SH54A-01
Antimatter Research with Pamela Space Mission
The Space Mission Pamela, launched in orbit on 15 June 2006, represents the state-of-the-art of the
investigation of the cosmic radiation to address the most compelling issues facing astrophysics and cosmology:
the nature of the dark matter that pervades the universe, the apparent absence of cosmological antimatter, the
origin and evolution of matter in the galaxy.
Pamela detector is composed of a permanent magnetic spectrometer equipped
with a series of scintillator counters arranged at the extremities 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.
The primary scientific goal of the Pamela investigation is the search for evidence of non baryonic particles falling
outside Standard Model particles physics and of heavy antinuclei.. Concomitant, but not secondary, goals are
the study of the energy dependence of cosmic ray lifetimes in the Galaxy, the validation of models of
acceleration, transport and secondary production of cosmic radiation in the Galaxy, the monitoring of the solar
activity and the knowledge of the role of solar and terrestrial relationships in the energetic particle propagation in
the heliosphere. The observational objectives are the measurements of the fluxes and the energy spectra of
antiprotons, protons. positrons, electrons and light nuclei in a very large energy range and the search for
antinuclei with a sensitivity of the order of 10-7 in antiHe/He .
The satellite is flying in high inclination, 70° low Earth Orbit (350-600 km), performing measurements in
different points and conditions of the geomagnetosphere. Pamela is able of detecting protons ( 80 MeV- 700
GeV), antiprotons (80 MeV-190 GeV), electrons (50 MeV - 400 GeV), positrons (50 MeV - 270 Gev) and light nuclei
( 100 MeV/n-200 GeV/n).
For its characteristics the device is capable of performing for the first time a very precise measurement of the
high energy component in solar events and, in particular, to detect solar positrons and possible antiprotons.
Also trapped, semi-trapped and albedo / secondary particles in Earth's magnetosphere will be studied
separating the matter component from the antimatter
http:wizard.roma2.infn.it
SH54A-02 INVITED
Preliminary Assessment of Antiparticle Sources in the Solar System
Natural high energy processes can exceed the threshold energy required for pair production at numerous locations in our solar system. In particular, the Galactic Cosmic Ray (GCR) flux reacts with the upper atmosphere of planets to generate neutron/anti-neutron pairs which can then scatter and decay within the trapping region of a planet's magnetic field to form a quasi-stable antiproton belt. The induced antimatter belt can co-exist with the traditional proton and electron radiation belts due to the relatively diffuse nature of the particle distribution. We review our progress in modeling the antiproton belt around the Earth to estimate the total mass trapped and assess the practicality of extracting the particles for useful applications such as space propulsion. We then extend these models to estimate the total supply of antimatter available at other locations in our solar system including the Jovian planets where the strong magnetic fields, planetary rings, and other features can significantly improve the ability to produce and trap the antiparticles.
SH54A-03
Antiprotons in the radiation belt
The main source of antiprotons for Earth's radiation belt is decay of albedo antineutrons formed by interactions of cosmic rays with the atmosphere. This is analogous to the CRAND (cosmic ray albedo neutron decay) process that is the main source of high-energy (>100~MeV) radiation belt protons. We describe the intensity and spatial distribution of both the antiproton and proton components based on numerical simulation of the inner radiation belt. The albedo process is modeled using Geant4, a Monte Carlo nuclear transport code. Other model inputs to the simulation include the galactic cosmic ray intensity, atmospheric densities, the geomagnetic field, the radial (cross-L) diffusion coefficient, cross sections for trapped particle losses due to inelastic nuclear processes including annihilation, and rates of energy loss to ionization of the atmosphere. The resulting antiproton intensity is compared to that from other sources.
SH54A-04
Source and Loss Processes of Antiprotons of the Equatorial Inner Magnetosphere
Significant fluxes of antiparticles in the Earth magnetosphere has been predicted on theoretical considerations. At several hundred kilometers of altitudes antiprotons are expected due to nuclear reactions of the high energy primary cosmic rays (CR) with the constituents of terrestrial atmosphere. Extraterrestrial antiprotons are themselves are of secondary in origin due to nuclear reactions of the CR particles in passing through 5-7 g/cm2 of interstellar matter encountered during their lifetime in the Galaxy. We expect that the fluxes of magnetospheric antiprotons are greater compared to interstellar fluxes as the fluxes get accumulated due to confinement in the magnetic field. Computations of the antiproton fluxes at 50 MeV to several GeV energies due to the CR particle interactions with the residual atmosphere at altitudes of ~ 1000 km over the Earth's surface are performed. The calculations for the flux intensities, energy spectrums, and radial distributions are obtained applying the diffusion theory and the Chirikov process for the non adiabatic behaviour. The estimates shows that the magnetospheric antiproton fluxes (at L~ 1.2) are greater by an order of magnitude compared to the interstellar fluxes measured at energies < 1 GeV. However, the contributin of these particles of magnetic origin to the interestellar fluxes measured in balloon experiments at high latitudes is not significant.
SH54A-05
Antiparticles In The Vicinity Of Earth
The study of cosmic ray electrons and positrons outside the atmosphere began in 60's with instruments installed on board satellites. Some indirect measurements were implemented on high altitude balloons. Beginning the first magnetic spectrometer on board Russian Space Station SALUT-7 Mariya 1985 the first separate positron data were obtained. This investigation gave the first result for positron and electron spectra in energy range 20- 200 MeV under radiation belt and inside it. Then Mariya-2 on board MIR station confirms reentrant albedo nature of positron fluxes. The experimental results of these experiments are presented. The results of calculations based on cosmic ray interaction with upper atmosphere were consistent with these experiments. The measurements of charge composition in radiation belt showed the lack of positrons and acceleration nature of electron fluxes. The attempt was made to search for antiprotons in radiation belt. The upper limit was obtained on the level 510-3. Next magnetic spectrometer in space was AMS-01 in 1998. 10 day flight measurements gave the possibility to receive results for antiparticles in energy range 0.2 - 3 GeV with very big statistics. Next steps in this study are PAMELA magnetic spectrometer measurements in orbit. It was launched 15.06.2006 and its goal is antiparticle spectra in near the Earth space in energy range 0.08 - 200 GeV.