Precision measurements of the positron component in the cosmic radiation provide important information about the propagation of cosmic rays and the nature of particle sources in our Galaxy. The ...satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray positron flux and fraction that extends previously published measurements up to 300 GeV in kinetic energy. The combined measurements of the cosmic-ray positron energy spectrum and fraction provide a unique tool to constrain interpretation models. During the recent solar minimum activity period from July 2006 to December 2009, approximately 24,500 positrons were observed. The results cannot be easily reconciled with purely secondary production, and additional sources of either astrophysical or exotic origin may be required.
The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray antiproton flux and the antiproton-to-proton flux ratio which extends previously published measurements ...down to 60 MeV and up to 180 GeV in kinetic energy. During 850 days of data acquisition approximately 1500 antiprotons were observed. The measurements are consistent with purely secondary production of antiprotons in the Galaxy. More precise secondary production models are required for a complete interpretation of the results.
The energy spectra of galactic cosmic rays carry fundamental information regarding their origin and propagation. These spectra, when measured near Earth, are significantly affected by the solar ...magnetic field. A comprehensive description of the cosmic radiation must therefore include the transport and modulation of cosmic rays inside the heliosphere. During the end of the last decade, the Sun underwent a peculiarly long quiet phase well suited to study modulation processes. In this paper we present proton spectra measured from 2006 July to 2009 December by PAMEFA. The large collected statistics of protons allowed the time variation to be followed on a nearly monthly basis down to 400 MV. Data are compared with a state-of-the-art three-dimensional model of solar modulation.
The propagation of cosmic rays inside our galaxy plays a fundamental role in shaping their injection spectra into those observed at Earth. One of the best tools to investigate this issue is the ratio ...of fluxes for secondary and primary species. The boron-to-carbon (B/C) ratio, in particular, is a sensitive probe to investigate propagation mechanisms. This paper presents new measurements of the absolute fluxes of boron and carbon nuclei as well as the B/C ratio from the PAMELA space experiment. The results span the range 0.44-129 GeV/n in kinetic energy for data taken in the period 2006 July to 2008 March.
Precision measurements of the electron component in the cosmic radiation provide important information about the origin and propagation of cosmic rays in the Galaxy. Here we present new results ...regarding negatively charged electrons between 1 and 625 GeV performed by the satellite-borne experiment PAMELA. This is the first time that cosmic-ray e⁻ have been identified above 50 GeV. The electron spectrum can be described with a single power-law energy dependence with spectral index -3.18 ± 0.05 above the energy region influenced by the solar wind (> 30 GeV). No significant spectral features are observed and the data can be interpreted in terms of conventional diffusive propagation models. However, the data are also consistent with models including new cosmic-ray sources that could explain the rise in the positron fraction.
ABSTRACT The cosmic-ray hydrogen and helium (1H, 2H, 3He, 4He) 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 2006 June 15. The rare isotopes 2H and 3He 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 2006 July to 2007 December.
Abstract
The multi-TeV energy region of the cosmic-ray spectra has
been recently explored by direct detection experiments that used
calorimetric techniques to measure the energy of the cosmic
...particles. Interesting spectral features have been observed in both
all-electron and nuclei spectra. However, the interpretation of the
results is compromised by the disagreements between the data
obtained from the various experiments, that are not reconcilable
with the quoted experimental uncertainties. Understanding the
reason for the discrepancy among the measurements is of fundamental
importance in view of the forthcoming high-energy cosmic-ray
experiments planned for space, as well as for the correct
interpretation of the available results.
The purpose of this work is to investigate the possibility that a
systematic effect may derive from the non-proportionality of the
light response of inorganic crystals, typically used in high-energy
calorimetry due to their excellent energy-resolution performance.
The main reason for the non-proportionality of the crystals is that
scintillation light yield depends on ionisation density.
Experimental data obtained with ion beams were used to characterize
the light response of various scintillator materials. The obtained
luminous efficiencies were used as input of a Monte Carlo simulation
to perform a comparative study of the effect of the light-yield
non-proportionality on the detection of high-energy electromagnetic
and hadronic showers. The result of this study indicates that, if
the calorimeter response is calibrated by using the energy deposit
of minimum ionizing particles, the measured shower energy might be
affected by a significant systematic shift, at the level of few
percent, whose sign and magnitude depend specifically on the type of
scintillator material used.
Future detection of extensive air showers (EAS) produced by ultra high energy cosmic particles by means of space-based fluorescence telescopes will open a new window on the universe and allow cosmic ...ray and neutrino astronomy at a level that is virtually impossible for ground based detectors. In the context of the extreme universe space observatory (EUSO) project, an end-to-end simulation of EAS observation with a spatial detector has been designed (EUSO simulation and analysis framework, ESAF). This paper describes the detailed Monte-Carlo developed to simulate all the physical processes involved in the fluorescence detection technique, from the EAS development to the instrument response. Particular emphasis is given to modeling the light propagation in the atmosphere and the effect of clouds. The simulation is used to assess the performances of EAS spatial detection. Main results on energy threshold and resolution, direction resolution and
X
max determination are reported. Results are based on EUSO telescope design, but are also extended to larger and more sensitive detectors.
Abstract
The measurement of cosmic-ray individual spectra provides
unique information regarding the origin and propagation of
astro-particles. Due to the limited acceptance of current space
...experiments, protons and nuclei around the “knee” region
(∼ 1 PeV) can only be observed by ground based
experiments. Thanks to an innovative design, the High Energy
cosmic-Radiation Detection (HERD) facility will allow direct
observation up to this energy region: the instrument is mainly based
on a 3D segmented, isotropic and homogeneous calorimeter which
properly measures the energy of particles coming from each direction
and it will be made of about 7500 LYSO cubic crystals. The read-out
of the scintillation light is done with two independent systems: the
first one based on wave-length shifting fibers coupled to
Intensified scientific CMOS cameras, the second one is made of two
photo-diodes with different active areas connected to a custom
front-end electronics. This photo-diode system is designed to
achieve a huge dynamic range, larger than 10
7
, while having a
small power consumption, few mW per channel. Thanks to a good
signal-to-noise ratio, the capability of a proper calibration, by
using signals of both non-interacting and showering particles, is
also guaranteed. In this paper, the current design and the
performance obtained by several tests of the photo-diode read-out
system are discussed.
Boron Isotopes in the PAMELA Experiment Bogomolov, E. A.; Vasilyev, G. I.; Menn, W. ...
Physics of atomic nuclei,
2024, Letnik:
87, Številka:
2
Journal Article
Recenzirano
In this work, a new analysis of the isotopic composition of boron nuclei (B) in galactic cosmic rays (GCRs) in the range of rigidities of 1–5 GV (nuclear energies 0.1–1.5 GeV/nucleon) was carried out ...using data from the PAMELA space experiment 2006–2014 on the rigidity of detected nuclei and their velocity (time-of-flight analysis and ionization losses in the instrument’s multilayer calorimeter). The new results of the PAMELA experiment expand the energy range of previous measurements, are consistent with the few existing data, and indicate deviations of the B isotope ratios from the GALPROP simulation data for the GCR, similar to the deviations for the Li and Be isotopes in the PAMELA data, which can be interpreted as evidence of observation against the background of the GCR of the contribution of several local sources from explosions of nearby (hundreds of parsecs) supernovae.
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