 MeV neq/cm2 with backside metallisation to achieve good propagation of the bias voltage. This manuscript shows the results that were obtained with non-irradiated and irradiated MALTA2 samples on Cz substrates from the CERN SPS test beam campaign from 2021 to 2023 using the MALTA telescope

Performance of the MALTA Telescope

MALTA is part of the Depleted Monolithic Active Pixel sensors designed in Tower 180nm CMOS imaging technology. A custom telescope with six MALTA planes has been developed for test beam campaigns at SPS, CERN, with the ability to host several devices under test. The telescope system has a dedicated custom readout, online monitoring integrated into DAQ with realtime hit map, time distribution and event hit multiplicity. It hosts a dedicated fully configurable trigger system enabling to trigger on coincidence between telescope planes and timing reference from a scintillator. The excellent time resolution performance allows for fast track reconstruction, due to the possibility to retain a low hit multiplicity per event which reduces the combinatorics. This paper reviews the architecture of the system and its performance during the 2021 and 2022 test beam campaign at the SPS North Area

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13