Measurement of the cosmic-ray energy spectrum above 2.5 × 10 18 eV using the Pierre Auger Observatory
Not Available
79 ASTRONOMY AND ASTROPHYSICS↗
Engineering topics
Bonifazi, C.
Publications and source records attributed to Bonifazi, C..
Features of the Energy Spectrum of Cosmic Rays above 2.5 × 10 18 eV Using the Pierre Auger Observatory
Not Available
79 ASTRONOMY AND ASTROPHYSICS↗
Studies on the response of a water-Cherenkov detector of the Pierre Auger Observatory to atmospheric muons using an RPC hodoscope
Extensive air showers, originating from ultra-high energy cosmic rays, have been successfully measured through the use of arrays of water-Cherenkov detectors (WCDs). Sophisticated analyses exploiting WCD data have made it possible to demonstrate that shower simulations, based on different hadronic-interaction models, cannot reproduce the observed number of muons at the ground. The accurate knowledge of the WCD response to muons is paramount in establishing the exact level of this discrepancy. In this work, we report on a study of the response of a WCD of the Pierre Auger Observatory to atmospheric muons performed with a hodoscope made of resistive plate chambers (RPCs), enabling us to select and reconstruct nearly 600 thousand single muon trajectories with zenith angles ranging from 0$^\circ$ to 55$^\circ$. Comparison of distributions of key observables between the hodoscope data and the predictions of dedicated simulations allows us to demonstrate the accuracy of the latter at a level of 2%. As the WCD calibration is based on its response to atmospheric muons, the hodoscope data are also exploited to show the long-term stability of the procedure.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Direct measurement of the muonic content of extensive air showers between 2 $\times$ 10 17 and 2 $\times$ 10 18 eV at the Pierre Auger Observatory
The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between 2 $\times$ 10 17 and 2 $\times$ 10 18 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at 10 17.5 eV and 10 18 eV. We find that, for the models to explain the data, an increase in the muon density of 38% $±$4%(12%) $±^{21\%}_{18\%}$ for EPOS-LHC, and of 50%(53%) $±$4%(13%) $±^{23\%}_{20\%}$ for QGSJETII-04, is respectively needed.
79 ASTRONOMY AND ASTROPHYSICS↗
Construction of precision wire readout planes for the Short-Baseline Near Detector (SBND)
The Short-Baseline Near Detector time projection chamber is unique in the design of its charge readout planes. These anode plane assemblies (APAs) have been fabricated and assembled to meet strict accuracy and precision requirements: wire spacing of 3 mm ± 0.5 mm and wire tension of 7 N ± 1 N across 3,964 wires per APA, and flatness within 0.5 mm over the 4 m × 2.5 m extent of each APA . Here, we describe the design, manufacture and assembly of these key detector components, with a focus on the quality assurance at each stage.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
A 3-Year Sample of Almost 1,600 Elves Recorded Above South America by the Pierre Auger Cosmic-Ray Observatory
Elves are a class of transient luminous events, with a radial extent typically greater than 250 km, that occur in the lower ionosphere above strong electrical storms. We report the observation of 1,598 elves, from 2014 to 2016, recorded with unprecedented time resolution (100 ns) using the fluorescence detector (FD) of the Pierre Auger Cosmic-Ray Observatory. The Auger Observatory is located in the Mendoza province of Argentina with a viewing footprint for elve observations of 3∙10sup>6 km ₂, reaching areas above the Pacific and Atlantic Oceans, as well as the Córdoba region, which is known for severe convective thunderstorms. Primarily designed for ultrahigh energy cosmic-ray observations, the Auger FD turns out to be very sensitive to the ultraviolet emission in elves. The detector features modified Schmidt optics with large apertures resulting in a field of view that spans the horizon, and year-round operation on dark nights with low moonlight background, when the local weather is favorable. The measured light profiles of 18% of the elve events have more than one peak, compatible with intracloud activity. Within the 3-year sample, 72% of the elves correlate with the far-field radiation measurements of the World Wide Lightning Location Network. The Auger Observatory plans to continue operations until at least 2025, including elve observations and analysis. To the best of our knowledge, this observatory is the only facility on Earth that measures elves with year-round operation and full horizon coverage.
79 ASTRONOMY AND ASTROPHYSICS↗
Satellite Particle Collection During Active States of the Tethered Satellite System (TSS)
The reflight of the Tethered Satellite System (TSS-1R) was carried aboard the Space Shuttle Columbia on February 22, 1996. After deploying a day later than planned, the satellite almost reached its full deployed distance before the tether broke. Data was collected for over 5 hours during deployment out to a distance of 19.7 km. Maximum emf attained during deployment was 3700 V while the maximum current achieved was just under 0.5 A. The current collected was factors of 2 to 4 greater than the predictions of the conventional Parker-Murphy theory. The microscopic view of the collection process at the satellite showed exotic behavior with the existence of 100 - 200 eV suprathermal electrons and significant spin phase modulation of the electron fluxes. Although the data set acquired from TSS- 1R was considerably less than planned, the quality of the data allows one of the main goals of the mission to be met--characterizing the system I-V response. A "quick look" assessment of the data has already shown that an understanding of the TSS-1R electrodynamic behavior will require modification of the standard picture of current collection in space plasmas
Wright, K. H., Jr.↗
TSS-1 - Orbiter current and voltage experiments
Although the deployment distance of the TSS-1 tethered satellite was only about 1 percent of nominal, experiments to study the current collection and vehicle charging effects at low voltages were performed. We present measurements of Orbiter charging resulting from electron beam emission from the Orbiter, currents in the TSS system with and without electron beam emissions, and the effects of Orbiter thrusters on charging and currents. Generally, charging induced by beam emission was limited to a few volts, though during times with low ambient plasma density the Orbiter was charged up to 80 V. Thrusters are seen to enhance Orbiter charging during beam emission, and reduce ion current collection at other times.
Thompson, D. C.↗
Experimental characterization of hollow-cathode plasma sources at Frascati
An experimental characterization has been conducted for hollow cathodes applicable as plasma contactors on Space Shuttle-based experiments. The diagnostics tests were conducted in an 0.5 cu m vacuum chamber by means of Langmuir probes at various distances from the source. Two electron populations are noted, one in the 0.3-1 eV and the other in the 7-11 eV temperature range. Current developments in the design of plasma chambers incorporating magnetic field compensation are noted.
Vannaroni, G.↗
Laboratory simulation of the electrodynamic interactions of a tethered satellite with an ionospheric plasma
An improved experimental set-up in the Orleans Plasma Chamber allowed investigations of the I-V characteristics of a conductive spherical body (10 cm diameter) in a plasma environment. Moreover, the influence of a transversal magnetic field at 0.6 and 1.2 G was investigated, for the first time, both on the sheath potential profile and current collection. Floating potential profiles were measured at 16 different radial distances from the test body up to 9 body radii in 8 different angular positions. The test body potential could be increased in the range from -200 V up to +100 V. Preliminary results are shown and discussed.
Bonifazi, C.↗
Tethered Satellite System (TSS) core equipment
To date, three Tethered Satellite System (TSS) missions of the Italian provided scientific satellite orbiting in the ionosphere connected to U.S. Space Shuttle is foreseen. The first mission will use an electrically conductive tether of 20 km deployed upward from the orbiter flying at 300 km altitude. This mission will allow investigation of the TSS electrodynamic interaction with the ionosphere due to the high voltage induced across the two terminators of the system during its motion throughout the geomagnetic field. The second mission will use a dielectric tether of 100 km deployed downward from the Orbiter flying at 230 km altitude. Tethered-vehicle access to altitude as low as 120 to 150 km from the Orbiter would permit direct long term observation of phenomena in the lower thermosphere and determination of other dynamical physical processes. The third mission would use the same configuration of the first electrodynamic mission with the complete Core Equipment. Study of power generation by tethered systems would be possible by operating the Core Equipment in the inverted current mode. This mode of operation would allow ion current collection upon the TSS satellite by controlling its potential with respect to the ambient ionospheric plasma. The main requirements of the Core Equipment configuration to date foreseen for the first TSS electrodynamic mission is described. Besides the Core Equipment purposes, its hardware and operational sub-modes of operation are described.
Bonifazi, C.↗
Solar wind deceleration and MHD turbulence in the earth's foreshock region - ISEE 1 and 2 and IMP 8 observations
The interaction of the solar wind with ions backstreaming from the earth's bow shock is investigated using plasma and magnetic field measurements on ISEE 1 and 2 and IMP 8 at widely separated positions in the earth's foreshock. This technique separates temporal and spatial variations within the foreshock. It is found that the solar wind acceleration associated with backstreaming ions is correlated with the amplitude of the MHD turbulence, and that the largest decelerations are seen close to the bow shock. The density of the backstreaming ion beam is strongly correlated with distance from the shock, and decreases by about a factor of three in a distance of about 3R(e).
Bonifazi, C.↗
Deceleration of the solar wind in the earth's foreshock region - Isee 2 and Imp 8 observations
The deceleration of the solar wind in the region of the interplanetary space filled by ions backstreaming from the earth's bow shock and associated waves is studied using a two-spacecraft technique. This deceleration depends on the solar wind bulk velocity; at low velocities (below 300 km/s) the velocity decrease is about 5 km/s, while at higher velocities (above 400 km/s) the decrease may be as large as 30 km/s. The energy balance shows that the kinetic energy loss far exceeds the thermal energy which is possibly gained by the solar wind; therefore at least part of this energy must go into waves and/or into the backstreaming ions.
Bonifazi, C.↗
Deceleration of the solar wind in the Earth foreshock region: ISEE 2 and IMP 8 observations
The deceleration of the solar wind in the region of the interplanetary space filled by ions backstreaming from the Earth bow shock was studied using a two spacecraft technique. This deceleration, which is correlated with the "diffuse" but not with the "reflected" ion population, depends on the solar wind bulk velocity: at low velocities (below 300 km/sec) the velocity decrease is about 5 km/sec, while at higher velocities (above 400 km/sec) the decrease may be as large as 30 km/sec. Along with this deceleration, the solar wind undergoes a deflection of about 1 deg away from the direction of the Earth bow shock. The energy balance shows that the kinetic energy loss far exceeds the thermal energy which is possibly gained by the solar wind, therefore, at least part of this energy must go into waves and/or into the backstreaming ions.
Bonifazi, C.↗