| 1. |
- Adriani, O., et al.
(författare)
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An anomalous positron abundance in cosmic rays with energies 1.5-100 GeV
- 2009
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 458:7238, s. 607-609
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Tidskriftsartikel (refereegranskat)abstract
- Antiparticles account for a small fraction of cosmic rays and are known to be produced in interactions between cosmic-ray nuclei and atoms in the interstellar medium(1), which is referred to as a 'secondary source'. Positrons might also originate in objects such as pulsars(2) and microquasars(3) or through dark matter annihilation(4), which would be 'primary sources'. Previous statistically limited measurements(5-7) of the ratio of positron and electron fluxes have been interpreted as evidence for a primary source for the positrons, as has an increase in the total electron+positron flux at energies between 300 and 600 GeV (ref. 8). Here we report a measurement of the positron fraction in the energy range 1.5-100 GeV. We find that the positron fraction increases sharply overmuch of that range, in a way that appears to be completely inconsistent with secondary sources. We therefore conclude that a primary source, be it an astrophysical object or dark matter annihilation, is necessary.
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| 2. |
- Adriani, O., et al.
(författare)
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New Measurement of the Antiproton-to-Proton Flux Ratio up to 100 GeV in the Cosmic Radiation
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5
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Tidskriftsartikel (refereegranskat)abstract
- A new measurement of the cosmic-ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 above an energy of 20 GeV. The high-energy results are a tenfold improvement in statistics with respect to all previously published data. The data follow the trend expected from secondary production calculations and significantly constrain contributions from exotic sources, e. g., dark matter particle annihilations.
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| 3. |
- Adriani, O., et al.
(författare)
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Positrons and electrons in primary cosmic rays as measured in the PAMELA experiment
- 2009
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Ingår i: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 73:5, s. 568-570
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Tidskriftsartikel (refereegranskat)abstract
- The PAMELA experiment is being carried out on board the Russian satellite Resurs DK1 placed in the near-earth near-polar orbit on June 15, 2006. The apparatus comprising a silicon-strip magnetic spectrometer and an electromagnetic calorimeter allows measurement of electron and positron fluxes in cosmic rays in a wide energy interval from ∼100 MeV to hundreds of GeV. The high-energy electron and positron separation technique is discussed and the data on positron-to-electron ratio in primary cosmic rays up to E ≃ 10 GeV from the 2006 - 2007 measurements are reported in this work.
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| 4. |
- Adriani, O., et al.
(författare)
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Secondary electron and positron fluxes in the near-Earth space observed in the ARINA and PAMELA experiments
- 2009
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Ingår i: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 73:3, s. 364-366
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Tidskriftsartikel (refereegranskat)abstract
- Secondary electron and positron fluxes in the energy range from 3 MeV to 7 GeV were measured with the ARINA and PAMELA spectrometers onboard the Resurs-DK satellite launched on June 15, 2006 into an elliptical orbit with an inclination of 70.4° and an altitude of 350-600 km. It is shown that positrons dominate over electrons by a factor of up to 4-5 in the geomagnetic equator region (L < 1.2 and B > 0.25).
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| 5. |
- Adriani, O., et al.
(författare)
-
The Pamela experiment ready for flight
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 572:1, s. 471-473
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Tidskriftsartikel (refereegranskat)abstract
- The Pamela apparatus will allow precise measurements of cosmic rays in Low Earth Orbit, mainly focusing on the antiparticles component. The apparatus is now ready for flight, and the launch is foreseen during June 2006. The paper briefly reports the status of the experiment, and the performances of the various components as measured before the launch.
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| 6. |
- Adriani, O., et al.
(författare)
-
The PAMELA space mission
- 2008
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Ingår i: Astroparticle, Part. Space Phys., Detect. Med. Phys. Appl. - Proc. Conf.. - : WORLD SCIENTIFIC. - 9812819088 - 9789812819086 ; , s. 858-864
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Konferensbidrag (refereegranskat)abstract
- The PAMELA (a Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics) experiment, is a satellite-borne particle spectrometer. It was launched on 15th June 2006 from the Baikonur cosmodrome in Kazakhstan, is installed into the Russian Resurs-DK1 satellite. PAMELA is composed of a time-of-flight system, a magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. Among the PAMELA major objectives are the study of charged particles in the cosmic radiation, the investigation of the nature of dark matter, by mean of the measure of the cosmic-ray antiproton and positron spectra over the largest energy range ever achieved. PAMELA has been in a nearly continuous data taking mode since llth July 2006. The status of the apparatus and performances will be presented.
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| 7. |
- Bongi, M, et al.
(författare)
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PAMELA : A satellite experiment for antiparticles measurement in cosmic rays
- 2004
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 51:3, s. 854-859
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Tidskriftsartikel (refereegranskat)abstract
- PAMELA is a satellite-borne experiment that will study the antiproton and positron fluxes in cosmic rays in a wide range of energy (from 80 MeV up to 190 GeV for antiprotons and from 50 MeV up to 270 GeV for positrons) and with high statistics, and that will measure the antihelium/helium ratio with a sensitivity of the order of 10(-8). The detector will fly on-board a polar orbiting Resurs DK1 satellite, which will be launched into space by a Soyuz rocket in 2004 from Baikonur cosmodrome in Kazakhstan, for a 3-year-long mission. Particle identification and energy measurements are performed in the PAMELA apparatus using the following subdetectors: a magnetic spectrometer made up of a permanent magnet equipped with double-sided microstrip silicon detectors, an electromagnetic imaging calorimeter composed of layers of tungsten absorber and silicon detectors planes, a transition radiation detector made of straw tubes interleaved with carbon fiber radiators, a plastic scintillator time-of-flight and trigger system, a set of anticounter plastic scintillator detectors, and a neutron detector. The features of the detectors and the main results obtained in beam test sessions are presented.
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| 8. |
- Bonvicini, V., et al.
(författare)
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Performance of the PAMELA Si-W imaging calorimeter in space
- 2009
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 160, s. 012039-
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Tidskriftsartikel (refereegranskat)abstract
- The Payload for Antimatter-Matter Exploration and Light Nuclei Astrophysics (PAMELA), primarily designed to directly measure antiparticles (antiprotons and positrons) in the cosmic radiation, was launched successfully on June 15th, 2006, and, since then, it is in continuous data taking. The calorimeter of the PAMELA apparatus has been designed to identify antiprotons from an electron background and positrons from a background of protons with high efficiency and rejection power. It is a sampling silicon-tungsten imaging calorimeter, which comprises 44 single-sided silicon sensor planes (380 μm thick) interleaved with 22 plates of tungsten absorber (0.74 X0 each). It is the first silicon-tungsten calorimeter to be launched in space. In this work we present the in-orbit performance of the calorimeter, including the measured identification capabilities. The calorimeter provides a proton rejection factor of ∼105 while keeping a high efficiency in selecting electrons and positrons, thus fulfilling the identification power needed to reach the primary scientific objectives of PAMELA. We show also that, after almost two years of operation in space, the calorimeter is still performing nominally.
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| 9. |
- Casolino, M., et al.
(författare)
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Cosmic-ray observations of the heliosphere with the PAMELA experiment
- 2006
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Ingår i: Astrophysics. - : Elsevier BV. ; , s. 1848-1852
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Konferensbidrag (refereegranskat)abstract
- The PAMELA experiment is a multi-purpose apparatus built around a permanent magnet spectrometer, with the main goal of studying in detail the antiparticle component of cosmic rays. The apparatus will be carried in space by means of a Russian satellite, due to launch in 2005, for a three year-long mission. The characteristics of the detectors composing the instrument, alongside the long lifetime of the mission and the orbital characteristics of the satellite, will allow to address several items of cosmic-ray physics. In this paper, we will focus on the solar and heliospheric observation capabilities of PAMELA.
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| 10. |
- Casolino, M., et al.
(författare)
-
Launch of the space experiment PAMELA
- 2008
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Ingår i: Advances in Space Research. - : Elsevier. - 0273-1177 .- 1879-1948. ; 42:3, s. 455-466
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Tidskriftsartikel (refereegranskat)abstract
- PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range (protons 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50 MeV-270 GeV) and search for antimatter with a precision of the order of 10-8. The experiment, housed on board the Russian Resurs-DK I satellite, was launched on June 15th, 2006 in a 350 x 600 km orbit with all inclination of 70'. The detector is composed of a series of scintillator counters arranged at the extremities of a permanent magnet spectrometer to provide charge, time-of-flight, and rigidity information. Lepton/hadron identification is performed by a silicon-tungsten calorimeter and a neutron detector placed at the bottom of the device. An anticounter system is used offline to reject false triggers coming from the satellite. In self-trigger mode the calorimeter, the neutron detector, and a shower tail catcher are capable of an independent measure of the lepton component up to 2 TeV. In this work we describe the experiment, its scientific objectives, and the performance in the first months after launch.
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| 11. |
- Galper, A. M., et al.
(författare)
-
International Russian-Italian mission "Rim-Pamela
- 2009
-
Ingår i: Proceedings of the 13th Lomonosov Conference on Elementary Particle Physics. - : WORLD SCIENTIFIC. - 9812837582 - 9789812837585 ; , s. 199-206
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Konferensbidrag (refereegranskat)abstract
- The successful launch of spacecraft "RESURS DK" 1 with precision magnetic spectrometer "PAMELA" onboard was executed at Baikonur cosmodrome 15 June 2006. The primary phase of realization of International Russian-Italian Project "RIM-PAMELA" with German and Swedish scientists' participation has begun since the launch of instrument "PAMELA" that has mainly been directed to investigate the fluxes of galactic cosmic rays. This report contains the main scientific Project's tasks and the conditions of science program's implementation after one year since exploration has commenced.
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| 12. |
- Orsi, Silvio
(författare)
-
A study of the in-orbit particle rate with the pamela anticoincidence system
- 2007
-
Ingår i: Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007. - : Universidad Nacional Autonoma de Mexico. ; , s. 95-98
-
Konferensbidrag (refereegranskat)abstract
- PAMELA is a satellite-borne experiment designed to study the charged component of the cosmic radiation of galactic, solar and trapped nature. The main scientific objective is the study of the antimatter component of cosmic rays over a wide range of energies. PAMELA is mounted on the Resurs DK1 satellite that was launched on June 15th 2006 from the Baikonur cosmodrome and is now on a semipolar (70) elliptical (350 600 km) orbit. The PAMELA apparatus consists of a permanent magnet silicon spectrometer, an electromagnetic imaging calorimeter, a time of flight system, a scintillator-based anticoincidence (AC) system, a tail catcher scintillator and a neutron detector. The AC system can be used to reject particles not cleanly entering the PAMELA acceptance. A standalone study of the functionality of the AC system during in-flight operations is presented. The in-orbit particle rates measured by the AC system during the first 6 months of operation are shown. The orbital dependence of the particle rates, the energy and the directionality of the trapped particles are also discussed.
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| 13. |
- Orsi, Silvio
(författare)
-
PAMELA : A payload for antimatter matter exploration and light nuclei astrophysics
- 2007
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 580:2, s. 880-883
-
Tidskriftsartikel (refereegranskat)abstract
- PAMELA is a satellite-borne experiment designed to study the charged component of the cosmic radiation, with particular emphasis on antiparticles. PAMELA is mounted on the Resurs DK1 satellite that was launched on June 15th 2006 from the Baikonur cosmodrome and has a foreseen lifetime of at least 3 years. The PAMELA apparatus consists of a magnetic spectrometer, an electromagnetic calorimeter, a time-of-flight system, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The signal from all detectors allows a reliable identification of antiparticles in a large background of other charged particles. The first studies of the in-flight performance are presented in this article.
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| 14. |
- Orsi, Silvio, et al.
(författare)
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Pre-flight performance studies of the anticoincidence systems of the PAMELA satellite experiment
- 2005
-
Ingår i: Proceedings of the 29th International Cosmic Ray Conference, Vol 3. - MUMBAI : TATA INST FUNDAMENTAL RESEARCH. ; , s. 369-372
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Konferensbidrag (refereegranskat)abstract
- The PAMELA satellite experiment will be launched on-board a Resurs DK1 earth observation satellite towards the end of 2005. During the three year mission, the primary objective of PAMELA is to measure the flux of antiproions (80 MeV - 190 GeV) and positrons (50. MeV - 270 GeV) in the cosmic radiation. The wide energy range and large statistics, similar to 10(4) antiprotons and similar to 10(5) positrons, will allow sensitive tests of cosmic ray propagation models and searches for exotic sources of antiparticles, such as the annihilation of dark matter particles. The PAMELA experiment contains two anticoincidence systems built from plastic scintillators read o ut by photomultipliers. One system surrounds the permanent magnet spectrometer and the other surrounds the volume between the first two time-of-flight layers. The pre-flight performance of both anticounter systems has been studied using data from ground tests of PAMELA.
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| 15. |
- Orsi, Silvio, 1976-
(författare)
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Studies of cosmic rays with the anticoincidence system of the PAMELA satellite experiment
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- PAMELA is a satellite-borne experiment designed to study the charged component of the cosmic radiation of galactic, solar and trapped nature. The main scientific objective is the study of the antimatter component of cosmic rays over a wide range of energies (antiprotons: 80 MeV–190 GeV, positrons: 50 MeV–270 GeV). PAMELA is also searching for antinuclei with a precision ~10^−7 in anti-He/He measurements. PAMELA is mounted on the Resurs DK1 satellite that was launched on June 15th 2006 from the Baikonur cosmodrome and is now on a semipolar (69.9°) elliptical (350 × 600 km) orbit. The experiment has been acquiring data since July 11th 2006 and has a foreseen lifetime of at least 3 years. The PAMELA apparatus consists of a permanent magnet silicon spectrometer, an electromagnetic imaging calorimeter, a time of flight system, a scintillator-based anticoincidence (AC) system, a tail catcher scintillator and a neutron detector. The AC system can be used to reject particles not cleanly entering the PAMELA acceptance. Tests of the PAMELA instrument in its final flight configuration involved long duration acquisition runs with cosmic particles (mainly muons) on ground. A study of the functionality of the AC system during these runs is presented here with a set of selected muons. Studies of activity in the AC detectors as function of the rigidity of the muons and in correlation with the activity in the spectrometer and in the calorimeter are presented. A study of the AC system functionality during in-flight operations provides a map of the particle flux in orbit, and shows the anisotropy in the arrival direction of trapped particles in the Van Allen radiation belts. The singles rates indicate that the AC system saturates in the South Atlantic anomaly (SAA). Information from the AC system in the SAA is therefore not reliable for physics analysis. The timing and multiplicity of AC activity correlated to particle triggers has been studied. A dependence on orbital position was observed. An LED (Light Emitting Diode) based monitoring system was designed to determine the in-orbit behaviour of the AC system independently of the radiation environment and to compare it to the pre-launch behaviour. The LED system shows that the properties of the AC system are stable during flight and that no significant changes in performance occurred as a result of the launch.
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| 16. |
- Orsi, Silvio
(författare)
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The Anticoincidence Shield of the PAMELA Satellite Experiment
- 2004
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The PAMELA space experiment is scheduled for launch towards the end of 2004 on-board a Russian Resurs DK1 satellite, orbiting Earth at an altitude of 300– 600 km. The main scientific goal is a study of the antimatter component of the cosmic radiation. The semipolar orbit (70.4◦) allows PAMELA to investigate a wide range of energies for antiprotons (80 MeV–190 GeV) and positrons (50 MeV– 270 GeV). Three years of data taking will provide unprecedented statistics in this energy range and will set the upper limit for the ratio He/He below 10−7. PAMELA is built around a permanent magnet silicon spectrometer, surrounded by a plastic scintillator anticoincidence shield built at KTH. The anticounter scintillators are used to aid in the rejection of background from particles not cleanly entering the acceptance of the tracker. Information from the anticounter system will be included as a veto in a second level trigger, to exclude the acquisition of events generated by false triggers. An LED-based monitoring system has been developed for the anticounter system. The LEDs mimic the light signal produced in the scintillator by an ionising particle. This allows the functionality of the AC system to be verified in-orbit. The development and testing of the monitoring system are presented and comparisons have been made with independent radioactive source-based calibration methods. The anticounter system has also been extensively tested with cosmic rays and particle beams. Most of these tests have been performed with the anticounters integrated with the other PAMELA subdetectors in a flight-like configuration.
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| 17. |
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| 18. |
- Orsi, Silvio, et al.
(författare)
-
The anticoincidence shield of the PAMELA space experiment
- 2006
-
Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 37:10, s. 1853-1856
-
Tidskriftsartikel (refereegranskat)abstract
- The PAMELA space experiment will be launched in 2005 onboard a Russian Resurs DK1 satellite, orbiting Earth at an altitude varying between 300 and 600 km. The main scientific goal is a study of the antimatter component of the cosmic radiation. The semi-polar orbit (71 degrees) allows PAMELA to investigate a wide range of energies for antiprotons (80 MeV-190 GeV) and positrons (50 MeV-270 GeV). Three years of data taking will provide unprecedented statistics in this energy range and will set the upper limit for the ratio He-/He below 10(-7). PAMELA is built around a permanent magnet silicon spectrometer, surrounded by a plastic scintillator anticoincidence shield. The anticounter scintillators are used to aid in the rejection of background from particles which do not cleanly enter the acceptance of the experiment but which are responsible for coincidental energy deposits in the trigger scintillators ('false triggers'). Information from the anticounter system can be included as a veto in a second level trigger, to exclude the acquisition of events generated by such false triggers. The construction of the anticounter system is described, along with its functionality and performance. The read-out electronics and the LED-based monitoring system are also described. Test-beam and simulation studies of the system are reviewed.
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| 19. |
- Orsi, Silvio
(författare)
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The second level trigger of the pamela space experiment
- 2007
-
Ingår i: Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007. - : Universidad Nacional Autonoma de Mexico. ; , s. 487-490
-
Konferensbidrag (refereegranskat)abstract
- PAMELA is a satellite-borne experiment designed to study the charged component of the cosmic radiation of galactic, solar and trapped nature. The main scientific objective is the study of the antimatter component of cosmic rays over a wide range of energies. PAMELA is mounted on the Resurs DK1 satellite that was launched on June 15th 2006 and is orbiting the Earth on a semipolar (70) elliptical (350 600 km2) orbit. The experiment has a foreseen lifetime of at least 3 years. PAMELA is built around a permanent magnet silicon spectrometer, surrounded by a plastic scintillator anticoincidence shield. An electromagnetic calorimeter is used for particle identification and energy measurements. If PAMELA data exceed the storage allowance on the satellite or the daily downlink quota (now 20 GB), a second level trigger may be activated by uplink from ground. Information from the anticoincidence system and from the calorimeter will be included in the second level trigger condition, providing a selective reduction of data. The data reduction and the systematic uncertainties in the proton and electron spectra are evaluated with in-orbit data and compared to simulations.
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| 20. |
- Picozza, P., et al.
(författare)
-
Dark Matter Research and the PAMELA Space Mission
- 2009
-
Ingår i: SOURCES AND DETECTION OF DARK MATTER AND DARK ENERGY IN THE UNIVERSE. - : AIP. ; , s. 141-150
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- On the 15th of June 2006, the PAMELA satellite-borne experiment was launched from the Bajkonur cosmodrome and since July 2006 it has been collected data. The core of the apparatus is a silicon-microstrip magnetic spectrometer combined with a time-of-flight system, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail counter scintillator and a neutron detector. The overall devices allow precision studies of the charged cosmic radiation to be conducted over a wide energy range (100 MeV - 100's GeV) with high statistics. The primary scientific goal is the measurement of the antiproton and positron energy spectra in order to search for exotic sources, such as dark matter particle annihilation. PAMELA is also searching for primordial antinuclei ((He) over bar). Concomitant, but not secondary, goals are the measurements of light nuclei and their isotopes for studying the energy dependence of cosmic ray lifetimes in the Galaxy, the monitoring of the solar activity and the study of the radiation belts.
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| 21. |
- Sparvoli, R, et al.
(författare)
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Space qualification tests of the PAMELA instrument
- 2006
-
Ingår i: ASTROPHYSICS. - : Elsevier BV. ; , s. 1841-1847
-
Konferensbidrag (refereegranskat)abstract
- PAMELA is a satellite-borne experiment which will measure the antiparticle component of cosmic rays over an extended energy range and with unprecedented accuracy. The apparatus consists of a permanent magnetic spectrometer equipped with a double-sided silicon microstrip tracking system and surrounded by a scintillator anticoincidence system. A silicon-tungsten imaging calorimeter, complemented by a scintillator shower tail catcher, and a transition radiation detector perform the particle identification task. Fast scintillators are used for Time-of-Flight measurements and to provide the primary trigger. A neutron detector is finally provided to extend the range of particle measurements to the TeV region. PAMELA will fly on-board of the Resurs-DKI satellite, which will be put into a semi-polar orbit in 2005 by a Soyuz rocket. We give a brief review of the scientific issues of the mission and report about the status of the experiment few months before the launch.
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| 22. |
- Stozhkov, Y. I., et al.
(författare)
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About Separation of Hadron and Electromagnetic Cascades in the Pamela Calorimeter
- 2005
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Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 20:29, s. 6745-6748
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Tidskriftsartikel (refereegranskat)abstract
- Results of calibration of the PAMELA instrument at the CERN facilities are discussed. In September, 2003, the calibration of the Neutron Detector together with the Calorimeter was performed with the CERN beams of electrons and protons with energies of 20-180 GeV. The implementation of the Neutron Detector increases a rejection factor of hadrons from electrons about ten times. The results of calibration are in agreement with calculations.
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