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PAMELA

PAMELA. P ayload for A ntimatter M atter E xploration and L ight Nuclei A strophysics. Italy:. CNR, Florence. Bari. Florence. Frascati. Naples. Rome. Trieste. Russia:. Moscow St. Petersburg. Germany:. Sweden:. Siegen. KTH, Stockholm. PAMELA Collaboration.

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PAMELA

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  1. PAMELA Payload for Antimatter Matter Exploration and Light NucleiAstrophysics

  2. Italy: CNR, Florence Bari Florence Frascati Naples Rome Trieste Russia: Moscow St. Petersburg Germany: Sweden: Siegen KTH, Stockholm PAMELA Collaboration

  3. Resurs-DK1 satellite + orbit • Resurs-DK1: multi-spectral imaging of earth’s surface • PAMELA mounted inside a pressurized container • Lifetime >3 years (assisted, first time last February). Expected till end 2011. • Data transmitted to NTsOMZ, Moscow via high-speed radio downlink. ~16 GB per day • Quasi-polar and elliptical orbit (70.0°, 350 km - 600 km) • Traverses the South Atlantic Anomaly • Crosses the outer (electron) Van Allen belt at south pole PAMELA Resurs-DK1 Mass: 6.7 tonnes Height: 7.4 m Solar array area: 36 m2 350 km 70o SAA 610 km ~90 mins

  4. Electron (e-) flux, energy measurement Two independent energy measurements: Rigidity from Tracker • bremsstrahlungabove tracker • decreasing energy resolution Energy from Calorimeter • sampling calorimeter • increasing energy resolution • possibility to cross-check the energy measurement Mirko Boezio, HEAD 2010, 2010/03/03

  5. Electron identification S1 CARD CAT S2 TOF SPE CAS S3 CALO S4 ND • Analyzed data July 2006 – December 2008 (~850 days) • Collected triggers >109 • Identified ~ 5.5 105 electrons between 1 and 200 GeV • Electron/positron identification: • rigidity (R)  SPE • |Z|=1 (dE/dx=MIP) SPE&ToF • b=1 ToF • e-/e+ separation (charge sign)  SPE • (e-/p-bar separation  CALO) • ~ no background, issues: • - spillover protons at high energy • - spectrometer resolution • - selection efficiencies Mirko Boezio, HEAD 2010, 2010/03/03

  6. PAMELA Electron (e-) Spectrum Mirko Boezio, HEAD 2010, 2010/03/03

  7. PAMELA Electron (e-) Spectrum Mirko Boezio, HEAD 2010, 2010/03/03

  8. Electron flux - break in the spectrum? PAMELA Electron (e-) Spectrum Mirko Boezio, HEAD 2010, 2010/03/03

  9. PAMELA Electron (e-) Spectrum Preliminary Mirko Boezio, HEAD 2010, 2010/03/03

  10. PAMELA Electron (e-) Spectrum Preliminary Mirko Boezio, HEAD 2010, 2010/03/03

  11. PAMELA Electron (e- + e+) Spectrum Mirko Boezio, HEAD 2010, 2010/03/03

  12. Positron to Electron Fraction In Nature article published data acquired till February 2008 New data reduction: data till end of 2008. With same approach of Nature paper ~30% increase in statistics better understanding of systematics. Secondary productionMoskalenko & Strong 98 Adriani et al, arXiv:1001.3522 [astro-ph.HE]

  13. Proton and Alpha Spectrum Preliminary Mirko Boezio, HEAD 2010, 2010/03/03

  14. Antiprotons Preliminary Errors might be underestimated, possible residual spillover-proton contamination Preliminary Antiprotons in CRs are in agreement with secondary production Mirko Boezio, HEAD 2010, 2010/03/03

  15. Summary • PAMELA has been in orbit and studying cosmic rays for ~42 months. >109 triggers registered and >18 TB of data has been down-linked. • e- spectrum up to ~200 GeV shows spectral features that may point to additional components. Analysis is ongoing to increase the statistics and expand the measurement of the e- spectrum up to ~500 GeV and e+ spectrum up to ~300 GeV (all electrum (e- + e+) spectrum up to ~1 TV). • High energy positron fraction (>10 GeV) increases significantly (and unexpectedly!) with energy. Primary source? • Data at higher energies might help to resolve origin of rise (spillover limit ~300 GeV). • Antiproton-to-proton flux ratio and antiproton energy spectrum (~100 MeV - ~200 GeV) show no significant deviations from secondary production expectations. http://pamela.roma2.infn.it

  16. Thanks! Mirko Boezio, HEAD 2010, 2010/03/03

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