arXiv subjects

Luis A. Núñez

Publications and source records attributed to Luis A. Núñez.

At least 19 recordsLinked to original sources

arXiv2026

RACiMo: Red Ambiental Ciudadana de Monitoreo: A Student-Centred Citizen Science Network for Environmental Monitoring, Data Literacy, and Climate Awareness in Colombia

This paper traces the evolution of Red Ambiental Ciudadana de Monitoreo (RACiMo), a citizen-science and environmental-education initiative developed by Universidad Industrial de Santander in Colombia. RACiMo has evolved through successive editions from a school-based open-hardware programme into a regional environmental monitoring network that integrates meteorological and air-quality data, open-data practices, and student-centred research. The project's central objective is to train citizens, especially secondary-school students, teachers, and university mentors, to record, curate, analyse, interpret, and communicate climate and air-quality data relevant to their local contexts. RACiMo has involved approximately 515 students from urban, metropolitan, rural, and páramo communities in Santander, Colombia. It has progressed from Arduino-Raspberry Pi stations assembled through a Do-It-With-Others approach to low-maintenance commercial instruments and a multi-municipality network of professional weather and air-quality stations. Its pedagogy has shifted from learning by building sensors to learning by analysing real environmental datasets through Python, Jupyter notebooks, visualisation tools, and student-led research projects. The current RACiMo-Orquídeas implementation expands the network across five municipalities, emphasises local environmental issues such as freight traffic and industrial activity, and provides public access to data through repositories and interactive tools. The paper discusses the trade-offs between openness, educational value, reliability, data quality, sustainability, and scalability. It argues that citizen environmental monitoring can strengthen climate awareness and adaptation when local communities are trained not only to collect data, but also to understand and use it critically.

physics.soc-ph↗

arXiv2026

Latin American HECAP Physics Briefing Book 2025

The first process for the Latin American Strategy Forum for Research Infrastructure for High Energy, Cosmology and Astroparticle Physics (LASF4RI-HECAP) came to a conclusion in October 2020, with a Physics Briefing Book (PBB) presented in (2104.06852). Here we present an updated PBB, the result of the first update of LASF4RI-HECAP. The update process began with a call for White Papers from the HECAP community. The submitted contributions were presented at the III LASF4RI for HECAP Symposium: Update of the Strategic Plan, held at ICTP-SAIFR in São Paulo in August 26-29, 2024, with the participation of the Preparatory Group, High Level Strategy Group, Funding Agencies and representatives of similar efforts from around the globe. This updated PBB was written by the Preparatory Group based mainly on 46 White Papers submitted by the community and is organized around seven working groups: Astronomy, Astrophysics and Astroparticle Physics; Cosmology; Dark Matter; Neutrinos; Electroweak and Strong Interactions, Higgs Physics, CP and Flavour Physics and BSM; Instrumentation and Computing; Advanced Training and Capacity Building. It is intended to provide the essential input for the creation of a long-term HECAP strategy in the region.

hep-ex↗

arXiv2026

Water Cherenkov Detectors in Precision Agriculture: A Novel Approach for High-Resolution Soil Moisture Monitoring

Water Cherenkov Detectors (WCDs), traditionally employed in cosmic-ray detection, are repurposed here for precision soil moisture monitoring using cosmic-ray neutron sensing. This approach offers advantages over conventional neutron probes, including enhanced sensitivity to low moisture levels and the ability to cover larger soil volumes without subsurface intrusion. This study evaluates the feasibility of WCDs for agricultural neutron hydrometry, addressing challenges such as background suppression and data interpretation in heterogeneous soils. We present experimental results from controlled wet and dry soil-condition emulations, alongside Monte Carlo simulations using Geant4 with an atmospheric neutron spectrum to correlate signal variation with soil-moisture differences. By bridging particle physics and agronomy, WCDs could advance soil moisture monitoring, offering a non-invasive, scalable, and accurate alternative for optimizing agricultural water use. Preliminary findings suggest a transformative potential for sustainable farming, though further research is needed to enhance cost-efficiency and adaptability to diverse soil types.

hep-ex↗

arXiv2026

Two-Stage Gamma-Neutron Source Classification in Water Cherenkov Detectors: Energy Threshold Screening and Machine Learning Pulse Analysis

Water Cherenkov detectors offer a robust and economical solution for real-time radiation monitoring by detecting Cherenkov light from charged particles moving faster than light in water. This work presents a novel two-stage classification framework for gamma-neutron discrimination: an initial physics-based energy threshold filters unambiguous low-energy gamma sources, followed by a machine learning ensemble that resolves ambiguities at higher energies. The detector response was characterized using $^{60}$Co (1.17/1.33~MeV), $^{137}$Cs (0.66~MeV), and a shielded $^{241}$AmBe source, with lead, paraffin, and cadmium shielding employed to isolate neutron and gamma interactions. Energy calibration established a linear ADU to MeV conversion ($R^2 = 0.966$), enabling identification of a neutron detection threshold at $2.62 \pm 0.77$~MeV via a $3σ$ significance analysis. Stage one categorizes sources as pure gamma (below threshold) or neutron-emitting (at threshold). For ambiguous cases above threshold, a machine learning pipeline utilizing pulse shape analysis was developed. A soft voting ensemble (Bagging, CatBoost, and MLP) achieved an accuracy of 0.816 and an AUC of 0.921. This hybrid scheme combines physics-based filtering with ML refinement, offering an interpretable and scalable solution for nuclear security, nonproliferation monitoring, and fundamental radiation research.

physics.ins-det↗

arXiv2026

Driving Computational Efficiency in Large-Scale Platforms using HPC Technologies

The Latin American Giant Observatory (LAGO) project utilizes extensive High-Performance Computing (HPC) resources for complex astroparticle physics simulations, making resource efficiency critical for scientific productivity and sustainability. This article presents a detailed analysis focused on quantifying and improving HPC resource utilization efficiency specifically within the LAGO computational environment. The core objective is to understand how LAGO's distinct computational workloads-characterized by a prevalent coarse-grained, task-parallel execution model-consume resources in practice. To achieve this, we analyze historical job accounting data from the EGI FedCloud platform, identifying primary workload categories (Monte Carlo simulations, data processing, user analysis/testing) and evaluating their performance using key efficiency metrics (CPU utilization, walltime utilization, and I/O patterns). Our analysis reveals significant patterns, including high CPU efficiency within individual simulation tasks contrasted with the distorting impact of short test jobs on aggregate metrics. This work pinpoints specific inefficiencies and provides data-driven insights into LAGO's HPC usage. The findings directly inform recommendations for optimizing resource requests, refining workflow management strategies, and guiding future efforts to enhance computational throughput, ultimately maximizing the scientific return from LAGO's HPC investments.

cs.DC↗

arXiv2026

A Scientific Data Integrity system based on Blockchain

In most High Performance Computing (HPC) projects nowadays, there is a lot of data obtained from different sources, depending on the project's objectives. Some of that data is very huge in terms of size, so copying such data sometimes is an unrealistic goal. On the other hand, science requires data used for different purposes to remain unaltered, so different groups of researchers can reproduce results, discuss theories, and validate each other. In this paper, we present a novel approach to help research groups to validate data integrity on such distributed repositories using Blockchain. Originally developed for cryptographic currencies, Blockchain has demonstrated a versatile range of uses. Our proposal ensures 1) secure access to data management, 2) easy validation of data integrity, and 3) an easy way to add new records to the dataset with the same robust integrity policy. A prototype was developed and tested using a subset of a public dataset from a real scientific collaboration, the Latin American Giant Observatory (LAGO) Project.

cs.CR↗

arXiv2025

Enhanced water Cherenkov detector for soil moisture detection

This work evaluates the ability of a water Cherenkov detector to measure thermal neutrons and explores its application to soil-moisture monitoring. We study a NaCl-doped detector and model its response to (i) monochromatic thermal neutrons and (ii) the natural thermal-neutron flux expected from dry soil at the elevation of Bucaramanga, Colombia. The ambient flux is estimated with the ARTI framework, and the detector response is simulated with MEIGA in Geant4. Doping with NaCl introduces additional capture channels on $^{35,37}\mathrm{Cl}$ and $^{23}\mathrm{Na}$; in particular, $^{35}\mathrm{Cl}$ has a thermal-neutron absorption cross section up to two orders of magnitude larger than hydrogen, boosting the capture signal. Our results indicate that water Cherenkov detectors can detect thermal neutrons with practical sensitivity under field conditions, enabling their integration into precision agriculture networks for soil moisture sensing. More broadly, this approach extends the cosmic-ray detection range of Cherenkov detectors using non-toxic, low-cost materials.

physics.ins-det↗

arXiv2025

Relativisitic non-pascalian fluid as a density contribution

Understanding the role of pressure anisotropy and dissipation is crucial for modelling compact objects' internal structure and observable properties. In this work, we reinterpret local pressure anisotropy in relativistic stellar structures as an additional contribution to the energy density. This perspective enables the formulation of anisotropic equations of state for self-gravitating systems by incorporating anisotropy as a fundamental component. We demonstrate that this approach yields more realistic stellar models that satisfy key physical constraints, including mass-radius relationships and stability conditions. Our results are compared with observational data, particularly the inferred compactness of pulsars PSR J0740+6620 and PSR J0030+0451, showing that both anisotropic and isotropic models can describe these objects. Additionally, we examine the influence of dissipation -- such as temperature gradients -- on radial pressure, demonstrating that it can be modelled similarly to anisotropy. This interpretation allows the transformation of dissipative anisotropic models into equivalent non-dissipative isotropic configurations.

gr-qc↗

arXiv2023

The physical acceptability conditions and the strategies to obtain anisotropic compact objects

We studied five methods to include anisotropy, or unequal stress distributions, in general relativistic matter configurations. We used nine acceptability conditions that the metric and physical variables must meet to determine if our models were astrophysically viable. Our analysis found the most effective way to introduce anisotropy while keeping a simple density profile. We also found a practical "rule of thumb" that relates the density at the boundary to the density at the centre of relativistic matter distributions. Additionally, we calculated the configuration radius and encountered that values observed by NICER for PSR J0740+6620 are consistent with several acceptable matter configurations, both isotropic and anisotropic.

gr-qc↗

arXiv2022

The ARTI Framework: Cosmic Rays Atmospheric Background Simulations

ARTI is a complete framework designed to simulate the signals produced by the secondary particles emerging from the interaction of single, multiple and even, the complete flux of primary cosmic rays with the atmosphere. These signals are simulated for any particle detector located at any place (latitude, longitude and altitude), including the real-time atmospheric, geomagnetic and detector conditions. Formulated through a sequence of codes written in C++, Fortran, Bash and Perl, it provides an easy-to-use integration of three different simulation environments: magnetocosmic, CORSIKA and Geant4. These tools evaluate the geomagnetic field effects on the primary flux, the atmospheric showers of cosmic rays and the detectors' response to the secondary flux of particles. In this work, we exhibit the usage of the ARTI framework by calculating the total expected flux of signals at eight selected sites of the Latin American Giant Observatory, a cosmic ray Observatory located in Latin America covering a wide range altitudes, latitudes and geomagnetic rigidities. ARTI also calculates the flux of signals expected during the sudden occurrence of a gamma-ray burst or the flux of energetic photons originating in steady gamma sources. It also compares these fluxes with the expected background to detect these phenomena in a single water Cherenkov detector deployed in high altitude sites. Even more, by using ARTI, it is possible to calculate in a very precise way the expected flux of high energetic muons and other secondaries on the ground and to inject it over a geological structure for muography applications.

astro-ph.IM↗

arXiv2022

LA-CoNGA physics: an Open Science Collaboration in Advanced Physics between Latin-America and Europe

LA-CoNGA physics (for Latin-American alliance for Capacity buildiNG in Advance physics) is an ERASMUS+ project aiming to support the modernization of university infrastructure and its pedagogical offer in advanced physics in four Latin-American countries: Colombia, Ecuador, Perú and Venezuela. This project is co-funded by the Education, Audiovisual and Culture Executive Agency of the European Commission. This virtual teaching and research network comprises three partner universities in Europe and eight in Latin America; high-level scientific partners (CEA, CERN, CNRS, DESY, ICTP), and several and two industrial partners. During 2019 we prepared the syllabuses and selected the lecturers. In 2020 the strict lockdowns modified our pedagogical strategies. The planned model -- an eight-node network of universities made-up by local groups for discussions -- was transformed into low-quality home participation. We simplified the connectivity requirements to the minimum bandwidth to operate remote labs. We also changed the lecture interaction and evaluation model, balancing the teamwork on course projects and continuous evaluation based on class exercises. Despite the lockdown scenario, we managed to support the needs of our instrumentation and computing courses thanks to the contribution and enthusiasm of our partners. With the support of 30 instructors, we gave 100 lectures to 67 students in four countries. We are now promoting the second cohort due to start in January 2022

physics.ed-ph↗

arXiv2022

Acceptability Conditions and Relativistic Anisotropic Generalized Polytropes

This paper explored the physical acceptability conditions for anisotropic matter configurations in General Relativity. The study considered a generalized polytropic equation of state $P=κρ^γ+αρ-β$ for a heuristic anisotropy. We integrated the corresponding Lane-Emden equation for several hundred models and found the parameter-space portion ensuring the configurations' acceptability. Polytrope based on the total energy density are more stable than those with baryonic density, and small positive local anisotropies produce acceptable models. We also found that polytropic configurations where tangential pressures are greater than radial ones are also more acceptable. Finally, convective disturbances do not generate cracking instabilities. Several models emerging from our simulations could represent candidate of astrophysical compact objects.

gr-qc↗

arXiv2021

Impact of Global Data Assimilation System atmospheric models on astroparticle showers

We present a methodology to simulate the impact of the atmospheric models in the background particle flux on ground detectors using the Global Data Assimilation System. The methodology was within the ARTI simulation framework developed by the Latin American Giant Observatory Collaboration. The ground level secondary flux simulations were performed with a tropical climate at the city of Bucaramanga, Colombia. To validate our methodology, we built monthly profiles over Malargüe between 2006 and 2011, comparing the maximum atmospheric depth, X$_\mathrm{max}$, with those calculated with the Auger atmospheric option in CORSIKA. The results show significant differences between the predefined CORSIKA atmospheres and their corresponding Global Data Assimilation System atmospheric profiles.

astro-ph.IM↗

arXiv2021

Characterization of the muography background using the Muon Telescope (MuTe)

In this work, we estimate the background components in muography using the MuTe: a hybrid muon telescope composed of two subdetectors -a scintillator hodoscope and a Water Cherenkov Detector (WCD). The hodoscope records the trajectories of particles crossing the telescope, while the WCD measures their energy loss. The MuTe hodoscope reconstructs 3841 different directions with an angular resolution of 32 mrad for an inter-panel distance of 2.5 m. The spatial resolution can reach $\sim$25.6 m assuming an 800 m distance to the target. The WCD measures the deposited energy from 50 MeV to 1.5 GeV with a resolution of 0.72 MeV. MuTe discriminates muography background sources such as: upward coming muons, scattered muons, the soft component of Extensive Air Showers (EAS), and particles arriving simultaneously. They are filtered by using measurements of deposited energy (WCD) and Time-of-Flight. The WCD differentiates single muons, electrons/positrons, and multiparticle events. On the other hand, the ToF measurements allow us to estimate the muon momentum establishing an energy threshold to decrease the background contribution of scattered muons. Upward coming muons are rejected by means of the particle arrival direction determined by the ToF sign. We concluded that near 36% of the recorded events belong to the electromagnetic component (electrons and positrons), roughly 30.4% is caused by multiple particle events that arrive with time differences < 100 ns and the last 34% are caused by muons. The muonic soft component (< 1 GeV/c) represents 46% of the single-muon events. The upward going particles add up the 22% of the total flux crossing the MuTe.

hep-ex↗

arXiv2020

Acceptability Conditions and Relativistic Barotropic Equations of State

We sketch an algorithm to generate exact anisotropic solutions starting from a barotropic EoS and setting an ansatz on the metric functions. To illustrate the method, we use a generalization of the polytropic equation of state consisting of a combination of a polytrope plus a linear term. Based on this generalization, we develop two models which are not deprived of physical meaning as well as fulfilling the stringent criteria of physical acceptability conditions. We also show that some relativistic anisotropic polytropic models may have singular tangential sound velocity for polytropic indexes greater than one. This happens in anisotropic matter configurations when the polytropic equation of state is implemented together with an ansatz on the metric functions. The generalized polytropic equation of state is free from this pathology in the tangential sound velocity.

gr-qc↗

arXiv2019

Calibration and first measurements of MuTe: a hybrid Muon Telescope for geological structures

In this work, we describe the calibration and first measurements in the commissioning of MuTe, a hybrid Muon Telescope with two subdetectors --a scintillator hodoscope and a Water Cherenkov Detector (WCD)-- for imaging the inner structures of Colombian volcanoes. The hodoscope estimates the trajectories of particles impinging on the front and rear panel, while the WCD acts as a calorimeter for the through going charged particle. MuTe combines particle identification techniques so as to discriminate noise background from data. It filters the primary noise sources for muography, i.e., the EM-component ($e^{\pm}$) of Extensive Air Showers (EAS) and scattered/upward-coming muons. The WCD identifies Electrons/positrons events by their deposited energy identifies, while scattered and backward muons are rejected using a pico-second Time-of-Flight(ToF) system. Muon generated events were found in the deposited energy deposited range of ($144$MeV$ < E_d <$ 400MeV), represent only about the 40$\%$ of the WCD-hodoscope acquired events. The other 60$\%$ of data is composed by ($e^{\pm}$) events under 144 MeV and multiparticle events above 400 MeV. Subsequently, low-momentum muons ($<$ 1 GeV/c), which are scattered by the volcano surface, measures a ToF $>$ 3.3 ns for traversing one meter length.

physics.ins-det↗

arXiv2018

Convection and cracking stability of spheres in General Relativity

In the present paper we consider convection and cracking instabilities as well as their interplay. We develop a simple criterion to identify equations of state unstable to convection, and explore the influence of buoyancy on cracking (or overturning) for isotropic and anisotropic relativistic spheres. We show that a density profile $ρ(r)$, monotonous, decreasing and concave , i.e. $ρ' < 0$ and $ρ'' < 0$, will be stable against convection, if the radial sound velocity monotonically decreases outward. We also studied the cracking instability scenarios and found that isotropic models can be unstable, when the reaction of the pressure gradient is neglected, i.e. $δ\mathcal{R}_p = 0$; but if it is considered, the instabilities may vanish and this result is valid, for both isotropic and anisotropic matter distributions.

gr-qc↗

arXiv2018

Results from The Latin American Giant Observatory Space Weather Simulation Chain

The Space Weather program of the Latin American Giant Observatory (LAGO) Collaboration was designed to study the variation of the flux of atmospheric secondary particles at ground level produced during the interaction of cosmic rays with the air. This work complements and expands the inference capabilities of the LAGO detection network to identify the influence of solar activity on the particle flux, at places having different geomagnetic rigidity cut-offs and atmospheric depths. This program is developed through a series of Monte Carlo sequential simulations to compute the intensity spectrum of the various components of the radiation field on the ground. A key feature of these calculations is that we performed detailed radiation transport computations as a function of incident direction, time, altitude, as well as latitude and longitude. Magnetic rigidity calculations and corrections for geomagnetic field activity are established by using the MAGNETOCOSMICS code, and the estimation of the flux of secondaries at ground level is implemented by using the CORSIKA code; thus we can examine the local peculiarities in the penumbral regions with a more realistic description of the atmospheric and geomagnetic response in these complex regions of the rigidity space. As an example of our calculation scheme, we report some result on the flux at ground level for two LAGO locations: Bucaramanga-Colombia and San Carlos de Bariloche-Argentina, for the geomagnetically active period of May 2005.

physics.geo-ph↗