Ray Telescope Research Articles

The Galactic population of canonical pulsar. II. Taking into account several evolutionary paths: Interstellar medium interaction, Galactic potential, and a death valley

Pulsars are highly magnetised rotating neutron stars, emitting in a broad electromagnetic energy range. These objects were discovered more than 55 years ago and are astrophysical laboratories for studying physics at extreme conditions. Reproducing the observed pulsar population helps refine our understanding of their formation and evolution scenarios, as well as their radiation processes and geometry. In this paper, we improve our previous population synthesis by focusing on both the radio and gamma -ray pulsar populations, investigating the impact of the Galactic gravitational potential and of the radio emission death line. To elucidate the necessity of a death line, we implemented our refined initial distributions of the spin period and spacial position at birth. This approach allowed us to elevate the sophistication of our simulations to the most recent state-of-the-art approaches. The motion of each individual pulsar was tracked in the Galactic potential by a fourth-order symplectic integration scheme. Our pulsar population synthesis took into account the secular evolution of the force-free magnetosphere and magnetic field decay simultaneously and self-consistently. Each pulsar was evolved from birth to the present time. The radio and gamma -ray emission locations were modelled by the polar cap geometry and striped wind model, respectively. By simulating ten million pulsars, we found that including a death line allows us to better reproduce the observational trend. However, when simulating one million pulsars, we obtained an even more realistic $P- P $ diagram, whether or not a death line was included. This suggests that the ages of the detected pulsars might be overestimated and so, it sets the need for a death line in pulsar population studies into question. Kolmogorov-Smirnov tests confirm the statistical similarity between the observed and simulated $P- P $ diagram. Additionally, simulations with increased gamma -ray telescope sensitivities hint at a significant contribution coming from the gamma -ray pulsars to the GeV excess in the Galactic centre.

Detection response of the active components of the SciBar Cosmic Ray Telescope at Sierra Negra

The Scibar Cosmic-Ray Telescope (SciCRT) is the most promising detector of the Sierra Negra Cosmic Rays Observatory (SN-CRO). At this location, being a target and a tracker of secondary cosmic rays, the SciCRT offers a high probability of observing solar energetic particles and lower energy galactic cosmic rays (LEGCR); also, it allows the identification of incoming particles by measuring their energy deposition. In this work we present a Geant4-based simulation of the energy deposited by neutrons, γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document}-rays, protons, electrons and muons in the optimally running SciCRT components. We also calculated the detection efficiency of the SciCRT at its current state. Our simulation results provide new information about the SciCRT detection response that may be used as a basis to estimate and analyze the energy spectra of primary particles.

Gamma-ray line emission from the Local Bubble

Deep-sea archives that include intermediate-lived radioactive 60Fe particles suggest the occurrence of several recent supernovae inside the present-day volume of the Local Bubble during the last ~10 Myr. The isotope 60Fe is mainly produced in massive stars and ejected in supernova explosions, which should always result in a sizeable yield of 26Al from the same objects. 60Fe and 26Al decay with lifetimes of 3.82 and 1.05 Myr, and emit γ rays at 1332 and 1809 keV, respectively. These γ rays have been measured as diffuse glow of the Milky Way, and would also be expected from inside the Local Bubble as foreground emission. Based on two scenarios, one employing a geometrical model and the other state-of-the-art hydrodynamics simulations, we estimated the expected fluxes of the 1332 and 1809 keV γ-ray lines, as well as the resulting 511 keV line from positron annihilation due to the 26Al β+ decay. We find fluxes in the range of 10−6–10−5 ph cm−2 s−1 for all three lines with isotropic contributions of 10–50%. We show that these fluxes are within reach for the upcoming COSI-SMEX γ-ray telescope over its nominal satellite mission duration of 2 yr. Given the Local Bubble models considered, we conclude that in the case of 10–20 Myr-old superbubbles, the distributions of 60Fe and26 Al are not co-spatial - an assumption usually made in γ-ray data analyses. In fact, this should be taken into account however when analysing individual nearby targets for their 60Fe to26 Al flux ratio as this gauges the stellar evolution models and the age of the superbubbles. A flux ratio measured for the Local Bubble could further constrain models of 60Fe deposition on Earth and its moon.

One large area trigger detector for cosmic ray telescope system

The large area trigger detector is a key instrument in cosmic ray telescope system. One large area detector, sensitive size 1.3 * 2 m2, is proposed in this paper based on plastic scintillator tiles and wavelength shift optical fibers. Thanks to the wavelength shift fibers coupling to the scintillator tiles, only one photomultiplier tube is used to output the signals for whole large area detector. So this detector is simple and economy. The signal uniformity of this detector is better than 96% over the whole surface including the edges or corners. The detection efficiency of the muon is higher than 95%, and the time resolution is better than 10 ns over the entire detector. These performances are sufficient for the trigger detector in most cosmic ray telescope system.

Ecological transition for the gas mixtures of the MRPC cosmic ray telescopes of the EEE Project

The Extreme Energy Events (EEE) Collaboration is fully involved in an ecological transition. The use of the standard gas mixture, C2H2F4 + SF6, has stopped in favor of an alternative green mixture based on C3H2F4 with the addition of He or CO2.The choise of these new mixtures is motivated by the significant lower Global Warming Potential (GWP) to reduce the emission of gases potentially contributing to the greenhouse effect.The EEE experiment consists of 61 muon telescopes based on Multigap Resistive Plate Chambers (MRPCs), each telescope composed of 3 chambers filled with gas.Several EEE detectors are today completely fluxed with the new ecological mixture. This contribution will report recent results about the telescope performance obtained from studies with the eco-friendly alternative mixture carried out in the last years.

The high-performance DIRC for the ePIC detector at the EIC

The next-generation nuclear physics facility in the United States will be the Electron-Ion Collider (EIC), scheduled to be built at Brookhaven National Laboratory (BNL). Excellent particle identification (PID) is one of the key requirements for the EIC central detector called ePIC. Identification of the hadrons in the final state is critical to study how different quark flavors contribute to nucleon properties. A detector using the Detection of Internally Reflected Cherenkov light (DIRC) principle, with a radial size of only 7-8 cm, was chosen as the PID system for the ePIC barrel region. Within the framework of the EIC R&D programs, the development of a high-performance DIRC (hpDIRC) detector was undertaken with the aim of significantly advancing state-of-the-art performance. Key components of the hpDIRC detector are a 3-layer compound lens and small pixel-size photo sensors. Currently, the hpDIRC R&D program is focused on developing and validating the radiation hard 3-layer lens, quality assurance of the BaBar DIRC radiation bars, and the early stage of the hpDIRC prototype program with Cosmic Ray Telescope at Stony Brook University, in preparation for beam tests at Fermilab in 2024.

A Comprehensive Comparison of Various Galactic Cosmic-Ray Models to the State-of-the-art Particle and Radiation Measurements

Galactic cosmic rays (GCRs) are the slowly varying background energetic particles that originate outside the solar system, are modulated by the heliospheric magnetic field, and pose ongoing radiation hazards to deep space exploration missions. To assess the potential radiation risk, various models have been developed to predict the GCR flux near Earth based on propagation theories and/or empirical functions. It is essential to benchmark these models by validating against the state-of-the-art measurements. In this work, a comprehensive model–observation comparison of the energy-dependent particle flux has been performed, by combining five typical GCR models and observational data from the Cosmic Ray Isotope Spectrometer on board the Advanced Composition Explorer spacecraft at relatively lower energies and data from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics and Alpha Magnetic Spectrometer at higher energies. The analysis shows that, out of the five models investigated in this study, the optimal model, characterized by minimal relative difference or reduced chi-square divergence from measurements, depends on the particle type, energy range, and epoch of interest. Furthermore, a silicon slab is applied to compute the absorbed dose rate using conversion factors applied to GCR model outputs, and the results are compared to measurements from the Cosmic Ray Telescope for the Effects of Radiation. The comparisons in this paper have implications for the strengths and limitations of individual GCR models, advance our comprehension of the underlying GCR transport mechanisms, and also have strong application aspects for mitigating space radiation risks.

A Multilayer Nested Space Ray Telescope Assembly and Adjustment System Based on Online Monitoring Feedback

In order to adapt to the rapid development of deep space exploration, pulsar navigation and space astronomical observation technology, the development of high-efficiency and high-performance X-ray space telescopes has become one of the hotspots for research in the fields of autonomous spacecraft navigation and astronomical observation. Since the X-ray multilayer nested mirror shells are thin-walled and deformable cylindrical structures with high requirements for surface shape accuracy, a slight change in the position or surface shape will lead to a reduction in the focusing imaging quality, so it is necessary to develop a high-precision assembly and adjustment system based on closed-loop real-time monitoring. In this paper, a multi-layer nested space ray telescope assembly and adjustment system with online monitoring feedback is developed, and a method for precision assembly and adjustment of multi-layer nested mirror shells based on online real-time detection and feedback is proposed, which specifically includes key innovative assembly technologies such as three-dimensional face shape measurement, flexible vacuum adsorption, precision adjustment that have been broken through in the process, and the imaging quality of the focused spot of the mirror shells is evaluated and analyzed in the end. The results of the experiment indicate that the assembly and adjustment of the multilayer nested mirror shells can effectively complete the high-precision assembly, and the relevant results can provide a certain reference significance for the further enhancement of the assembly and adjustment performance of the multilayer nested mirror shells.

Long‐Term Variation of the Galactic Cosmic Ray Radiation Dose Rates

AbstractIn this work, a model for calculating the galactic cosmic rays (GCRs) radiation dose rate is developed. The model is based on a GCR modulation model, which is established by Shen and Qin, and the fluence‐dose conversion coefficients (FDCCs) published by the International Commission on Radiological Protection (ICRP). With the model, the radiation absorbed dose rate of GCRs near the lunar surface over long time periods is calculated and compared with the observation data from the Cosmic Ray Telescope for the Effects of Radiation and the Lunar Lander Neutron and Dosimetry. First, the energy spectrum of GCRs at 1 AU in the ecliptic, where the lunar orbit is located, is computed using the GCR modulation model. Then, using the FDCCs of ICRP 123, the absorbed dose rates of 15 human organs/tissues at the lunar orbit position are calculated to represent the general absorbed dose rate of the body (in water). Furthermore, considering the albedo radiation (excluding neutrons) and using the water‐silicon conversion coefficients, the total absorbed dose rates of GCRs near the lunar surface (in silicon) are calculated, it is shown that our modeling results generally agree with the observations from spacecraft. This work is useful for future manned space exploration to the Moon or other celestial bodies in the solar system.

Exploring the Interaction of Cosmic Rays with Water by Using an Old-Style Detector and Rossi’s Method

Cosmic ray air showers are a phenomenon that can be observed on Earth when high-energy particles from outer space collide with the Earth’s atmosphere. These energetic particles in space are called primary cosmic rays and consist mainly of protons (about 89%), along with nuclei of helium (10%) and heavier nuclei (1%). Particles resulting from interactions in the atmosphere are called secondary cosmic rays. The composition of air showers in the atmosphere can include several high-energy particles such as mesons, electrons, muons, photons, and others, depending on the energy and type of the primary cosmic ray. Other than air, primary cosmic rays can also produce showers of particles when they interact with any type of matter; for instance, particle showers are also produced within the soil of planets without an atmosphere. In the same way, secondary cosmic particles can start showers of tertiary particles in any substance. In the 1930s, Bruno Rossi conducted an experiment to measure the energy loss of secondary cosmic rays passing through thin metal sheets. Surprisingly, he observed that as the thickness of the metal sheets increased, the number of particles emerging from the metal also increased. However, by adding more metal sheets, the number of particles eventually decreased. This was consistent with the expectation that cosmic rays were interacting with the atoms in the metals and losing energy to produce multiple secondary particles. In this paper, we describe a new–old approach for measuring particle showers in water using a cosmic ray telescope and Rossi’s method. Our instrument consists of four Geiger–Müller tubes (GMT) arranged to detect muons and particle showers. GMT sensors are highly sensitive devices capable of detecting electrons and gamma rays with energies ranging from a few tens of keV up to several tens of MeV. Since Rossi studied the effects caused by cosmic rays as they pass through metals, we wondered if the same process could also happen in water. We present results from a series of experiments conducted with this instrument, demonstrating its ability to detect and measure particle showers produced by the interaction of cosmic rays in water with good confidence. To the best of our knowledge, this experiment has never been conducted before. Our approach offers a low-cost and easy-to-use alternative to more sophisticated cosmic ray detectors, making it accessible to a wider range of researchers and students.

The 48-Year Data Analysis Collected by Nagoya Muon Telescope—A Detection of Possible (125 ± 45) Day Periodicity

Muons produced by cosmic rays above the atmosphere provide valuable information on the intensity of cosmic rays and variations in the upper atmosphere. Since 1970, the Nagoya University Cosmic Ray Laboratory has been observing the muon intensity using a multi-directional cosmic ray telescope with two layers of 36 plastic scintillators of 1m2 each, which measure the muon intensity in different incident directions. The energy of an incident proton that produces a muon incident from a vertical direction is over 11.5 GV. This paper analyzes vertical muon intensities obtained over 48 years from 1970 to 2018 using methods that differ from the East–West method. As a result, a new periodicity of (125±45) days and a new periodicity of (4–16) days were found. The latter appears only in winter time, so it may be caused by a synoptic-scale disturbance associated with the arrival of the Siberian cold air mass. On the other hand, the former periodicity may be related to solar dynamo activity. In 1984, the Solar Maximum Mission’s Gamma Ray Spectrometers reported a periodicity of about (154±10) days in the flux of solar gamma rays. The (125±45)-day periodicity found here is most likely related to solar dynamo activity, since the intensity of cosmic rays around 11.5 GV is affected by the magnetic field induced by the Sun. However, this (125±45)-day periodicity differs from the report measured by the GRS instrument in a point that it also appears during periods of low solar activity. Furthermore, it has not appeared often during lower solar activity since 1992. This information is important for future investigation of the origin of this periodicity.

Gamma Ray Pulsars and Opportunities for the MACE Telescope

Rapidly rotating neutron stars with very strong surface magnetic fields are observed to emit pulsed emission in the whole range of electromagnetic spectrum from radio to high-energy gamma rays. These so-called pulsars are known for their exceptional rotational stability. The radio emission from pulsars is generally believed to be powered by the rotational energy of neutron stars. More than 3000 pulsars have been currently known from radio observations; however, only about 10% are observed in the high-energy gamma ray band. The Fermi-LAT observations in the energy range above 100 MeV have discovered more than 300 pulsars. However, the origin of high-energy non-thermal radiation from pulsars is not completely understood and remains an active area of research. In this contribution, we report a summary of observational features of the gamma ray pulsars and briefly discuss observability for the MACE gamma ray telescope, which has just started its regular science operation at Hanle in India. Six gamma ray pulsars, other than the well-known Crab and Geminga, are identified as probable candidates for MACE observations.

Searching for Short-Timescale Transients in Gamma-ray Telescope Data

Astrophysical sources show variability in their emissions over a range of timescales, with transients such as fast radio bursts (FRBs) and magnetar giant flares (MGFs) showing variability on timescales as short as a few milliseconds. Recent advances in gamma-ray astronomy such as telescopes’ high temporal resolution and relatively high uptime, combined with follow-up programs between different facilities, should allow serendipitous observations of burst-like phenomena. Even so, no very-high-energy gamma-ray counterparts for FRBs have been detected so far, and there is a general lack of software tools suited to search for such phenomena. We present a tool capable of searching gamma-ray telescope data for transient phenomena over arbitrary timescales—it is based on the Gammapy package and recursively scans the given field of view for clusters of events within user-defined time and angular-separation intervals. The generalized implementation allows for its application in many other cases and multiple gamma-ray telescopes. The main features and methodology of the developed tool are presented here, along with an analysis of the open gamma ray telescope data performed using it.

Generative Adversarial Network based method for generation of synthetic image parameters for TACTIC [formula omitted]-ray telescope

Very High Energy (VHE) γ and cosmic rays interact with the atmosphere and generate an Extensive Air Shower (EAS) of particles comprising mainly electron–positron pairs. These energetic secondary charged particles move down the atmosphere and upon de-excitation, the medium generates a flash of Cherenkov light. The subtle differences in the shape of Cherenkov flash images generated by γ/cosmic rays at the top of the atmosphere can be explored by the ground-based Imaging Atmospheric Cherenkov technique (IACT) telescopes. To characterize and calibrate such IACT telescopes, an extensive library of EAS for γ-rays and cosmic rays of various energies are required. However, the main difficulty in generating a simulation database is that the process of shower generation is computationally extensive. To overcome the challenge of creating a huge database of simulated shower images, we propose a method based on the generation of synthetic data by employing the unsupervised machine learning (ML)-based method, namely the Generative Adversarial Networks (GAN). The present study discusses the methodology for generating synthetic image parameters using GAN for the TACTIC telescope. A comparison between Monte Carlo simulation-generated image parameters for the TACTIC and GAN-generated parameters is presented. Results are also presented from the independent Random Forest-based ML classifier to identify similarities between the simulation and synthetic data species. The potential applications of GAN-generated data towards IACT data analysis for TACTIC are also discussed.

Neutrino magnetic moment portal and supernovae: New constraints and multimessenger opportunities

We scrutinize the hypothesis that gauge singlet fermions -- sterile neutrinos -- interact with Standard Model particles through the transition magnetic moment portal. These interactions lead to the production of sterile neutrinos in supernovae followed by their decay into photons and active neutrinos which can be detected at $\gamma$-ray telescopes and neutrino detectors, respectively. We find that the non-observation of active neutrinos and photons from sterile-neutrino decay associated to SN1987A yields the strongest constraints to date on magnetic-moment-coupled sterile neutrinos if their masses are inside a $0.1-100$ MeV window. Assuming a near-future galactic supernova explosion, we estimate the sensitivity of several present and near-future experiments, including Fermi-LAT, e-ASTROGAM, DUNE, and Hyper-Kamiokande, to magnetic-moment-coupled sterile neutrinos. We also study the diffuse photon and neutrino fluxes produced in the decay of magnetic-moment coupled sterile neutrinos produced in all past supernova explosions and find that the absence of these decay daughters yields the strongest constraints to date for sterile neutrino masses inside a $1-100$ keV window.

Cosmic ray test of a STCF DTOF detector prototype

A time-of-flight detector based on detection of internally reflected Cherenkov light (DTOF), is proposed for the endcap particle identification at the Super Tau-Charm Facility (STCF). A prototype with a trapezoidal fused silica radiator that had a size of 533 mm/ 295 mm × 454 mm × 15 mm is constructed, which is approximately one-third of the size of the DTOF sector proposed for STCF. A field-programmable-gate-array-based dual-threshold time-over-threshold measurement circuit is employed to read signals from the microchannel-plate photomultiplier tube, which performs functions such as signal amplification, discrimination, and digitization. The DTOF prototype was tested in a cosmic ray telescope, which realizes 3D tracking of cosmic ray muons with an angular resolution of < 1 mrad, position resolution of <200μm, and reference time resolution of 24 ps. To analyze and understand the performance of the DTOF prototype, a GEANT4 simulation is employed. The time resolution of the DTOF prototype is 25 ps by using 10 or more photoelectrons in the cosmic ray test, which is in good agreement with the simulation result, proving the feasibility of this technology.

Energetic charged particle dose rates in water ice on the Moon

Water ice in permanently shadowed regions on the Moon is exposed to galactic cosmic rays (GCRs) and solar energetic particles (SEPs). Because this radiation alters the chemistry of the ice, constraining the total radiation dose is important for understanding both the origin and evolution of the ice. The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) onboard the Lunar Reconnaissance Orbiter (LRO) has measured the energetic charged particle dose rate for more than a solar cycle, providing the longest continuous dataset of radiation in the lunar environment. CRaTER’s unique design enables us to measure the dose rates behind three amounts of mass shielding and thus constrain the GCR and SEP dose rates as a function of depth in the regolith. In a further improvement on prior studies, we combine these dose rates with a model for how impact gardening affects the exposure time of the regolith. We can thus calculate the total dose received by water ice in gardened regolith and find that impact-gardened ice has received a dose of ∼0.1–1 eV molecule−1 over the past 1 Gyr. This dose is one to two orders of magnitude lower than the doses calculated in studies that do not incorporate the effects of gardening. Relatively undisturbed ice may have received a higher dose, but no more than ∼10 eV molecule−1 in the top centimeter. This result provides a valuable constraint for researchers studying radiation processing of lunar water ice.

Using of Distant Education Approaches to Introduce Cutting Edge Science into the Secondary School Classroom

The μΝet (microNet) project aims to deploy and operate an extensive school network of educational cosmic ray telescopes in Greece. As part of the μNet project, an extended educational program will be conducted, focusing on the construction, testing, and operation of a Cosmic Ray Telescope, as well as the remote operation of cosmic ray detection stations and Astroparticle physics detectors deployed at the Hellenic Open University (HOU) campus. During the 2021–2022 school year, a preparatory phase of the program took place engaging 150 students and 21 science teachers from all over Greece. The high school teachers and students were trained to the experimental procedures of cosmic ray physics using distance learning methods. In this report, we briefly present the methodology we followed, the tools we developed to support the educational program, as well as the findings and results of this preparatory phase.

Air shower radio signal electric field orientation as measured with the Astroneu Cosmic Ray telescope.

The Astroneu cosmic ray telescope is a small scale hybrid array consisting of both scintillator counters and electromagnetic radiation detectors in the radio-wave frequency (RF) band (antennas). Astroneu was installed and operated in the area of the Hellenic Open University (HOU) campus near the city of Patras in Greece. In the present development phase, the Astroneu telescope includes two stations consisting of 3 scintillation detectors modules (SDM) and one RF antenna while a third station includes 3 particle detectors and 4 RF antennas (3SDM-4RF). In this context we present the resent results from both the 3SDM-4RF autonomous station and simulations related to the estimation of the direction of the electric field emitted during the air shower development. The electric field measured in the ground level is the superposition of the two dominant emission mechanism, the time depended transverse current induced by the geomagnetic field and the net negative charge variation at the shower front. Since the electric field emitted by the two contributions is polarized in different directions the measured electric field in the ground encloses information about the charge-excess to geomagnetic ratio (CGR). Furthermore the orientation of the electric field emitted by charge-excess mechanism is strongly depends from the distance to the shower core (the intersection of the shower axis with the ground level). In this study we use the core information as reconstructed using the radio data and simulations. The estimated charge-excess to geomagnetic ratio is in agreement with previous studies which reveals that the shower core reconstruction method is efficient. Finally we report on that CGR measurements can be used for an efficient noise rejection in a future self trigger mode

Detection system of the lobster eye telescope with large field of view.

The lobster eye telescope is promising for large-field x ray imaging in astronomy. The special structure of the lobster eye system makes the focal plane a sphere, resulting in detector defocus when the field is large. In this study, we established a model based on the principle of lobster eye imaging and simulated the imaging at different image distances. The results reveal the relationship between the defocus and position accuracy and angular resolution. To ensure the optical performance of the large field lobster eye telescope, we propose a detection system design method using multiple detectors stitched together to form a spherical-like surface and apply it to the development of the Einstein Probe/wide-field x ray telescope (EP/WXT) submodule. About 70% of the detection area is out of focus within 0.5 mm. The scanning image of the integrated WXT submodule shows good uniformity of the point spread function (PSF) for various incident angles, and the effect of defocus on imaging is acceptable.