Astroparticle Physics Research Articles

Cp3-bench: a tool for benchmarking symbolic regression algorithms demonstrated with cosmology

We introduce cp3-bench, a tool for comparing/benching symbolic regression algorithms, which we make publicly available at https://github.com/CP3-Origins/cp3-bench. In its current format, cp3-bench includes 12 different symbolic regression algorithms which can be automatically installed as part of cp3-bench. The philosophy behind cp3-bench is that is should be as user-friendly as possible, available in a ready-to-use format, and allow for easy additions of new algorithms and datasets. Our hope is that users of symbolic regression algorithms can use cp3-bench to easily install and compare/bench an array of symbolic regression algorithms to better decide which algorithms to use for their specific tasks at hand.To introduce and motivate the use of cp3-bench we present a small benchmark of 12 symbolic regression algorithms applied to 28 datasets representing six different cosmological and astroparticle physics setups. Overall, we find that most of the benched algorithms do rather poorly in the benchmark and suggest possible ways to proceed with developing algorithms that will be better at identifying ground truth expressions for cosmological and astroparticle physics datasets. Our demonstration benchmark specifically studies the significance of dimensionality of the feature space and precision of datasets. We find both to be highly important for symbolic regression tasks to be successful. On the other hand, we find no indication that inter-dependence of features in datasets is particularly important, meaning that it is not in general a hindrance for symbolic regression algorithms if datasets e.g. contain both z and H(z) as features. Lastly, we note that we find no indication that performance of algorithms on standardized datasets are good indicators of performance on particular cosmological and astrophysical datasets. This suggests that it is not necessarily prudent to choose symbolic regression algorithms based on their performance on standardized data. Instead, a more robust approach is to consider a variety of algorithms, chosen based on the particular task at hand that one wishes to apply symbolic regression to.

EDITORIAL FOREWORD

New Trends in High-Energy Physics is a series of conferences initiated by the Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine in 1992. It is focused on topical problems in experiment, phenomenology and theory of particle, nuclear and astroparticle physics. The conferences were held yearly or biannually at various sites in Ukraine and abroad, namely in Kyiv, Alushta, Yalta, Novy Svit, Odesa (Ukraine), Sukhumi (Georgia), Budva/Beˇci´ci (Montenegro), and Natal (Brazil).

A Promising Approach for Determining Neutrino Mass Hierarchy by Using Supernova Neutrino Detections

The determination of neutrino mass hierarchy is crucial for particle physics, astrophysics, and cosmology. In this work, we propose an easy-to-use method to determine the neutrino hierarchy based on core-collapse supernova (CCSN) neutrino detections. By analyzing the expected event rates of the neutrino burst at a terrestrial water Cherenkov detector, we found that the event rates predicted by the normal and inverted hierarchy models have marked differences in the neutrino energy range 10 ∼ 20 MeV and the postbounce time <0.5 s. Within this specific energy and time range, the analytical relationship between the cumulative event number and proto–neutron star (PNS) baryon mass is extracted. Based on the normal and inverted hierarchy models, two different PNS masses can be inferred from this relationship by using the time profile of neutrino events. Then, the neutrino hierarchy can be determined by comparing the PNS mass inferred from the neutrino detections and the electromagnetic or gravitational-wave channels. Furthermore, the nonadiabatic part of the Mikheyev–Smirnov–Wolfenstein flavor conversions may also be quantified with this method, which would be very helpful for the studies of the explosion mechanism and nucleosynthesis of CCSNe.

Particle identification in high-granularity 3D calorimeters for space-borne applications

High granularity 3D calorimeters offer the potential to precisely reconstruct the 3D topology of electromagnetic and hadronic showers originating from isotropic sources. This distinctive capability creates the opportunity for applying reconstruction and analysis methods that could yield additional information compared to those based on the traditional layer-by-layer energy deposit analysis common in particle and astroparticle physics experiments utilizing calorimeters with layer segmentation. In this study, we present a strategy for analyzing the energy deposit in a crystal array calorimeter, utilizing the 3D parametrization of both longitudinal and transversal shapes of showers to implement likelihood tests on single events. While this analysis was developed using the High Energy cosmic Radiation Detector (HERD) calorimeter as a case study, its applicability may extend to any high granularity, homogeneous, isotropic calorimeter employed in particle physics experiments.

High-density gas target at the LHCb experiment

The recently installed internal gas target at LHCb presents exceptional opportunities for an extensive physics program for heavy-ion, hadron, spin, and astroparticle physics. A storage cell placed in the LHC primary vacuum, an advanced Gas Feed System, the availability of multi-TeV proton and ion beams, and the recent upgrade of the LHCb detector make this project unique worldwide. In this paper, we outline the main components of the system, the physics prospects it offers, and the hardware challenges encountered during its implementation. The commissioning phase has yielded promising results, demonstrating that fixed-target collisions can occur concurrently with the collider mode without compromising efficient data acquisition and high-quality reconstruction of beam-gas and beam-beam interactions. Published by the American Physical Society 2024

Unexpected planetary relationship as the new signature in Astro-particle physics

Unexpected planetary relationship as the new signature in Astro-particle physics

Preface— New Trends in Cosmology, Particle Physics and Astrophysics: Selected Papers from the 6th International Conference on Particle Physics and Astrophysics (ICPPA2022)

The preface to the special issue of Int. J. Mod. Phys. D “New trends in Cosmology, Particle Physics and Astrophysics” briefly reviews some new ideas in the development of Modern Astrophysics, Cosmology, Particle and Astroparticle Physics inspired by discussions at the Sixth International Conference on Particle Physics and Astrophysics (ICPPA2022).

Frontier 23: elementary particle physics, dark matter and astroparticle physics

Frontier 23: elementary particle physics, dark matter and astroparticle physics

Expression of concern“On the same origin of quantum physics and general relativity from Riemannian geometry and Planck scale formalism” Astroparticle Physics, Volume 164, 103036.

Expression of concern“On the same origin of quantum physics and general relativity from Riemannian geometry and Planck scale formalism” Astroparticle Physics, Volume 164, 103036.

Dimensional Analysis in General Theory of Relativity

Use of natural unit is utmost important for research in high energy physics, particularly in the fields of ‘Elementary Particle Physics’, ‘Astro-particle Physics’ and `Physical Cosmology', because all the parameters turn out to be dimensionless. However, it is suggestive to work in a system of units, in which all the kinematical parameters may be expressed in terms of different powers of the Planck's mass or equivalently the energy. Here we explicitly exhibit the use of the natural units, some associated problems and also the proposed system of units in connection with their application in ‘General Theory of Relativity

Solar flare observations with the Radio Neutrino Observatory Greenland (RNO-G)

The Radio Neutrino Observatory – Greenland (RNO-G) seeks discovery of ultra-high energy neutrinos from the cosmos through their interactions in ice. The science program extends beyond particle astrophysics to include radioglaciology and, as we show herein, solar observations, as well. Currently seven of 35 planned radio-receiver stations (24 antennas/station) are operational. These stations are sensitive to impulsive radio signals with frequencies between 80 and 700 MHz and feature a neutrino trigger threshold for recording data close to the thermal floor. RNO-G can also trigger on elevated signals from the Sun, resulting in nanosecond resolution time-domain flare data; such temporal resolution is significantly shorter than from most dedicated solar observatories. In addition to possible RNO-G solar flare polarization measurements, the Sun also represents an extremely useful above-surface calibration source.Using RNO-G data recorded during the summers of 2022 and 2023, we find signal excesses during solar flares reported by the solar-observing Callisto network and also in coincidence with ∼2/3 of the brightest excesses recorded by the SWAVES satellite. These observed flares are characterized by significant time-domain impulsivity. Using the known position of the Sun, the flare sample is used to calibrate the RNO-G absolute pointing on the radio signal arrival direction to sub-degree resolution. We thus establish the Sun as a regularly observed astronomical calibration source to provide the accurate absolute pointing required for neutrino astronomy.

The DUNE Far Detector Vertical Drift Technology. Technical Design Report

DUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including themystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on a near and a far detector as it aims to determine the neutrino mass hierarchy and to make high-precision measurements of the PMNS matrix parameters, including the CP-violating phase. It will also stand ready to observe supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model.The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines the many tens-of-kiloton fiducial mass necessary for rare event searches with the sub-centimeter spatial resolutionrequired to image those events with high precision. The addition of a photon detection system enhances physics capabilities for all DUNE physics drivers and opens prospects for further physics explorations. Given its size, the far detector will be implemented as a set of modules, with LArTPC designs that differ from one another as newer technologies arise.In the vertical drift LArTPC design, a horizontal cathode bisects the detector, creating two stacked drift volumes in which ionization charges drift towards anodes at either the top or bottom. The anodes are composed of perforated PCB layers with conductive strips, enabling reconstruction in 3D.Light-trap-style photon detection modules are placed both on the cryostat's side walls and on the central cathode where they are optically powered.This Technical Design Report describes in detail the technical implementations of each subsystem of this LArTPC that, together with the other far detector modules and the near detector, will enable DUNE to achieve its physics goals.

First Scan Search for Dark Photon Dark Matter with a Tunable Superconducting Radio-Frequency Cavity.

Dark photons have emerged as promising candidates for dark matter, and their search is a top priority in particle physics, astrophysics, and cosmology. We report the first use of a tunable niobium superconducting radio-frequency cavity for a scan search of dark photon dark matter with innovative data analysis techniques. We mechanically adjusted the resonant frequency of a cavity submerged in liquid helium at a temperature of 2K, and scanned the dark photon mass over a frequency range of 1.37MHz centered at 1.3GHz. Our study leveraged the superconducting radio-frequency cavity's remarkably high quality factors of approximately 10^{10}, resulting in the most stringent constraints to date on a substantial portion of the exclusion parameter space on the kinetic mixing coefficient ε between dark photons and electromagnetic photons, yielding a value of ε<2.2×10^{-16}.

SiPMs and examples of applications for low light detection in particle and astroparticle physics

SiPMs and examples of applications for low light detection in particle and astroparticle physics

A closer look at the electromagnetic signatures of Bethe-Heitler pair production process in blazars

The “twin birth” of a positron and an electron by a photon in the presence of a nucleus, known as Bethe-Heitler pair production, is a key process in astroparticle physics. The Bethe-Heitler process offers a way of channeling energy stored in a population of relativistic protons (or nuclei) to relativistic pairs with extended distributions. Contrary to accelerated leptons, whose maximum energy is limited by radiative losses, the maximal energy of pairs is determined by the kinematics of the process and can be as high as the parent proton energy. We take a closer look at the features of the injected pair distribution, and provide a novel empirical function that describes the spectrum of pairs produced by interactions of single-energy protons with single-energy photons. The function is the kernel of the Bethe-Heitler pair production spectrum that replaces a double numerical integration involving the complex differential cross section of the process, and can be easily implemented in numerical codes. We further examine under which conditions Bethe-Heitler pairs produced in blazar jets can emit γ-ray photons via synchrotron radiation, thus providing an alternative to the inverse Compton scattering process for high-energy emission in jetted active galactic nuclei. For this purpose, we create 36 numerical models using the code ATHEνA optimized so that the Bethe-Heitler synchrotron emission dominates their γ-ray emission. After taking into consideration the broadband spectral characteristics of the source, the jet energetics, and the properties of radiation fields present in the blazar environment, we conclude that γ-rays in high-synchrotron-peaked blazars are unlikely to be produced by Bethe-Heitler pairs, because the emitting region is found to be opaque in photon-photon pair production at photon energies ≳ 10 GeV. On the contrary, γ-ray spectra of low-synchrotron-peaked blazars may arise from Bethe-Heitler pairs in regions of the jet with typical transverse size ∼ 1015 – 1016 cm and co-moving magnetic field 50 – 500 G. For such cases, an external thermal target photon field with temperatures T ∼ 4 · 102– 6 · 103 K is needed. The latter values could point to the dusty torus of the AGN. Interestingly, a Bethe-Heitler-dominated high-energy component is mostly found in models of intermediate-synchrotron peaked blazars, for a wide range of magnetic fields and source radii.

Improvements in charged lepton and photon propagation for the software PROPOSAL

Accurate particle simulations are essential for the next generation of experiments in astroparticle physics. The Monte Carlo simulation library PROPOSAL is a flexible tool to efficiently propagate high-energy leptons and photons through large volumes of media, for example in the context of underground observatories. It is written as a C++ library, including a Python interface. In this paper, the most recent updates of PROPOSAL are described, including the addition of electron, positron, and photon propagation, for which new interaction types have been implemented. This allows the usage of PROPOSAL to simulate electromagnetic particle cascades, for example in the context of air shower simulations. The precision of the propagation has been improved by including rare interaction processes, new photonuclear parametrizations, deflections in stochastic interactions, and the possibility of propagating in inhomogeneous density distributions. Additional technical improvements regarding the interpolation routine and the propagation algorithm are described. New version program summaryProgram Title: PROPOSAL.CPC Library link to program files:https://doi.org/10.17632/g478pjdcxy.2.Developer's repository link:https://github.com/tudo-astroparticlephysics/PROPOSAL.Licensing provisions: LGPL.Programming language: C++, Python.Journal reference of previous version: Comput. Phys. Commun. 242 (2019) 132.Does the new version supersede the previous version?: Yes.Reasons for the new version: Substantial addition of features. Various bugfixes.Summary of revisions: The library now also treats photons and has the corresponding processes implemented. New parametrizations for photonuclear interaction have been implemented. The angular deflection in stochastic energy losses has been implemented in addition to the already existing multiple scattering implementation, which has been improved to reduce the runtime. The implementation of the Landau-Pomeranchuk-Migdal effect has been corrected. The propagation algorithm has been improved, including the support of inhomogeneous density distributions.Nature of problem: Three-dimensional propagation of charged leptons and photons through different media. Particles lose energy stochastically by ionization, bremsstrahlung, pair production, and photonuclear interaction for charged leptons (including annihilation with atomic electrons for positrons) and Compton scattering, pair production, photoelectric effect and photohadronic interaction for photons. Additionally, they are deflected while propagating through the medium due to both multiple elastic Coulomb scattering as well as deflections in individual stochastic interactions. Unstable particles eventually decay, producing secondary particles.Solution method: Monte-Carlo simulation. The library samples the next interaction point, the type of interaction process, the energy lost in this interaction process, and the energy lost until this point. Particles are propagated until they decay, lose all their kinetic energy (for photons: reach a lower energy limit defined by the validity of the underlying cross sections), or until a user-defined termination criterion is reached. For each propagation step, the angular deflection and endpoint shift due to multiple scattering is calculated.To improve the performance and deal with the divergence of the bremsstrahlung cross section for small photon energies, energy losses below a predefined relative or absolute energy threshold are treated continuously. The computation time is improved by the use of interpolation tables.

Editorial to the Special Issue: “Recent Advances in Gamma Ray Astrophysics and Future Perspectives”

This Special Issue is a collection of reviews highlighting the recent progress in the very vast and closely related fields of γ-ray astrophysics and astro-particle physics in recent years, looking toward a very promising future [...]

An enormous increase in atmospheric positron flux during a summer thunderstorm on Mount Aragats

On July 11, 2023, we observed a remarkable 500% increase in positron flux, coinciding with a significant Thunderstorm Ground Enhancement (TGE). The enhanced flux of electrons and gamma rays was attributed to relativistic runaway electron avalanches (RREAs) generated within the dipole formed between the main negatively charged layer in the middle of the thundercloud and the Lower Positively Charged Region (LPCR) at the bottom of the thundercloud. Concurrently, a substantial enhancement in the 511 keV gamma-ray flux resulting from electron-positron annihilation was recorded. This surge is intricately linked to the LPCR within the thundercloud. The emergence of the LPCR induces a polarity change in the atmospheric electric field (AEF) below the LPCR (fourth dipole), leading to the deceleration of electrons and the acceleration of positrons.Particle flux measurements were conducted using scintillation and NaI(TL) spectrometers. To mitigate the contamination of natural gamma radiation and refine the 511 keV flux measurements, the ORTEC spectrometer was shielded with a 4 cm thick lead filter. CORSIKA simulations corroborate the observed positron flux enhancement.Highlighting the synergy between high-energy physics in the atmosphere and astroparticle physics, we introduce a new scenario to elucidate the enigmatic large flux of galactic positrons measured by the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station (ISS).

New dark matter analysis of milky way dwarf satellite galaxies with madhatv2

We obtain bounds on dark matter annihilation using 14 years of publicly available Fermi-LAT data from a set of 54 dwarf spheroidal galaxies, using spectral information from 16 energy bins. We perform this analysis using our updated and publicly available code , which can be used to test a variety of models for dark matter particle physics and astrophysics in an accessible manner. In particular, we note that including Carina III in the analysis strengthens constraints on s-wave annihilation into two-body Standard Model final states by a factor of ∼3 but broadens the error on the constraint due to the large uncertainty of its J-factor. Our findings illustrate the importance of verifying if Carina III is in fact a dwarf spheroidal galaxy and measuring more precisely its J-factor. More generally, they highlight the significance of forthcoming discoveries of nearby ultrafaint dwarfs for dark matter indirect detection. Published by the American Physical Society 2024

LUX, ZEPLIN and LUX-ZEPLIN: Developments in liquid xenon detectors and the search for WIMP dark matter

The search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs) remains one of the enduring scientific and technical challenges in physics despite four decades of research. A discovery would have broad implications for particle physics, astrophysics, and cosmology. Over the last 15 years, liquid xenon time projection chambers have been on the forefront of this search, starting with detector masses on the 10-kg scale and now reaching the 10-tonne scale. Advances in a number of technical areas across xenon-detector collaborations worldwide, along with progress in related techniques in low-background and liquid noble detectors, have led to significant and steady improvements in sensitivity. In this contribution to Nobel Symposium 182, I highlight several of the contributions made by the LUX, ZEPLIN, and LUX-ZEPLIN (LZ) collaborations, and members thereof. I also discuss briefly the status of the currently-operating and world-leading LZ experiment.