arXiv subjects

L. Marcelli

Publications and source records attributed to L. Marcelli.

At least 37 records · Page 2Linked to original sources

arXiv2020

Time dependence of the flux of helium nuclei in cosmic rays measured by the PAMELA experiment between July 2006 and December 2009

Precise time-dependent measurements of the Z = 2 component in the cosmic radiation provide crucial information about the propagation of charged particles through the heliosphere. The PAMELA experiment, with its long flight duration (15th June 2006 - 23rd January 2016) and the low energy threshold (80 MeV/n) is an ideal detector for cosmic ray solar modulation studies. In this paper, the helium nuclei spectra measured by the PAMELA instrument from July 2006 to December 2009 over a Carrington rotation time basis are presented. A state-of-the-art three-dimensional model for cosmic-ray propagation inside the heliosphere was used to interpret the time-dependent measured fluxes. Proton-to-helium flux ratio time profiles at various rigidities are also presented in order to study any features which could result from the different masses and local interstellar spectra shapes.

astro-ph.HE↗

arXiv2019

Mini-EUSO data acquisition and control software

We present the data acquisition and control software for the operation of the Mini-Extreme Universe Space Observatory (EUSO), a space-based fluorescence telescope for the observation of extensive air showers and atmospheric phenomena. This framework has been extensively tested alongside the development of Mini-EUSO and was finalized ahead of the successful launch of the instrument to the ISS on August 22, 2019. The data acquisition, housekeeping, and subsystem control are achieved using custom-designed front-end electronics based on a Xilinx Zynq XC7Z030 chip interfaced with a PCIe/104 CPU module via the integrated Zynq processing system. The instrument control interface is handled using an object-oriented C++ design, which can be run both autonomously and interactively as required. Although developed for Mini-EUSO, the modular design of both the software and hardware can easily be scaled up to larger instrument designs and adapted to different subsystem and communication requirements. As such, this framework will also be used in the upgrade of the EUSO-TA instrument and potentially for the next EUSO-SPB2 NASA Balloon flight. The software and firmware presented are open source and released with detailed and integrated documentation.

astro-ph.IM↗

arXiv2019

Mini-EUSO experiment to study UV emission of terrestrial and astrophysical origin onboard of the International Space Station

Mini-EUSO will observe the Earth in the UV range (300 - 400 nm) offering the opportunity to study a variety of atmospheric events such as Transient Luminous Events (TLEs), meteors and marine bioluminescence. Furthermore it aims to search for Ultra High Energy Cosmic Rays (UHECR) above $10^{21}$ eV and Strange Quark Matter (SQM). The detector is expected to be launched to the International Space Station in August 2019 and look at the Earth in nadir mode from the UV-transparent window of the Zvezda module of the International Space Station. The instrument comprises a compact telescope with a large field of view ($44^{\circ}$), based on an optical system employing two Fresnel lenses for light collection. The light is focused onto an array of 36 multi-anode photomultiplier tubes (MAPMT), for a total of 2304 pixels and the resulting signal is converted into digital, processed and stored via the electronics subsystems on-board. In addition to the main detector, Mini-EUSO contains two ancillary cameras for complementary measurements in the near infrared (1500 - 1600 nm) and visible (400 - 780 nm) range and also a 8x8 SiPM imaging array.

astro-ph.IM↗

arXiv2019

Space Debris detection and tracking with the techniques of cosmic ray physics

Space Debris (SD) consist of non-operational artificial objects orbiting around the Earth, which could possibly damage space vehicles, such as the International Space Station (ISS) or other manned spacecrafts. The vast majority of such objects are cm-sized, not catalogued and usually the tracking data are not precise enough. Here we present the feasibility study of SD detection and tracking with techniques usually employed in cosmic-ray physics. For this purpose, we have evaluated the possibility of using Mini-EUSO, a space-borne fluorescence telescope to be deployed on the ISS, to track SD illuminated by the Sun. By means of ESAF (EUSO Simulation and analysis Framework) simulation and by developing the trigger algorithms, we estimated the minimum size and maximum distances of detectable SD. We then studied the number of possible SD detections using an ESA software called MASTER (Meteoroid and SD Terrestrial Environment Reference). With the Mini-EUSO Engineering Model (Mini-EUSO EM), we performed some measurements to estimate the reflectance of the most common SD materials and to demonstrate the ability of Mini-EUSO to detect SD events. We also performed some tests in open-sky conditions, identifying and tracking fast-moving objects. In particular, the detection of a rocket body allowed us to confirm the simulation outcomes predictions and the expected performance of the detector.

astro-ph.IM↗

arXiv2019

Mini-EUSO engineering model: tests in open-sky condition

Mini-EUSO is a UV telescope that will look downwards to the Earth's atmosphere onboard the International Space Station. With the design of the ultra-high energy cosmic ray fluorescence detectors belonging to the JEM-EUSO program, it will make the first UV map of the Earth by observing atmospheric phenomena such as transient luminous events, sprites and lightning, as well as meteors and bioluminescence from earth. Diffused light from laser shots from the ground, which mimic the fluorescence light emitted by Nitrogen molecules when extensive air showers pass through the atmosphere, can be used to verify the capability of this kind of detector to observe ultra-high energy cosmic rays. To validate the electronics and the trigger algorithms developed for Mini-EUSO, a scaled down version of the telescope with 1:9 of the original focal surface and a lens of 2.5 cm diameter has been built. Tests of the Mini-EUSO engineering model have been made in laboratory and in open sky condition. In this paper, we report results of observations of the night sky, which include the detection of stars, meteors, a planet and a rocket body reflecting the sunlight. Interesting results of the observation of city lights are also reported.

astro-ph.HE↗

arXiv2019

The EUSO@TurLab: Test of Mini-EUSO Engineering Model

The TurLab facility is a laboratory, equipped with a 5 m diameter and 1 m depth rotating tank, located in the Physics Department of the University of Turin. Originally, it was mainly built to study systems of different scales where rotation plays a key role in the fluid behavior such as in atmospheric and oceanic flows. In the past few years the TurLab facility has been used to perform experiments related to the observation of Extreme Energy Cosmic Rays (EECRs) from space using the fluorescence technique. For example, in the case of the JEM-EUSO mission, where the diffuse night brightness and artificial light sources can vary significantly in time and space inside the Field of View of the telescope. The Focal Surface of Mini-EUSO Engineering Model (Mini-EUSO EM) with the level 1 (L1) and 2 (L2) trigger logics implemented in the Photo-Detector Module (PDM) has been tested at TurLab. Tests related to the possibility of using an EUSO-like detector for other type of applications such as Space Debris (SD) monitoring and imaging detector have also been pursued. The tests and results obtained within the EUSO@TurLab Project on these different topics are presented.

astro-ph.IM↗

arXiv2018

Solar energetic particle events observed by the PAMELA mission

Despite the significant progress achieved in recent years, the physical mechanisms underlying the origin of solar energetic particles (SEPs) are still a matter of debate. The complex nature of both particle acceleration and transport poses challenges to developing a universal picture of SEP events that encompasses both the low-energy (from tens of keV to a few hundreds of MeV) observations made by space-based instruments and the GeV particles detected by the worldwide network of neutron monitors in ground-level enhancements (GLEs). The high-precision data collected by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment offer a unique opportunity to study the SEP fluxes between $\sim$80 MeV and a few GeV, significantly improving the characterization of the most energetic events. In particular, PAMELA can measure for the first time with good accuracy the spectral features at moderate and high energies, providing important constraints for current SEP models. In addition, the PAMELA observations allow the relationship between low and high-energy particles to be investigated, enabling a clearer view of the SEP origin. No qualitative distinction between the spectral shapes of GLE, sub-GLE and non-GLE events is observed, suggesting that GLEs are not a separate class, but are the subset of a continuous distribution of SEP events that are more intense at high energies. While the spectral forms found are to be consistent with diffusive shock acceleration theory, which predicts spectral rollovers at high energies that are attributed to particles escaping the shock region during acceleration, further work is required to explore the relative influences of acceleration and transport processes on SEP spectra.

astro-ph.SR↗

arXiv2018

Lithium and Beryllium isotopes with the PAMELA experiment

The cosmic-ray lithium and beryllium ($^{6}$Li, $^{7}$Li, $^{7}$Be, $^{9}$Be, $^{10}$Be) isotopic composition has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. The rare lithium and beryllium isotopes in cosmic rays are believed to originate mainly from the interaction of high energy carbon, nitrogen and oxygen nuclei with the interstellar medium (ISM), but also on "tertiary" interactions in the ISM (i.e. produced by further fragmentation of secondary beryllium and boron). In this paper the isotopic ratios $^{7}$Li/$^{6}$Li and $^{7}$Be/($^{9}$Be + $^{10}$Be) measured between 150 and 1100 MeV/n using two different detector systems from July 2006 to September 2014 will be presented.

astro-ph.HE↗

arXiv2018

Evidence of energy and charge sign dependence of the recovery time for the December 2006 Forbush event measured by the PAMELA experiment

New results on the short-term galactic cosmic ray (GCR) intensity variation (Forbush decrease) in December 2006 measured by the PAMELA instrument are presented. Forbush decreases are sudden suppressions of the GCR intensities which are associated with the passage of interplanetary transients such as shocks and interplanetary coronal mass ejections (ICMEs). Most of the past measurements of this phenomenon were carried out with ground-based detectors such as neutron monitors or muon telescopes. These techniques allow only the indirect detection of the overall GCR intensity over an integrated energy range. For the first time, thanks to the unique features of the PAMELA magnetic spectrometer, the Forbush decrease commencing on 2006 December 14, following a CME at the Sun on 2006 December 13 was studied in a wide rigidity range (0.4 - 20 GV) and for different species of GCRs detected directly in space. The daily averaged GCR proton intensity was used to investigate the rigidity dependence of the amplitude and the recovery time of the Forbush decrease. Additionally, for the first time, the temporal variations in the helium and electron intensities during a Forbush decrease were studied. Interestingly, the temporal evolutions of the helium and proton intensities during the Forbush decrease were found in good agreement, while the low rigidity electrons (< 2 GV) displayed a faster recovery. This difference in the electron recovery is interpreted as a charge-sign dependence introduced by drift motions experienced by the GCRs during their propagation through the heliosphere.

astro-ph.HE↗

arXiv2018

Ten Years of PAMELA in Space

The PAMELA cosmic ray detector was launched on June 15th 2006 on board the Russian Resurs-DK1 satellite, and during ten years of nearly continuous data-taking it has observed new interesting features in cosmic rays (CRs). In a decade of operation it has provided plenty of scientific data, covering different issues related to cosmic ray physics. Its discoveries might change our basic vision of the mechanisms of production, acceleration and propagation of cosmic rays in the Galaxy. The antimatter measurements, focus of the experiment, have set strong constraints to the nature of Dark Matter. Search for signatures of more exotic processes (such as the ones involving Strange Quark Matter) was also pursued. Furthermore, the long-term operation of the instrument had allowed a constant monitoring of the solar activity during its maximum and a detailed and prolonged study of the solar modulation, improving the comprehension of the heliosphere mechanisms. PAMELA had also measured the radiation environment around the Earth, and it detected for the first time the presence of an antiproton radiation belt surrounding our planet. The operation of Resurs-DK1 was terminated in 2016. In this article we will review the main features of the PAMELA instrument and its constructing phases. Main part of the article will be dedicated to the summary of the most relevant PAMELA results over a decade of observation

astro-ph.HE↗

arXiv2018

Unexpected cyclic behavior in cosmic ray protons observed by PAMELA at 1 AU

Protons detected by the PAMELA experiment in the period 2006-2014 have been analyzed in the energy range between 0.40-50 GV to explore possible periodicities besides the well known solar undecennial modulation. An unexpected clear and regular feature has been found at rigidities below 15 GV, with a quasi-periodicity of $\sim$450 days. A possible Jovian origin of this periodicity has been investigated in different ways. The results seem to favor a small but not negligible contribution to cosmic rays from the Jovian magnetosphere, even if other explanations cannot be excluded.

physics.space-ph↗

arXiv2018

Proton fluxes measured by the PAMELA experiment from the minimum to the maximum solar activity for the 24th solar cycle

Precise measurements of the time-dependent intensity of the low energy ($<50$ GeV) galactic cosmic rays are fundamental to test and improve the models which describe their propagation inside the heliosphere. Especially, data spanning different solar activity periods, i.e. from minimum to maximum, are needed to achieve comprehensive understanding of such physical phenomenon. The minimum phase between the 23$^{rd}$ and the 24$^{th}$ solar cycles was peculiarly long, extending up to the beginning of 2010 and followed by the maximum phase, reached during early 2014. In this paper, we present proton differential spectra measured from January 2010 to February 2014 by the PAMELA experiment. For the first time the galactic cosmic ray proton intensity was studied over a wide energy range (0.08-50 GeV) by a single apparatus from a minimum to a maximum period of solar activity. The large statistics allowed the time variation to be investigated on a nearly monthly basis. Data were compared and interpreted in the context of a state-of-the-art three-dimensional model describing the galactic cosmic rays propagation through the heliosphere.

physics.space-ph↗

arXiv2017

Secondary positrons and electrons measured by PAMELA experiment

We present a measurements of electron and positron fluxes below the geomagnetic cutoff rigidity in wide energy range from 50 MeV to several GeV by the PAMELA magnetic spectrometer. The instrument was launched on June 15th 2006 on-board the Resurs-DK satellite on low orbit with 70 degrees inclination and altitude between 350 and 600 km. The procedure of trajectories calculations in the geomagnetic field separates stably trapped and albedo components produced in interactions of cosmic ray protons with the residual atmosphere from galactic cosmic rays. Features of spatial distributions of secondary electrons and positrons in the near Earth space, including the South Atlantic Anomaly, were investigated.

astro-ph.HE↗

arXiv2016

Geomagnetically trapped, albedo and solar energetic particles: trajectory analysis and flux reconstruction with PAMELA

The PAMELA satellite experiment is providing comprehensive observations of the interplanetary and magnetospheric radiation in the near-Earth environment. Thanks to its identification capabilities and the semi-polar orbit, PAMELA is able to precisely measure the energetic spectra and the angular distributions of the different cosmic-ray populations over a wide latitude region, including geomagnetically trapped and albedo particles. Its observations comprise the solar energetic particle events between solar cycles 23 and 24, and the geomagnetic cutoff variations during magnetospheric storms. PAMELA's measurements are supported by an accurate analysis of particle trajectories in the Earth's magnetosphere based on a realistic geomagnetic field modeling, which allows the classification of particle populations of different origin and the investigation of the asymptotic directions of arrival.

physics.space-ph↗

arXiv2016

Time dependence of the electron and positron components of the cosmic radiation measured by the PAMELA experiment between July 2006 and December 2015

Cosmic-ray electrons and positrons are a unique probe of the propagation of cosmic rays as well as of the nature and distribution of particle sources in our Galaxy. Recent measurements of these particles are challenging our basic understanding of the mechanisms of production, acceleration and propagation of cosmic rays. Particularly striking are the differences between the low energy results collected by the space-borne PAMELA and AMS-02 experiments and older measurements pointing to sign-charge dependence of the solar modulation of cosmic-ray spectra. The PAMELA experiment has been measuring the time variation of the positron and electron intensity at Earth from July 2006 to December 2015 covering the period for the minimum of solar cycle 23 (2006-2009) till the middle of the maximum of solar cycle 24, through the polarity reversal of the heliospheric magnetic field which took place between 2013 and 2014. The positron to electron ratio measured in this time period clearly shows a sign-charge dependence of the solar modulation introduced by particle drifts. These results provide the first clear and continuous observation of how drift effects on solar modulation have unfolded with time from solar minimum to solar maximum and their dependence on the particle rigidity and the cyclic polarity of the solar magnetic field.

astro-ph.HE↗

arXiv2016

PAMELA's measurements of geomagnetic cutoff variations during the 14 December 2006 storm

Data from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment were used to measure the geomagnetic cutoff for high-energy (>80 MeV) protons during the 14 December 2006 geomagnetic storm. The variations of the cutoff latitude as a function of rigidity were studied on relatively short timescales, corresponding to spacecraft orbital periods (94 min). Estimated cutoff values were compared with those obtained by means of a trajectory tracing approach based on a dynamical empirical modeling of the Earth's magnetosphere. We found significant variations in the cutoff latitude, with a maximum suppression of about 7 deg at lowest rigidities during the main phase of the storm. The observed reduction in the geomagnetic shielding and its temporal evolution were related to the changes in the magnetospheric configuration, investigating the role of interplanetary magnetic field, solar wind and geomagnetic parameters. PAMELA's results represent the first direct measurement of geomagnetic cutoffs for protons with kinetic energies in the sub-GeV and GeV region.

physics.space-ph↗

arXiv2015

Measurements of Cosmic-Ray Hydrogen and Helium Isotopes with the PAMELA experiment

The cosmic-ray hydrogen and helium ($^1$H, $^2$H, $^3$He, $^4$He) isotopic composition has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. The rare isotopes $^2$H and $^3$He in cosmic rays are believed to originate mainly from the interaction of high energy protons and helium with the galactic interstellar medium. The isotopic composition was measured between 100 and 1100 MeV/n for hydrogen and between 100 and 1400 MeV/n for helium isotopes using two different detector systems over the 23rd solar minimum from July 2006 to December 2007.

astro-ph.HE↗

arXiv2015

Time dependence of the e^- flux measured by PAMELA during the July 2006 - December 2009 solar minimum

Precision measurements of the electron component in the cosmic radiation provide important information about the origin and propagation of cosmic rays in the Galaxy not accessible from the study of the cosmic-ray nuclear components due to their differing diffusion and energy-loss processes. However, when measured near Earth, the effects of propagation and modulation of galactic cosmic rays in the heliosphere, particularly significant for energies up to at least 30 GeV, must be properly taken into account. In this paper the electron (e^-) spectra measured by PAMELA down to 70 MeV from July 2006 to December 2009 over six-months time intervals are presented. Fluxes are compared with a state-of-the-art three-dimensional model of solar modulation that reproduces the observations remarkably well.

astro-ph.SR↗