Antimatter and Dark Matter Searches in Space: the PAMELA Space Mission

1. Antimatter and Dark Matter Searches in Space: the PAMELA Space Mission Piergiorgio Picozza INFN and University of Rome Tor Vergata XIII Workshop on “Neutrino Telescopes” Venice March 10-13, 2009

2. PAMELA Payload for Antimatter Matter Exploration and Light NucleiAstrophysics

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

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

6. Design Performance • Simultaneous measurement of many cosmic-ray species • New energy range • Unprecedented statistics Energy range Antiprotons 80 MeV - 150 GeV Positrons 50 MeV – 300 GeV Electrons up to 500 GeV Protons up to 700 GeV Electrons+positrons up to 2 TeV (from calorimeter) Light Nuclei (He/Be/C) up to 200 GeV/n AntiNuclei search sensitivity of 3x10-8 in He/He

7. 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

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

9. 350 km SAA 70o 610 km Orbit Characteristics • Low-earth elliptical orbit • 350 – 610 km • Quasi-polar (70o inclination) • SAA crossed

10. 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)‏

11. The Physics of PAMELA 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?)

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

13. Lightest Kaluza-Klein Particle (LKP): B(1) Another possible scenario: KK Dark Matter Bosonic Dark Matter: fermionic final states no longer helicity suppressed. e+e- final states directly produced. As in the neutralino case there are 1-loop processes that produces monoenergetic γγ in the final state.

14. PAMELA Status • Today 1003 days in flight • data taking ~73% live-time • ~13 TBytes of raw data downlinked • >109 triggers recorded and under analysis

15. Antiprotons

16. Flight data: 84 GeV/c interacting antiproton

17. PAMELA antiproton discrimination Proton Spillover

18. Positrons

19. Proton / positron discrimination Time-of-flight: trigger, albedo rejection, mass determination (up to 1 GeV) Bending in spectrometer: sign of charge Ionisation energy loss (dE/dx): magnitude of charge Interaction pattern in calorimeter: electron-like or proton-like, electron energy Proton Positron

20. Positron selection with calorimeter p (non-int) p (int) planes LEFT HIT RIGHT strips Fraction of energy released along the calorimeter track (left, hit, right) e- p (non-int) e+ p (int) 0.6 RM Rigidity: 20-30 GV

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

22. 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

23. (~RM) Selections on total detected energy, starting point of shower e- e+ p - (p) - +

24. Flight data: 51 GeV/c positron

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

26. 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

27. The “pre-sampler” method CALORIMETER: 22 W planes: 16.3 X0 2 W planes: ≈1.5 X0 20 W planes: ≈15 X0

28. The “pre-sampler” method POSITRON SELECTION 20 W planes: ≈15 X0 2 W planes: ≈1.5 X0 PROTON SELECTION 2 W planes: ≈1.5 X0 20 W planes: ≈15 X0

29. e+ background estimation from data Rigidity: 20-28 GV e- ‘presampler’ p e+ p + • Energy-momentum match • Starting point of shower

30. e+ background estimation from data Rigidity: 28-42 GV e- ‘presampler’ p e+ p + • Energy-momentum match • Starting point of shower

31. e+ background estimation from data Rigidity: 6.1-7.4 GV e- ‘presampler’ p e+ p + • Energy-momentum match • Starting point of shower

32. RESULTS

33. Antiproton to proton ratioPRL 102, 051101 (2009) Seconday Production Models

34. Antiproton to proton ratioPRL 102, 051101 (2009)

35. Antiproton Flux statistical errors only energy in the spectrometer Preliminary

36. Antiproton Flux statistical errors only energy in the spectrometer Preliminary Preliminary Secondary production: V. S. Ptuskin et al, ApJ 642 (2006) 902 Secondary production: F. Donato et al., 536 (2001) 172 Mirko Boezio, SLAC Seminar, 2009/01/12

37. Positrons to all electrons ratio Secondary production Moskalenko & Strong 98

38. Positron to Electron Ratioastro-ph 0810.4995

39. Interpretation

40. 0808.3725 DM 0808.3867 DM 0809.2409 DM 0810.2784 Pulsar 0810.4846 DM / pulsar 0810.5292 DM 0810.5344 DM 0810.5167 DM 0810.5304 DM 0810.5397 DM 0810.5557 DM 0810.4147 DM 0811.0250 DM 0811.0477 DM During first week after PAMELA results posted on arXiv )

41. PAMELA Positron Fraction Pulsar Component Yüksel et al. 08 KKDM (mass 300 GeV) Hooper & Profumo 07 Pulsar Component Atoyan et al. 95 Pulsar Component Zhang & Cheng 01 Secondary production Moskalenko & Strong 98

42. Example: e+ & p DM P. Grajek et al., arXiv: 0812.4555v1 See Gordon Kane’s talk

44. Astrophysical Explanation: Pulsars S. Profumo Astro-ph 0812-4457 • Positrons production and acceleration mechanism • Young Pulsars (T ~ 105 years) and nearby (< 1kpc) • Too young: contribution does not escape from the nebula cloud of the pulsar. • Too old: much diffusion, low energy, too low flux. • Geminga: 157 parsecs from Earth and 370,000 years old • B0656+14: 290 parsecs from Earth and 110,000 years old. • Diffuse mature pulsars?

45. Example: pulsars H. Yüksak et al., arXiv:0810.2784v2 Contributions of e- & e+ from Geminga assuming different distance, age and energetic of the pulsar Hooper, Blasi, and SerpicoarXiv:0810.1527 Mirko Boezio, LHC & DM Workshop, 2009/01/06

46. Standard Positron Fraction Theoretical Uncertainties γ = 3.54 γ = 3.34 T. Delahaye et al., arXiv: 0809.5268v3

47. Explanation with supernovae remnants Shaviz and al. astro-ph.HE0902.0376

48. Only secondaries?P. Serpico hep-ph 0810.4846 • Anomalous primary electron source spectrum • Spectral feature in the proton flux responsible for secondaries • Role of Helium nuclei in secondary production • Difference between local and ISM spectrum of protons • Anomalous energy-dependent behaviour of the diffusion coefficient • Rising cross section at high energies • High energy beaviour of the e+/e-

49. PAMELA Proton Spectrum

50. Galactic H and He spectra Preliminary !!!