Results from PAMELA

Mirko BoezioINFN Trieste, Italy

On behalf of the PAMELA collaborationIndirect and Direct Detection of Dark Matter

February 7th 2011

Isotopic composition

[ACE]Solar Modulation

[PAMELA,ULYSSES

] AntimatterAntimatter

Dark MatterDark Matter[BESS, PAMELA, AMS]

Elemental Composition

[CREAM, ATIC, TRACER, NUCLEON,CALET, GAMMA-400?]

Extreme Energy CR[AUGER, EUSO, TUS/KLYPVE, OWL??]

PAMELAPAMELAPPayload for ayload for AAntimatter ntimatter MMatter atter EExploration xploration

and and LLight Nucleiight Nuclei AAstrophysicsstrophysics

PAMELA CollaborationPAMELA Collaboration

PAMELA InstrumentPAMELA Instrument

GF ~21.5 cmGF ~21.5 cm2srsr Mass: 470 kg Mass: 470 kg

Size: 130x70x70 cmSize: 130x70x70 cm3

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Design Performance Energy range

• Antiprotons 80 MeV - 190 GeV

• Positrons 50 MeV – 300 GeV

• Electrons up to 800 GeV• Protons up to 1 TeV

• Helium up to 400 GeV/n

• Electrons+positrons up to 2 TeV ( by calorimeter)

• Light Nuclei (Li/Be/B/C) up to 200 GeV/n • AntiNuclei search sensitivity of 3x10-8 in He/He

Mirko Boezio, IDDDM, Aspen, 2011/02/07

PAMELA

Launch15/06/06

16 Gigabytes trasmitted daily to GroundNTsOMZ Moscow

OrbitOrbit Characteristics Characteristics

km

km

SAA

• Low-earth elliptical orbit

• 350 – 610 km

• Quasi-polar (70o inclination)

• SAA crossed

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Download @orbit 3754 – 15/02/2007 07:35:00 MWT

S1 S2 S3

orbit 3752 orbit 3753orbit 3751

NP SP

EQ EQ

95 min

Outer radiation belt

Inner radiation belt

(SSA)

Subcutoff particlesSubcutoff particles

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Main antenna in NTsOMZ

Launch from Baikonur June 15th 2006, 0800 UTC.

‘First light’ June 21st 2006, 0300 UTC.

• Detectors operated as expected after launch• Different trigger and hardware configurations evaluated

PAMELA in continuous data-taking mode sincecommissioning phase ended on July 11th 2006

Trigger rate* ~25HzFraction of live time* ~ 75%Event size (compressed mode) ~5kB 25 Hz x 5 kB/ev ~ 10 GB/day(*outside radiation belts)

Till ~now:~1400 days of data taking~20 TByte of raw data downlinked>2x109 triggers recorded and analyzed

PAMELA milestones

Scientific goalsScientific goalsScientific goalsScientific goals• Search for dark matter annihilation

• Search for antihelium (primordial antimatter)• Search for new Matter in the Universe

(Strangelets?)

• Study of cosmic-ray propagation (light nuclei and isotopes)

• Study of electron spectrum (local sources?)

• Study solar physics and solar modulation• Study terrestrial magnetosphere

Dark MatterDark Matter

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Indirect Detection

DM annihilationsDM particles are stable. They can annihilate in pairs.

Primary annihilation channels Decay Final states

σσa= <= <σσv>v>

Particle ID with PAMELAParticle ID with PAMELA

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Flight data: 0.169 GV electron

Flight data: 0.171 GV positron

Flight data: 0.763 GeV/cantiproton annihilation

Bending in spectrometer: sign of chargeIonisation 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 Antiproton / Positron Identification Identification

Flight data: 14.7 GVInteracting nucleus

(Z = 8)

Antiproton to proton ratio Antiproton to proton ratio (0.06 GeV - 180 GeV)(0.06 GeV - 180 GeV)

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

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

PRL 102, 051101 (2009) and PRL. 105, 121101 (2010)

Antiproton FluxAntiproton Flux (0.06 GeV - 180 GeV)(0.06 GeV - 180 GeV)

Donato et al. (ApJ 563 (2001) 172)

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

PRL. 105, 121101 (2010)

Systematics errors included

Antiprotons inside SAAGalactic AntiprotonsAntiprotons below cutoff at equator

Galactic antiprotons

PAMELA trapped PAMELA trapped antiprotonsantiprotons

Preliminary

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Positron to Electron Positron to Electron FractionFraction

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

Uncertainties on:• Secondary production (primary fluxes, cross section)• Propagation models• Electron spectrum

A Challenging Puzzle for CR PhysicsA Challenging Puzzle for CR Physics

A Challenging Puzzle for CR PhysicsA Challenging Puzzle for CR Physics

P.Blasi, PRL 103 (2009) 051104; arXiv:0903.2794Positrons (and electrons) produced as secondaries in the sources (e.g. SNR) where CRs are accelerated.

I. Cholis et al., Phys. Rev. D 80 (2009) 123518; arXiv:0811.3641v1

Contribution from DM annihilation.

D. Hooper, P. Blasi, and P. Serpico, JCAP 0901:025,2009; arXiv:0810.1527 Contribution from diffuse mature &nearby young pulsars.

G. Kane, R. Lu, and S. Watson, Phys.Lett.B681, 151 (2009); arXiv:0906.4765v3

A Challenging Puzzle for CR PhysicsA Challenging Puzzle for CR Physics

T. Delahaye et al., A&A 501, 821(2009); arXiv: 0809.5268v3

Cosmic Ray SpectraCosmic Ray Spectra

Cosmic-Ray Acceleration and Propagation in the Galaxy

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Diffusion Halo ModelDiffusion Halo Model

Mirko Boezio, IDDDM, Aspen, 2011/02/07

PAMELA

Proton and Helium Nuclei Proton and Helium Nuclei SpectraSpectra

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Proton and Helium Nuclei Proton and Helium Nuclei SpectraSpectra

GALPROP

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Proton and Helium Nuclei Proton and Helium Nuclei SpectraSpectra

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Boron and Carbon nuclei Boron and Carbon nuclei SpectraSpectraCarbon Boron

Mirko Boezio, IDDDM, Aspen, 2011/02/07

0.9 GV < R < 1 GV

p

d

H isotopes separationH isotopes separation

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Positrons detectionWhere do positrons come from?

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

Typical lifetime

PAMELA electron (ePAMELA electron (e--) ) spectrumspectrum

e+ + e-

e-

Mirko Boezio, IDDDM, Aspen, 2011/02/07

PAMELA electron (ePAMELA electron (e--) ) spectrumspectrum

Preliminary

Tracker based

Calorimeter based

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Theoretical uncertainties on Theoretical uncertainties on “standard” positron fraction“standard” positron fraction

T. Delahaye et al., arXiv: 0809.5268v3

γ = 3.54 γ = 3.34

Flux=A • E-

PAMELA electron (ePAMELA electron (e--) ) spectrumspectrum

Flux=A • E-

= 3.18 ±0.05GALPROP

prediction from e- flux

Mirko Boezio, IDDDM, Aspen, 2011/02/07

“New Primary Contribution”

Independently to the fit of the electron spectra, we also perform a χ2

comparison between the expected positron fraction from GALPROP simulation and PAMELA measurement of the positron fraction.

Confidence level, in parameter space (2;ϕ0) obtained from a fit of the electron spectra (red) and of the positron fraction (green). Cruces show the best-fit combination.

Interestingly, the best fit value for the two independent fit are very similar.

Preliminary

positron fraction

electron spectrum

Fit of electron spectrumFit of electron spectrum

90%

95%

99%

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Solar ModulationSolar Modulation

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Positron to Electron Positron to Electron FractionFraction

Secondary production Moskalenko & Strong 98

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

Solar Modulation?

Solar Modulation of Galactic Solar Modulation of Galactic Cosmic RaysCosmic Rays

Courtesy of M. Potgieter

PAMELAPAMELA

Preliminar

y

Time Dependence of PAMELA Proton Time Dependence of PAMELA Proton FluxFlux

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Preliminar

y

Time Dependence of PAMELA Proton Time Dependence of PAMELA Proton FluxFlux

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Preliminar

y

Time Dependence of PAMELA Electron Time Dependence of PAMELA Electron (e(e--) Flux) Flux

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Preliminar

y

Time Dependence of PAMELA Electron Time Dependence of PAMELA Electron (e(e--) Flux) Flux

Mirko Boezio, IDDDM, Aspen, 2011/02/07

Flux variation as a function of time for rigidities between 0.72 and 1.04 GV

Time DependenceTime Dependence

Preliminar

y

Increase of the flux measured by PAMELA from July 2006 to December 2008

Time DependenceTime Dependence

Preliminar

y

U.W. Langner, M.S. Potgieter, Advances in Space Research 34 (2004).

PAMELA Electron to Positron Ratio and Theoretical PAMELA Electron to Positron Ratio and Theoretical ModelsModels

Preliminary

Summary PAMELA ResultsSummary PAMELA Results

Mirko Boezio, IDDDM, Aspen, 2011/02/07

PAMELA Data

SummarySummary• PAMELA has been in orbit and studying cosmic rays for ~4.5 years. >109 triggers registered and >19 TB of data has been down-linked.

• Antiproton-to-proton flux ratio and antiproton energy spectrum (~100 MeV - ~200 GeV) show no significant deviations from secondary production expectations. • High energy positron fraction (>10 GeV) increases significantly (and unexpectedly!) with energy. Primary source?

•The proton and helium nuclei spectra have been measured up to 1.2 TV. The observations challenge the current paradigm of cosmic ray acceleration and propagation.

• The e- spectrum up to 600 GeV shows spectral features that may point to additional components.

• Analysis ongoing to finalize the antiparticle measurements (positron flux, positron fraction), continuous study of solar modulation effects at low energy.

• Waiting for AMS to compare contemporary measurements.Mirko Boezio, IDDDM, Aspen, 2011/02/07

Taiwan

CSISTNCUAcademia SinicaNSPO

KoreaIHEP

HelsinkiTurku

Aarhus

Ciemat-Madrid

LIP-Lisbon

MITYaleJohns HopkinsMarylandFlorida

A&MMexico

BolognaMilanoPerugiaPisaRomaSiena

AnnecyGrenobleMontpellier

IEE, IHEP

Jiao Tong UniversitySoutheast University

ESANIKHEF

NLR, Amsterdam

ETH-ZurichGeneva Univ.

Kurchatov Inst.Inst. of Theor. & Experimental Physics

Moscow State Univercity

Achen I & IIIKarlsruheMunich

Bucharest

AMS-02 on ISSIn Orbit April 2011

TRD

RICH

VacuumCase

Tracker

MA

GN

ET

He V

essel

The Completed AMS Detector on ISSTransition Radiation

Detector (TRD)

Silicon Tracker

Electromagnetic Calorimeter (ECAL)

Magnet

Ring Image Cerenkov Counter (RICH)

Time of Flight Detector (TOF)

Size: 3m x 3m x 3mWeight: 7 tons

AMS-02 new AMS-02 new configurationconfiguration

AMS S.C. Magnet:MDR 2.18 TV

AMS Perm. Magnet:MDR 2.14 TV

AMS Capability Space Part AMS Capability Space Part 20062006

Mirko Boezio, IDDDM, Aspen, 2011/02/07