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

PAMELA Payload for Antimatter Matter Exploration and Light Nuclei Astrophysics

PAMELA Collaboration Moscow St. Petersburg Russia: Sweden: KTH, Stockholm Germany: Siegen Italy: BariFlorenceFrascatiTriesteNaplesRome CNR, Florence

PAMELA Instrument GF ~21.5 cmsr GF ~21.5 cm 2 sr Mass: 470 kg Size: 130x70x70 cm Size: 130x70x70 cm 3

Design Performance Energy range Antiprotons 80 MeV 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  Simultaneous measurement of many cosmic-ray species  New energy range  Unprecedented statistics

Resurs-DK1 satellite Mass: 6.7 tonnes Height: 7.4 m Solar array area: 36 m 2  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

PAMELA Launch 15/06/06 16 Gigabytes trasmitted daily to Ground NTsOMZ Moscow

Orbit Characteristics    km  km SAA Low-earth elliptical orbit 350 – 610 km Quasi-polar (70 o inclination) SAA crossed

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

The Physics of PAMELA Study of solar physics and solar modulation Study of terrestrial magnetosphere Study of high energy electron spectrum (local sources?) Search for dark matter annihilation Search for antihelium (primordial antimatter)‏ Search for new Matter in the Universe (Strangelets?) Study of cosmic-ray propagation

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

Another possible scenario: KK Dark Matter Lightest Kaluza-Klein Particle (LKP): B (1) 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 γ γ in the final state.

PAMELA Status Today 1003 days in flight Today 1003 days in flight data taking ~73% live-time data taking ~73% live-time ~13 TBytes of raw data downlinked ~13 TBytes of raw data downlinked >10 9 triggers recorded and under analysis >10 9 triggers recorded and under analysis

Antiprotons

Flight data: 84 GeV/c interacting antiproton

PAMELA antiproton discrimination Proton Spillover

Positrons

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) PositronProton Proton / positron discrimination

p (non-int) e-e-e-e- e+e+e+e+ Fraction of energy released along the calorimeter track (left, hit, right) p (int) Rigidity: GV Positron selection with calorimeter LEFTHITRIGHT strips planes 0.6 R M

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

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

(~R M ) + - Selections on total detected energy, starting point of shower e-e- e+e+ (p) - p

Flight data: 51 GeV/c positron

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

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

The “pre-sampler” method 2 W planes: ≈1.5 X 0 20 W planes: ≈15 X 0 CALORIMETER: 22 W planes: 16.3 X 0

The “pre-sampler” method POSITRON SELECTION PROTON SELECTION 2 W planes: ≈1.5 X 0 20 W planes: ≈15 X 0 2 W planes: ≈1.5 X 0

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

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

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

RESULTS

Antiproton to proton ratio PRL 102, (2009) Seconday Production Models

Antiproton to proton ratio PRL 102, (2009)

Antiproton Flux Preliminary statistical errors only energy in the spectrometer

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

Positrons to all electrons ratio Secondary production Moskalenko & Strong 98

Positron to Electron Ratio astro-ph

Interpretation

DM DM DM Pulsar DM / pulsar DM DM DM DM DM DM DM DM DM During first week after PAMELA results posted on arXiv )

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

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

Astrophysical Explanation: Pulsars S. Profumo Astro-ph Positrons production and acceleration mechanism Positrons production and acceleration mechanism Young Pulsars (T ~ 10 5 years) and nearby (< 1kpc) Young Pulsars (T ~ 10 5 years) and nearby (< 1kpc) Too young: contribution does not escape from the nebula cloud of the pulsar. Too young: contribution does not escape from the nebula cloud of the pulsar. Too old: much diffusion, low energy, too low flux. Too old: much diffusion, low energy, too low flux. Geminga: 157 parsecs from Earth and 370,000 years old Geminga: 157 parsecs from Earth and 370,000 years old B : 290 parsecs from Earth and 110,000 years old. B : 290 parsecs from Earth and 110,000 years old. Diffuse mature pulsars? Diffuse mature pulsars?

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

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

Explanation with supernovae remnants Shaviz and al. astro-ph.HE

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

PAMELA Proton Spectrum

Galactic H and He spectra Preliminary !!!

Secondary nuclei B nuclei of secondary origin: CNO + ISM  B + … Local secondary/primary ratio sensitive to average amount of traversed matter (l esc ) from the source to the solar system Local secondary abundance:  study of galactic CR propagation (B/C used for tuning of propagation models) LBM Preliminary

Antiproton to proton ratio PRL 102, (2009)

Positron Fraction

Solar Modulation of galactic cosmic rays BESS Caprice / Mass /TS93 AMS-01 Pamela Study of charge sign dependent effects Asaoka Y. et al. 2002, Phys. Rev. Lett. 88, ), Bieber, J.W., et al. Physi-cal Review Letters, 84, 674, J. Clem et al. 30th ICRC 2007 U.W. Langner, M.S. Potgieter, Advances in Space Research 34 (2004)

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

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

Thanks! PAMELA Physics Workshop May 11-12, 2009 ROMA pamela.roma2.infn.it /workshop09 pamela.roma2.infn.it /workshop09

A > 0 Positive particles A < 0 p, e + p, e - -

Secondary production Bergström et al. ApJ 526 (1999) 215 Secondary production (upper and lower limits)‏ Simon et al. ApJ 499 (1998) 250. from χχ annihilation P

Proton fluxes at TOA Annual Variation of P spectrum Kinetic Energy (GeV)

Comparison of p/p ratio with model Time variation of p/p ratio at solar maximum Observed data by BESS Charge dependent model prediction(Bieber et al.) Charge dependent solar modulation model well follows the suddenly increase of p/p ratio observed by BESS at the solar polarity reversal between 1999 and 2000

Solar Physics with PAMELA

December 2006 Solar particle events Dec 13 th largest CME since 2003, anomalous at sol min

December 13th 2006 event Preliminary!

December 13th 2006 He differential spectrum December 13th 2006 He differential spectrum

December 14th 2006 event Preliminary! Solar Quiet spectrum Low energy tail of Dec 13th event Below galactic spectrum: Start of Forbush decrease Magnetic Field Neutron Monitor X-ray P,e- Decrease of primary spectrum Arrival of magnetic cloud from CME of Dec 13th Shock 1774km/s (gopalswamy, 2007) Decrease of Neutron Monitor Flux Magnetic Field Neutron Monitor X-ray P,e- Arrival of event of Dec 14th End of event of Dec 14th

Radiation Belts South Atlantic Anomaly Secondary production from CR interaction with atmosphere

SAA SAA morphology Latitude Altitude Longitude Neutron rate (background) South-Atlantic Anomaly (SAA)

Grigorov, Sov. Phys. Dokl. 22, NINA ApJ Supp , 2001 AMS Phys. Lett. B , Phys. Lett. B –22 Lipari, Astrop. Ph. 14, 171, 2000 Huang et al, Pys Rev. D 68, Sanuki et al, Phys Rev D Honda et al, Phys Rev D  Atmospheric neutrino contribution  Astronaut dose on board International Space Station  Indirect measurement of cross section in the atmosphere nell’atmosfera  Agile e Glast background estimation --- M. Honda, 2008 Proton flux at various cutoffs

Proton spectrum in SAA, polar and equatorial regions

Other Objectives

High Energy electrons The study of primary electrons is especially important because they give information on the nearest sources of cosmic rays The study of primary electrons is especially important because they give information on the nearest sources of cosmic rays Electrons with energy above 100 MeV rapidly loss their energy due to synchrotron radiation and inverse Compton processes Electrons with energy above 100 MeV rapidly loss their energy due to synchrotron radiation and inverse Compton processes The discovery of primary electrons with energy above eV will evidence the existence of cosmic ray sources in the nearby interstellar space (r  300 pc) The discovery of primary electrons with energy above eV will evidence the existence of cosmic ray sources in the nearby interstellar space (r  300 pc)

A calorimeter self-triggering showering event. Note the high energy release in the core of the shower and the high number (26) neutrons detected. CALO SELF TRIGGER EVENT: 167*10 3 MIP RELEASED 279 MIP in S4 26 Neutrons in ND

An example is the search for “strangelets”. There are six types of Quarks found in accelerators. All matter on Earth is made out of only two types of quarks. “Strangelets” are new types of matter composed of three types of quarks which should exist in the cosmos. i.A stable, single “super nucleon” with three types of quarks ii. “Neutron” stars may be one big strangelet Carbon Nucleus Strangelet u d s sdd s s u d u d uu d d s u s uu d dd d d d u u u u s u s s s d d u u u d u u d d d u u u d d d u d d u d d u d d u u u d u u d u u d p n AMS courtesy Search for New Matter in the Universe:

Positron selection with calorimeter Test Beam Data