arXiv subjects

Tim Evans

Publications and source records attributed to Tim Evans.

9 recordsLinked to original sources

arXiv2026

A converged architecture for processing 32 Tbps of physics data in real-time at the LHCb experiment

The LHCb detector at the Large Hadron Collider has been upgraded to acquire an unprecedented 32 Tbps of particle-collision data to provide new insights in the High Energy Physics domain. The data produced by the detector is filtered in real-time to select interesting collisions. As part of the upgrade, a pre-filtering stage has been removed leading to a factor 40 increase in data rate. To deal with the high throughput demands of LHCb real-time data processing, we present an off-the-shelf network architecture using zero-copy techniques in conjunction with an efficient, fully-GPU-based filter. Our converged architecture is able to process the full 32 Tbps of particle-collision data in real-time, the highest in any physics experiment to date. Our result extends the reach of the LHCb physics programme and sets a new standard for real-time data processing at particle physics experiments.

hep-ex↗

arXiv2025

The Timepix4 Beam Telescope

The spatial and temporal performance of a telescope system comprising planar silicon sensors bump-bonded to Timepix4-v2 ASICs are assessed at the CERN SPS using a $180$~GeV/$c$ mixed hadron beam. The pointing resolution at the centre of the telescope is $2.3 \pm 0.1\;\mathrm{\mu m}$ and $2.4 \pm 0.1\mathrm{\mu m}$ in x and y directions, respectively. The temporal resolution for the combined timestamps on a track using only the information from the Timepix4 planes is found to be $92 \pm 5$~ps. The telescope is extensively described including its data acquisition system and dedicated software as well as the corrections applied to the raw measurements.

hep-ex↗

arXiv2025

Techniques in high-speed imaging and X-ray micro-computed tomography for characterisation of iron ore fragmentation

Fragmentation and breakage of rocks is essential to iron ore mining and extraction. The breakage energy requirements and resulting ore particle size and mineral distributions are key to understanding and optimising mining and processing practices. This study combines high-speed and experimental X-ray micro-CT (micro-computed tomography) imaging with 3D image analyses to study the fragmentation of iron ore particles. Here a case study of a hematite-rich iron ore particle is used to illustrate the application and results produced by this imaging procedure. The particle was micro-CT scanned before a high-speed camera was used to image particle breakage in a custom drop weight test, capturing the dynamic processes of particle fracturing and subsequent fragmentation at a resolution of 50 microseconds. Fragments produced were collected, micro-CT scanned and analysed in three-dimension by particle shape, size, and volume.

physics.geo-ph↗

arXiv2022

Reconstruction of charged tracks with Timepix4 ASICs

The design of a detector system comprised of four silicon sensors bump-bonded to Timepix4 ASICs is described together with its data acquisition system, operational infrastructure, and dedicated software. The spatial and temporal performance of the system are assessed with a 180 GeV/c mixed hadron beam at the CERN SPS and reported in detail. Particle tracks are reconstructed using time-space measurements from the four detector planes. The spatial hit resolution is assessed to be $(15.5\pm 0.5)$ $\mu$m and $(4.5\pm0.3)$ $\mu$m for 100 and 300 $\mu$m thick sensors, respectively. The timestamps from the detectors are also measured with fine precision, yielding time resolutions of $(452\pm10)$ ps, $(420\pm10)$ ps, $(639\pm10)$ ps, $(631\pm10)$ ps for the two 100 and two 300 $\mu$m thick sensors respectively. These measurements are combined to a track time resolution of $(340\pm 5)$ ps.

physics.ins-det↗

arXiv2021

Comment on "Massive electrodynamics and the magnetic monopoles"

In this paper we correct previous work on magnetic charge plus a photon mass. We show that contrary to previous claims this system has a very simple, closed form solution which is the Dirac string potential multiplied by a exponential decaying part. Interesting features of this solution are discussed, namely, (i) the Dirac string becomes a real feature of the solution, (ii) the breaking of gauge symmetry via the photon mass leads to a breaking of the rotational symmetry of the monopole's magnetic field, (iii) the Dirac quantization condition is potentially altered.

hep-th↗

arXiv2019

Improved sensitivity to the CKM phase $\gamma$ through binning phase space in $B^- \to DK^-$, $D \to K^+\pi^-\pi^-\pi^+$ decays

A binning scheme is proposed for $D^0 \to K^+\pi^-\pi^-\pi^+ $ phase space that will improve the sensitivity of a $B^- \to DK^-$ analysis to the angle $\gamma$ of the Cabibbo-Kobayashi-Maskawa Unitarity Triangle. The scheme makes use of amplitude models recently reported by the LHCb collaboration. Assuming that a four-bin scheme optimised on the models retains a similar sensitivity when applied in data, it is estimated that the statistical uncertainty on $\gamma$ from the $B$-meson sample so far collected by the LHCb experiment will be as low as 5 degrees. This will be one of the most precise results available for any single decay mode in a $B^- \to D K^-$ measurement. Quantum-correlated $D\bar{D}$ data accumulated by the CLEO-c experiment are analysed to provide first constraints on the coherence factors and average strong-phase differences in the four bins, which are necessary inputs for the measurement. These constraints are compared with the predictions of the model, and consequences for the measurement of $\gamma$ are discussed.

hep-ex↗

arXiv2019

LHCb VELO Timepix3 Telescope

The LHCb VELO Timepix3 telescope is a silicon pixel tracking system constructed initially to evaluate the performance of LHCb VELO Upgrade prototypes. The telesope consists of eight hybrid pixel silicon sensor planes equipped with the Timepix3 ASIC. The planes provide excellent charge measurement, timestamping and spatial resolution and the system can function at high track rates. This paper describes the construction of the telescope and its data acquisition system and offline reconstruction software. A timing resolution of 350~ps was obtained for reconstructed tracks. A pointing resolution of better than 2~\mum was determined for the 180~GeV/c %\gevc mixed hadron beam at the CERN SPS. The telescope has been shown to operate at a rate of 5 million particles~\unit{s^{-1}\cdot cm^{-2}} without a loss in efficiency.

physics.ins-det↗

arXiv2018

How the network properties of shareholders vary with investor type and country

We construct two examples of shareholder networks in which shareholders are connected if they have shares in the same company. We do this for the shareholders in Turkish companies and we compare this against the network formed from the shareholdings in Dutch companies. We analyse the properties of these two networks in terms of the different types of shareholder. We create a suitable randomised version of these networks to enable us to find significant features in our networks. For that we find the roles played by different types of shareholder in these networks, and also show how these roles differ in the two countries we study.

q-fin.GN↗

arXiv2010

Uncovering space-independent communities in spatial networks

Many complex systems are organized in the form of a network embedded in space. Important examples include the physical Internet infrastucture, road networks, flight connections, brain functional networks and social networks. The effect of space on network topology has recently come under the spotlight because of the emergence of pervasive technologies based on geo-localization, which constantly fill databases with people's movements and thus reveal their trajectories and spatial behaviour. Extracting patterns and regularities from the resulting massive amount of human mobility data requires the development of appropriate tools for uncovering information in spatially-embedded networks. In contrast with most works that tend to apply standard network metrics to any type of network, we argue in this paper for a careful treatment of the constraints imposed by space on network topology. In particular, we focus on the problem of community detection and propose a modularity function adapted to spatial networks. We show that it is possible to factor out the effect of space in order to reveal more clearly hidden structural similarities between the nodes. Methods are tested on a large mobile phone network and computer-generated benchmarks where the effect of space has been incorporated.

physics.soc-ph↗