Mark Pearce

Measurements of electron and positron fluxes below the geomagnetic cutoff by the PAMELA magnetic spectrometer

We present a measurements of electron and positron fluxes below the geomagnetic cutoff rigidity in wide energy range from 50 MeV to several GeVs by the PAMELA magnetic spectrometer. The instrument ...

Effect of the Jupiter magnetosphere on the cosmic ray protons measured with the PAMELA experiment

The very intense Jovian magnetic field produces a magnetosphere where high-energy charged particles are trapped, allowing the possibility for acceleration mechanism that could inject those particle ...

Ten years of positron and electron solar modulation measured by the PAMELA experiment

The satellite-borne PAMELA experiment was launched on the 15th June 2006 from the Baikonur cosmodrome. Till January 2016 PAMELA has detected the charged component of cosmic-rays (CRs) over a wide e ...

Time dependence of the proton and helium flux measured by PAMELA

The energy spectra of galactic cosmic rays carry fundamental information regarding their origin and propagation, but, near Earth, ncosmic rays are significantly affected by the solar magnetic field which changes over time. The time dependence of proton and electron spectra were measured from July 2006 to December 2009 by PAMELA experiment, that is a ballooon-borne experiment collecting data since 15 June 2006. nThese studies allowed to obtain a more complete description of the cosmic radiation, providing fundamental information about the transport and modulation of cosmic rays inside the heliosphere. In this talk the study of the time dependence of the cosmic-ray protons and helium nuclei from the unusual 23rd solar minimum through the following period of solar maximum activity is presented.

PAMELA measurements of solar energetic particle spectra

The charged particle acceleration and transport during solar events have been widely studied in the past decades. The satellite-borne PAMELA experiment has been continuously collecting data since 2006. The apparatus is designed to study charged particles in the cosmic radiation. The combination of permanent magnet, silicon micro-strip spectrometer and silicon-tungsten imaging calorimeter, with the redundancy of instrumentation allows very precise studies on the physics of cosmic rays in a wide energy range and with high statistics. This makes PAMELA a well suited instrument for Solar Energetic Particle (SEP) observations. Not only it spans the energy range between the ground-based neutron monitor data and the observations of SEPs from space, but also PAMELA carries out the first direct measurements of SEP energy spectra, composition and angular distribution. PAMELA has observed many SEP events in solar cycle 24, offering unique opportunity to address several questions on high-energy SEP’s origin. A preliminary analysis on proton spectra during several events of the 24th solar cycle is presented.

Cosmic-Ray Lithium and Beryllium Isotopes in the PAMELA-Experiment

The PAMELA space experiment was launched on the 15th of June 2006 from the Baikonur cosmodrome. The scientific objectives addressed by the mission are the measurement of the antiprotons and positrons spectra in cosmic rays, the hunt for antinuclei as well as the determination of light nuclei fluxes from hydrogen to oxygen in a wide energy range and with high statistics. The apparatus comprises a time-of-flight system, a magnetic spectrometer (permanent magnet) with an silicon-microstrip tracking system, an imaging calorimeter built from layers of silicon-microstrip detectors interleaved with plates of tungsten, an anti-coincidence system, a shower tail scintillator-counter and a neutron detector. The instrument in its detector-combination is also capable to identify isotopes, using the rigidity information from the magnetic spectrometer together with the time-of-flight measurement or with the multiple dE/dx measurement in the calorimeter. In this paper details about the analysis method and new results of the isotopic ratios of lithium and beryllium with increased statistics will be presented.

Short-term variation in the galactic cosmic ray intensity measured with the PAMELA experiment

New results on the galactic cosmic ray (GCR) short-term intensity variation nassociated with Forbush decrease and co-rotating interaction regions (CIRs) measured by the PAMELA instrument between November 2006 and March 2007 are presented. Most of the past measurements on Forbush decrease events were carried out with neutron monitor detector. This tecnique allows only 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 associated with the December 13th coronal mass ejection (CME) was studied in a wide rigidity range (0.4-20 GV) and for different species of GCRs detected directly in space. Using GCR protons, the amplitude and the recovery time of the Forbush decrease were studied for ten rigidity interval with a temporal resolution of one day. For comparison the helium and the electron intensity over time were also studied. The temporal evolution of the helium and proton intensity was found in good agreement while the electrons show, on average, a faster recovery time. This was interpreted as a charge-sign dependence introduced by drift motion experienced by the low rigidity (<5 GV) GCRs during their propagation through the heliosphere. Moreover a clear 13.5 days cyclical variation was observed in the GCR proton intensity after the Forbush decrease. This phenomena could be interpreted as an effect of prominent structures of compressed plasma in the solar wind, i.e. CIRs, or to the latitudinal gradient due to the crossing of the heliospheric current sheet (HCS).

The PAMELA Experiment: A Cosmic Ray Experiment Deep Inside the Heliosphere

It was the 15th of June of 2006 when the PAMELA satellite-borne experiment was launched from the Baikonur cosmodrome in Kazakstan. Then, for nearly ten years, PAMELA has been making high-precision measurements of the charged component of the cosmic radiation opening a new era of precision studies in cosmic rays and challenging our basic vision of the mechanisms of production, acceleration and propagation of cosmic rays in the galaxy and in the heliosphere. The study of the time dependence of the various components of the cosmic radiation from the unusual 23rd solar minimum through the maximum of solar cycle 24 clearly shows solar modulation effects as well as charge sign dependence. PAMELA measurement of the energy spectra during solar energetic particle events fills the existing energy gap between the highest energy particles measured in space and the ground-based domain. Finally, by sampling the particle radiation in different regions of the magnetosphere, PAMELA data provide a detailed study of the Earth~s magnetosphere. In this highlight paper, PAMELA main results as well as recent progress about solar and heliospheric physics with PAMELA will be presented.