| 1. |
- Abele, H., et al.
(författare)
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Particle physics at the European Spallation Source
- 2023
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Ingår i: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 1023, s. 1-84
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Forskningsöversikt (refereegranskat)abstract
- Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world’s brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
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| 2. |
- Aguilar, J., et al.
(författare)
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Search for Leptonic CP Violation with the ESSnuSBplus Project
- 2024
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Ingår i: Letters in High Energy Physics. - : Andromeda Publishing And Academic Services LTD. - 2632-2714.
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Tidskriftsartikel (refereegranskat)abstract
- ESSνSB is a design study for a next-generation long-baseline neutrino experiment that aims at the precise measurement of the CP-violating phase, δCP, in the leptonic sector at the second oscillation maximum. The conceptual design report published from the first phase of the project showed that after 10 years of data taking, more than 70% of the possible δCP range will be covered with 5σ C.L. to reject the no-CP-violation hypothesis. The expected value of δCP precision is smaller than 8◦ for all δCP values. The next phase of the project, the ESSνSB+, aims at using the intense muon flux produced together with neutrinos to measure the neutrino-nucleus cross-section, the dominant term of the systematic uncertainty, in the energy range of 0.2–0.6 GeV, using a Low Energy neutrinos from STORed Muons (LEnuSTORM) and a Low Energy Monitored Neutrino Beam (LEMNB) facilities.
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| 3. |
- Burgman, A., et al.
(författare)
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The ESSnuSB Design Study: Overview and Future Prospects
- 2023
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Ingår i: Universe. - : MDPI. - 2218-1997. ; 9:8
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Forskningsöversikt (refereegranskat)abstract
- ESSnuSB is a design study for an experiment to measure the CP violation in the leptonic sector at the second neutrino oscillation maximum using a neutrino beam driven by the uniquely powerful ESS linear accelerator. The reduced impact of systematic errors on sensitivity at the second maximum allows for a very precise measurement of the CP violating parameter. This review describes the fundamental advantages of measurement at the second maximum, the necessary upgrades to the ESS linac in order to produce a neutrino beam, the near and far detector complexes, and the expected physics reach of the proposed ESSnuSB experiment, concluding with the near future developments aimed at the project realization.
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| 4. |
- Burgman, A., et al.
(författare)
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The European Spallation Source neutrino super-beam conceptual design report
- 2022
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Ingår i: The European Physical Journal Special Topics. - : Springer Nature. - 1951-6355 .- 1951-6401. ; 231:21, s. 3779-3955
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Forskningsöversikt (refereegranskat)abstract
- A design study, named ESSνSB for European Spallation Source neutrino Super Beam, has been carried out during the years 2018–2022 of how the 5 MW proton linear accelerator of the European Spallation Source under construction in Lund, Sweden, can be used to produce the world’s most intense long-baseline neutrino beam. The high beam intensity will allow for measuring the neutrino oscillations near the second oscillation maximum at which the CP violation signal is close to three times higher than at the first maximum, where other experiments measure. This will enable CP violation discovery in the leptonic sector for a wider range of values of the CP violating phase δCPδCP and, in particular, a higher precision measurement of δCPδCP. The present Conceptual Design Report describes the results of the design study of the required upgrade of the ESS linac, of the accumulator ring used to compress the linac pulses from 2.86 ms to 1.2 μs, and of the target station, where the 5 MW proton beam is used to produce the intense neutrino beam. It also presents the design of the near detector, which is used to monitor the neutrino beam as well as to measure neutrino cross sections, and of the large underground far detector located 360 km from ESS, where the magnitude of the oscillation appearance of νe from νμ is measured. The physics performance of the ESSνSB research facility has been evaluated demonstrating that after 10 years of data-taking, leptonic CP violation can be detected with more than 5 standard deviation significance over 70% of the range of values that the CP violation phase angle δCPδCP can take and that δCPδCP can be measured with a standard error less than 8° irrespective of the measured value of δCPδCP. These results demonstrate the uniquely high physics performance of the proposed ESSνSBESSνSB research facility.
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| 5. |
- Khodadad, Davood, et al.
(författare)
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Single-shot dual-polarization holography : measurement of the polarization state of a magnetic sample
- 2015
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Ingår i: SPECKLE 2015. - : SPIE - International Society for Optical Engineering. - 9781628418781
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Konferensbidrag (refereegranskat)abstract
- In this paper a single-shot digital holographic set-up with two orthogonally polarized reference beams is proposed to achieve rapid acquisition of Magneto-Optical Kerr Effect images. Principles of the method and the background theory for dynamic state of polarization measurement by use of digital holography are presented. This system has no mechanically moving elements or active elements for polarization control and modulation. An object beam is combined with two reference beams at different off-axis angles and is guided to a detector. Then two complex fields (interference terms) representing two orthogonal polarizations are recorded in a single frame simultaneously. Thereafter the complex fields are numerically reconstructed and carrier frequency calibration is done to remove aberrations introduced in multiplexed digital holographic recordings. From the numerical values of amplitude and phase, a real time quantitative analysis of the polarization state is possible by use of Jones vectors. The technique is demonstrated on a magnetic sample that is a lithographically patterned magnetic microstructure consisting of thin permalloy parallel stripes.
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| 6. |
- Albertsson, Kim, et al.
(författare)
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Displaced Event Classification Using Graph Networks
- 2020
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Ingår i: Proceedings of the 2020 Connecting The Dots Workshop. - : CTD/WIT IAC committee.
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Konferensbidrag (refereegranskat)abstract
- Long-lived massive particles, predicted in numerous Standard Model extensions, are a particularly difficult target for online event reconstruction. This work presents a study of detecting the presence of displaced vertices in a collider experiment in several environmental conditions. In particular Graph Neural Networks performing classification on input hit-level data are shown to perform well in the task of separating prompt against displaced events with results translating, with some degradation, into more busy environments. Furthermore, promising results are shown for identifying events from a benchmark supersymmetric process with future work investigating higher pileup environments.
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| 7. |
- Albertsson, Kim
(författare)
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Machine Learning in High-Energy Physics: Displaced Event Detection and Developments in ROOT/TMVA
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many proposed extensions to the Standard Model of particle physics predict long-lived particles, which can decay at a significant distance from the primary interaction point. Such events produce displaced vertices with distinct detector signatures when compared to standard model processes. The Large Hadron Collider (LHC) operates at a collision rate where it is not feasible to record all generated data—a problem that will be exac-erbated in the coming high-luminosity upgrade—necessitating an online trigger system to decide which events to keep based on partial information. However, the trigger is not directly sensitive to signatures with displaced vertices from Long-lived particles (LLPs). Current LLP detection approaches require a computationally expensive reconstruction step, or rely on auxiliary signatures such as energetic particles or missing energy. An improved trigger sensitivity increases the reach of searches for extensions to the standard model.This thesis explores the possibility to apply machine learning methods directly on low-level tracking features, such as detector hits and hit-pairs to identify displaced high-mass decays while avoiding a full vertex and track reconstruction step.A dataset is developed where modelled displaced signatures from novel and known physics processes are mixed in a custom simulation environment, which models the in-ner detector of a general purpose particle detector. Two machine learning models are evaluated using the dataset: a multi-layer dense Artificial Neural Network (ANN), and a Graph Neural Network (GNN). Two case studies suggest that dense ANNs have difficulty capturing relational information in low-level data, while GNNs can feasibily discriminate heavy displaced decay signatures from a Standard Model background. Furthermore it was found that GNNs can perform at a background rejection factor of 103 and a signal efficiency of 20% in collision environments with moderate levels of pile-up interactions, i.e. low-energy particle collisions simultaneous with the primary hard scatter. Further work is required to integrate the approach into a trigger environment. In particular, detector material and measurement resolution effects should be included in the simulation, which should be scaled to model the High-Luminosity Large Hadron Collider (HL-LHC) with its more complicated geometry and its high levels of pile-up.In parallel, the machine learning landscape is quickly evolving and concentrating into large software frameworks with expanding scope, while the High-Energy Physics (HEP) community maintains its own set of tools and frameworks, one example being the Toolkit for Multivariate Analysis (TMVA) which is part of the ROOT framework. This thesis discusses the long- and short-term evolution of these tools, both current trends and some relations to parallel developments in Industry 4.0.
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| 8. |
- Albertsson, Kim, et al.
(författare)
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Towards Fast Displaced Vertex Finding
- 2019
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Ingår i: CTDWIT 19 proceedings. - : CERN.
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Konferensbidrag (refereegranskat)abstract
- Many Standard Model extensions predict metastable massive particles that can be detected by looking for displaced decay vertices in the inner detector volume. Current approaches to search for these events in high-energy particle collisions rely on the presence of additional energetic signatures to make an online selection during data-taking, as the reconstruction of displaced vertices is computationally intensive. Enabling trigger-level reconstruction of displaced vertices could significantly enhance the reach of such searches.This work is a first step approximating the location of the primary vertex in an idealised detector geometry using a 4-layer dense neural networks for regression of the vertex location yielding a precision of O(1 mm) [O(20 mm)] RMS in a low [high] track multiplicity environment.
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| 9. |
- Lilli, Giordano, et al.
(författare)
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Formal Verification of the Control Software of a Radioactive Material Remote Handling System, Based on IEC 61499
- 2023
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Ingår i: IEEE Open Journal of the Industrial Electronics Society. - : Institute of Electrical and Electronics Engineers Inc.. - 2644-1284. ; 4, s. 417-431
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Tidskriftsartikel (refereegranskat)abstract
- Automation systems within nuclear laboratories are intended to work under harsh operating conditions. Selective Production of Exotic Species (SPES) is a nuclear research facility currently under construction by the Istituto Nazionale di Fisica Nucleare, dedicated to the production and study of radioactive ion beams. Isotopes are produced within the target ion source unit, a vacuum vessel that must be replaced on a regular basis. The highly radioactive environment necessitates the deployment of a set of automated systems dedicated to the unit's remote management. To meet high-level security standards, the design of such instrumentation and control systems must include extensive verification. Based on specific safety requirements, model checking can be used to assess the systems' correctness. This article describes how to employ an integrated toolchain to design, simulate, formally verify, and deploy the control software for the Horizontal Handling Machine, a safety-critical remote handling system in operation at SPES. The IEC 61499 standard's adoption led to a redesign of the control logic. Following a preliminary online simulation, the closed-loop system has been formally verified using the NuSMV symbolic model checker, with the help of the FB2SMV converter. In addition, the Function Blocks Modeling Environment tool was used for automating verification and analyzing counterexamples.
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