Search for: All records

Year after year, computing systems continue to grow in complexity at an exponential rate. While this can have far-ranging positive impacts on society, it has become extremely difficult to ensure the security of these systems in the field. Hardware security - in conjunction with more traditional cybersecurity topics like software and network security - is critical for designing secure systems. Moving forward, hardware security education must ensure the next generation of engineers have the knowledge and tools to address this growing challenge. A good foundation in hardware security draws on concepts from several different fields, including fundamental hardware design principles, signal processing and statistics, and even machine learning for modeling complex physical processes. It can be difficult to convey the material in a manageable way, even to advanced undergraduate students. In this paper, we describe how we have leveraged Python, and its rich ecosystem of open-source libraries, and scaffolding with Jupyter notebooks, to bridge the gap between theory and implementation of hardware security topics, helping students learn through experience. 

With the rapid growth of the Internet of Things (IoT) and increasing reliance on network-connected devices, IoT security, which integrates components of hardware and cybersecurity, is more important than ever. Hence, we must improve and expand training opportunities for students in IoT security. Experiential learning is an essential component of education for engineering and cybersecurity in particular. In this work, we describe three comprehensive hands-on IoT security experiments built using off-the-shelf development boards which can provide a low-cost and accessible experiential learning opportunity for students in this area. 

Abstract Data collected so far by the Pierre Auger Observatory have enabled major advances in ultra-high energy cosmic ray physics and demonstrated that improved determination of masses of primary cosmic-ray particles, preferably on an event-by-event basis, is necessary for understanding their origin and nature. Improvement in primary mass measurements was the main motivation for the upgrade of the Pierre Auger Observatory, called AugerPrime. As part of this upgrade, scintillator detectors are added to the existing water-Cherenkov surface detector stations. By making use of the differences in detector response to the electromagnetic particles and muons between scintillator and water-Cherenkov detectors, the electromagnetic and muonic components of cosmic-ray air showers can be disentangled. Since the muonic component is sensitive to the primary mass, such combination of detectors provides a powerful way to improve primary mass composition measurements over the original Auger surface detector design. In this paper, the so-called Scintillator Surface Detectors are discussed, including their design characteristics, production process, testing procedure and deployment in the field. 

Abstract Stratigraphic interpretation generally relies upon the assumption that the fluvio‐deltaic surface responds uniformly to sea‐level changes; however, recent theoretical work suggests that changes in its relief and concavity can influence the propagation of sea‐level information upstream and result in geologically long‐lived lags in the system response. We test this theoretical result using measurements from a experimental delta subject to high and low magnitude sea‐level oscillations. In both cases, changes in relief and curvature of the fluvio‐deltaic profile result in the proximal portion of the profile being out of phase with respect to sea‐level cycles, whereas the nearshore regions remain in phase. These results underscore the importance of delayed response to sea‐level variations in the upstream portion of river deltas, often resulting in net erosion during sea‐level rise and potentially complicating the reconstruction of paleo sea‐level from deltaic deposits. 

Abstract The modulation of low-energy galactic cosmic rays reflects interplanetary magnetic field variations and can provide useful information on solar activity. An array of ground-surface detectors can reveal the secondary particles, which originate from the interaction of cosmic rays with the atmosphere. In this work, we present an investigation of the low-threshold rate (scaler) time series recorded in 16 yr of operation by the Pierre Auger Observatory surface detectors in Malargüe, Argentina. Through an advanced spectral analysis, we detected highly statistically significant variations in the time series with periods ranging from the decadal to the daily scale. We investigate their origin, revealing a direct connection with solar variability. Thanks to their intrinsic very low noise level, the Auger scalers allow a thorough and detailed investigation of the galactic cosmic-ray flux variations in the heliosphere at different timescales and can, therefore, be considered a new proxy of solar variability. 

Abstract Ultrahigh-energy cosmic rays are known to be mainly of extragalactic origin, and their propagation is limited by energy losses, so their arrival directions are expected to correlate with the large-scale structure of the local Universe. In this work, we investigate the possible presence of intermediate-scale excesses in the flux of the most energetic cosmic rays from the direction of the supergalactic plane region using events with energies above 20 EeV recorded with the surface detector array of the Pierre Auger Observatory up to 2022 December 31, with a total exposure of 135,000 km²sr yr. The strongest indication for an excess that we find, with a posttrial significance of 3.1σ, is in the Centaurus region, as in our previous reports, and it extends down to lower energies than previously studied. We do not find any strong hints of excesses from any other region of the supergalactic plane at the same angular scale. In particular, our results do not confirm the reports by the Telescope Array Collaboration of excesses from two regions in the Northern Hemisphere at the edge of the field of view of the Pierre Auger Observatory. With a comparable integrated exposure over these regions, our results there are in good agreement with the expectations from an isotropic distribution. 

Abstract Diffuse photons of energy above 0.1 PeV, produced through the interactions between cosmic rays and either interstellar matter or background radiation fields, are powerful tracers of the distribution of cosmic rays in the Galaxy. Furthermore, the measurement of a diffuse photon flux would be an important probe to test models of super-heavy dark matter decaying into gamma-rays. In this work, we search for a diffuse photon flux in the energy range between 50 PeV and 200 PeV using data from the Pierre Auger Observatory. For the first time, we combine the air-shower measurements from a 2 km²surface array consisting of 19 water-Cherenkov surface detectors, spaced at 433 m, with the muon measurements from an array of buried scintillators placed in the same area. Using 15 months of data, collected while the array was still under construction, we derive upper limits to the integral photon flux ranging from 13.3 to 13.8 km^-2sr^-1yr^-1above tens of PeV. We extend the Pierre Auger Observatory photon search program towards lower energies, covering more than three decades of cosmic-ray energy. This work lays the foundation for future diffuse photon searches: with the data from the next 10 years of operation of the Observatory, this limit is expected to improve by a factor of ∼20. 

A dedicated search for upward-going air showers at zenith angles exceeding 110° and energies $E>0.1\mathrm{EeV}$has been performed using the Fluorescence Detector of the Pierre Auger Observatory. The search is motivated by two “anomalous” radio pulses observed by the ANITA flights I and III that appear inconsistent with the standard model of particle physics. Using simulations of both regular cosmic-ray showers and upward-going events, a selection procedure has been defined to separate potential upward-going candidate events and the corresponding exposure has been calculated in the energy range [0.1–33] EeV. One event has been found in the search period between January 1, 2004, and December 31, 2018, consistent with an expected background of $0.27\pm 0.12$events from misreconstructed cosmic-ray showers. This translates to an upper bound on the integral flux of $(7.2\pm 0.2)\times {10}^{-21}{\mathrm{cm}}^{-2}{\mathrm{sr}}^{-1}{\mathrm{y}}^{-1}$and $(3.6\pm 0.2)\times {10}^{-20}{\mathrm{cm}}^{-2}{\mathrm{sr}}^{-1}{\mathrm{y}}^{-1}$for an $E^{-1}$and $E^{-2}$spectrum, respectively. An upward-going flux of showers normalized to the ANITA observations is shown to predict over 34 events for an $E^{-3}$spectrum and over 8.1 events for a conservative $E^{-5}$spectrum, in strong disagreement with the interpretation of the anomalous events as upward-going showers. Published by the American Physical Society2025 

We report an investigation of the mass composition of cosmic rays with energies from 3 to 100 EeV ( $1\mathrm{EeV}={10}^{18}\mathrm{eV}$) using the distributions of the depth of shower maximum $X_{\max }$. The analysis relies on $\sim 50,000$events recorded by the surface detector of the Pierre Auger Observatory and a deep-learning-based reconstruction algorithm. Above energies of 5 EeV, the dataset offers a 10-fold increase in statistics with respect to fluorescence measurements at the Observatory. After cross-calibration using the fluorescence detector, this enables the first measurement of the evolution of the mean and the standard deviation of the $X_{\max }$distributions up to 100 EeV. Our findings are threefold: (i) The evolution of the mean logarithmic mass toward a heavier composition with increasing energy can be confirmed and is extended to 100 EeV. (ii) The evolution of the fluctuations of $X_{\max }$toward a heavier and purer composition with increasing energy can be confirmed with high statistics. We report a rather heavy composition and small fluctuations in $X_{\max }$at the highest energies. (iii) We find indications for a characteristic structure beyond a constant change in the mean logarithmic mass, featuring three breaks that are observed in proximity to the ankle, instep, and suppression features in the energy spectrum. Published by the American Physical Society2025 

We present measurements of the atmospheric depth of the shower maximum $X_{\max }$, inferred for the first time on an event-by-event level using the surface detector of the Pierre Auger Observatory. Using deep learning, we were able to extend measurements of the $X_{\max }$distributions up to energies of 100 EeV ( ${10}^{20}\mathrm{eV}$), not yet revealed by current measurements, providing new insights into the mass composition of cosmic rays at extreme energies. Gaining a 10-fold increase in statistics compared to the fluorescence detector data, we find evidence that the rate of change of the average $X_{\max }$with the logarithm of energy features three breaks at $6.5\pm 0.6\left(\mathrm{stat}\right)\pm 1\left(\mathrm{syst}\right)\mathrm{EeV}$, $11\pm 2\left(\mathrm{stat}\right)\pm 1\left(\mathrm{syst}\right)\mathrm{EeV}$, and $31\pm 5\left(\mathrm{stat}\right)\pm 3\left(\mathrm{syst}\right)\mathrm{EeV}$, in the vicinity to the three prominent features (ankle, instep, suppression) of the cosmic-ray flux. The energy evolution of the mean and standard deviation of the measured $X_{\max }$distributions indicates that the mass composition becomes increasingly heavier and purer, thus being incompatible with a large fraction of light nuclei between 50 and 100 EeV. Published by the American Physical Society2025