PAMELA Space Mission Antimatter and Dark Matter Research

1. PAMELA Space MissionAntimatter and Dark Matter Research Piergiorgio Picozza INFN & University of Rome “ Tor Vergata” , Italy TeV Particle Astrophysics 23-28 September, 2008 Beijing, China

2. Robert L. Golden

3. PAMELA AMS in Space AMS Search for the origin of the Universe Search for the existence of anti Universe Accelerators The Big Bang origin of the Universe requires matter and antimatter to be equally abundant at the very hot beginning Search for the existence of Antimatter in the Universe

4. Antimatter Direct research • Antimatterwhich has escaped as a cosmic ray from a distant antigalaxy Sreitmatter, R. E., Nuovo Cimento, 19, 835 (1996) • Antimatterfrom globular clusters of antistars in our Galaxy as antistellar wind or anti-supernovae explosion K. M. Belotsky et al., Phys. Atom. Nucl. 63, 233 (2000), astro-ph/9807027

5. 4% 23% 73%

7. Signal (supersymmetry)… (GLAST AMS-02)‏ … and background

8. Antimatter and Dark Matter Research Wizard Collaboration - MASS – 1,2 (89,91) -TrampSI (93) • CAPRICE (94, 97, 98) -BESS (93, 95, 97, 98, 2000) - Heat (94, 95, 2000) • IMAX (96) • BESS LDF (2004, 2007) • AMS-01 (1998)

9. Antimatter “We must regard it rather an accident that the Earth and presumably the whole Solar System contains a preponderance of negative electrons and positive protons. It is quite possible that for some of the stars it is the other way about” P. Dirac, Nobel lecture (1933)‏

10. P Secondary production (upper and lower limits)‏ Simon et al. ApJ 499 (1998) 250. Secondary production Bergström et al. ApJ 526 (1999) 215 from χχ annihilation (Primary production m(c) = 964 GeV) Ullio : astro-ph/9904086

11. CR antimatter Charge-dependent solar modulation Solar polarity reversal 1999/2000 Asaoka Y. Et al. 2002 Positron excess? ? ? ¯ + CR + ISM  p-bar + … kinematic treshold: 5.6 GeV for the reaction Present status Positrons Antiprotons ___ Moskalenko & Strong 1998 CR + ISM p± + x m ± + x  e±+ x CR + ISM  p0 + x gg  e±

12. What do we need? • Measurements at higher energies • Better knowledge of background • High statistic • Continuous monitoring of solar modulation Long Duration Flights

13. PAMELA Payload for Antimatter Matter Exploration and Light NucleiAstrophysics

14. Pamela as a Space Observatory at 1AU Search for dark matter annihilation Search for antihelium (primordial antimatter)‏ Search for new Matter in the Universe (Strangelets?) Study of cosmic-ray propagation Study of solar physics and solar modulation Study of terrestrial magnetosphere Study of high energy electron spectrum (local sources?)

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

17. PAMELA Instrument GF ~21.5 cm2sr Mass: 470 kg Size: 130x70x70 cm3

18. Design performance • Energy range • Antiproton flux 80 MeV - 190 GeV • Positron flux 50 MeV – 270 GeV • Electron/positron flux up to 2 TeV (from calorimeter) • Electron flux up to 400 GeV • Proton flux up to 700 GeV • Light nuclei (up to Z=6) up to 200 GeV/n He/Be/C: • Antinuclei search Sensitivity of O(10-8) in He-bar/He • Unprecedented statistics and new energy rangefor cosmicray physics • Simultaneous measurements of many species

19. Resurs-DK1 satellite • Main task: multi-spectral remote sensing of earth’s surface • Built by TsSKB Progress in Samara, Russia • Lifetime >3 years (assisted) • Data transmitted to ground via high-speed radio downlink • PAMELA mounted inside a pressurized container Mass: 6.7 tonnes Height: 7.4 m Solar array area: 36 m2

20. PAMELALaunch15/06/0616 Gigabytes trasmitted daily to GroundNTsOMZ Moscow

21. 350 km SAA 70o 610 km Orbit Characteristics • Low-earth elliptical orbit • 350 – 610 km • Quasi-polar (70o inclination) • SAA crossed

22. Download @orbit 3754 – 15/02/2007 07:35:00 MWT 95 min orbit 3753 orbit 3751 orbit 3752 PAMELA Orbit Outer radiation belt NP SP EQ EQ S1 S2 S3 Inner radiation belt (SSA)‏

23. Flight data: 0.632 GeV/c antiproton annihilation

24. Flight data: 0.763 GeV/c antiproton annihilation

25. PAMELA Status • ~630 days of data taking (~73% live-time) • ~10 TByte of raw data downlinked • >109 triggers recorded and under analysis

26. Antiprotons

27. Flight data: 84 GeV/c interacting antiproton

28. PAMELA Protons Spillover

29. Antiproton-Proton Ratio PAMELA Preliminary

30. Antiproton to proton ratio Preliminary

31. Antiproton to proton ratio

32. Antiproton to proton ratio Preliminary

33. Positrons

34. Flight data: 92 GeV/c positron

35. Flight data: 36 GeV/c interacting proton Mirko Boezio, INFN Trieste - San Diego IEEE2006

36. Positron selection with calorimeter p (non-int) p (int) Rigidity: 20-30 GV e- p (non-int) e+ p (int) Preliminary Fraction of charge released along the calorimeter track (left, hit, right)

37. Positron selection with calorimeter Rigidity: 20-30 GV e- e+ p Preliminary + Fraction of charge released along the calorimeter track (left, hit, right) • Energy-momentum match • Starting point of shower

38. Positron selection with calorimeter Rigidity: 20-30 GV e- e+ p Preliminary + Fraction of charge released along the calorimeter track (left, hit, right) • Energy-momentum match • Starting point of shower • Longitudinal profile

39. Positron selection with calorimeter Fraction of charge released along the calorimeter track (left, hit, right) Flight data: rigidity: 20-30 GV Test beam data Momentum: 50GeV/c e- e- e- p e+ e+ p • Energy-momentum match • Starting point of shower

40. Positron selection Rigidity: 20-30 GV Fraction of charge released along the calorimeter track (left, hit, right) Neutrons detected by ND e- e- p e+ e+ p • Energy-momentum match • Starting point of shower

41. Positron to Electron Fraction Preliminary!!! Charge sign dependent solar modulation End 2007: ~20 000 positrons total

42. Positrons with HEAT

44. Flux (p/cm^2 sr s) Kinetic Energy (GeV) Proton flux July 2006

45. Galactic H and He spectra Preliminary !!!

46. Challenges • Solar Modulation at low energies • Charge-sign dependence of solar modulation • Background calculation

47. Pamela AMS-01 Caprice / Mass /TS93 BESS Solar Modulation of galactic cosmic rays • Continuous monitoring of solar activity • Study of charge sign dependent effects • Asaoka Y. et al. 2002, Phys. Rev. Lett. 88, 051101), • Bieber, J.W., et al. Physi-cal Review Letters, 84, 674, 1999. J. Clem et al. 30th ICRC 2007

48. Solar modulation Interstellar spectrum Decreasing solar activity PAMELA Ground neutron monitor sun-spot number Preliminary!! (statistical errors only) Increasing GCR flux July 2006 August 2007 February 2008

49. Charge dependent solar modulation ¯ ¯ + + A > 0 Positive particles A < 0 Preliminary!! Pamela 2006 (Preliminary!)

50. Charge sign dependence of cosmic ray modulation. • Two systematic deviations from reflection symmetry of the interplanetary magnetic field: • 1) The Parker field has opposite magnetic polarity above and below the equator, but the spiral field lines themselves are mirror images of each other. This antisymmetry produces drift velocity fields that for positive particles converge on the heliospheric equator in the A+ state or diverge from it in A- state. Negatively charged particles behave in the opposite manner and the drift patterns interchange when the solar polarity diverge. • 2) Systematic ordering of turbulent helicity can cause diffusion coefficients to depend directly on charge sign and polarity state. Bieber, J.W., et al. Phys. Rev. Letters, 84, 674, 1999.