 Subjects -> INSTRUMENTS (Total: 63 journals)
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- The near ultraviolet transient surveyor (NUTS): An ultraviolet telescope
to observe variable sources-
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Abstract: Abstract Observing the ultraviolet (UV) sky for time-varyiable phenomena is one of the many exciting science goals that can be achieved by a relatively small aperture telescope in space. The Near Ultraviolet Transient Surveyor (NUTS) is a wide-field (3∘) imager with a photon-counting detector in the near-UV (NUV, 200 – 300 nm), to be flown on an upcoming small satellite mission. It has a Ritchey–Chrétien (RC) telescope design with correction optics to enable wide-field observations while minimizing optical aberrations. We have used an intensified CMOS detector with a solar blind photocathode, to be operated in photon-counting mode. The main science goal of the instrument is the observation of transient sources in the UV, including flare stars, supernovae, and active galactic nuclei. NUTS’s aperture size and effective area enable observation of relatively unexplored, brighter parts of the UV sky which are usually not accessible to larger missions. We have designed, fabricated, and assembled the instrument, and the final calibrations and environmental tests are being carried out. In this paper, we provide the scientific motivation and technical overview of the instrument and describe the assembly and calibration steps.
PubDate: 2022-07-02
- Precise astrometry: Earth Analogs and Beyond
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Abstract: Abstract A long-baseline, space-based Michelson interferometer will be able to detect Earth Analog planets orbiting nearby G stars. The Star Watch astrometry observatory is capable of providing 1 micro-arcsecond (µas) measurements during individual observations. Over a series of “looks”, a precision of 0.3 µas can be achieved. Hardware was constructed and validated to a TRL-6 readiness level during NASA’s Space Interferometry Mission project. European industry has demonstrated its expertise in laser metrology in the LISA Pathfinder project. This will allow Europe to either proceed with the Star Watch astrometry mission on its own or through collaboration with NASA.
PubDate: 2022-07-02
- Metal poor stars
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Abstract: Abstract In this contribution I provide an overview of the study of metal poor stars, with an emphasis on the efforts that are on-going to find large number of these rare objects. These efforts will provide, in the next few years, an interesting number of targets for which it will be desirable to have a chemical inventory, as complete as possible. In this respect CUBES, providing access to the near-UV region provides a unique opportunity to access some abundance indicators that have no counterparts in other spectral regions available from ground-based observations. I also take the opportunity to encourage the community to reflect on the possibility of placing a copy of CUBES on a telescope in the northern hemisphere. This contribution is not intended to be an exhaustive review of the field, but aims at stimulating interest in near-UV observations of metal poor stars.
PubDate: 2022-06-08
- A fast response mission to rendezvous with an interstellar object
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Abstract: Abstract A solar sail propelled small satellite mission concept to intercept and potentially rendezvous with newly discovered transient interstellar objects (ISOs) is described. The mission concept derives from the proposal for a technology demonstration mission for exiting the solar system at high velocity, eventually to reach the focal region of the solar gravitational lens. The ISO mission concept is to fly a solar sail toward a holding orbit around the Sun and when the ISO orbit is confirmed, target the sailcraft to reach an escape velocity of over 6 AU/year. This would permit rapid response to a new ISO discovery and an intercept within 10 AU from the Sun. Two new proven interplanetary technologies are utilized to enable such a mission: i) interplanetary smallsats, such as those demonstrated by the MarCO mission, and ii) solar sails, such as demonstrated by LightSail and IKAROS missions and developed for NEA Scout and Solar Cruiser missions. Current technology work suggests that already within this decade such a mission could fly and reach an ISO moving through the solar system. It might enable the first encounter with an ISO to allow for imaging and spectroscopy, measurements of size and mass, potentially giving a unique information about the object’s origin and composition. A similar approach may be used to allow for a sample return.
PubDate: 2022-06-01
- A compact instrument for gamma-ray burst detection on a CubeSat platform
II-
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Abstract: Abstract The Gamma-ray Module, GMOD, is a miniaturised novel gamma-ray detector which will be the primary scientific payload on the Educational Irish Research Satellite (EIRSAT-1) 2U CubeSat mission. GMOD comprises a compact (25 mm \(\times\) 25 mm \(\times\) 40 mm) cerium bromide scintillator coupled to a tiled array of 4 \(\times\) 4 silicon photomultipliers, with front-end readout provided by the IDE3380 SIPHRA. This paper presents the detailed GMOD design and the accommodation of the instrument within the restrictive CubeSat form factor. The electronic and mechanical interfaces are compatible with many off-the-shelf CubeSat systems and structures. The energy response of the GMOD engineering qualification model has been determined using radioactive sources, and an energy resolution of 5.4% at 662 keV has been measured. EIRSAT-1 will perform on-board processing of GMOD data. Trigger results, including light-curves and spectra, will be incorporated into the spacecraft beacon and transmitted continuously. Inexpensive hardware can be used to decode the beacon signal, making the data accessible to a wide community. GMOD will have scientific capability for the detection of gamma-ray bursts, in addition to the educational and technology demonstration goals of the EIRSAT-1 mission. The detailed design and measurements to date demonstrate the capability of GMOD in low Earth orbit, the scalability of the design for larger CubeSats and as an element of future large gamma-ray missions.
PubDate: 2022-06-01
- Two-mirror aplanatic telescopes with a flat field
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Abstract: Abstract A complete description is given of two-mirror telescopes with a flat medial focal surface, on which the images of stars are circles of least confusion. Particular attention is paid to aplanats, since their field of view is noticeably larger than that of classical systems. Two sets of appropriate solutions correspond to Schwarzschild and Gregorian telescopes. As a result, it becomes possible to use flat light detectors with wide-field two-mirror telescopes. New designs are of particular interest when as few reflective surfaces as possible are required, which is typical for space exploration and non-optical observations.
PubDate: 2022-06-01
- The removal method and generation mechanism of spikes in Insight-HXMT/HE
telescope-
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Abstract: Abstract Spikes are some obvious sharp increases that appear on the raw light curves of Insight-HXMT’s High Energy X-ray telescope(HE), which could have influences on data products like energy and power spectra. They are considered to be fake triggers generated by large signals. In this paper, we study the spikes’ characteristic and propose two methods to remove spikes from the raw data. According to the different influences on energy and power spectra, the best parameters for removing the spikes is selected and used in the Insight-HXMT data analysis software. The generation mechanism of spikes is also studied using the backup HE detectors on ground and the spikes can be reduced by the electronic design.
PubDate: 2022-06-01
- Development of a very faint meteor detection system based on an EMCCD
sensor and matched filter processing-
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Abstract: Abstract The mass ranges of meteors, imaged by electro-optical (EO) cameras and backscatter radar receivers, for the most part do not overlap. Typical EO systems detect meteoroid masses down to 10− 5 kg or roughly magnitude + 2 meteors when using moderate field of view optics, un-intensified optical components, and meteor entry velocities around 45 km/sec. This is near the high end of the mass range of typical meteor radar observations. Having the same mass meteor measured by different sensor wavelength bands would be a benefit in terms of calibrating mass estimations for both EO and radar. To that end, the University of Western Ontario (UWO) has acquired and deployed a very low light imaging system based on an electron-multiplying CCD camera technology. This embeds a very low noise, per pixel intensifier chip in a cooled camera setup with various options for frame rate, region of interest and binning. The EO system of optics and sensor was optimally configured to collect 32 frames per second in a square field of view 14.7 degrees on a side, achieving a single-frame stellar limiting magnitude of mG = + 10.5. The system typically observes meteors of + 6.5. Given this hardware configuration, we successfully met the challenges associated with the development of robust image processing algorithms, resulting in a new end-to-end processing pipeline now in operation since 2017. A key development in this pipeline has been the first true application of matched filter processing to process the faintest meteors possible in the EMCCD system while also yielding high quality automated metric measurements of meteor focal plane positions. With pairs of EMCCD systems deployed at two sites, triangulation and high accuracy orbits are one of the many products being generated by this system. These measurements will be coupled to observations from the Canadian Meteor Orbit Radar (CMOR) used for meteor plasma characterization and the Canadian Automated Meteor Observatory (CAMO) high resolution mirror tracking system.
PubDate: 2022-06-01
- Optimal performance of data transmission between Malaysia-China for
VLBI-based radio astronomy observation using Jive5ab-
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Abstract: Abstract A Very Long Baseline Interferometry (VLBI) station in Malaysia is significant to improve the coverage of the Asia-Oceania Network. This study investigates the transmission network performance between Malaysia and China through high bandwidth real-time data transfer using Malaysia Research and Education Network (MYREN) and China Science and Technology Network (CSTNET) for e-VLBI purposes. The transmission network tests and data transfer tests were conducted from two VLBI station locations: Universiti Malaya campus in Kuala Lumpur and the Biotechnology Research Centre in Jelebu, to the Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of Sciences. This research investigates data transfers using several different protocols; the File transfer protocol (FTP), user datagram protocol (UDP), and UDP-based data transfer (UDT) using Jive5ab software. Based on the results, the University Malaya network demonstrated its capability with a maximum throughput of 800 Mbps and an acceptable packet loss of 0.049%. Also, the Jive5ab-UDT protocol has the best performance, with a maximum throughput of 302.56 Mbps and 467.43 Mbps for the download and upload speeds, respectively. The results also confirm University Malaya as a suitable site to perform data transfer using its high-speed connection to SHAO.
PubDate: 2022-06-01
- Evaluating the night sky background directly from the signal images
detected by the ASTRI telescopes-
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Abstract: Abstract ASTRI-Horn is an Imaging Atmospheric Cherenkov Telescope characterized by a dual-mirror optical system with a primary mirror diameter of 4.3 m and a curved focal surface covered by silicon photomultiplier (SiPM) sensors managed by an innovative fast front-end electronics. ASTRI-Horn is installed in Italy at the INAF “M.C. Fracastoro” observing station (Mount Etna, Italy); it is the prototype of nine similar telescopes forming the ASTRI MiniArray that will be installed at the Teide Astronomical Observatory, in Tenerife (Canary Islands, Spain). In the ASTRI-Horn camera, the output signals from SiPMs are AC coupled to the front-end electronics stopping any slow varying signals. However, the random arrival of the night sky background photons produces fast fluctuations in the signal that the electronics is able to detect. The noise generated by this effect is proportional to the level of the diffuse night sky background. In this work, we present the analysis of the background data in ASTRI-Horn observations during the period December 2018–March 2019, using images of triggered showers. We compare the results relative to 2018 December 7-8 and 2019 March 6-7 nights with the contemporary night sky background fluxes measured by UVscope. This is a small auxiliary instrument mounted on the external structure of the ASTRI-Horn telescope and devoted to the night sky background evaluation in the UV band. A strong correlation between the considered data was detected. This correlation can be a diagnostic tool to assure the proper behavior of the ASTRI-Horn camera in view of the ASTRI MiniArray implementation. ASTRI-Horn is also equipped with the Variance technique able to sample the level of the pixel signals in absence of showers with an high rate. The method presented in this paper, based on shower images, is a new approach that has never been investigated until now. It does not substitute the Variance, that will the baseline for the background evaluation after exhaustive testings, but it is complementary to it when Variance data are available. This is the only one method working very well, that can be applied whenever the standard Variance method is not operative.
PubDate: 2022-06-01
- Monitoring fast solar chromospheric activity: the MeteoSpace project
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Abstract: Abstract We present in this reference paper an instrumental project dedicated to the monitoring of solar activity during solar cycle 25. It concerns the survey of fast evolving chromospheric events implied in Space Weather, such as flares, coronal mass ejections, filament instabilities and Moreton waves. Coronal waves are produced by large flares around the solar maximum and propagate with chromospheric counterparts; they are rare, faint, difficult to observe, and for that reason, challenging. They require systematic observations with automatic, fast and multi-channel optical instruments. MeteoSpace is a high cadence telescope assembly specially designed for that purpose. The large amount of data will be freely available to the solar community. We describe in details the optical design, the qualification tests and capabilities of the telescopes, and show how waves can be detected. MeteoSpace will be installed at Calern observatory (Côte d’Azur, 1270 m) and will be in full operation in 2023.
PubDate: 2022-06-01
- Unveiling unresolved stellar components from photometry
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Abstract: Abstract Space-born missions designed to search for exo-planets are providing us with high-precision photometric time series very well suited to measure the rotation period of solar- and lower-mass stars. Considering the large number of stars monitored during the mission life, the possibility to inspect each periodogram is out of question and, therefore, each method to search for rotation periods applied either individually or in combination is designed to automatically select the best rotation period estimate. In the case of unresolved binary stars it is possible to measure the rotation period of both components, when these are both variable and have comparable magnitude. On the other hand, the detection of two different rotation periods from the same photometric timeseries can represents a tool to unveil the binary nature of the star. In this paper, we present the case of the star TWA 23, a member of the young TWA association, as just one example of numerous cases. These may occur when the star is an unresolved binary and the variability of the secondary component is present in the time series. However, the frequency of the primary and dominant power peak in the periodogram, originating from the primary component, needs to be pre-whitened to allow the frequency of the secondary component to be detected. Considering the possible presence of undiscovered close binaries in the input catalogs of various ongoing or future missions aimed at exoplanet search, it becomes advisable to follow routinely this filtering approach to prevent to miss relevant information on the true binary nature of stars.
PubDate: 2022-06-01
- CUBES phase a design overview
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Abstract: Abstract We present the baseline conceptual design of the Cassegrain U-Band Efficient Spectrograph (CUBES) for the Very Large Telescope. CUBES will provide unprecedented sensitivity for spectroscopy on a 8 – 10 m class telescope in the ground ultraviolet (UV), spanning a bandwidth of ≥ 100 nm that starts at 300 nm, the shortest wavelength accessible from the ground. The design has been optimized for end-to-end efficiency and provides a spectral resolving power of R≥ 20000, that will unlock a broad range of new topics across solar system, Galactic and extraglactic astronomy. The design also features a second, lower-resolution (R \(\sim\) 7000) mode and has the option of a fiberlink to the UVES instrument for simultaneous observations at longer wavelengths. Here we present the optical, mechanical and software design of the various subsystems of the instrument after the Phase A study of the project. We discuss the expected performances for the layout choices and highlight some of the performance trade-offs considered to best meet the instrument top-level requirements. We also introduce the model-based system engineering approach used to organize and manage the project activities and interfaces, in the context that it is increasingly necessary to integrate such tools in the development of complex astronomical projects.
PubDate: 2022-05-24
- An autonomous lunar geophysical experiment package (ALGEP) for future
space missions-
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Abstract: Abstract Geophysical observations will provide key information about the inner structure of the planets and satellites and understanding the internal structure is a strong constraint on the bulk composition and thermal evolution of these bodies. Thus, geophysical observations are a key to uncovering the origin and evolution of the Moon. In this article, we propose the development of an autonomous lunar geophysical experiment package, composed of a suite of instruments and a central station with standardized interface, which can be installed on various future lunar missions. By fixing the interface between instruments and the central station, it would be possible to easily configure an appropriate experiment package for different missions. We describe here a series of geophysical instruments that may be included as part of the geophysical package: a seismometer, a magnetometer, a heat flow probe, and a laser reflector. These instruments will provide mechanical, thermal, and geodetic parameters of the Moon that are strongly related to the internal structure. We discuss the functionality required for future geophysical observations of the Moon, including the development of the central station that will be used commonly by different payloads.
PubDate: 2022-05-12
- Portraying the missing baryonic mass at the cosmic noon: the contribution
of CUBES-
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Abstract: Abstract The cosmological and galactic missing baryon problems are briefly reviewed with a particular focus on the contributions to the baryonic census derived from the analysis of quasar absorption spectra. The CUBES spectrograph foreseen for the ESO VLT, with its exceptional efficiency ( \(> 40\) %), blue wavelength coverage ( \(\lambda \simeq 300-405\) nm) and intermediate resolution ( \(R\simeq 24,000\) ) will allow us to tackle this issue with two approaches: using H i Lyman- \(\alpha\) lines at \(z \simeq 1.5-2.3\) , just after the peak of star formation, and using O vi absorbers at \(z \simeq 1.9-2.9\) , at the cosmic noon. In both cases, in order to derive the baryonic masses it will be necessary to acquire also higher-resolution spectra of the same target quasars to cover the region at longer wavelengths. We simulate the observations with the CUBES E2E simulator considering a sample of 40 bright quasars at redshifts \(z_\mathrm{em}\sim 2-3\) observed for a total time of \(\sim 13\) h to reach a signal-to-noise ratio of \(\sim 15\) in the H i Lyman- \(\alpha\) , O vi forests.
PubDate: 2022-04-30
- Mock HUBS observations of hot gas with IllustrisTNG
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Abstract: Abstract The lack of adequate X-ray observing capability is seriously impeding the progress in understanding the hot phase of circumgalactic medium (CGM), which is predicted to extend to the virial radius of a galaxy or beyond, and thus in acquiring key boundary conditions for studying galaxy evolution. To this end, the Hot Universe Baryon Surveyor (HUBS) is proposed. HUBS is designed to probe hot CGM by detecting its emission or absorption lines with a non-dispersive X-ray spectrometer of high resolution and high throughput. The spectrometer consists of a 60 × 60 array of microcalorimeters, with each detector providing an energy resolution of 2 eV, and is placed in the focal plane of an X-ray telescope of 1∘ field-of-view. With such a design, the spectrometer is highly optimized for detecting X-ray-emitting hot gas in the CGM of local galaxies, as well as in intra-group medium (IGrM), intra-cluster medium (ICM), or intergalactic medium (IGM). To assess the scientific potential of HUBS, in this work, we created mock observations of galaxies, groups, and clusters at different redshifts with the IllustrisTNG simulation. Focusing exclusively on emission studies, we took into account the effects of light cone, Galactic foreground emission, and background AGN contribution in the mock observations. From the observations, we made mock X-ray images and spectra, analyzed them to derive the properties of the emitting gas in each case, and compared the results with the input parameters from the simulation. The results show that HUBS is well suited for studying hot CGM at low redshifts. The redshift range is significantly extended for measuring IGrM and ICM. The sensitivity limits are also presented for detecting extended emission of low surface brightness.
PubDate: 2022-04-29
- Heavy elements
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Abstract: Abstract How are the heavy elements formed' This has been a key open question in physics for decades. Recent direct detections of neutron star mergers and observations of evolved stars show signatures of chemical elements in the blue range of their spectra that bear witness of recent nuclear processes that led to heavy element production. The formation of heavy elements typically takes place through neutron-capture reactions creating radioactive isotopes, which following beta-decay turn into the stable isotopes we today can measure indirectly in the surfaces of cool, low-mass stars or meteoritic grains. The conditions (such as the neutron density or entropy) of these n-capture reactions remain to date poorly constrained, and only through a multidisciplinary effort can we, by combining and comparing observations, experiments, and theoretical predictions, improve on one of the top 10 most important open physics questions posed at the turn of the century. This emphasises the need for detailed observations of the near-UV to blue wavelength region. The shortage of spectrographs and hence spectra covering this range with high-resolution and high signal-to-noise has for decades played a limiting factor in our understanding of how heavy elements form in the nuclear reactions as well as how they behave in the stellar surfaces. With CUBES (Cassegrain U-Band Efficient Spectrograph) we can finally improve the observations, by covering the crucial blue range in more remote stars and also achieve a higher signal-to-noise ratio (SNR). This is much needed to detect and accurately deblend the absorption lines and in turn derive more accurate and precise abundances of the heavy elements.
PubDate: 2022-04-28
- Closing gaps to our origins
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Abstract: Abstract This article reproduces the contents of the White Paper entitled by the same name submitted to the call issued by the European Space Agency soliciting ideas from the scientific community for the science themes that should be covered during the Voyage 2050 planning cycle. This contribution focus in the investigation of the emergence of life and the role that astronomy has to play in it. Three fundamental areas of activity are identified: [1] measuring the chemical enrichment of the Universe, [2] investigating planet formation and searching for exoplanets with signatures of life and, [3] determining the abundance of amino acids and the chemical routes to amino acid and protein growth in astronomical bodies. This proposal deals with the first two. The building blocks of life in the Universe began as primordial gas processed in stars and mixed at galactic scales. The mechanisms responsible for this development are not well-understood and have changed over the intervening 13 billion years. To follow the evolution of matter over cosmic time, it is necessary to study the strongest (resonance) transitions of the most abundant species in the Universe. Most of them are in the ultraviolet (UV; 950 Å - 3000 Å ) spectral range that is unobservable from the ground; the “missing” metals problem cannot be addressed without this access. Habitable planets grow in protostellar discs under ultraviolet irradiation, a by-product of the accretion process that drives the physical and chemical evolution of discs and young planetary systems. The electronic transitions of the most abundant molecules are pumped by this UV field that is the main oxidizing agent in the disc chemistry and provides unique diagnostics of the planet-forming environment that cannot be accessed from the ground. Knowledge of the variability of the UV radiation field is required for the astrochemical modelling of protoplanetary discs, to understand the formation of planetary atmospheres and the photochemistry of the precursors of life. Earth’s atmosphere is in constant interaction with the interplanetary medium and the solar UV radiation field. The exosphere of the Earth extends up to 35 planetary radii providing an amazing wealth of information on our planet’s winds and the atmospheric compounds. To access to it in other planetary systems, observation of the UV resonance transitions is required. The investigation for the emergence of life calls for the development of large astronomical facilities, including instrumentation in optical and UV wavelengths. In this contribution, the need to develop a large observatory in the optical and in the UV is revealed, in order to complete the scientific goals to investigate the origin of life, inaccessible through other frequencies in the electromagnetic spectrum.
PubDate: 2022-04-23
- Venus sample return mission revisited
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Abstract: Abstract A Venus sample return mission is very interesting from a scientific point of view, for example, analysing the composition of the soil will help us to understand the differences between Venus and Earth. However, such a mission is extremely challenging. On Venus the ground conditions are very harsh (460 °C, 9.6 MPa), the Delta V requirement from surface to orbit is close to the Earth case, and atmospheric drag means that a rocket launch must occur above 55 km and so an Unmanned Aerial Vehicle is required to lift the samples to rocket altitude. Sample return missions have been studied in depth by NASA/JPL and ESA, and in the former case the proposed profile involves several critical points, each with a significant probability of failure: Thermal exposure during sample drilling and ascent to launch altitude. Fast balloon inflation, at 55 km altitude. Difficulties to perform a rendezvous with an orbital vehicle if the upper stage is not manoeuvrable. The purpose of this paper is to propose new methods for meeting the challenge at each critical step and reducing the risks to such a mission. In particular, we propose two innovative methods for thermal control on the lander: advanced thermal insulation and phase change materials.
PubDate: 2022-04-22
DOI: 10.1007/s10686-022-09858-5
- Study of water Cherenkov detector to improve the angular resolution of an
air-shower array for ultra-high-energy gamma-ray observation-
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Abstract: Abstract For research on cosmic gamma rays with energies in the range of several tens of teraelectronvolts or more, we investigated a method to improve the angular resolution of an air shower. In an air shower, the density of secondary gamma rays is several times higher than that of electrons and those measurement is important for determining the shower direction. It was found that the angular resolution in the shower front-fit method decreases in inverse proportion to the square root of the number of measured particles. Even if the total number of measured particles is the same, secondary gamma rays contribute more to the improvement of angular resolution than electrons. If secondary gamma rays could be measured at an altitude of 4,740 m with a sensitivity of 100 %, an improvement of approximately 40 % was determined for a 500 TeV shower. A water Cherenkov detector with high gamma-ray sensitivity was investigated through Monte Carlo simulation. Detection efficiencies of approximately 0.38 and 0.76 were obtained for vertically incident gamma rays and electrons, respectively, using 19 8-inch diameter PMTs inside a detector installed in a water tank of radius 4.5 m and water depth 1.6 m. The detection time error for secondary gamma rays is approximately 2.18 ns at an incident angle of 0∘ and the standard error in the detection time for shower front particles was found to be approximately 10 times lower than that obtained by using a plastic scintillation detector with an area of 1 m2.
PubDate: 2022-04-14
DOI: 10.1007/s10686-022-09855-8
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