P A M E L A

Payload for Antimatter /

Matter Exploration and

Light-nuclei Astrophysics

Anticoincidence reduces out of

acceptance background

Sign of charge,

rigidity, dE/dx

Electron energy, dE/dx,

lepton-hadron

separation

e- p -

e+ p (He,...)

Trigger, ToF, dE/dx

- +

~470 kg

~360 W

~1.3

m

21.5 cm2sr

Resurs-DK1 satellite

Mass: 6.7 tonnes

Height: 7.4 m

Solar array area: 36 m2

• 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

Launch: 15th June 2006, 0800 UTC

• Quasi-polar (70.0°) • Elliptical (350 km - 600 km) • PAMELA traverses the South Atlantic Anomaly • At the South Pole PAMELA crosses the outer (electron) Van Allen belt

70.0o

610 km

350 km

SAA

Orbit characteristics

6.5 GV

interacting proton

candidate

PAMELA event

13 GV

Interacting helium nucleus

candidate

5.7 GV

non-interacting carbon nucleus

candidate

18 GV

non-interacting anti-proton

candidate

84 GV

interacting antiproton

candidate

92 GV positron

candidate

Antiprotons

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

Time-of-flight: trigger, albedo rejection, mass determination (up to 1 GeV)

Positron (NB: p/e+ ~103-4)

Antiproton (NB: e-/p ~ 102)

Antiproton / positron identification

Antiproton Results

O. Adriani et al., PRL 102, 051101 (2009); PRL 105, 121101 (2010)

Donato et al. (PRL 102 (2009) 071301)

Simon et al. (ApJ 499 (1998) 250) Ptuskin et al. (ApJ 642 (2006) 902)

Cosmic-Ray Antiprotons and DM limits

D. G. Cerdeno, T. Delahaye & J. Lavalle, arXiv: 1108:1128 Antiproton flux predictions for a 12 GeV WIMP annihilating into different mass combinations of an intermediate two-boson state which further decays into quarks.

See also: •M. Asano, T. Bringmann & C. Weniger, arXiv:1112.5158. • M. Garny, A. Ibarra & S. Vogl, arXiv:1112.5155 • R. Kappl & M. W. Winkler, arXiv:1140.4376

PAMELA trapped antiprotons

Adriani et al., APJL 737 L29 (2011); arXiv:1107.4882

Positrons

Positron to Electron Fraction

Secondary production Moskalenko & Strong 98

Adriani et al, Astropart. Phys. 34 (2010) 1 arXiv:1001.3522 [astro-ph.HE]

But antiprotons in CRs are in agreement with secondary production

CR Positron spectrum significantly harder than expectations from secondary production

A Challenging Puzzle for CR Physics

Preliminary

Donato et al. (PRL 102 (2009) 071301)

Ptuskin et al. (ApJ 642 (2006) 902)

Simon et al. (ApJ 499 (1998) 250)

Preliminary

Astrophysical Explanation: SNR

P.Blasi et al., PRL 103 (2009) 051104 arXiv:0903.2794 [astro-ph]

Positrons (and electrons) produced as secondaries in the sources (e.g. SNR) where CRs are accelerated. But also other secondaries are produced: significant increase expected in the p/p and B/C ratios.

Positrons detection Where do positrons come from?

Mostly locally within 1 Kpc, due to the energy losses by Synchrotron Radiation and Inverse Compton

Typical lifetime

Astrophysical Explanation: Pulsars

Are there “standard” astrophysical explanations of the high energy positron data?

Young, nearby pulsars

Not a new idea: Boulares, ApJ 342 (1989), Atoyan et al (1995)

Geminga pulsar

Mechanism: the spinning B of the pulsar strips e- that accelerated at the polar cap or at the outer gap emit γ that make production of e±

that are trapped in the cloud, further accelerated and later released at τ ~ 105 years.

Young (T < 105 years) and nearby (< 1kpc) If not: too 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

Astrophysical Explanation: Pulsars

Astrophysical Explanation: Pulsars

H. Yüksak et al., arXiv:0810.2784v2 Contributions of e- & e+ from Geminga assuming different distance, age and energetic of the pulsar diffuse mature &nearby young pulsars

Hooper, Blasi, and Serpico arXiv:0810.1527

M. Cirelli et al., Nucl. Phys. B 813 (2009) 1; arXiv: 0809.2409v3

Interpretation: DM Which DM spectra can fit the data?

DM with and dominant annihilation channel (possible candidate: Wino)

positrons antiprotons

Interpretation: DM Which DM spectra can fit the data? DM with and dominant annihilation channel (no “natural” SUSY candidate)

positrons antiprotons But B≈104

M. Cirelli et al., Nucl. Phys. B 813 (2009) 1; arXiv: 0809.2409v3

Interpretation: DM

DM with and dominant annihilation channel

positrons antiprotons

M. Cirelli et al., Nucl. Phys. B 813 (2009) 1; arXiv: 0809.2409v3

Interpretation: DM I. Cholis et al. Phys. Rev. D 80 (2009)

123518; arXiv:0811.3641v1

Electrons

Results from three ATIC flights

ATIC-4 with 10 BGO layers has improved e , p separation. (~4x lower background)

“Bump” is seen in all three flights.

ATIC 1+2

“Source on/source off” significance of bump for ATIC1+2 is about 3.8 sigma J Chang et al. Nature 456, 362 (2008)

Significance for ATIC1+2+4 is 5.1 sigma

ATIC 1+2+4 ATIC 1 ATIC 2 ATIC 4

FERMI All Electron Spectrum

A. Abdo et al., Phys.Rev.Lett. 102 (2009) 181101 M. Ackermann et al., Phys. Rev. D 82, 092004 (2010)

Electrons measured with H.E.S.S.

PAMELA electron (e-) spectrum

e+ + e-

e-

Flux=A • E-

= 3.18 ±0.05

O. Adriani et al., PRL 106 (2011) 201101.

Theoretical uncertainties on “standard” positron fraction

D. Grasso et al., arXiv:0905.0636

Does not fit at all the

PAMELA ratio:

Modify the injection indices of

GALPROP?

The Completed AMS Detector on ISS

The Completed AMS Detector on ISS

S. Schael, UCLA Dark Matter Conference 2012,