Shower Energy Research Articles

Study of cosmic rays with energies above 5 EeV using radio method

At the Yakutsk array in 1986 regular measurements of radio emission produced by relativistic air shower particles were started. After monitoring of background noise in the array area frequency of 30–35 MHz was chosen, since noise level is minimal in this frequency range. During this time, air showers with highest energies of 100 EeV were registered. By using hybrid measurements of charged particles, Cherenkov light and radio emission it was shown that signal amplitude proportional to air shower energy and shape of lateral distribution at sea level correlates with the depth of maximum development. Using the obtained characteristics, atomic weight of primary particles that generated air shower was estimated within QGSjetII-04 framework simulation.

Study of time resolution measurements and prospects for energy resolution of an ultra-compact sampling calorimeter (RADiCAL) module at EM shower maximum over the energy range 25 GeV 150 GeV

The RADiCAL Collaboration is conducting R&D on high performance electromagnetic (EM) calorimetry to address the challenges expected in future collider experiments under conditions of high luminosity and/or high irradiation (FCC-ee, FCC-hh, fixed target and forward physics environments). Under development is a sampling calorimeter approach, known as RADiCAL modules, based on scintillation, wavelength-shifting (WLS) technologies and photosensor, including SiPM or SiPM-like technology. The modules discussed herein consist of alternating layers of very dense tungsten (W) absorber and scintillating crystal Lutetium Yttrium Orthosilicate LYSO(Ce) plates, assembled to a depth of 25 X0. The scintillation signals produced by the EM showers in the region of EM shower maximum (shower max) are transmitted to SiPM located at the upstream/downstream ends of the modules via quartz capillaries which penetrate the full length of the module. The capillaries contain DSB1 organic plastic WLS filaments positioned within the region of shower max, where the shower energy deposition is greatest, then fused with quartz rod elsewhere. The wavelength shifted light from this spatially-localized shower max region is then propagated to the photosensors. This paper presents the results of an initial measurement of the time resolution of a RADiCAL module over the energy range 25 GeV ≤ E ≤ 150 GeV using the H2 electron beam at CERN. The data indicate an energy dependence of the time resolution that follows the functional form: σt=a/E⊕b, where a = 256 GeV ps and b = 17.5 ps. The time resolution measured at the highest electron beam energy for which data was currently recorded (150 GeV) was found to be σt = 27 ps.

The RPC in the astroparticle physics of the next future

Following the brilliant results of the ARGO-YBJ experiment (Tibet, 4300 m asl), this paper intends to investigate how to optimize the potential of Resistive Plate Chambers (RPCs) for detecting cosmic-ray showers. This requires improving parameters like construction simplicity, low cost, and working reliability in hostile environments, rather than high-rate capability and time resolution as required in collider experiments. RPCs are particularly suitable for the detection of very low energy showers, as shown by ARGO-YBJ. An example of RPC detector, conceived for cosmic-ray physics and gamma-ray astronomy, particularly Gamma Ray Burst (GRB) observation, will be shown. This is of great interest in view of a large-size cosmic-shower detector to be installed in the Southern hemisphere.

Complementarities in behavioral interventions: Evidence from a field experiment on resource conservation

Behavioral policy often aims at influencing behavior by mitigating biases due to, e.g., imperfect information or inattention. We study how this is affected by the simultaneous presence of multiple biases arising from different sources, through a field experiment on resource conservation in an energy- and water-intensive everyday activity (showering). One intervention, shower energy reports, primarily targeted knowledge about environmental impacts; another intervention, real-time feedback, primarily targeted salience of resource use. We find a striking complementarity. While only the latter induced significant conservation effects when implemented in isolation, each intervention became more effective when implemented jointly. This is consistent with predictions from a theoretical framework that highlights the importance of targeting all relevant sources of bias to achieve behavioral change.

The first test of a monolithic silicon pixel detector ASIC for the detection of electromagnetic showers of TeV energy in the FASER experiment at the LHC

The FASER experiment at the LHC is designed to look for new, long-lived fundamental particles. A W-Si preshower detector is currently under construction, with the objective of enabling the discrimination of photon pairs with O(TeV) energies and separation down to 200 μm, extending the discovery potential of the experiment. The detector will be based on a new monolithic silicon pixel sensor in 130 nm SiGe BiCMOS. The first test of the ASIC from a pre-production run shows that the building blocks of the monolithic silicon pixel detector are functional.

Measuring the attenuation length of muon number in the air shower with muon detectors of 3/4 LHAASO array

LHAASO KM2A consists of 5915 scintillation detectors and 1188 muon detectors, and the muon detectors cover 4% area of the whole array with 30 m interdetector spacing. The muon number in air shower events, with very high energy, is investigated with the data recorded by muon detector of the 3/4 LHAASO array in 2021. The attenuation length of muon number in the air shower is measured by fitting the muon number with constant flux in various zenith angles, based on the constant intensity cut method. The variation of the attenuation length as shower energy from hundreds TeV to tens PeV is presented. The results of simulation also is presented for comparing.

The full coverage approach to the detection of Extensive Air Showers

A shower array exploiting the full coverage approach with a high segmentation of the readout allow to image the front of atmospheric showers with unprecedented resolution and detail. The grid distance determines the energy threshold (small energy showers are lost in the gap between detectors) and the quality of the shower sampling. Therefore, this experimental solution is needed to detect showers with a threshold in the 100 GeV range. The full coverage approach has been exploited in the ARGO-YBJ experiment. In this contribution we will summarise the advantages of this technique and discuss possible applications in new wide field of view detectors.

Performance and systematic uncertainties of CTA-North in conditions of reduced atmospheric transmission

The Cherenkov Telescope Array (CTA) is the next-generation stereoscopic system of Imaging Atmospheric Cherenkov Telescopes (IACTs). In IACTs, the atmosphere is used as a calorimeter to measure the energy of extensive air showers induced by cosmic gamma rays, which brings along a series of constraints on the precision to which energy can be reconstructed. The presence of clouds during observations can severely affect Cherenkov light yield, contributing to the systematic uncertainty in energy scale calibration. To minimize these systematic uncertainties, a calibration of telescopes is of great importance. For this purpose, the influence of cloud transmission and altitude on CTA-N performance degradation was investigated using detailed Monte Carlo simulations for the case where no action is taken to correct for the effects of clouds. Variations of instrument response functions in the presence of clouds are presented. In the presence of clouds with low transmission (≤ 80%) the energy resolution is aggravated by 30% at energies below 1 TeV, and by 10% at higher energies. For higher transmissions, the energy resolution is worse by less than 10% in the whole energy range. The angular resolution varies up to 10% depending both on the transmission and altitude of the cloud. The sensitivity of the array is most severely reduced at lower energies, even by 60% at 40 GeV, depending on the clouds' properties. A simple semi-analytical model of sensitivity degradation has been introduced to summarize the influence of clouds on sensitivity and provide useful scaling relations.

The High-Altitude Water Cherenkov (HAWC) observatory in México: The primary detector

The High-Altitude Water Cherenkov (HAWC) observatory is a second-generation continuously operated, wide field-of-view, TeV gamma-ray observatory. The HAWC observatory and its analysis techniques build on experience of the Milagro experiment in using ground-based water Cherenkov detectors for gamma-ray astronomy. HAWC is located on the Sierra Negra volcano in México at an elevation of 4100 meters above sea level. The completed HAWC observatory principal detector (HAWC) consists of 300 closely spaced water Cherenkov detectors, each equipped with four photomultiplier tubes to provide timing and charge information to reconstruct the extensive air shower energy and arrival direction. The HAWC observatory has been optimized to observe transient and steady emission from sources of gamma rays within an energy range from several hundred GeV to several hundred TeV. However, most of the air showers detected are initiated by cosmic rays, allowing studies of cosmic rays also to be performed. This paper describes the characteristics of the HAWC main array and its hardware.

Beam test results of Secondary Emission Ionization Calorimetry modules at Fermilab

Increasing the collision energy and the luminosity at particle colliders requires high radiation resistance in GigaRad levels and fast-timing detectors in picosecond levels. Secondary Emission (SE) Ionization Calorimetry, a novel technology to measure the energy of electromagnetic showers and hadronic particles in extreme radiation circumstances, is such a detector. In this study, the bias circuits of Hamamatsu single anode R7761 and multi-anode R5900-00-M16 Photomultiplier Tubes (PMTs) were modified for use as novel calorimeter sensors in different SE modules. The test beam was provided by Fermi National Accelerator Laboratory, and these new sensor modules were tested with high-energy protons and shower particles at the Fermilab Test Beam Facility (FTBF). The test results showed that the SE modules are sensitive to the electromagnetic showers and they are a promising technology. Here we discuss the design, characterization tests and the beam tests of SE sensor modules, and the projections for a full-scale calorimeter.

Performance of the electromagnetic pixel calorimeter prototype Epical-2

The first evaluation of an ultra-high granularity digital electromagnetic calorimeter prototype using 1.0–5.8 GeV/c electrons is presented. The 25 × 106 pixel detector consists of 24 layers of ALPIDE CMOS MAPS sensors, with a pitch of around 30 μm, and has a depth of almost 20 radiation lengths of tungsten absorber. Ultra-thin cables allow for a very compact design. The properties that are critical for physics studies are measured: electromagnetic shower response, energy resolution and linearity. The stochastic energy resolution is comparable with the state-of-the art resolution for a Si-W calorimeter, with data described well by a simulation model using Geant4 and Allpix2. The performance achieved makes this technology a good candidate for use in the ALICE FoCal upgrade, and in general demonstrates the strong potential for future applications in high-energy physics.

Signal model and event reconstruction for the radio detection of inclined air showers

The detection of inclined air showers (zenith angles θ ≳ 65°) with kilometer-spaced radio-antenna arrays allows measuring cosmic rays at ultra-high energies (E ≲ 1020 eV). Radio and particle detector arrays provide independent measurements of the electromagnetic and muonic shower components of inclined air showers, respectively. Combined, these measurements have a large sensitivity to discriminate between air showers initiated by lighter and heavier cosmic rays. We have developed a precise model of the two-dimensional, highly complex and asymmetric lateral radio-signal distributions of inclined air shower at ground — the “radio-emission footprints”. Our model explicitly describes the dominant geomagnetic emission with a rotationally symmetric lateral distribution function, on top of which additional effects disturb the symmetry. The asymmetries are associated with the interference between the geomagnetic and sub-dominant charge-excess emission as well as with geometrical projection effects, so-called “early-late” effects. Our fully analytic model describes the entire footprint with only two observables: the geometrical distance between the shower impact point at the ground and the shower maximum d max, and the geomagnetic radiation energy E geo. We demonstrate that with this model, the electromagnetic shower energy can be reconstructed by kilometer-spaced antenna arrays with an intrinsic resolution of 5% and a negligible bias.

Search for upward-going showers with the Pierre Auger Observatory

Motivated by the ANITA report of pulses compatible with upward-going extensive air showers, we present a recent search for such showers using the Pierre Auger Observatory. The dataset, registered using the fluorescence detector of the Observatory, is scanned to identify showers ascending from the ground. Consistent with the exit angles reported from the first and third ANITA flights, we focus on shower geometries that are incompatible with Standard Model interactions of neutrinos in the Earth. We present the effective area of the Observatory to generic upward-going showers as a function of shower energy and altitude. This can be used to constrain predictions based on physics beyond Standard Model and the upgoing-shower interpretation of the ANITA results. To demonstrate the method, we calculate limits to the production rate of tau leptons near the ground emerging under a range of exit angles.

Design and optimization of the CEPC scintillator hadronic calorimeter

The Circular Electron Positron Collider (CEPC) is a next-generation electron–positron collider proposed for precision measurement of the properties of the Higgs boson. A major challenge for the CEPC detector is achieving a boson mass resolution (BMR) of 4%, which is required to separate the Higgs, Z, and W bosons in their hadronic decays. The baseline design of the CEPC detector was guided by the particle flow algorithm (PFA) concept to satisfy the BMR requirements. The BMR performance obtained by the PFA approach is primarily determined by the shower separation capability and energy resolution of the calorimeters of the detector system. A hadronic calorimeter with high granularity is crucial for providing the required separation power and energy resolution for the desired BMR. In this context, the analogue hadron calorimeter (AHCAL), a scintillator hadronic calorimeter with analogue readout, is a potential hadronic calorimeter option for the CEPC detector. In this study, key design parameters of the AHCAL, including scintillator cell size, number of sampling layers, absorber thickness, and scintillator thickness, were optimized for BMR performance on the benchmark process of e + e - ⟶ νν̅H,H ⟶ gg. Notably, herein, a set of optimized design parameters is presented for the CEPC AHCAL that meets the required BMR with reduced readout channels. Specifically, the set of proposed AHCAL design parameters is as follows: 40 sampling layers, 20 mm steel thickness, and 40× 40× 3 mm3 scintillator size for every tile. This design achieves a BMR of 3.73% and remarkably reduces the number of readout channels.

RADiCAL—Precision Timing, Ultracompact, Radiation-Hard Electromagnetic Calorimetry

To address the challenges of providing high-performance calorimetry in future hadron collider experiments under conditions of high luminosity and high radiation (FCC-hh environments), we conducted R&D on advanced calorimetry techniques suitable for such operation, based on scintillation and wavelength-shifting technologies and photosensor (SiPM and SiPM-like) technology. In particular, we focused our attention on ultra-compact radiation-hard EM calorimeters based on modular structures (RADiCAL modules) consisting of alternating layers of the very dense absorber and scintillating plates, read out via radiation hard wavelength shifting (WLS) solid fiber or capillary elements to photosensors positioned either proximately or remotely, depending upon their radiation tolerance. RADiCAL modules provide the capability to measure simultaneously and with high precision the position, energy and timing of EM showers. This paper provides an overview of the instrumentation and photosensor R&D associated with the RADiCAL program.

Light yield non-proportionality of inorganic crystals and its effect on cosmic-ray measurements

The multi-TeV energy region of the cosmic-ray spectra has been recently explored by direct detection experiments that used calorimetric techniques to measure the energy of the cosmic particles. Interesting spectral features have been observed in both all-electron and nuclei spectra. However, the interpretation of the results is compromised by the disagreements between the data obtained from the various experiments, that are not reconcilable with the quoted experimental uncertainties. Understanding the reason for the discrepancy among the measurements is of fundamental importance in view of the forthcoming high-energy cosmic-ray experiments planned for space, as well as for the correct interpretation of the available results. The purpose of this work is to investigate the possibility that a systematic effect may derive from the non-proportionality of the light response of inorganic crystals, typically used in high-energy calorimetry due to their excellent energy-resolution performance. The main reason for the non-proportionality of the crystals is that scintillation light yield depends on ionisation density. Experimental data obtained with ion beams were used to characterize the light response of various scintillator materials. The obtained luminous efficiencies were used as input of a Monte Carlo simulation to perform a comparative study of the effect of the light-yield non-proportionality on the detection of high-energy electromagnetic and hadronic showers. The result of this study indicates that, if the calorimeter response is calibrated by using the energy deposit of minimum ionizing particles, the measured shower energy might be affected by a significant systematic shift, at the level of few percent, whose sign and magnitude depend specifically on the type of scintillator material used.

Evaluation of the DECAL Fully Depleted monolithic sensor for outer tracking and digital calorimetry

The DECAL sensor is a depleted monolithic active pixel sensor (DMAPS) being developed to explore technological solutions for digital electromagnetic calorimeters. For this application, the number of pixels above threshold is used to estimate the shower energy and therefore the pixel size is required to be sufficiently small to avoid hit saturation. The DECAL and DECAL Fully Depleted (FD) sensors have been designed and fabricated in the TowerJazz 180 nm CMOS standard and modified imaging processes, respectively. The latter uses modifications to the implant configuration that improve charge collection and radiation hardness, including to the levels required for barrel ECAL regions of FCC-hh (few 1015 neq/cm2). Both DECAL variants feature a matrix of 64 × 64 pixels with a pitch of 55μm, read out every 25 ns. For DECAL FD, the logic has been modified to extend the in-pixel comparator threshold trim range from five to six bits, with the sixth bit used to de-activate the comparator. Characterisation results for the DECAL FD, including the pixel equalisation matrix, threshold scans testing under monochromatic X-rays and 90Sr source, are presented.

Progress in the Simulation and Modelling of Coherent Radio Pulses from Ultra High-Energy Cosmic Particles

In the last decade, many experiments have been planned, designed or constructed to detect Ultra High Energy showers produced by cosmic rays or neutrinos using the radio technique. This technique consists in detecting short radio pulses emitted by the showers. When the detected wavelengths are longer than typical shower length scales, the pulses are coherent. Radio emission can be simulated by adding up the contributions of all the particle showers in a coherent way. The first program to use this approach was based on an algorithm developed more than thirty years ago and referred to as “ZHS”. Since then, much progress has been obtained using the ZHS algorithm with different simulation programs to investigate pulses from showers in dense homogeneous media and the atmosphere, applying it to different experimental initiatives, and developing extensions to address different emission mechanisms or special circumstances. We here review this work, primarily led by the authors in collaboration with other scientists, illustrating the connections between different articles, and giving a pedagogical approach to most of the work.

The Unreasonable Effectiveness of the Air-Fluorescence Technique in Determining the EAS Shower Maximum

We review all existing air-fluorescence measurements of the elongation rate of extensive air showers (slope of mean EAS shower maximum Xmax vs. log of shower energy E) above 1017 eV. We find remarkable agreement for all current and historic experiments over a 30 yr period for the energy range from 1017 to 3 × 1018 eV. The mean elongation rate in this energy interval is near 80 g/cm2/decade. Above this energy, experiments in the Northern hemisphere are in good agreement with an average elongation rate of 48 ± 10 g/cm2/decade while Southern hemisphere experiments have a flatter elongation rate of 26 ± 2 g/cm2/decade. We point out that, given the agreement at lower energies, possible systematic reasons for this difference are unlikely. Given this, the world elongation rate data alone may indicate a composition difference of UHECR in the Northern and Southern hemisphere and thus a diversity of UHECR sources in the Northern and Southern sky.

Convolutional neural networks for shower energy prediction in liquid argon time projection chambers

When electrons with energies of O(100) MeV pass through a liquid argon time projection chamber (LArTPC), they deposit energy in the form of electromagnetic showers. Methods to reconstruct the energy of these showers in LArTPCs often rely on the combination of a clustering algorithm and a linear calibration between the shower energy and charge contained in the cluster. This reconstruction process could be improved through the use of a convolutional neural network (CNN). Here we discuss the performance of various CNN-based models on simulated LArTPC images, and then compare the best performing models to a typical linear calibration algorithm. We show that the CNN method is able to address inefficiencies caused by unresponsive wires in LArTPCs and reconstruct a larger fraction of imperfect events to within 5 % accuracy compared with the linear algorithm.