Atmospheric Muons Research Articles

Origin of the signals registered on february 23, 1987 in gravity antennas

During the SN1987A outburst on February 23, 1987, four underground neutrino detectors and two gravitational antennas in Rome and Maryland detected signals associated with the gravitational collapse of the star’s core. Since it is impossible to detect direct gravitational radiation from the collapse of SN1987A with antennas, it is still not clear what events were recorded by gravitational antennas. In this work, an amplitude analysis of the signals from gravitational antennas in Rome and Maryland in the vicinity of the signals from neutrino detectors during Supernova SN1987A was carried out. It is shown that the amplitude distributions in all antenna signals are consistent with the distribution of fluctuating energy losses of atmospheric muons crossing the antennas. A conclusion has been made about the muon origin of signals detected by “Weber” type antennas — aluminized cylinders with a mass of 2–3 tons.

Angular distributions of atmospheric cosmic muons at the Earth: A study with PYTHIA8

In this work, the angular distribution of atmospheric cosmic muons is studied using PYTHIA8 simulations, comparing it to the experimental data. The standalone code in PYTHIA8 consists of an atmosphere of only nitrogen molecules. Here, the standalone code has been augmented adding oxygen molecules with a relative abundance of 78:22 (Nitrogen:Oxygen) to resemble a more realistic atmosphere. The vertical flux intensity ([Formula: see text]) of cosmic muons varies with zenith angle as a function of [Formula: see text], where [Formula: see text] is the zenith angle and n is the exponent term. The vertical flux intensity of cosmic muons has been characterized as a function of zenith angle ([Formula: see text]), momentum (p) and energy (E). Simulations are compared to the experimental results found in the literature and to the measurements performed at the surface laboratories of SINP (Kolkata) and JUSL (Jadugoda) at two different latitudes and altitudes in May 2024. The integrated vertical muon flux ([Formula: see text]) and the exponent term (n) are extracted by fitting each experimental dataset. The simulated vertical flux intensity ([Formula: see text]) as a function of the zenith angle ([Formula: see text]) of cosmic muons shows a good level of agreement with the spectral shape of our experimental data as well as with that from literature. This study highlights the relevance of PYHTIA8 in the context of air-shower simulations, improving its predictive power by incorporating a more realistic atmospheric model.

Energy Distribution in Atmospheric Muons

This study models the parameters of atmospheric muons that decay at altitudes ranging from 200 to 4200 meters. Using experimental data, this research determined the correlation between the most likely number of decayed muons, the altitude of decay and the distance traversed before decaying. Next, using the data obtained, this study determined the fraction of total decayed muons that exhibited a certain velocity and determined their altitude of decay. The velocities of the fractions of decayed muons were further used to determine their corresponding kinetic energies. The study also presented equations that give the relation between the kinetic energy of a muon and its altitude of decay. Furthermore, an equation relating the energy of a muon to the fraction of muons corresponding to that energy was also created in the present study. To diminish the standard deviation in the data obtained thus far, this paper also determines and plots the relation between the specific energy of atmospheric muons and the fraction of muons with a kinetic energy greater than or equal to the specified energy. Overall, this study describes, plots, and generates equations for the kinetic energies of muons and calculates the muon fraction for different energies to determine the energy distribution for atmospheric muons that decay between 200 meters and 4200 meters.

Prototype Cherenkov detector characterization for muon tomography applications

Muography is an innovative imaging technique using naturally produced elementary particles – atmospheric muons – used to determine the distribution of density inside massive objects. The modification of the particles flux – by scattering or absorption – reflects the contrasts in density within the medium and therefore offers the possibility for an image of the crossed volumes. In most muography setups the imaging process is based on the tracking of the particles which accounts for the absorption or the scattering of the muons trajectories. Neither the energy nor the identity of the particles (the so-called PID) is exploited since this information traditionally relies on the use of calorimeters and/or high intensity magnetic fields. Both these techniques hinder detector portability which in the case of muography is important and this renders them impractical for its purpose. In this paper we characterize the performance of a simple and small water Cherenkov detector capable of providing some insights on the energy of muons and the PID for the crossing particles that could potentially improve the background rejection for a muography survey when operating in conjunction with a muon telescope. We tested a prototype of such water Cherenkov detector in combination with two small muon hodoscopes. Both systems are using the same opto-electronics chain – optical fibers and pixellized photosensors – and the same data acquisition (DAQ) readout system which ensures an easy integration and implementation within presently running systems. This article presents the test setup, the detector response to cosmic muons and its performance evaluation against a basic simulation of its geometry and detection principle.

Atmospheric muons measured with the KM3NeT detectors in comparison with updated numeric predictions

The measurement of the flux of muons produced in cosmic ray air showers is essential for the study of primary cosmic rays. Such measurements are important in extensive air shower detectors to assess the energy spectrum and the chemical composition of the cosmic ray flux, complementary to the information provided by fluorescence detectors. Detailed simulations of the cosmic ray air showers are carried out, using codes such as CORSIKA, to estimate the muon flux at sea level. These simulations are based on the choice of hadronic interaction models, for which improvements have been implemented in the post-LHC era. In this work, a deficit in simulations that use state-of-the-art QCD models with respect to the measurement deep underwater with the KM3NeT neutrino detectors is reported. The KM3NeT/ARCA and KM3NeT/ORCA neutrino telescopes are sensitive to TeV muons originating mostly from primary cosmic rays with energies around 10 TeV. The predictions of state-of-the-art QCD models show that the deficit with respect to the data is constant in zenith angle; no dependency on the water overburden is observed. The observed deficit at a depth of several kilometres is compatible with the deficit seen in the comparison of the simulations and measurements at sea level.

Water-based quantum dots liquid scintillator for particle physics

Liquid scintillators are typically composed from organic compounds dissolved in organic solvents. However, usage of such material is often restricted due to fire safety and environmental reasons. Because of this, R&D of water-based liquid scintillators is of extreme relevance; yet, no such scintillators have been made commercially available as yet. Here, we investigate an alternative, water-based quantum dots liquid scintillator. Pre-determined and controllable optical properties of the quantum dots, as well as the existence of large libraries of established protocols for their dispersion in aqueous solutions, make them an attractive option for nuclear and particle physics applications. We characterize the optical properties of water-based quantum dots liquid scintillator and find that most of its optical properties are preserved upon quantum dots' phase transfer into water, through the addition of an oleic acid hydrophilic layer. Using the developed scintillator, the time and charge responses from atmospheric muons are measured, highlighting the practical viability of water-based quantum dots liquid scintillators for nuclear and particle physics, special interest on neutrino physics.

Atmospheric muons and their variations with temperature

Seasonal variations of atmospheric muons are traditionally interpreted in terms of an effective temperature that relates the atmospheric temperature profile at a given time to the dependence of muon production on atmospheric depth. This paper aims to review and generalize the treatment of muon production and effective temperature that has been used to interpret seasonal variations of atmospheric muons by many experiments. The formalism is developed both in integral form – for application to compact detectors at a fixed depth that record all muons with Eμ>Eμmin – and in differential form — for application to extended detectors like IceCube, KM3NeT, and Baikal-GVD, where the rates are proportional to energy-dependent effective areas.

Prototyping a High Purity Germanium cryogenic veto system for a bolometric detection experiment

The use of High Purity Germanium detectors operated in ionization mode at cryogenic temperatures is investigated as an external background mitigation solution for bolometers used in rare-event search experiments. A simple experimental setup, running a 52-g Li2WO4 bolometer sandwiched in-between two 2-cm thick High Purity Germanium cylindrical detectors in a dry cryostat, shows promising rejection to environmental gammas and atmospheric muons backgrounds. The acquired data are used together with a Monte Carlo simulation of the setup to extract the main contributions to the external backgrounds expected in an above ground experiment, such as e.g. current and future experimental efforts targeting the detection of coherent elastic neutrino-nucleus scattering at reactor facilities. Based on all these results, a 4π coverage similar veto system achieving a O(10 keV) energy threshold is expected to achieve a ≳73% and a ≳92% rejection power for gamma-like and muon-like events, respectively.

Spectra and Angle Distributions of Atmospheric Neutrinos and Muons from the Decay of Charm Particles

Spectra and Angle Distributions of Atmospheric Neutrinos and Muons from the Decay of Charm Particles

Development of a polarization monitor for the J-PARC muon g − 2/EDM experiment

In the J-PARC Muon g−2/EDM experiment, the Polarization Monitor plays a crucial role in assessing the quality of muon beams by measuring the spin polarization of muons in the muonium production chamber. This is achieved through analyzing the asymmetry in muon decay, which serves as an indicator of beam quality. The development of this detector system is segmented into three distinct phases. The initial two phases have undergone validation using atmospheric muons. A significant aspect of Phase 1 is the simulation study, which, when integrated with energy deposition calibration derived from experimental data, effectively minimizes background noise caused by muon decays within the scintillator. Furthermore, the construction of the Phase 1 apparatus has been completed, and preliminary data collection has revealed a notable difference in asymmetry between polarized and unpolarized muons. This finding is instrumental in advancing the development of Phases 2 and 3 of the detector system.

Muography as a support technique for non-invasive research and three-dimensional localization of tombs in archaeological sites: a case study from Palazzone Necropolis (Perugia – Italy)

Transmission muography is a non-invasive imaging technique that exploits the penetrating power of atmospheric muons into matter to obtain two-dimensional and three-dimensional density images of the monitored structure. The detectors used are particle trackers. Muography enables the monitoring of large structures and it is also particularly useful in the archaeological field for a mapping of low-density underground anomalies potentially related to unknown or inaccessible tombs or tunnels. The Palazzone necropolis, located south of Perugia (Italy), dating back to Etruscan period, contains about 200 known tombs, some of which, such as the Volumni Hypogeum, can be visited thanks to a touristic route. The eastern area of the necropolis, on the other hand, does not have a touristic path and is partially unknown. The objective of the muographic measurement campaign is to support the re-evaluation of this archaeological area by searching for new anthropic cavities and identifying them three-dimensionally. One of the goals of this study is to obtain a three-dimensional localization of cavities starting from a single muographic measurement by exploiting an image focusing algorithm. For this purpose, an area that contains a known cavity was used as the reference cavity for the test of the three-dimensional reconstruction algorithm.

Measurement of muon flux variations with scintillators in Mexico City and their correlation to solar activity

In this work we report the variations of the atmospheric muons flux in Mexico City. The measurements were performed from September to December 2023 at the Institute of Nuclear Sciences of UNAM, located at coordinates 19.32°N 99.18°W with an altitude of 2274 meters above sea level and a cutoff rigidity of 8.24 GV. The experimental setup consists of a pair of scintillators, with dimensions of 50cm x 1m. To compensate for fluctuations in air pressure, we calculate the barometric coefficient using data, which is determined to be -0.21%/mb. The observed muon flux corresponds to 98.3 ± 2.6 m−2 s−1 sr−1 and is consistent with other measurements at the same location. We have identified three variations in the pressure-corrected muon flux that exhibit a pattern similar to those observed by a neutron cosmic ray detector at UNAM. Through an extensive analysis of the publicly available geomagnetic data, we have correlated these variations with a phenomenon known as a Forbush decrease.

Muon tomography with Resistive Plate Chambers for geological characterization

Muon tomography is one of several fields of applied physics that have witnessed the successful use of particle detection based on Resistive Plate Chambers (RPC). In this work, we report on an innovative project concerning transmission muography for geological characterization. For this purpose, a muon telescope built of four RPC planes was mounted on an adjustable structure and the telescope’s response to atmospheric muons was studied. Data acquisition campaigns took place at different locations for producing muographic images of the building of the Physics Department of the University of Coimbra, in Portugal. More recently, the detector was moved to an underground gallery of an old mine, where it is taking data that is being assessed in combination with the results from conventional geophysics techniques.

Impact of errors in the magnetic field measurement on the precision determination of neutrino oscillation parameters at the proposed ICAL detector at INO

The magnetised iron calorimeter (ICAL) detector proposed at the India-based Neutrino Observatory will be a 51 kton detector made of 151 layers of 56 mm thick soft iron with 40 mm air gap in between where the RPCs, the active detectors, will be placed. The main goal of ICAL is to make precision measurements of the neutrino oscillation parameters, especially of the neutrino mass ordering, using the atmospheric neutrinos as source. The charged current interactions of the atmospheric muon neutrinos and anti-neutrinos in the detector produce charged muons. The magnetic field, with a maximum value of ∼ 1.5 T in the central region of ICAL, is a critical component since it will be used to distinguish the charges and determine the momentum and direction of these muons. It is difficult to measure the magnetic field inside the iron. The existing methods can only estimate the internal field and hence will be prone to error. This paper presents the first simulations study of the effect of errors in the measurement of the magnetic field in ICAL on its physics potential, especially the neutrino mass ordering and precision measurement of oscillation parameters in the 2–3 sector. The study is a GEANT4-based analysis, using measurements of the magnetic field at the prototype ICAL detector. We find that there is only a small effect on the determination of the mass ordering. While local fluctuations in the magnetic field measurement are well-tolerated, calibration errors must remain well within 5% to retain good precision determination of the parameters sin2 θ 23 and Δm 2 32.

Calculation of the Flux and Charge Ratio of High-Energy Atmospheric Muons at Sea Level*

Calculation of the Flux and Charge Ratio of High-Energy Atmospheric Muons at Sea Level*

Atmospheric muons at PeV energies in radio neutrino detectors

Experiments seeking to detect radio emission stemming from neutrino interactions will soon reach sensitivities that bring a detection within reach. Since experiments like RNO-G or the future IceCube-Gen2 target more than an order of magnitude more effective volume than existing experiments, the renewed and detailed study of rare backgrounds is needed. In this paper, we study the potential background from energy losses of highly energetic atmospheric muons. Due to both limited experimental measurements and limited modeling in hadronic interaction models, the expected event rate is subject to large uncertainties. Here, we estimate rate predictions and their uncertainties for different models and instrumental parameters. We also study possible routes towards mitigation of the muon background, such as parent air shower detection, and illustrate what is needed to make the first measurement of the prompt muon flux at energies above 10 PeV.

Cosmic ray measurements with IceCube and IceTop

IceCube is a cubic-kilometer Cherenkov detector in the deep ice at the geographic South Pole. The dominant event yield in the deep ice detector consists of penetrating atmospheric muons with energies above approximately 300 GeV, produced in cosmic ray air showers. In addition, the surface array, IceTop, measures the electromagnetic component and GeV muons of air showers. Hence, IceCube and IceTop yield unique opportunities to study cosmic rays with unprecedented statistics in great detail. We will present recent results of comic ray measurements from IceCube and IceTop. In this overview, we will highlight measurements of the energy spectrum of cosmic rays from 250 TeV up to the EeV range and their mass composition above 3 PeV. We will also report recent results from measurements of the muon content in air showers and discuss their consistency with predictions from current hadronic interaction models.

The JUNO experiment Top Tracker

The main task of the Top Tracker detector of the neutrino reactor experiment Jiangmen Underground Neutrino Observatory (JUNO) is to reconstruct and extrapolate atmospheric muon tracks down to the central detector. This muon tracker will help to evaluate the contribution of the cosmogenic background to the signal. The Top Tracker is located above JUNO’s water Cherenkov Detector and Central Detector, covering about 60% of the surface above them. The JUNO Top Tracker is constituted by the decommissioned OPERA experiment Target Tracker modules. The technology used consists in walls of two planes of plastic scintillator strips, one per transverse direction. Wavelength shifting fibres collect the light signal emitted by the scintillator strips and guide it to both ends where it is read by multianode photomultiplier tubes. Compared to the OPERA Target Tracker, the JUNO Top Tracker uses new electronics able to cope with the high rate produced by the high rock radioactivity compared to the one in Gran Sasso underground laboratory. This paper will present the new electronics and mechanical structure developed for the Top Tracker of JUNO along with its expected performance based on the current detector simulation.

Observation of seasonal variations of the flux of high-energy atmospheric neutrinos with IceCube

Atmospheric muon neutrinos are produced by meson decays in cosmic-ray-induced air showers. The flux depends on meteorological quantities such as the air temperature, which affects the density of air. Competition between decay and re-interaction of those mesons in the first particle production generations gives rise to a higher neutrino flux when the air density in the stratosphere is lower, corresponding to a higher temperature. A measurement of a temperature dependence of the atmospheric nu _{mu } flux provides a novel method for constraining hadronic interaction models of air showers. It is particularly sensitive to the production of kaons. Studying this temperature dependence for the first time requires a large sample of high-energy neutrinos as well as a detailed understanding of atmospheric properties. We report the significant (> 10 ; sigma ) observation of a correlation between the rate of more than 260,000 neutrinos, detected by IceCube between 2012 and 2018, and atmospheric temperatures of the stratosphere, measured by the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA’s AQUA satellite. For the observed 10% seasonal change of effective atmospheric temperature we measure a 3.5(3)% change in the muon neutrino flux. This observed correlation deviates by about 2-3 standard deviations from the expected correlation of 4.3% as obtained from theoretical predictions under the assumption of various hadronic interaction models.

MUCH: A compact imaging Čerenkov telescope for volcano muography

Significant progress has been made in the last years in the field of volcanic muography. This technique takes advantage of the large penetrating power of atmospheric muons and allows us to infer information about the internal structure of volcanoes observing the differential absorption of muons passing through the target. This, in conjunction with other monitoring techniques, can help to determine the state of activity of a volcano and to reduce the risk related to paroxysmal events. The main challenge in the application of this technique is given by the background noise, that affects detectors. To improve the signal-to-noise ratio it is necessary to use several detection layers and shielding plates that make the detector expensive and difficult to transport. In order to overcome these issues, the use of Imaging Atmospheric Čerenkov Telescopes (IACTs) devoted to muography has been recently proposed.Here we present the MUography CHerenkov (MUCH) telescope, a compact IACT specifically designed for volcano muography. The telescope design is characterized by a Schmidt-like optical system and a Silicon Photo-Multipliers (SiPMs) camera working at wavelengths between 280nm and 900nm, equipped with a fast read-out electronics capable to operate SiPMs contemporarily in charge integration and photon counting mode.