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• 1.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Technical Design Report for the Phase-II Upgrade of the ATLAS Tile Calorimeter2018Report (Other academic)

This Technical Design Report describes the project to upgrade the ATLAS Tile Calorimeter for the operation at the High Luminosity LHC. The High Luminosity LHC is planned to begin operation in 2026 and to deliver more than ten times the integrated luminosity (up to 4000 fb"^{-1}" of the LHC Runs 1-3 combined. To achieve this integrated luminosity in a reasonable amount of time, an instantaneous luminosity of up to "7.5\times 10^{34} cm^{-2}s^{-1}" is required, corresponding to up to 200 simultaneous pp interactions per bunch crossing. The large luminosity offers the opportunity for a wealth of physics measurements but presents significant challenges to the detector as well as to the trigger and data acquisition systems in the form of increased trigger rates and detector occupancy. This document summarises the requirements and motivations for the Tile Calorimeter upgrade and gives a detailed technical description of the different components. It describes the beam tests with the prototypes in recent years and the plans for the assembly, quality assurance and the integration of the final system. The document also presents the key aspects of project management with an overview of the organisation, the schedule and the cost.

• 2.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Energy reconstruction methods in the IceCube neutrino telescope2014In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 9, p. P03009-Article in journal (Refereed)

Accurate measurement of neutrino energies is essential to many of the scientific goals of large-volume neutrino telescopes. The fundamental observable in such detectors is the Cherenkov light produced by the transit through a medium of charged particles created in neutrino interactions. The amount of light emitted is proportional to the deposited energy, which is approximately equal to the neutrino energy for v(e) and v(mu) charged-current interactions and can be used to set a lower bound on neutrino energies and to measure neutrino spectra statistically in other channels. Here we describe methods and performance of reconstructing charged-particle energies and topologies from the observed Cherenkov light yield, including techniques to measure the energies of uncontained muon tracks, achieving average uncertainties in electromagnetic-equivalent deposited energy of similar to 15% above 10 TeV.

• 3. Buszello, C. P.
Stockholm University, Faculty of Science, Department of Physics.
Muon reconstruction and identification with the Run II D0 detector2014In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 737, p. 281-294Article in journal (Refereed)

We present an overview of the muon reconstruction and identification methods employed by the DO collaboration to analyze the Run II (2001-2011) p (p) over bar data of the Fermilab Tevatron collider at root s = 1.96 TeV. We discuss the performance of these methods, how it is measured using DO data, and how it is properly modeled by the DO simulation program. In its pseudorapidity acceptance, vertical bar eta vertical bar < 2, the muon system identifies high-p(T) muons (p(T) greater than or similar to 10 GeV) with efficiencies ranging from 72% to 89%. Muons tracks are reconstructed in the DO central tracking system with efficiencies ranging from 85% to 92% and with a typical relative momentum resolution of 10% for p(T) = 40 GeV. Isolation criteria reject multijet background with efficiencies of 87-99%.

• 4.
Lawrence Berkeley National Laboratory, USA.
Neuromorphic Kalman filter implementation in IBM's TrueNorth2017In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 898, no 4, article id 042021Article in journal (Refereed)

Following the advent of a post-Moore’s law field of computation, novel architectures continue to emerge. With composite, multi-million connection neuromorphic chips like IBM’s TrueNorth, neural engineering has now become a feasible technology in this novel computing paradigm. High Energy Physics experiments are continuously exploring new methods of computation and data handling, including neuromorphic, to support the growing challenges of the field and be prepared for future commodity computing trends. This work details the first instance of a Kalman filter implementation in IBM’s neuromorphic architecture, TrueNorth, for both parallel and serial spike trains. The implementation is tested on multiple simulated systems and its performance is evaluated with respect to an equivalent non-spiking Kalman filter. The limits of the implementation are explored whilst varying the size of weight and threshold registers, the number of spikes used to encode a state, size of neuron block for spatial encoding, and neuron potential reset schemes.

• 5.
Lawrence Berkeley National Lab, USA.
Results of FE65-P2 Pixel Readout Test Chip for High Luminosity LHC Upgrades2017In: PoS - Proceedings of Science, ISSN 1824-8039, E-ISSN 1824-8039, Vol. 282Article in journal (Refereed)

A pixel readout test chip called FE65-P2 has been fabricated on 65 nm CMOS technology. FE65-P2 contains a matrix of 64 x 64 pixels on 50 micron by 50 micron pitch, designed to read out a bump bonded sensor. The goals of FE65-P2 are to demonstrate excellent analog performance isolated from digital activity well enough to achieve 500 electron stable threshold, be radiation hard to at least 500 Mrad, and prove the novel concept of isolated analog front ends embedded in a flat digital design, dubbed “analog islands in a digital sea”. Experience from FE65-P2 and hybrid assemblies will be applied to the design for a large format readout chip, called RD53A, to be produced in a wafer run in early 2017 by the RD53 collaboration. We review the case for 65 nm technology and report on threshold stability test results for the FE65-P2.

• 6.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Universität Innsbruck, Austria. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
DESIREE electrospray ion source test bench and setup for collision induced dissociation experiments2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 7, article id 075102Article in journal (Refereed)

In this paper, we give a detailed description of an electrospray ion source test bench and a single-pass setup for ion fragmentation studies at the Double ElectroStatic Ion Ring ExpEriment infrastructure at Stockholm University. This arrangement allows for collision-induced dissociation experiments at the center-of-mass energies between 10 eV and 1 keV. Charged fragments are analyzed with respect to their kinetic energies (masses) by means of an electrostatic energy analyzer with a wide angular acceptance and adjustable energy resolution.

• 7.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Point source searches by IceCube: Recent results and progress2013In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 725, p. 41-44Article in journal (Refereed)

The IceCube Neutrino Observatory began full data-taking operations in May of 2011. During the previous years of construction, data-taking was performed with each growing stage of the detector. In these proceedings we review the most recent all-sky searches for point sources of neutrinos, based on data taken between 2008 and 2010 when IceCube was operated in its 40-string and 59-string configurations. Based on better than expected performance with the partial detectors, operation of the full IceCube detector is well on track to reach the sensitivity goals for detecting high energy astrophysical neutrinos.

• 8.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
A Strategy to Detect and Identify Gluino R-hadrons with the ATLAS Experiment at the LHC2005In: ATL-COM-PHYS, no 065Article in journal (Refereed)

The potential of the ATLAS detector at the LHC to detect and quantify the production of gluino R-hadrons is investigated. Using QCD-based models and a full detector simulation, a search strategy is outlined which uses the property that gluino R-hadrons can change the sign of their charge when propagating through matter. By comparing charged tracks in the Inner and Muon tracking systems, it is shown that this observable can be used to both detect and identify gluino R-hadrons of masses up to around 1 TeV in early LHC running

• 9.
Stockholm University, Faculty of Science, Department of Physics.
Deutsches Elektronen-Synchrotron (DESY). Deutsches Elektronen-Synchrotron (DESY),. Stockholm University, Faculty of Science, Department of Physics.
An Advanced FPGA Based Phase-Lock-Loop System as an Alternative Solution for the XFEL Timing System2009In: Nuclear Science Symposium Conference Record (NSS/MIC), 2009 IEEE, 2009, p. 1871-1872Conference paper (Refereed)

The European XFEL project requires a high-speed, very precise clock and timing distribution over large distances. A prototype system which fulfils current requirements that uses high-end components has just been completed and is being tested. However, the system is quite complicated and the boards are very complex, being designed using the small micro-TCA form factor. A way to simplify the system, and perhaps reduce cost, would be to implement an Advanced PLL in the programmable logic of an FPGA, which then would control an external VCO. By doing so several major issues could be resolved at the same time, while making more use of the advanced features of modern FPGAs. Such a system could be an alternative solution to the complex part of the Timing and Triggering System for XFEL.

• 10.
Stockholm University, Faculty of Science, Department of Physics.
Deutsches Elektronen-Synchrotron (DESY). Deutsches Elektronen-Synchrotron (DESY),. Stockholm University, Faculty of Science, Department of Physics.
Timing and Triggering System Prototype for the XFEL Project2010In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 58, no 4, p. 1852-1856Article in journal (Refereed)

The European X-ray Free Electron Laser (XFEL) [1] at DESY in Hamburg will begin operating in the next few years, enabling new, ground-breaking research opportunities. The entire system requires very precise clock and trigger distribution, synchronous with the 1.3 GHz system RF-frequency, over distances of more than 3.4 km. The new experiment demanded features that other commercial solutions could not yet provide. Researchers at Stockholm University and DESY have developed a prototype for the timing system of XFEL. It has been decided that XFEL will use modern ATCA and Micro-TCA systems because of their advanced features and reliability. The timing system has been adapted to the Micro-TCA bus standard and also follows the new upcoming xTCA for physics standard. The prototype is fully functional and complete. It will serve as a platform for future development of the whole timing system. This paper describes the hardware design and some test results using the prototype board.

• 11.
Stockholm University, Faculty of Science, Department of Physics.
Deutsches Elektronen-Synchrotron (DESY). Deutsches Elektronen-Synchrotron (DESY),. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
A System for Distributing High-Speed Synchronous High-Precision Clock and Trigger Data over Large Distances2008In: Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE, 2008, p. 2581-2584Conference paper (Refereed)

The distribution of precise timing throughout the European X-ray Free Electron Laser project [1] (XFEL) and its triggering system is a very challenging part of the system design. ADCs in data acquisition systems and DACs in control systems will require very high precision clocks. The clocks need to be synchronous to each other, both in frequency and phase, with a jitter performance better than 5 ps (RMS). At some high-speed ADCs it might even need a precision down to 0.1ps. The frequencies that must be available are the main 1.3 GHz and some frequencies below, which are all derived from the main frequency. The phase needs to be adjustable to allow synchronization between separate devices.

• 12.
Stockholm University, Faculty of Science, Department of Physics.

Modern physical experiments often demand advanced instrumentation based on advances in  technology. This work describes four instrumentation physics projects that are based on modern, high-capacity Field-Programmable Gate Arrays, making use of their versatility, programmability, high bandwidth communication interfaces and signal processing capabilities.

In the first project, a jet-finding algorithm for the ATLAS detector at the LHC experiment at CERN was developed and implemented, and different verification methods were created to validate the functionality and reliability. The experiment uses a three level trigger system, where the first level uses custom FPGA-based hardware for analysis of collision events in real-time.

The second project was an advanced timing and triggering distribution system for the new European X-Ray Free Electron Laser (XFEL) facility at DESY in Hamburg. XFEL will enable scientists to study nano structures on the atomic scale. Its laser pulses will have the strongest peak power in the world with extremely short duration and a high repetition rate, which will even allow filming of chemical reactions. The timing system uses modern FPGAs to distribute high-speed signals over optical fibers and to deliver clocks and triggers with high accuracy.

The third project was a new data acquisition board based on high-speed ADCs combined with high-performance FPGAs, to process data from segmented Ge-detectors in real-time. The aim was to improve system performance by greatly oversampling and filtering the analog signals to achieve greater effective resolution.

Finally, an innovative solution was developed to replace an aging system used at CERN and Stockholm University to test vital electronics in the Tile Calorimeters of the ATLAS detector system. The new system is entirely based on a commercial FPGA development board, where all necessary custom communication protocols were implemented in firmware to emulate obsolete hardware.

• 13.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Exploring vacuum phototriodes for photon calorimetryManuscript (preprint) (Other academic)

In this work properties of a vacuum phototriode (VPT) and preamplifier unit designed for the electromagneticcalorimeter of the PANDA experiment being built at FAIR are investigated. With the use of leadtungstate and lanthanum bromide scintillators the VPT properties are studied at low photon energies, fromtens of keV in the lanthanum bromide measurements and between 10 MeV and 60 MeV in the lead tungstatemeasurements. At these energies the noise of the VPT unit can be expected to influence its performancesignificantly. It is shown that the noise contribution to the measured energy resolution, under optimal conditions,is consistent with a fluctuation of (one standard deviation) approximately 200 electrons at the VPTanode. For a lead tungstate crystal this is equivalent to a noise of 1.2 MeV. For lanthanum bromide thismakes it possible to use VPTs for gamma ray spectroscopy above a few hundreds of keV without noticableeffects on the energy resolution compared to measurements with a standard photomultiplier. The gain sensitivityto rate is shown to be small. The gain changes by less than 1.5 % for a rate of 2105 s−1 comparedto low rates.

• 14.
Stockholm University, Faculty of Science, Department of Physics.
Instrumentation development for physics with antiproton beams2013Doctoral thesis, comprehensive summary (Other academic)

This thesis summarises work done in the preparation for the PANDA (antiproton ANnihilations at DArmstadt) experiment, that will be built at the HESR (High Energy Storage Ring) at FAIR (Facility for Antiproton and Ion Research) and for the PAX (Polarised Antiproton eXperiment) experiment proposed for the HESR.

For PANDA, characteristics of the electromagnetic calorimeter have been measured at the tagged photon beam facility at the MAX IV laboratory for 61 photon energies in the range 12-63 MeV. The tested detector array consisted of 5×5 PbWO4 (lead tungstate) crystals designed for the forward end-cap. The array was cooled to -25 °C and read out with either conventional photomultiplier tubes or vacuum phototriodes (VPTs), the photo-sensor proposed for the forward end-cap. The measured relative energy resolution with photomultiplier tubes, σ/E, (for example 6 % at 20 MeV) is well within the limits of the PANDA requirements. In tests with VPTs the lower signal-to-noise ratio deteriorates the resolution to a level suggesting that VPTs should not be used in PANDA.

For PAX, the analysing power with respect to the neutron in pd → ppn, with a transversely polarised proton beam with energy 49.3 MeV, has been measured. Data was taken at the COSY storage ring, Forschungszentrum Jülich, during an experiment in which the PAX collaboration successfully polarised a stored proton beam by spin filtering. In the measurement the beam was scattered of a deuterium cluster-jet target and the scattered protons were detected in the two silicon tracking telescopes of the ANKE detector system. The measured analysing power is compared to the predictions by chiral effective field theory at next-to-next-to-leading order by interpolating on a precalculated grid and using the sampling method.

• 15.
Stockholm University, Faculty of Science, Department of Physics.
Studies of Top Physics Sensitivity and of Pile-Up Effects on Energy Reconstruction in the ATLAS Detector: A Licentiate Thesis About the Treatment of Troublesome $\tau$ and Producing Pulses to Probe Pile-up Problems2016Licentiate thesis, monograph (Other academic)

This thesis presents two studies conducted using the ATLAS detectorat the Large Hadron Collider. The first one is a technical study abouthow out-of-time pile-up affects energy reconstruction using the optimalfiltering 2 algorithm in the TILE calorimeter sub detector. The studyis conducted using a pulse simulator software that is also described.Although the algorithm is potentially sensitive to the effects ofout-of-time pile-up, the effects under actual running conditions areestimated to be lower than 1.5 ADC counts for 68 \% of the pulses,which is considered a small effect. It is also shown that out-of-timepile-up is a potential reason to get negatively reconstructed energies.The second study regards a measurement of the $t\bar{tZ}$ cross sectionwith one hadronically decaying $\tau$ leptons and two lighter leptonsin the final state using 8 TeV data. The conclusion is that it isnot possible to make a significant such measurement from the 8 TeVdata due to low efficiencies in reconstruction of $\tau$ leptons.In addition to these two studies, this thesis also contain brief overviewsof the atlas detector and the standard model of particles and interactions.

• 16.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
Development of a readout link board for the demonstrator of the ATLAS Tile calorimeter upgrade2013In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 8, article id C03025Article in journal (Refereed)

A hybrid readout system is being developed for installation in one module of the ATLAS scintillating Tile Calorimeter (TileCal) during the long LHC shutdown in 2013/2014. The hybrid combines a fully functional demonstrator of the full-digital system planned for installation in 2022 with circuitry to maintain compatibility with the existing system. This is the report on a second generation prototype link and controller board connecting the on-and off-detector electronics. The main logic component within this board is a XILINX Kintex-7 FPGA connected to an 12x5 Gbps SNAP12 opto transmitter and a 4x10 Gbps QSFP+ connector, for off-detector communication. One of the latter two will be chosen for the final design.

• 17.
Stockholm University, Faculty of Science, Department of Physics.
Single event upsets: measurements and modelling of proton- and neutron-induced errors in a 28 nm SRAM-based FPGA2018Licentiate thesis, comprehensive summary (Other academic)

Single event upsets are radiation-induced errors affecting electronic devices, which can cause corruption of processed data. The electromagnetic calorimeter of the PANDA experiment — a hadron-physics experiment currently under development — will employ Xilinx Kintex-7 field-programmable gate arrays (FPGAs) in its readout electronics. During operation of the experiment, the FPGAs will be exposed to a high flux of radiation. Single-event upsets caused by protons and neutrons in the configuration memory of the FPGA have been studied through experiments and theoretical modelling. The device was irradiated with protons and neutrons of energies up to 184 MeV, and the corresponding single event upset cross sections were determined. In order to describe the energy-dependence of the cross sections, and to predict the error rates during operation of PANDA, a Monte Carlo model of energy-deposition mechanisms in silicon has been developed. The model predictions agree well with the experimental data for both protons and neutrons. Using the developed model, the mean time between failures due to neutrons during initial operation of PANDA is estimated to be 180 ± 40 hours per FPGA.

• 18.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Measurements and Simulations of Single-Event Upsets in a 28-nm FPGA2017In: PoS - Proceedings of Science, ISSN 1824-8039, E-ISSN 1824-8039, Vol. 313Article in journal (Refereed)

Single-event upsets in the configuration memory of the 28-nm Xilinx Kintex-7 FPGA, used in the PANDA electromagnetic calorimeter, have been studied. Results from neutron and proton irradiations at energies up to 184 MeV are presented and compared with previous experimental results. In order to gain information about the energy-dependence of the single-event upset cross section, a GEANT4-based Monte Carlo simulation of upset mechanisms in nanometric silicon volumes has been developed. The results from this model are shown to agree with the experimental data for both neutrons and protons. Knowledge about the energy dependence of the cross section and of the particle flux at the location of the front-end modules in PANDA enables better estimates of the mean time between failures in the electromagnetic calorimeter. At PANDA, a total neutron flux of 1·102 cm−2 s−1 at the location of the front-end modules is expected at the lowest antiproton beam momentum and a luminosity of 1·1031 cm−2 s−1, leading to a predicted Mean Time Between Failures of 47 ± 10 hours per FPGA in the electromagnetic calorimeter.

• 19.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE2013In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 84, no 5, p. 055115-Article in journal (Refereed)

We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (C-n(-), n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C-2(-) molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10(-14) mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

• 20.
Stockholm University, Faculty of Science, Department of Physics.
Calibration of b-tagging efficiency and search for Dark Matter production in association with heavy avour quarks with the ATLAS experiment2016Licentiate thesis, monograph (Other academic)

The Large Hadron Collider (LHC) is the most powerful and complex particle accelerator ever built. The ATLAS detector is a general-purpose particle detector at the LHC, designed to cover a wide range of physics measurements.This thesis presents two physics studies performed using data of proton-proton collisions collected with the ATLAS detector at √s = 8 TeV.

The identication of jets originating from b quarks (b-tagging) is a crucial tool for many physics analyses at the LHC. A new technique to calibrate the efficiency of b-tagging algorithms using high transverse momentum jets is described. This technique allows to perform the calibration using jets with transverse momenta up to 1200 GeV, while the current calibration methods only reach approximately 300 GeV. The results of the calibration are presented.

The second study presented in this thesis is a search for Dark Matter (DM) production in association with a pair of heavy flavour quarks. A reinterpretation of the results of the ATLAS search for DM at √s = 8 TeV has been done based on simplied models. A set of simplied models with various DM masses, masses of the exchange particle, that mediates the interaction between DM and the regular matter, and couplings is considered. This study aims to choose benchmark models to be used in future searches at √s = 13 TeV.

Additionally an accomplished technical project on the development of the b-tagging ATLAS software is presented.

• 21.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
An Updated Front-End Data Link Design for the Phase-2 Upgrade of the ATLAS Tile Calorimeter2017In: 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC): Conference Proceedings, IEEE Computer Society, 2017Conference paper (Other academic)

We present a new design for the advanced Link Daughter Board (DB) for the front-end electronics upgrade of the ATLAS hadronic Tile Calorimeter. The DB provides control, configuration and continuous ADC readout for the front-end through bi-directional multi-GB/s optical links with the off-detector readout system. The DB will operate in high luminosity LHC conditions with limited detector access, so the design is fault tolerant with a high level of redundancy to avoid single-point failure modes. The new design is based on the new Xilinx Kintex Ultrascale+ FPGA family, which provides improved high-speed link timing performance and radiation tolerance, as well as better signal compatibility with the CERN-developed GBTx link and timing distribution ASICs. Two GBTx ASICs each provide redundant phase-adjusted, LHC synchronous clocks, parallel control buses and remote JTAG configuration access to the two FPGAs on the DB.

• 22.
Stockholm University, Faculty of Science, Department of Physics.
Upgrade of Tile Calorimeter of the ATLAS Detector for the High Luminosity LHC.2017In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 928, article id 012024Article in journal (Refereed)

The Tile Calorimeter (TileCal) is the hadronic calorimeter of ATLAS covering the central region of the ATLAS experiment. TileCal is a sampling calorimeter with steel as absorber and scintillators as active medium. The scintillators are read out by wavelength shifting fibers coupled to photomultiplier tubes (PMT). The analogue signals from the PMTs are amplified, shaped and digitized by sampling the signal every 25 ns. The High Luminosity Large Hadron Collider (HL-LHC) will have a peak luminosity of 5 × 1034 cm −2 s −1, five times higher than the design luminosity of the LHC. TileCal will undergo a major replacement of its on- and off-detector electronics for the high luminosity programme of the LHC in 2026. The calorimeter signals will be digitized and sent directly to the off-detector electronics, where the signals are reconstructed and shipped to the first level of trigger at a rate of 40 MHz. This will provide a better precision of the calorimeter signals used by the trigger system and will allow the development of more complex trigger algorithms. Three different options are presently being investigated for the front-end electronic upgrade. Extensive test beam studies will determine which option will be selected. Field Programmable Gate Arrays (FPGAs) are extensively used for the logic functions of the off- and on-detector electronics. One hybrid demonstrator prototype module with the new calorimeter module electronics, but still compatible with the present system, may be inserted in ATLAS at the end of 2016.

• 23.
Stockholm University, Faculty of Science, Department of Physics.
Beam Tests on the ATLAS Tile Calorimeter Demonstrator Module2018Conference paper (Refereed)

The Large Hadron Collider (LHC) Phase II upgrade aims to increase the accelerator luminosity by a factor of 5-10. Due to the expected higher radiation levels and the aging of the current electronics, a new read-out system of the ATLAS experiment hadronic calorimeter (TileCal) is needed. A prototype of the electronics – the Demonstrator - has been tested exposing a module of the calorimeter to particles at the Super Proton Synchrotron (SPS) accelerator of CERN. Data were collected with beams of muons, electrons and hadrons and muons, at various incident energies and impact angles. The measurements aim to check the calibration and to determine the performance the detector exploiting the features of the interactions of the muons, electrons and hadrons with matter. We present the current status and results where the new Demonstrator new electronics were situated in calorimeter modules and exposed to beams of muons, electrons and hadrons with different energies and impact angles.

• 24.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
Readiness of the ATLAS Tile Calorimeter link daughterboard for the High Luminosity LHC era2019Conference paper (Refereed)

The Daughterboard (DB) is the read-out link and control board that interfaces the on- and offdetector electronics for the High-Luminosity Large Hadron Collider (HL-LHC) of the the ATLAS Tile Calorimeter (TileCal). The DB sends high-speed read-out of digitized Photomultiplier (PMT) samples, while receiving and distributing configuration, control and LHC timing. A redundant design based on Xilinx Soft Error Mitigation (SEM), Triple Mode Redundancy (TMR), Forward Error Correction (FEC) and CRC Cyclic Redundancy Check (CRC) strategies minimizes single failure points while withstanding single-event upsets and damage from minimum ionizing and hadronic radiation. We present the current results of the performed TID, NIEL and SEU tests, aiming to demonstrate the readiness of the Daughterboard to satisfy the radiation requirements imposed by the HL-LHC.

• 25.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
Redesign of the ATLAS Tile Calorimeter read-out link and control board for the high-luminosity LHC era2019Conference paper (Refereed)

The R&D for the new on-detector electronics for the Phase-II ATLAS upgrade for the High-Luminosity Large Hadron Collider (HL-LHC) has motivated progressive redesigns of the ATLAS Tile Calorimeter (TileCal) Daughterboard (DB). The DB is the read-out link and control board interface to the off-detector electronics of TileCal. The DB receives configuration commands and LHC timing via two CERN radiation-hard GBTx ASICs and two redundant 4.8 Gbps downlinks. Two Ultrascale+ FPGAs send continuous high-speed read-out of digitized Photomultiplier Tube (PMT) samples through four 9.6 Gbps uplinks. We present a DB redesign that improves the timing scheme, and enhances the radiation tolerance by mitigating Single Event Latch-up (SEL) induced errors and implementing a more robust power-up and current monitoring scheme. The design minimizes single points of failure and reduces sensitivity to Single Event Upsets (SEUs) and radiation damage by employing a double-redundant scheme, using Triple Mode Redundancy (TMR) and Xilinx Soft Error Mitigation (SEM) in the FPGAs, adopting Cyclic Redundancy Check (CRC) error verification in the uplinks and Forward Error Correction (FEC) in the downlinks.

• 26.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
An updated design of the read out link and control board for the Phase-2 upgrade of the ATLAS Tile Calorimeter2019In: The 39th International Conference on High Energy Physics, Trieste: SISSA, the International School for Advanced Studies , 2019Conference paper (Refereed)

The ATLAS hadronic Tile Calorimeter (TileCal) is being upgraded for the High Luminosity Large Hadron Collider (HL-LHC). We present a redesign of the TileCal Phase II read out link and control Daughterboard (DB). The DB has a double redundant radiation tolerant design that will provide continuous high-speed readout of digitized data samples of 12 photomultiplier channels each with two gains, while handling the timing, control and communication between the frontend and off-detector electronics, all over multi-gigabit optical links. Four SFP+ modules serve 4×9.6 Gbps uplinks and 2×4.8 Gbps downlinks, handled respectively by two re-programmable Kintex Ultrascale+ FPGAs and two CERN developed gigabit link ASICs (GBTx). Better highspeed uplink timing and improved radiation tolerance have been achieved by migrating the previous design from the Xilinx Kintex-7 FPGAs to the Kintex Ultrascale+ architecture. Preliminary TID radiation tests were performed on a Daughterboard revision 5 following the TOTAL DOSE STEADY-STATE IRRADIATION TEST METHOD ESCC22900 and the ATLAS protocol and safety factors.

• 27.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Physics.
ATLAS Tile Calorimeter Link Daughterboard2019In: Topical Workshop on Electronics for Particle Physics, Trieste: SISSA, the International School for Advanced Studies , 2019Conference paper (Refereed)

We have developed an updated Daughterboard design for control and readout of the upgraded ATLAS Hadronic Tile Calorimeter electronics for HL-LHC. In the new design, four SFP+ modules handle: 4×9.6 Gbps uplinks operated by two Kintex Ultrascale+ FPGAs, and 2×4.8 Gbps downlinks operated by two GBTxs. The uplink sends continuous high-speed readout of digitized PMT samples, while the downlink receives control, configuration and LHC timing. Triple Mode Redundancy (TMR), Forward Error Correction (FEC) and CRC (Cyclic Redundancy Check) strategies, plus a double redundant design with radiation tolerant components, minimize single failure points and improves resistance to single-event upsets caused by hadronic radiation. Preliminary TID and NIEL tests were performed following the ATLAS policy on radiation tolerant electronics and those specified in the European Space Components Coordination specification 22900 (ESCC22900).

• 28.
Stockholm University, Faculty of Science, Department of Physics. CERN.

The Phase-II upgrade plan for the ATLAS Hadronic Tile Calorimeter facing the High-Luminosity LHC (HL-LHC) era includes approximately 1000 radiation tolerant read-out link and control boards (Daughterboards) that will provide full-granularity digital data to a fully-digital trigger system off-detector through multi-Gbps optic fibres. Different Daughterboard (DB) revisions have been developed, each successively aiming to meet the demanding HL-LHC requirements. The DB communicates with the off-detector systems via four 9.6 Gbps uplinks and two 4.8 Gbps downlinks. The DB performs high-speed read-out of digitized Photomultiplier (PMT) samples, while receiving and distributing configuration, control and LHC-synchronous timing to the front-end system. The design aims to minimize radiation-induced errors and enhance data reliability by embracing a fully double redundant design using CERN radiation hard GBTx ASICs and Xilinx FPGAs, implementing Triple Mode Redundancy (TMR), adopting Soft Error Mitigation (SEM) to correct for configuration memory Single Event Upsets (SEU), and employing Cyclic Redundancy Check (CRC) and Forward Error Correction (FEC) in the data format of the uplink and downlink, respectively. Total Ionizing Dose (TID), Non-Ionizing Energy Losses (NIEL) and Single Event Effects (SEE) radiation tests have been performed in order to assess the radiation tolerance strategies followed in the design and to qualify the DB for the HL-LHC requirements according to the ATLAS policy on radiation tolerant electronics. This thesis presents the author's contribution to the development of the DB through the different revisions, the integration of the DB to the Demonstrator and the radiation tests performed aiming to demonstrate the readiness of the DB to withstand the radiation requirements imposed by the HL-LHC. Resulting of this document, the author proposes strategies to be used in the new DB design moving forward the final design to be produced and inserted in ATLAS during the 2024-2026 period.

• 29. Viel, Simon
Lawrence Berkeley National Laboratory and University of California, United States of America.
Performance of silicon pixel detectors at small track incidence angles for the ATLAS Inner Tracker Upgrade2016In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 831, p. 254-259Article in journal (Refereed)

In order to enable the ATLAS experiment to successfully track charged particles produced in high-energy collisions at the High-Luminosity Large Hadron Collider, the current ATLAS Inner Detector will be replaced by the Inner Tracker (ITk), entirely composed of silicon pixel and strip detectors. An extension of the tracking coverage of the ITk to very forward pseudorapidity values is proposed, using pixel modules placed in a long cylindrical layer around the beam pipe. The measurement of long pixel clusters, detected when charged particles cross the silicon sensor at small incidence angles, has potential to significantly improve the tracking efficiency, fake track rejection, and resolution of the ITk in the very forward region. The performance of state-of-the-art pixel modules at small track incidence angles is studied using test beam data collected at SLAC and CERN.

• 30.
Stockholm University, Faculty of Science, Department of Physics.
ATLAS Pixel Detector Readout Integrated Circuits and Data Acquisition2016Licentiate thesis, comprehensive summary (Other academic)

The Large Hadron Collider (LHC) is a particle collider built by CERN for testing the predictions of theories within high energy physics, thereby contributing to advancements in our understanding of physical laws. In order to improve the discovery potential of the collider, the LHC will undergo an upgrade to be able to reach luminosities of 5x1034 cm2s-1 and the increased collision rate following the upgrade facilitates the need for a new readout system for the ATLAS experiment at the LHC that meets the challenging demands on low mass, high-speed readout capability and radiation tolerance, something which is especially important for the pixel detector closest to the particle interaction point. This work describes preparations of the ATLAS pixel detector for the phase 2 inner tracker upgrade, in the form of testing and verification of new readout techniques and recently developed pixel chip prototypes, as well as characterization and simulation of a data transmission link for high-speed readout of the pixel front-end chips. Equally as important as the development of improved readout electronics for an upgraded system is the maintenance of the present ATLAS detector hardware, as well as detailed simulations of the detector operation. This thesis also covers work related to the update of a test bench system for one of the calorimeters of the ATLAS experiment, and the simulation of radiation damage effects in the pixel sensors.

• 31.
Stockholm University, Faculty of Science, Department of Physics.
Performance Improvements for Particle Tracking Detectors in Extreme Rate and Radiation Environments2019Doctoral thesis, comprehensive summary (Other academic)

In order to increase its discovery potential, the Large Hadron Collider (LHC) at CERN is being transformed into a higher luminosity machine expected to be operational around 2026. The number of particle collisions will increase by a factor of 10 beyond the current design value, which means that the detectors installed around the LHC are facing various new challenges. The most demanding challenges include handling the enormous data quantities that will be transferred from the front-end readout modules at significantly higher rates than previously, as well as the radiation effects that arise as a consequence of the intense particle flow and that cause damage to sensor elements and electronics.

At the ATLAS experiment, a multipurpose detector operating at the LHC, the impact of the luminosity increase is especially severe for the silicon pixel tracking detector, being the central subsystem located closest to the particle interaction point and therefore exposed to the highest radiation dose and hit density. The extreme radiation doses that the pixel modules will be subject to will cause deformation of the sensor material structure and thus loss of the signals, which after subsequent digitization by the pixel readout chip must be transferred over relatively long distances through a low-mass data link, causing further signal distortion.

The work presented here addresses both major challenges described and outlines solutions for the upcoming upgrade of the ATLAS pixel detector system with regards to these. Firstly, it is demonstrated how improved accuracy of detector simulations and reconstruction of particle trajectories through the detector can be achieved as higher particle fluences are approached, by modeling radiation damage effects that occur in the pixel sensors. Secondly, it is shown how a receiver integrated circuit utilizing an industry standard technique novel within high-energy physics applications has been designed as an integral part of a high-speed transmission link to efficiently restore the signal quality in order to achieve adequate data readout rates.

• 32.
Stockholm University, Faculty of Science, Department of Physics.
Response of a PANDA electromagnetic calorimeter prototype to energies below 100 MeV.2019Licentiate thesis, comprehensive summary (Other academic)

The antiProton annihilation at Darmstadt (PANDA) experiment is designed for studies of the strong force. It will be built and placed in the high energy storage ring (HESR) at the facility for antiproton and ion research (FAIR) in Darmstadt. The beam of the HESR consists of anti protons in an energy range from 0.8 GeV to 14 GeV and will collide with a fixed hydrogen target. The detectors of PANDA are designed for e.g. detailed hadron spectroscopy by detecting the anti-proton-proton interactions in the transition region between perturbative and non perturbative quantum chromo dynamics (QCD).This thesis summarizes preparatory experiments with a PANDA forward endcap ElectroMagnetic Calorimeter (EMC) prototype performed at MAX IV laboratory, for studying the response to photon energies below 100 MeV using vacuum photo tetrodes (VPTTs) as photo sensors. The prototype was cooled down to -25 °C. Two different sets of VPTTs were investigated as well as two different analog to ditigital converters (ADCs), peak-sensing ADCs and sampling ADCs. The results show that with VPTT photosensors, in combination with sampling ADCs, the technical design report (TDR) requirement, with regard to energy resolution, can be fulfilled even at low energies.

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