arXiv subjects

M. Arnold

Publications and source records attributed to M. Arnold.

7 recordsLinked to original sources

arXiv2022

European Strategy for Particle Physics -- Accelerator R&D Roadmap

The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified in the Strategy update. The R&D objectives include: improvement of the performance and cost-performance of magnet and radio-frequency acceleration systems; investigations of the potential of laser / plasma acceleration and energy-recovery linac techniques; and development of new concepts for muon beams and muon colliders. The goal of the roadmap is to document the collective view of the field on the next steps for the R&D programme, and to provide the evidence base to support subsequent decisions on prioritisation, resourcing and implementation.

physics.acc-ph↗

arXiv2021

A family of integrable transformations of centroaffine polygons: geometrical aspects

Two polygons, $(P_1,\ldots,P_n)$ and $(Q_1,\ldots,Q_n)$ in ${\mathbb R}^2$ are $c$-related if $\det(P_i, P_{i+1})=\det(Q_i, Q_{i+1})$ and $\det(P_i, Q_i)=c$ for all $i$. This relation extends to twisted polygons (polygons with monodromy), and it descends to the moduli space of $SL(2,{\mathbb R}^2)$-equivalent polygons. This relation is an equiaffine analog of the discrete bicycle correspondence studied by a number of authors. We study the geometry of this relations, present its integrals, and show that, in an appropriate sense, these relations, considered for different values of the constants $c$, commute. We relate this topic with the dressing chain of Veselov and Shabat. The case of small-gons is investigated in detail.

math.DS↗

arXiv2021

MaxRay: A Raytracing-based Integrated Sensing and Communication Framework

Integrated Sensing And Communication (ISAC)forms a symbiosis between the human need for communication and the need for increasing productivity, by extracting environmental information leveraging the communication network. As multiple sensory already create a perception of the environment, an investigation into the advantages of ISAC compare to such modalities is required. Therefore, we introduce MaxRay, an ISAC framework allowing to simulate communication, sensing, and additional sensory jointly. Emphasizing the challenges for creating such sensing networks, we introduce the required propagation properties for sensing and how they are leveraged. To compare the performance of the different sensing techniques, we analyze four commonly used metrics used in different fields and evaluate their advantages and disadvantages for sensing. We depict that a metric based on prominence is suitable to cover most algorithms. Further we highlight the requirement of clutter removal algorithms, using two standard clutter removal techniques to detect a target in a typical industrial scenario. In general a versatile framework, allowing to create automatically labeled datasets to investigate a large variety of tasks is demonstrated.

cs.HC↗

arXiv2021

Indoor positioning systems: Smart fusion of a variety of sensor readings

Robust and versatile localization techniques are key to the success of the next industrial revolution. Yet, it is uncertain which combination of sensors will be the most robust and valuable. Thus, we present a versatile and reproducible measurement system incorporating a manifold number of state-of-the art sensors to compare and fuse the raw input data. It is shown that some techniques show very good results on the same scenario and data-set, but fall apart on translating to a slightly different scenario. In general we show that the vanilla approach to fuse the raw data achieves reasonable results in the generalization domain, demonstrating that radiofrequency (RF) localization techniques in combination with an inertial measurement unit (IMU) could result in a very robust and promising candidate for solving this challenging task.

cs.IT↗

arXiv2020

Precision measurement of the $E2$ transition strength to the 2$^+_1$ state of $^{12}$C

The form factor of the electromagnetic excitation of $^{12}$C to its 2$^+_1$ state was measured at extremely low momentum transfers in an electron scattering experiment at the S-DALINAC. A combined analysis with the world form factor data results in a reduced transition strength $B(E2; 2^+_1\rightarrow 0^+_1) =7.63(19)$ e$^2$fm$^4$ with an accuracy improved to 2.5\%. In-Medium-No Core Shell Model results with interactions derived from chiral effective field theory are capable to reproduce the result. A quadrupole moment $Q(2^+_1) = 5.97(30)$ efm$^2$ can be extracted from the strict correlation with the $B((E2)$ strength emerging in the calculations.

nucl-ex↗

arXiv2016

Iterating evolutes and involutes

We study iterations of two classical constructions, the evolutes and involutes of plane curves, and we describe the limiting behavior of both constructions on a class of smooth curves with singularities given by their support functions. Next we study two kinds of discretizations of these constructions: the curves are replaced by polygons, and the evolutes are formed by the circumcenters of the triples of consecutive vertices, or by the incenters of the triples of consecutive sides. The space of polygons is a vector bundle over the space of the side directions, and both kinds of evolutes define vector bundle morphisms. In both cases, we describe the linear maps of the fibers. In the first case, the induced map of the base is periodic, whereas, in the second case, it is an averaging transformation. We also study the dynamics of the related inverse constructions, the involutes of polygons. In addition to the theoretical study, we performed numerous computer experiments; some of the observations remain unexplained.

math.DS↗

arXiv2013

High-order harmonic generation by enhanced plasmonic near-fields in metal nanoparticules

We present theoretical investigations of high-order harmonic generation (HHG) resulting from the interaction of noble gases with localized surface plasmons. These plasmonic fields are produced when a metal nanoparticle is subject to a few-cycle laser pulse. The enhanced field, which largely depends on the geometrical shape of the metallic structure, has a strong spatial dependency. We demonstrate that the strong non-homogeneity of this laser field plays an important role in the HHG process and leads to a significant increase of the harmonic cut-off energy. In order to understand and characterize this new feature, we include the functional form of the laser electric field obtained from recent attosecond streaking experiments [F. S{ü}ßmann and M. F. Kling, Proc. of SPIE, {\bf Vol. 8096}, 80961C (2011)] in the time dependent Schrödinger equation (TDSE). By performing classical simulations of the HHG process we show consistency between them and the quantum mechanical predictions. These allow us to understand the origin of the extended harmonic spectra as a selection of particular trajectory sets. The use of metal nanoparticles shall pave a completely new way of generating coherent XUV light with a laser field which characteristics can be synthesized locally.

physics.atom-ph↗